Method and apparatus for filtering working fluid

Abstract

The present invention provides a working fluid filtration system and a method of using the same. The system includes a filter system comprising two or more containers, at least one filter positioned between the two or more containers, and a valve system. The valve system is operable to transfer working fluid between the two or more containers through at least one filter.

Description

Technical Field

[0001] The present invention relates to a hydraulic fluid system, and more particularly to an apparatus and method for filtering a hydraulic fluid. Aspects of the present invention relate to an apparatus and method for filtering a hydraulic fluid that can be used in a hydraulic fluid system.

Background Art

[0002] (Background of the Invention) Hydraulic fluid is essential for the operation of machines and engine components. Hydraulic fluid is an incompressible liquid used for power transmission, lubrication, and component protection within hydraulic machines and equipment.

[0003] Current hydraulic systems require large amounts of hydraulic fluid, which can become contaminated over time by wear particles resulting from mechanical erosion, pitting, delamination, fatigue, and / or corrosion of machine components. Also, the hydraulic fluid can be contaminated by the ingress of foreign matter, chemicals, and / or water.

[0004] Contamination of the hydraulic fluid can cause degradation of the fluid that limits its ability to transmit power, lubricate, and protect machine components. In a closed hydraulic system, contaminated particles can circulate thousands of times over many years. As a result, damage to the hydraulic system, reduced efficiency, system failures, and long periods of downtime for costly repairs can occur.

[0005] Contaminated hydraulic fluid needs to be drained from the system and discarded. The removed fluid is replaced with new fluid. This fluid replacement operation may be required multiple times a year depending on the usage of the hydraulic system. Regular fluid replacement and disposal of contaminated fluid are costly and can cause significant environmental problems.

[0006] It is well known to provide hydraulic fluid filters in hydraulic systems. Typically, the hydraulic fluid filter is installed in the high-pressure line, suction line, or return line, and the hydraulic fluid passes through the filter before being stored in the hydraulic fluid storage tank. However, over time the filter may become clogged or deteriorate, and the clogged or deteriorated filter may release foreign matter into the hydraulic system, potentially causing further damage to the hydraulic system. [Overview of the project] [Means for solving the problem]

[0007] (Summary of the invention) An object of one aspect of the present invention is to eliminate, or at least mitigate, the disadvantages of prior art hydraulic fluid filtration devices and methods.

[0008] One object of this invention is to provide a robust, reliable, and compact working fluid filtration device and method of use.

[0009] Another object of one aspect of the present invention is to provide a working fluid filtration device configured to be integrated with or connected to a hydraulic system which is part of a facility.

[0010] A further object of one aspect of the present invention is to provide a hydraulic fluid filtration apparatus and method for improving the purity of a hydraulic fluid before, during, and / or after use in a hydraulic system which is part of a facility.

[0011] Another object of the present invention is to provide a method for filtering a working fluid before, during, and / or after use in a hydraulic system which is part of a facility.

[0012] Further objectives of the present invention will become apparent from the following description.

[0013] According to a first aspect of the present invention: Two or more containers; A working fluid filtration system is provided, comprising a filter system including at least one filter positioned between two or more containers, and a valve system; The valve system is operable to transfer the working fluid between the two or more containers through the at least one filter.

[0014] The valve system can be configured to control the transfer of a working fluid back and forth between two or more containers via at least one filter. The valve system can also be configured to control the alternating transfer of a working fluid between two or more containers via at least one filter.

[0015] The valve system can be configured to control the reciprocating flow of a working fluid between two or more containers via at least one filter. The valve system can be configured to alternately switch the direction of flow of the working fluid between two or more containers via at least one filter. The system can be configured to circulate the working fluid between two or more containers via at least one filter until a desired level of cleanliness of the working fluid is achieved.

[0016] The valve system may be configured to select at least one filter through which the working fluid passes. The working fluid filtration system may include a control unit configured to control the operation of one or more valves in the valve system. The control unit may be configured to control the reciprocating flow of the working fluid between two or more vessels via at least one filter. The control unit may be configured to alternately switch the flow direction of the working fluid between two or more vessels via at least one filter. At least one filter may be placed in the flow path between two or more vessels. At least one filter may have a micron rating selected from the range of 10 nm to 100 μm. The micron rating may be selected from the range of 100 nm to 25 μm.

[0017] This system may include at least one pump. At least one pump may be a liquid pump, an impeller, or a thruster. At least one pump may be a reversible pump. At least one pump may be configured to pump the working fluid between two or more containers via at least one filter at a flow rate range of 0.1 to 200 liters / minute. The flow rate range may be 1 to 10 liters / minute.

[0018] The control unit can be configured to generate control signals to at least one pump for controlling the flow of working fluid between two or more containers through at least one filter.

[0019] This system may include at least one heating device. The heating device may be configured to raise the temperature of the working fluid to a desired temperature. The heating device may be configured to raise the temperature of the working fluid to a desired temperature in order to help remove moisture and / or air from the working fluid. The circulating working fluid may pass through at least a portion of the heating device to heat the working fluid. The heating device may be incorporated into at least one filter or the housing of the at least one filter. The at least one heating device may be an electric heater, a friction generator, and / or a heat exchanger. The friction generator may include a valve that can be operated to generate heat by increasing internal liquid friction in the liquid, thereby raising the temperature of the liquid. The electric heater may be configured to heat the buffer liquid and raise the temperature of the working fluid by forced convection and / or parallel or countercurrent flow between the heated buffer liquid and the working fluid. The at least one heating device may include a tube for transporting a heated liquid, such as water, in parallel or countercurrent flow.

[0020] The system may include at least one cooling device. The cooling device may be configured to lower the temperature of the working fluid to a desired temperature. The cooling device may be configured to lower the temperature of the working fluid to a desired temperature in order to help remove moisture and / or air, or other liquids or phases from the working fluid. The circulating working fluid may be cooled by passing it through at least a portion of the cooling device. The cooling device may be incorporated into at least one filter or the housing of at least one filter. At least one cooling device may be a Peltier cooling device. At least one cooling device may be a powered cooling source such as a heat pump. At least one cooling device may be a heat exchanger. At least one cooling device may include tubes for transporting a cooling liquid, such as water, in parallel or countercurrent flow.

[0021] The system may include at least one cooling device and / or at least one heating device. The temperature of the working fluid can be increased and / or decreased at different stages of filtration. The system may be configured to control and / or adjust the temperature of the working fluid. The system may be configured to control and / or adjust the temperature of the working fluid at different stages of filtration. The temperature of the working fluid can be increased first and then decreased. The temperature of the working fluid can be decreased first and then increased. The temperature of the working fluid can be increased and / or decreased to help remove water and / or air from the working fluid. The temperature of the working fluid can be increased and / or decreased to decrease the viscosity of the liquid and / or to allow processing of otherwise high-viscosity liquids.

[0022] Each container may include at least one inlet and at least one outlet. At least one valve can be configured to selectively open a path between the outlet of at least one container and the inlet of at least one filter. At least one valve can be configured to selectively open a path between the inlet of at least one filter and the outlet of the first container or the outlet of the second container. At least one valve can be configured to selectively open a path between the outlet of at least one filter and the inlet of at least one container. At least one valve can be configured to selectively open a path between the outlet of at least one filter and the inlet of the first container or the inlet of the second container.

[0023] At least one filter may include a filter housing. The filter housing may include a magnet. The filter housing may include an electromagnet. The magnet or the electromagnet can be configured to attract iron particles to the magnet or the electromagnet.

[0024] The electromagnet may be operable between a first state in which the electromagnet is active and attracts iron particles in the liquid to the electromagnet, and a second state in which the electromagnet is inactive and iron particles in the liquid are not attracted to the electromagnet.

[0025] The hydraulic filtration system may include at least one sensor. The at least one sensor can be selected from the group including a particle counter, a humidity sensor, an optical sensor, an optical sensor, a capacitance sensor, a flow meter, a density sensor, a viscosity sensor, a pressure sensor, a temperature sensor, a liquid level gauge, an ultrasonic sensor, a magnetostrictive sensor, a level probe, a rod sensor, a limit sensor, a liquid level and filling level switch, a spectroscopic sensor, an optical spectroscopic measurement sensor, and / or a float switch. The particle counter may be a digital, laser, and / or camera-based particle counter.

[0026] This system may include a device to assist in removing air from the working fluid. This system may include an ultrasonic device such as an ultrasonic transducer. The ultrasonic device can be configured to transmit a pulsed wave or a vibration wave to at least a portion of the working fluid. The pulsed wave or the vibration wave can be configured to remove dissolved gas and / or entrained air bubbles from the working fluid. This system may include a degassing device for removing air and / or gas from the working fluid. The degassing device can be selected from the group including a vortex separator, a cyclone separator, a vacuum degassing device, a liquid stirrer, a degassing device, and / or a centrifugal degassing device.

[0027] The shape of this system can be designed to assist air in rising from the liquid. The shape of this system can be designed to minimize the generation or maintenance of air bubbles in the working fluid. The diameter of the tube, inlet, and / or outlet can be configured to minimize the influence of the air bubble flow in the working fluid. The shape of the tube, inlet, and / or outlet can be selected to minimize the influence of the air bubble flow in the working fluid. The shape of the tube, inlet, and / or outlet can be selected to minimize the generation or maintenance of air bubbles in the working fluid. The shape of the tube, inlet, and / or outlet can be selected from the group including circular, rectangular, trapezoidal, or spiral.

[0028] At least one filter may comprise a filter material. The filter material can be selected from the group including fibers, paper, cellulose, synthetic fibers, mesh, metal mesh, carbon, activated carbon, water absorbent materials, sodium acrylate, and additive adding materials. The additive adding materials can increase or decrease the density, weight, and / or viscosity of the liquid. The additive adding materials can release one or more additives to restore the concentration of additives in the working fluid. The filter can be configured to dehydrate and / or degas the working fluid.

[0029] The two or more containers may be storage containers. The two or more containers may be processing containers. The two or more containers may be configured to store and / or process the hydraulic fluid. The hydraulic fluid may be petroleum-based hydraulic fluid. The hydraulic fluid may be hydraulic oil. The hydraulic fluid may be synthetic hydraulic fluid. Each of the two or more containers may be a separate container or compartment. Each of the two or more containers may be a separate tank. The two or more containers may be part of a single tank. Each of the two or more containers may be a separate container or compartment within a single tank.

[0030] The valve system may include two or more filters. The valve system may be configured to pass the working fluid through two or more filters. The valve system may be configured to pass the working fluid through two or more filters sequentially. The filter materials of the two or more filters may be the same. The filter materials of the two or more filters may be different.

[0031] The first filter may be equipped with an absorbent material to remove moisture from the working fluid. The second or subsequent filters may be equipped with cellulose to filter the dehydrated working fluid. The second or subsequent filters may be configured to prevent or mitigate overloading, clogging, and / or saturation of the upstream or preceding filter.

[0032] Each of at least one filter may have a different micron rating. Each of two or more filters may have a different micron rating. The micron rating can be selected from the range of 10 nm to 100 μm. The micron rating can be selected from the range of 100 nm to 25 μm.

[0033] The control unit can be configured to switch the flow from one filter to another. The control unit can be configured to select the flow that passes through a specific filter based on sensor data. The control unit can be configured to change the flow from a first filter to a second filter based on measured sensor data. The control unit can be configured to select the flow that passes through a specific filter based on particle count measurements. The control unit can be configured to change the flow from a first filter to a second or subsequent filter based on measured particle count data.

[0034] The control unit can be configured to change the flow from a first flow cycle in which the working fluid is transferred between two or more containers via a high-micron filter to a second flow cycle in which the working fluid is transferred between the two or more containers via a low-micron filter. The control unit can also be configured to change the flow from the first flow cycle to the second flow cycle based on measured particle count data.

[0035] This system can be configured to circulate the working fluid back and forth between two or more containers through a first filter until the working fluid reaches a first desired level of cleanliness or purity. This system can be configured to circulate the working fluid back and forth between two or more containers through a second filter until the working fluid reaches a second desired level of cleanliness or purity. This system can be configured to circulate the working fluid back and forth between two or more containers through a third or subsequent filter until the working fluid reaches a third or subsequent desired level of cleanliness or purity.

[0036] This system can be configured to repeatedly filter a working fluid that moves back and forth between two or more containers through at least one filter.

[0037] This system can be configured to process 100 liters of working fluid down to an ISO 4406 reading of at least 0 / 0 / 0 within 72 hours.

[0038] The working fluid filtration system can be installed on or within a housing or frame. Two or more tanks can be made of plastic or metal. The bottoms of the two or more tanks may be sloped or have grooves. Sloped bottoms or grooves can be configured to discharge as much contaminant as possible from the tanks at the end of each cycle. The shape of the two or more tanks can be configured to redirect the contaminant toward the tank outlets. The tank outlets can be designed to be trap-free or gap-free.

[0039] This system may include a waste tank for disposing of foreign matter and / or fragments that are separated from and accumulated in the working fluid.

[0040] According to a second aspect of the present invention: Two or more containers; A filter system including at least one filter placed between two or more containers; A working fluid filtration system, including a valve system, is provided; The valve system is operable to control the alternating transfer of hydraulic fluid between two or more oil storage containers via at least one filter.

[0041] This system may include a control unit. The control unit may be configured to control the operation of at least one valve in the valve system.

[0042] The control unit can be configured to switch the flow from one filter to another. The control unit can be configured to select the flow that passes through a particular filter based on sensor data. The control unit can be configured to change the flow from a first filter to a second filter based on measured sensor data. The control unit can be configured to select the flow that passes through a particular filter based on moisture content, particle count measurements, or other sensor measurements. The control unit can be configured to change the flow from a first filter to a second or subsequent filter based on moisture content, measured particle count data, or other sensor measurement data.

[0043] The control unit can be configured to change the flow direction of the working fluid between two or more containers. The control unit can be configured to change the flow of the working fluid between two or more containers based on sensor data. The control unit can be configured to change the flow of the working fluid between two or more containers based on particle count data. The control unit can be configured to change the flow from a first flow cycle in which the working fluid is transferred between two or more containers via a high-micron filter to a second flow cycle in which the working fluid is transferred between the two or more containers via a low-micron filter (lower than the filter in the first cycle). The control unit can be configured to change the flow from the first flow cycle to the second flow cycle based on measured particle count data.

[0044] Embodiments of the second aspect of the present invention may include one or more features of the first aspect of the present invention or its embodiments, and vice versa.

[0045] A third aspect of the present invention provides a method for removing contaminants from a working fluid, the method being: This includes transferring the working fluid back and forth between two or more containers via at least one filter.

[0046] A third embodiment of the present invention may include one or more features of the first or second embodiment of the present invention or their embodiments, and vice versa.

[0047] According to a fourth aspect of the present invention, a method for removing contaminants from a working fluid is provided, the method being: Two or more containers; A filter system including at least one filter placed between two or more containers; To provide a working fluid filtration system, including a valve system; This includes transferring the working fluid back and forth between the two or more containers through at least one filter.

[0048] This method may include reciprocating the working fluid between two or more containers through a first filter until the working fluid reaches a first desired level of cleanliness or purity. This method may include reciprocating the working fluid between two or more containers through a second filter until the working fluid reaches a second desired level of cleanliness or purity. This method may include reciprocating the working fluid between two or more containers through a third or subsequent filter until the working fluid reaches a third or subsequent desired level of cleanliness or purity.

[0049] The number of times the working fluid is transferred back and forth between two or more containers via a filter is determined by the level of contamination of the working fluid and / or the desired level of cleanliness or purity to be achieved.

[0050] This method may include transferring the working fluid back and forth between two or more containers via a filter two or more times. This method may include transferring the working fluid back and forth between two or more containers via a filter at least five times. This method may include transferring the working fluid back and forth between two or more containers via a filter at least ten times. This method may include transferring the working fluid back and forth between two or more containers via a filter at least twenty times. This method may include transferring the working fluid back and forth between two or more containers via a filter 20 to 100 times. This method may include transferring the working fluid back and forth between two or more containers via a filter 100 to 200 times. This method may include transferring the working fluid back and forth between two or more containers via a filter 100 to 500 times. This method may include transferring the working fluid back and forth between two or more containers via a filter 100 to 1000 times.

[0051] This method may include removing a contaminant from a container by contacting a certain amount of filtered working fluid with the contaminant and diffusing the particles of the contaminant into the filtered working fluid. This method may include removing a contaminant from a container by contacting a transferred working fluid with the contaminant and diffusing the particles of the contaminant into the transferred working fluid. This method may include removing a liquid containing a contaminant from a container by contacting a certain amount of filtered working fluid with a liquid containing a contaminant and diffusing the particles of the contaminant from the liquid containing the contaminant into the filtered working fluid. This method may include removing an impurity from a container by contacting a certain amount of filtered working fluid with a contaminated liquid and diffusing the particles of the impurity from the contaminated liquid into the filtered working fluid.

[0052] This method may include diffusing contaminants present in at least one container into the transferred working fluid. This method may include diffusing contaminants present in each container into the transferred working fluid. This method may include diffusing contaminants present in a first container into the transferred working fluid before the transferred working fluid is transferred to a second container via at least one filter. This method may include diffusing impurity particles present in a container into the transferred working fluid. This method may include diffusing contaminants from each of the two or more containers into the working fluid each time the working fluid is transferred back and forth between two or more containers via at least one filter.

[0053] This method may include measuring and / or monitoring at least one characteristic or parameter of the working fluid. The at least one characteristic or parameter of the working fluid can be selected from the group including temperature, pressure, viscosity, particle count, gas content, air content, water content, and / or humidity.

[0054] This method may include measuring the number of particles in at least one sample of the working fluid. This method may also include measuring the number of particles in at least one sample of the working fluid each time it passes through the filter.

[0055] This method may include switching the flow from one filter to another. This method may include selecting the flow to pass through a particular filter based on sensor data. This method may include changing the flow from a first filter to a second filter based on measured sensor data. This method may include selecting the flow rate to pass through a particular filter based on the measured particle count. This method may include changing the flow from a first filter to a second or subsequent filter based on measured particle count data.

[0056] This method may include changing the flow from a first flow cycle in which the working fluid is transferred between two or more containers via a high-micron filter to a second flow cycle in which the working fluid is transferred between two or more containers via a low-micron filter. This method may also include changing the flow from the first flow cycle to the second flow cycle based on measured particle count data.

[0057] This method may include dehydrating and / or degassing the working fluid before measuring the particle count.

[0058] Contaminants can be selected from the group including solid particles, metallic particles, impurities, wear particles, fibers, free radicals, solutes, chemicals, water, gases, and / or air. The working fluid may be new working fluid. "New working fluid" means working fluid that has never been used in a hydraulic system. This method can be used to remove contaminants and / or increase the purity of new working fluid before it is first introduced and used in a hydraulic system.

[0059] The hydraulic fluid may be recycled hydraulic fluid or hydraulic fluid previously used and recovered in the hydraulic system. The filtration system may be an online system in which the hydraulic fluid is temporarily removed from the hydraulic system and / or circulated within the hydraulic system. The filtration system may be an offline system in which the hydraulic fluid is removed from the hydraulic system and / or removed from the hydraulic system before filtration.

[0060] A fourth embodiment of the present invention may include one or more features of the first to third embodiments of the present invention or their embodiments, and vice versa.

[0061] A fifth aspect of the present invention provides a method for removing contaminants from a working fluid before introducing it into a new hydraulic system, the method of which: Two or more containers; A filter system including at least one filter placed between two or more containers; To provide a hydraulic system, including a valve system; This includes transferring the working fluid back and forth between the two or more containers via at least one filter.

[0062] This method may include reciprocating the working fluid between two or more containers through a first filter until the working fluid reaches a first desired level of cleanliness or purity. This method may include reciprocating the working fluid between two or more containers through a second filter until the working fluid reaches a second desired level of cleanliness or purity. This method may include reciprocating the working fluid between two or more containers through a third or subsequent filter until the working fluid reaches a third or subsequent desired level of cleanliness or purity.

[0063] This method may include measuring and / or monitoring at least one characteristic or parameter of the working fluid. The at least one characteristic or parameter of the working fluid can be selected from the group including temperature, pressure, viscosity, particle count, gas content, air content, water content, and / or humidity.

[0064] A fifth embodiment of the present invention may include one or more features of the first to fourth embodiments of the present invention or their embodiments, and vice versa.

[0065] According to a sixth aspect of the present invention, a method is provided for removing contaminants from the working fluid of a hydraulic system, the method being: Two or more containers; A filter system including at least one filter placed between two or more containers; To provide a working fluid filtration system, including a valve system: This includes transferring the working fluid back and forth between the two or more containers via at least one filter.

[0066] A sixth embodiment of the present invention may include features of one or more of the first to fifth embodiments of the present invention or their embodiments, and vice versa.

[0067] According to a seventh aspect of the present invention, a method is provided for removing contaminants from the working fluid of a hydraulic system which is part of a facility, the method being: Two or more containers; A filter system including at least one filter placed between two or more containers; To provide a working fluid filtration system, including a valve system: Connecting the hydraulic fluid filtration system to the hydraulic system; This includes transferring the working fluid back and forth between the two or more containers via at least one filter.

[0068] This method may include reciprocating the working fluid between two or more containers through a first filter until the working fluid reaches a first desired level of cleanliness or purity. This method may include reciprocating the working fluid between two or more containers through a second filter until the working fluid reaches a second desired level of cleanliness or purity. This method may include reciprocating the working fluid between two or more containers through a third or subsequent filter until the working fluid reaches a third or subsequent desired level of cleanliness or purity.

[0069] This method may include measuring and / or monitoring at least one characteristic or parameter of the working fluid. The at least one characteristic or parameter of the working fluid can be selected from the group including temperature, pressure, viscosity, particle number, particle content, gas content, air content, water content, and / or humidity. The particle content can be selected from the group including metallic particles, non-metallic particles, minerals, fibers, and / or free radicals.

[0070] Embodiments of the seventh aspect of the present invention may include features of one or more of the first to sixth aspects of the present invention or their embodiments, and vice versa.

[0071] According to an eighth aspect of the present invention, a method is provided for removing contaminants from the working fluid of a hydraulic system, the method being: Two or more containers; A filter system including at least one filter placed between two or more containers; To provide a working fluid filtration system, including a valve system; To remove the working fluid from the hydraulic system; This includes transferring the working fluid back and forth between the two or more containers via at least one filter.

[0072] This method may include reintroducing the treated working fluid into the hydraulic system.

[0073] An embodiment of the eighth aspect of the present invention may include one or more features of the first to seventh aspects of the present invention or their embodiments, and vice versa.

[0074] According to a ninth aspect of the present invention, a method for recycling working fluid is provided, which is: Two or more containers; To provide a working fluid filtration system that includes a filter system comprising at least one filter positioned between two or more containers; This includes transferring the working fluid back and forth between the two or more containers through the at least one filter to remove contaminants from the working fluid.

[0075] This method may include reciprocating the working fluid between two or more containers through a first filter until the working fluid reaches a first desired level of cleanliness or purity. This method may include reciprocating the working fluid between two or more containers through a second filter until the working fluid reaches a second desired level of cleanliness or purity. This method may include reciprocating the working fluid between two or more containers through a third or subsequent filter until the working fluid reaches a third or subsequent desired level of cleanliness or purity.

[0076] This method may include measuring and / or monitoring at least one characteristic or parameter of the working fluid. This method may include measuring and / or monitoring at least one characteristic or parameter of the working fluid each time the working fluid passes through the filter. The at least one characteristic or parameter of the working fluid can be selected from the group including temperature, pressure, viscosity, particle count, gas content, air content, water content, and / or humidity.

[0077] This invention may include an embodiment of the ninth aspect of the present invention, one or more features of the first to eighth aspects of the present invention, or any of those embodiments, and vice versa. [Brief explanation of the drawing]

[0078] (Brief explanation of the drawing) Here, various embodiments of the present invention will be described for illustrative purposes only, with reference to the following drawings.

[0079] [Figure 1] Figure 1 is a schematic diagram of a working fluid filtration system according to a first embodiment of the present invention. [Figure 2] Figure 2 shows a flowchart of the filtration operation using the working fluid filtration system shown in Figure 1. [Figure 3] Figures 3A to 3C are perspective views, exploded views, and partial cross-sectional views of a working fluid filtration system according to one embodiment of the present invention. [Figure 4] Figure 4 is a schematic diagram of the liquid circuit of the working fluid filtration system shown in Figure 3A. [Figure 5] Figure 5 is a schematic diagram of the liquid circuit of the working fluid filtration system shown in Figure 3A, and illustrates the backflush liquid circuit. [Figure 6] Figures 6A to 6C show plots of particle size and number over time at three different micron levels. [Modes for carrying out the invention]

[0080] (Detailed explanation) Figure 1 shows the liquid circuit of the filtration system 10. This system includes two tanks 12a and 12b for storing the working fluid. Each of the tanks 12a and 12b is liquidally connected to the filter system 14 via a valve system 16. In this example, the tanks are made of steel and each has a storage capacity of 205 liters. However, the tanks can be manufactured from other materials and may have various sizes and storage capacities.

[0081] The filter system 14 in this example includes five filters 14a, 14b, 14c, 14d, and 14e. Each filter may have a different micron rating. In this example, filter 14a is a 10 μm filter; filter 14b is a 3 μm filter; filter 14c is a 1 μm filter; filter 14d is a 100 nm filter; and filter 14e is a 10 μm filter. The filters in this example are formed from cellulose. However, one or more filters may be formed from a different filter material.

[0082] The valve system 16 includes four filter valves 18a, 18b, 18c, and 18d. These filter valves are configured to control the inflow and outflow to each filter. The valve system 16 optionally includes a pressure reducing valve 20 to regulate the pressure in the liquid circuit to prevent high pressure from being generated by the filters.

[0083] The valve system 16 includes an outlet valve 22 connected to the outlet 26a of tank 12a and the outlet 26b of tank 12b. The valve system 16 also includes an inlet valve 24 connected to the inlet 28a of tank 12a and the inlet 28b of tank 12b. The system includes a detection system 30 (a particle counter 32 in this example) for monitoring contaminants in the working fluid.

[0084] Figure 2 is a flowchart 80 illustrating the operation of the filtration method using system 10. As shown in step 82 of Figures 1 and 2, the working fluid to be treated is stored in tank 12a. Valve 22 opens the path between flow paths 40 and 42. Pump 70 connected to flow path 42 draws the working fluid from the tank outlet 26a of container 12a into flow path 44 to the filter valve. The first filter valve 18a is activated, opening the path to the first filter 14a. The working fluid passes through the 10 μm filter 14a, removing large contaminants from the liquid. The filtered liquid flows from filter 14a into flow path 46. To monitor the purity of the working fluid, valve 60 applies a small pressure resistance, causing it to flow through flow path 48 to the particle counter 32, and then through flow paths 50 and 52 to the inlet valve 24. Valve 24 is activated, opening the flow path to the tank inlet 28b, allowing the treated liquid to flow into tank 12b. In this example, purity sampling is performed continuously.

[0085] The liquid in tank 12a continues to flow through the filter system to tank 12b until the low-level indicator in tank 12a detects a low liquid level. The indicator signals the pump to stop, preventing air from entering the filter system. In this example, tank 12b is equipped with a high-level indicator to prevent overflow. The high-level indicator can detect a high oil level and stop the pump that is drawing in the liquid. This high-level indicator may also function to stop the pump if an overflow occurs due to expansion caused by the temperature of the liquid.

[0086] When the low-level indicator in tank 12a detects a low liquid level, pump 70 stops, and the outlet valve 22 is activated, opening the path between flow paths 41 and 42, which are connected to the outlet of tank 12b. Pump 70, connected to flow path 42, gradually draws the working fluid from tank 12b into flow path 44 to the filter valve. In the first filtration operation, the first filter valve 18a is activated, opening the path to the first filter 14a. The working fluid passes through a 10 μm filter, removing large contaminants from the liquid. The filtered liquid flows from filter 14a into flow path 46. If purity sampling is required, the valve at position 60 can be closed, and the treated working fluid flows through flow path 48 to the particle counter 32, and then through flows 50 and 52 to valve 24. Valve 24 is activated, opening the flow path to the tank inlet 28a, and the treated liquid flows into tank 12a. The liquid in tank 12b continues through the filter system to tank 12a until the low-level indicator in tank 12b detects a low liquid level, preventing air from being drawn into the filter system. Similar to tank 12b, tank 12a also has a high-level indicator to prevent overflow.

[0087] The above sequence, in which the working fluid passes back and forth between tanks 12a and 12b through the first 10 μm filter 14a, continues until the level of contaminants measured by the particle counter drops to a preset desired target level. This indicates that the majority of the contaminants in the liquid are smaller than 10 μm and are not removed by the 10 μm filter 14a.

[0088] In this example, by flowing the working fluid through a first path from the first tank to the second tank via a 10-micron filter, 99.9% of all particles larger than 10 microns are removed from the working fluid. The liquid is further purified by returning this liquid from the second tank to the first tank via a filter.

[0089] The purified liquid returning to the first tank is exposed to a small amount of contaminated liquid containing foreign matter adhering to the walls and bottom of the first tank. These foreign matter are attracted to the purified liquid entering the first tank by diffusion. There is no need to physically clean the tank walls to remove the contaminated liquid. The contaminated liquid becomes purified liquid through the diffusion of fine particles into the high-purity liquid. When the liquid moves again from the first tank to the second tank, 99.9% of the remaining 0.01% of particles in the liquid are further removed. By repeating this reciprocal filtration cycle multiple times (e.g., 50 cycles), a liquid of high purity / cleanliness can be obtained.

[0090] In this stage, shown in step 84 of Figure 2, the sequence through which the working fluid passes back and forth between tanks 12a and 12b is adjusted by activating the second filter valve 18b to open a path to the second filter 14b, allowing the fluid to pass through the 3 μm second filter 14b instead of the first filter 14a. The working fluid continues back and forth between tanks 12a and 12b through the second 3 μm filter 14b until the decrease in the level of contaminants measured by the particle counter reaches a preset level. This indicates that the majority of the contaminants in the fluid are smaller than 3 μm and are not removed by the 3 μm filter 14b.

[0091] In this third stage, shown in step 86 of Figure 2, the sequence through which the working fluid passes back and forth between tanks 12a and 12b is adjusted by activating a third filter valve 18c to open a path to a third filter 14c, allowing the fluid to pass through the 1 μm third filter 14c instead of the second filter 14b. The working fluid reciprocates between tanks 12a and 12b through the third 1 μm filter 14c until the reduction in the level of contaminants measured by the particle counter reaches a preset target level. This indicates that the majority of the contaminants in the fluid are smaller than 1 μm and are not removed by the 1 μm filter 14c.

[0092] In this fourth step, shown in step 88 of Figure 2, the sequence through which the working fluid passes back and forth between tanks 12a and 12b is regulated by activating a fourth filter valve 18d to open a path to a fourth filter 14d, allowing the fluid to pass through the 100 nm filter 14d instead of the third filter 14c. The working fluid continues to pass back and forth between tanks 12a and 12b through the fourth 100 nm filter 14d until the reduction in the level of contaminants measured by the particle counter reaches a preset target level. This indicates that the majority of the contaminants in the fluid are smaller than 100 nm and are not removed by the 100 nm filter 14d.

[0093] Because the 100 nm filter is fine and delicate, the 100 nm filter 14d may degrade and disintegrate over time. This can introduce fibrous particles and fragments of the filter into the liquid. Optionally, as shown in step 90 of Figure 2, a fifth filter 14e with a higher micron rating of 10 μm is provided, configured to capture and remove fibrous particles from the filter 14d if it disintegrates. The working fluid reciprocates between tanks 12a and 12b through the fifth 10 μm filter 14e.

[0094] Optionally, the control system can control the selective switching between filters based on particle counter data. This system may be an automated system.

[0095] The system described above describes filtration through which the liquid passes sequentially through all five filters, but it should be understood that the system may have four or fewer filters, or six or more filters. It should also be understood that this system may include different filter micron levels than those in the example above. Furthermore, it should be understood that this method does not require the liquid to pass through all filters. The filtration method can be carried out until the desired level of cleanliness or purity of the liquid is achieved.

[0096] The systems shown in Figures 1 and 2 can be used to sequentially filter the used working fluid to remove contaminants. In addition, or alternatively, this system can be used to remove contaminants from new working fluid before introducing it into the hydraulic system for the first time.

[0097] ISO 4406 is a standard that specifies codes used to define the amount of solid particles in a hydraulic fluid used in a given hydraulic power system. According to this standard, code numbers are assigned to particle count values ​​obtained at three different micron levels: 4 microns, 6 microns, and 14 microns. ISO codes are assigned based on Table 1.

[0098] ISO 4406 provides a typical particle count scheme that divides the number of particles per milliliter. Therefore, the particle counts of 15 / 13 / 11 mean 160-320 particles for 4 microns; 40-80 particles for 6 microns; and 10-20 particles for 14 microns.

[0099] [Table 1] Table 1 is the ISO 4406 particle concentration table (number of particles / mL).

[0100] New hydraulic fluids typically have ISO codes ranging from 18 / 17 / 16 to 14 / 13 / 11, although this can vary considerably. ISO code 11 means that the fluid contains 10 to 20 particles of 14 μm size per ml. The size of these particles is typically 500 to 400 grit, as seen in industrial grinding pastes. Because the hydraulic fluid passes through the hydraulic system thousands of times, from high pressure to low pressure and back again, these particles can cause significant damage. However, before use in a hydraulic system, the particles can be removed from the hydraulic system by treating the new hydraulic fluid through system 10 as described above in relation to Figures 1 and 2, thereby reducing wear on the hydraulic system.

[0101] Figures 3A-3C and 4 show the filtration system 100. This system 100 is similar to the filtration system 10 described in relation to Figures 1 and 2, and will be understood from the description of Figures 1 and 2. However, this system is configured to remove water from the working fluid.

[0102] This system includes two tanks 112a and 112b for storing working fluid. Each of tanks 112a and 112b is liquidally connected to a filter system 114 via a valve system 116. The tanks are made of steel and each has a storage capacity of 205 liters. However, the tanks can be manufactured from other materials and may have various sizes and storage capacities. Figure 3C shows a cross-sectional view of tank 112b, and the features of tanks 112a and 112b in this example are the same. In Figure 3C, connecting tubes are omitted for clarity. Each tank has an inlet 128 and an outlet 126. The tanks are arranged so that the liquid returning to the corner tank from the inlet 128 flows along the inner surface or walls of each tank, cleaning the walls and removing any debris or dirt accumulated therein. The tanks are equipped with supports and baffles 115 that provide structural support to the tanks. The bottom surface 117 of the tanks in this example is sloped. The inclined bottom 117 is configured to discharge as much contaminant as possible from the tank at the end of each cycle. The inclined bottom is designed to self-purge / discharge the bottom / bottom naturally. Each tank is equipped with an upper liquid level sensor 119a to prevent overfilling and a lower liquid level sensor 119b to prevent air from entering the filtration system.

[0103] In this example, the filter system 114 includes four filters 114a, 114b, 114c, and 114d. The filters have different micron ratings. Filter 114a is a 10 μm filter; filter 114b is a 3 μm filter; filter 114c is a 1 μm filter; and filter 114d is a 100 nm filter. The filters in this example are manufactured from different filter materials. Filter 114a is manufactured from an absorbent material such as sodium acrylate. Filters 114b, 114c, and 114d are manufactured from cellulose.

[0104] In this example, an electromagnet is located within the housing of filter 114b to remove and recover iron-based materials from the working fluid. Alternatively, the electromagnet may be incorporated into the flow path. The operation of the electromagnet can be controlled to enable selective recovery and / or controlled release of recovered iron-based materials into a specific filter at a predetermined time. This can reduce the reduction or interruption of the magnetic field due to the recovery of iron-based materials.

[0105] The system also includes a control unit 130 and a particle counter 132. Optionally, the system may include a heating device, a cooling device, and / or an acoustic transducer to help remove air and water from the working fluid (not shown).

[0106] As best illustrated in Figure 4, during use, the working fluid to be processed is stored in a first tank, such as tank 112a. The control unit 130 acts on valve 122 to open the path between flow paths 140 and 142. Pump 170, connected to flow path 142, draws the working fluid from tank 112a and sends it through flow path 144 to the filter valve.

[0107] The first filter valve 118a is activated, opening the flow path to the first filter 114a. The working fluid passes through a 10 μm filter, where water is absorbed by the absorbent material and larger contaminants (10 μm or larger) are removed from the liquid. The filtered liquid flows from filter 114a into flow path 146. If purity sampling is required, valve 160 is closed (completely or partially), and the treated working fluid flows through flow path 148 to the particle counter 132, and then through flows 150 and 152 to the inlet valve 124. Valve 124 is activated, opening the flow path to the tank inlet 128b, and the treated liquid flows into tank 112b.

[0108] The liquid in tank 112a continues to flow through the filter system into tank 112b until the low-level indicator in tank 112a detects a low liquid level. This prevents air from entering the filter system. In this example, tank 112b is equipped with a high-level indicator to prevent overflow. The high-level indicator can detect a high oil level and stop the pump that draws the liquid. This high-level indicator may also function to stop the pump if an overflow occurs due to expansion caused by the temperature of the liquid.

[0109] When the low-level indicator in tank 112a detects a low liquid level, pump 170 stops, and outlet valve 122 activates, opening the path between flow path 141 and flow path 142, which are connected to the outlet of tank 112b. Pump 170, connected to flow path 142, draws the working fluid from tank 112b into flow path 144 to the filter valve. In the first filtration operation, the first filter valve 118a activates, opening the path to the first filter 114a. The working fluid passes through a 10 μm filter, where water is absorbed by the absorbent material and larger contaminants (larger than 10 μm) that were missed in the first pass are removed from the liquid. The filtered liquid flows from filter 114a into flow path 146. If purity sampling is required, valve 160 is closed (completely or partially), and the treated working fluid flows through flow path 148 to particle counter 132, and then through flow paths 150 and 152 to valve 124. Valve 124 is activated, opening the flow path to the tank inlet 128a, and the treated liquid flows into tank 112a.

[0110] The above sequence, in which the working fluid passes back and forth between tanks 112a and 112b, can be repeated multiple times through a 10 μm water-absorbing filter 114a until the level of contaminants, as measured by the humidity sensor and particle counter, reaches a preset target level. This indicates that moisture has been removed from the liquid or reduced to the desired level, and that the majority of contaminants in the liquid are less than 10 μm in size.

[0111] At this stage, the control unit adjusts the filtration sequence by activating the second filter valve 118b to open a path to the second filter 114b, which is a 3 μm cellulose filter, instead of the first filter 114a. The risk of water damage to the cellulose is reduced because the water content of the working fluid is removed or significantly reduced. The working fluid makes multiple round trips between tanks 112a and 112b through the second 3 μm filter 114b until the level of contaminants measured by the particle counter drops to a preset level. This indicates that the majority of the contaminants in the liquid are smaller than 3 μm and are not removed by the 3 μm filter 114b.

[0112] In this third stage, the control unit activates the third filter valve 118c to open a path to the third filter 114c, thereby adjusting the filtration sequence by allowing the liquid to pass through the 1 μm third filter 114c instead of the second filter 114b. The working fluid makes multiple round trips between tanks 112a and 112b through the third 3 μm filter 114c until the reduction in the level of contaminants measured by the particle counter reaches a preset target level. This indicates that the majority of the contaminants in the liquid are smaller than 1 μm and are not removed by the 3 μm filter 14c.

[0113] In this fourth stage, the control unit activates the fourth filter valve 118d to open a path to the fourth filter 114d, thereby adjusting the filtration sequence by allowing the liquid to pass through the 100 nm filter 114d instead of the third filter 114c. The working fluid makes multiple round trips between tanks 112a and 112b through the fourth 100 nm filter 14d until the reduction in the level of contaminants measured by the particle counter reaches a preset target level. This indicates that the majority of the contaminants in the liquid are smaller than 100 nm.

[0114] The presence of air bubbles in the working fluid can affect the accuracy of particle counter readings. Figures 6A to 6C show plots of particle size and number over time at three different micron levels. Figure 6A is a plot of separated 4 μm particle number data over time. Figure 6B is a plot of separated 6 μm particle number data over time. Figure 6C is a plot of separated 14 μm particle number data over time.

[0115] Bubbles can have adverse effects and may cause particle counters to mistakenly identify them as "particles." In each plot, "actual" particles are indicated by data points sloping towards the baseline. As shown in Figures 6A–6C, at 6 μm, and especially at 4 μm, bubbles do not readily float to the surface of the liquid. The cluster of points in the central plot is actually mostly bubbles, and these bubbles are counted as "particles" because they interfere with the laser detector and negatively impact the sensor. Figure 6C shows that at 14 μm, the number of bubble particles decreases more easily over time.

[0116] This system may include devices to help remove air from the working fluid. In one example, an ultrasonic device, such as an ultrasonic transducer, can be incorporated into the system to remove dissolved gases and / or air bubbles from the working fluid. The ultrasonic device generates ultrasonic cavitation, which can convert any tiny bubbles into larger bubbles that burst at the surface of the working fluid. In another example, a vortex separator can be used to remove air from the working fluid.

[0117] In addition, or instead, the system's shape can be designed to help air rise from the working fluid. The diameters of the tubing, inlet, and / or outlet can be configured to minimize the effect of air bubble flow in the working fluid. The shapes of the tubing, inlet, and / or outlet can be selected to minimize the effect of air bubble flow in the working fluid. The shapes of the tubing, inlet, and / or outlet can be selected from a group including circular, rectangular, trapezoidal, or helical shapes.

[0118] The tank inlets can be positioned so that the liquid returning to each tank moves downward along the inner surface or walls of each tank, thereby cleaning the walls and removing any debris or dirt from them. The bottoms of two or more tanks may be sloped or have grooves. Sloped bottoms or grooves can be configured to discharge as much contaminant as possible from the tanks at the end of each cycle. The shape of two or more tanks can be configured to redirect the direction of the contaminant so that it moves towards the tank outlets.

[0119] In addition to or instead of the particle counter sensor, the system may include other sensors or devices selected from the group consisting of humidity sensors, light irradiation sensors, capacitance sensors, flow meters, density sensors, viscosity sensors, pressure sensors, temperature sensors, liquid level gauges, ultrasonic sensors, magnetostrictive sensors, level probes, rod sensors, limit sensors, liquid level switches, fill level switches, and / or float switches.

[0120] As shown in Figure 5, the system, including the tanks and filters, can be periodically flushed to remove contaminants collected during the filtration operation. After the filtration operation, a certain amount of clean working fluid is introduced into tank 112a, and the control unit operates pump 170 to pump it in the reverse direction, indicated by arrow "C" in Figure 5. This flow proceeds along channel 152 to the first filter 114a, back-flushing the filter to remove the collected filtrate. The flushing fluid proceeds along channel 144 to channel 180 and is collected in waste tank 182. This process can be repeated in the second tank 112b. The control unit sequentially opens the paths to each filter to flush out the contaminants accumulated in each filter.

[0121] The above example illustrates the dehydration of a working fluid using a filter material containing an absorbent, but it should be understood that this system may also include other dehydration methods, including separation by gravity, heating, cooling, positive pressure dehydrator, centrifugal separation, or vacuum dehydrator.

[0122] It should be understood that the above system may be a closed or offline system in which a measured batch of working fluid is introduced into the system, processed, and discharged when it reaches a desired improved processing state. It should also be understood that the above system may be an open or online system in which the system is in liquid communication with a hydraulic system that is part of the equipment, and working fluid is drawn from the liquid system in a controlled measured amount, processed, and discharged back into the liquid system when it reaches a desired improved processing state.

[0123] One aspect of the present invention provides a hydraulic fluid filtration system that allows a hydraulic fluid to be circulated back and forth between two containers via a filter. Each time the hydraulic fluid moves from one container to the other, it is purified in stages. By repeatedly passing the hydraulic fluid through the filter, a high level of cleanliness or purity of the hydraulic fluid can be obtained.

[0124] The inventors have found that by providing two containers and repeatedly moving the working fluid back and forth between them via a filter system, a high level of cleanliness or purity of the working fluid can be obtained without requiring numerous filters, tanks, or large installation space for the equipment. The inventors have also found that it is not necessary to clean the containers or equipment between filtration cycles. After the first filtration cycle, the filtered working fluid is returned to the first contaminated container, which may contain liquid containing impurities, but the inventors have found that by repeatedly moving the working fluid back and forth through the filter system, the impurities are gradually removed from both containers and the working fluid over time.

[0125] Throughout this specification, unless otherwise specified in the context, the terms “comprise” or “include,” or variations such as “comprises,” “comprising,” “includes,” or “including,” should be understood to mean that they include the integer or group of integers described, but not to exclude other integers or groups of integers. Furthermore, relative terms such as “inlet” and “outlet” are used herein to indicate orientation and location applicable to the accompanying drawings and should not be construed as limiting the invention and its features to any particular arrangement or orientation. The term “outlet” should be interpreted as an opening that can also function as an “inlet” depending on the direction in which the liquid moves, and vice versa.

[0126] The present invention provides a hydraulic fluid filtration system and a method of using the same. The system includes a filter system comprising two or more containers, at least one filter positioned between the two or more containers, and a valve system. The valve system is operable to transfer hydraulic fluid between the two or more containers through at least one filter. The present invention can provide a robust, reliable, and compact hydraulic fluid filtration device and a method of using the same that can remove contaminants from hydraulic fluid before, during, and / or after use in a hydraulic system that is part of equipment.

[0127] One embodiment of the present invention can provide a filtration system comprising multiple filters, wherein if one filter is damaged or deteriorated, the liquid passes through another filter, and contaminants and / or deteriorated filter components are captured by the filters rather than flowing into a hydraulic system which is part of the equipment.

[0128] One embodiment of the present invention can provide a hydraulic fluid filtration system configured to be integrated with or connected to a hydraulic system which is part of a facility. The hydraulic fluid filtration system can filter the hydraulic fluid online or offline.

[0129] The above description of the present invention is presented for illustrative and explanatory purposes only and is not exhaustive, nor is it intended to limit the invention to the exact form disclosed herein. The embodiments described are selected and described to best illustrate the principles of the invention and their practical applications, so that those skilled in the art can best utilize the invention in various embodiments with various modifications to suit specific intended uses. Accordingly, further modifications or improvements can be made without departing from the scope of the invention as intended herein.

Claims

1. Two or more containers; A filter system including at least one filter placed between two or more containers; and A working fluid filtration system including a valve system, The valve system is operable to reciprocate a working fluid between two or more containers via the at least one filter.

2. The system according to claim 1, wherein the valve system is configured to circulate the working fluid back and forth between the two or more containers through the at least one filter until the working fluid reaches a desired level of cleanliness.

3. The system according to claim 1 or 2, further comprising a control unit configured to control the operation of one or more valves in the valve system.

4. The system according to any one of claims 1 to 3, wherein at least one filter has a micron rating selected from the range of 10 nm to 100 μm.

5. The system according to any one of claims 1 to 4, comprising at least one pump, wherein the at least one pump is a reversible pump.

6. The system according to any one of claims 1 to 5, comprising at least one heating device configured to raise the temperature of the working fluid to a desired temperature, thereby reducing the viscosity of the working fluid and / or to help remove water and / or air from the working fluid.

7. The system according to any one of claims 1 to 6, comprising at least one cooling device configured to lower the temperature of the working fluid to a desired temperature, thereby reducing the viscosity of the working fluid, and / or to help remove water and / or air from the working fluid.

8. The system according to any one of claims 1 to 7, wherein the at least one filter comprises a filter housing, the filter housing comprises at least one device selected from the group consisting of magnets, electromagnets, cooling devices, and / or heating devices.

9. The system according to any one of claims 1 to 8, comprising at least one sensor selected from the group including a particle counter, a humidity sensor, a light sensor, an optical sensor, a capacitance sensor, a flow meter, a density sensor, a viscosity sensor, a pressure sensor, a temperature sensor, a liquid level gauge, an ultrasonic sensor, a magnetostrictive sensor, a level probe, a rod sensor, a limit sensor, a liquid level and fill level switch, a spectroscopic sensor, an optical spectroscopic measurement sensor, and / or a float switch.

10. The system according to any one of claims 1 to 9, comprising a degassing device selected from the group including a vortex separator, a cyclone separator, an ultrasonic transducer, a vacuum degassing device, a liquid agitator, a degassing device, and / or a centrifugal degassing device.

11. The system according to any one of claims 1 to 10, wherein the at least one filter comprises a filter material selected from the group consisting of fibers, paper, cellulose, synthetic fibers, mesh, metal mesh, carbon, activated carbon, water absorbent, sodium acrylate, and additives.

12. The system according to any one of claims 1 to 11, wherein the valve system includes two or more filters.

13. The system according to claim 12, wherein the valve system is configured to selectively and sequentially pass the working fluid through the two or more filters.

14. The system according to claim 12 or 13, wherein each of the two or more filters has a different micron rating selected from the range of 10 nm to 100 μm.

15. The system according to any one of claims 1 to 14, wherein the valve system is configured to select a flow that passes through a specific filter in accordance with sensor data.

16. A method for removing contaminants from a working fluid: Two or more containers; A filter system including at least one filter placed between two or more containers; To provide a working fluid filtration system including a valve system; The method comprising transferring a working fluid back and forth between two or more containers through at least one filter.

17. The method according to claim 16, comprising transferring the working fluid back and forth between the two or more containers through a first filter until the working fluid reaches a first desired level of cleanliness or purity.

18. The method according to claim 16 or 17, comprising transferring the working fluid back and forth between the two or more containers through a second filter until the working fluid reaches a second desired level of cleanliness or purity.

19. The method according to any one of claims 16 to 18, comprising transferring the working fluid back and forth between the two or more containers through a third or subsequent filter until the working fluid reaches a third or subsequent desired level of cleanliness or purity.

20. The method according to any one of claims 16 to 19, comprising measuring and / or monitoring at least one characteristic or parameter of the working fluid, wherein the at least one characteristic or parameter of the working fluid is selected from the group including temperature, pressure, viscosity, particle count, gas content, air content, water content, and / or humidity.

21. The method according to any one of claims 16 to 20, comprising selecting a flow that passes through a specific filter in accordance with sensor data.

22. The method according to any one of claims 16 to 21, wherein the working fluid is fresh, and contaminants are removed from the working fluid before it is first introduced into the hydraulic system and used.

23. The method according to any one of claims 16 to 22, wherein the working fluid is a working fluid previously used and recovered in a hydraulic system.

24. The method according to any one of claims 16 to 23, comprising connecting the working fluid filtration system to a hydraulic system to temporarily remove working fluid from the hydraulic system and / or filtering the working fluid circulating in the hydraulic system.

25. The method according to any one of claims 16 to 24, comprising taking the working fluid from the hydraulic system.

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