Method and apparatus for cleaning and/or replacing hydraulic oil in hydraulic drives

Abstract

A flushing module for hydraulic drives, in particular for self-contained drives, for cleaning and/or replacing hydraulic medium. The flushing module has a pump and at least one shutoff valve and a housing. The flushing module is portable.

Claims

1. A method of replacing hydraulic fluid of a hydraulic drive, the method comprising: providing a flushing module for hydraulic drives, for cleaning and/or replacing hydraulic medium, the flushing module having a pump, at least one shutoff valve and a housing configured to form a portable flushing module; connecting the flushing module to the hydraulic drive; draining the hydraulic fluid; prior to connecting the flushing module to the hydraulic drive, bleeding the flushing module, by connecting hose connections intended for connecting to the hydraulic drive to the flushing module, and connecting to each other the hose connections at respective ends that are configured for connecting to the hydraulic drive, and connecting an inlet and outlet of the flushing module to an oil container that has been filled with new oil; flooding the hydraulic drive by supplying fresh hydraulic fluid without preload pressure; flushing the hydraulic drive by supplying fresh hydraulic fluid at a pressure below a predetermined preload pressure of the hydraulic drive; adjusting the predetermined preload pressure; and disconnecting the flushing module.

2. The method according to claim 1, which comprises, during the flooding and flushing steps, connecting an inlet and an outlet of the hydraulic drive to the oil container via the flushing module.

3. The method according to claim 1, which comprises stowing the hose connections for connecting to the hydraulic drive in the flushing module after maintenance of filtering or replacing the hydraulic fluid has been performed.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention will be described in more detail below, with reference to exemplary embodiments. These exemplary embodiments are not intended to be limiting. The drawings show as follows:

(2) FIG. 1: Flushing module connected to a hydraulic drive; hydraulic circuit diagram

(3) FIG. 2: Flushing module equipped with two hydraulic containers

(4) FIG. 3: Flushing module with accessory compartment

(5) FIG. 4: Flushing module in “bleeding” operating mode

(6) FIG. 5: View of the operating unit of the flushing module

(7) FIG. 6: Flushing module in “bypass filtering” operating mode

(8) FIG. 7: Flushing module in operating mode “draining oil”

(9) FIG. 8: Flushing module in “filling fresh oil” operating mode

(10) FIG. 9: Flushing module with two shutoff valves

(11) FIG. 10: Flushing module with two shutoff valves and bypass filtering functionality

(12) FIG. 11: Flushing module with only one shutoff valve

(13) FIG. 12: Flushing module with a directional control valve as a shutoff valve

(14) FIG. 13: Flushing module with foldable receptacles

(15) FIG. 14: Flushing module with hydraulic containers

DESCRIPTION OF THE INVENTION

(16) The general structure will first be described, with reference to FIG. 1. The flushing module 3 has a motor-pump assembly 13 comprising a pump 17. The pump 17 is driven by a motor 15, and in particular by an electric motor 15. Parallel to the pump 17, a valve 14 is arranged for pressure protection, so that in the case of a defect, a buildup of pressure over a predetermined amount is prevented. The flushing module has a valve-filter unit 19. In the embodiment shown, this valve-filter unit 19 comprises a first shutoff valve 21 and a second shutoff valve 23 and a third shutoff valve 25. These shutoff valves 21, 23, 25 are shown in parallel in the hydraulic diagram. The flushing module 3 is provided with a manometer 29 and a pressure adjustment valve 27, so that a preload pressure may be set. By means of the valves 21, 23, 25, various hydraulic connections may be provided either through or in the flushing module. For some operating modes, only a portion of the valves 21, 23, 25 are required, as explained below.

(17) The flushing module provides a supply line 42 from a first hydraulic container 5 to a hydraulic drive 1, in particular a self-contained hydraulic drive. The flushing unit is designed in particular for use in hydraulic drives having a filling volume of up to 5 liters of hydraulic fluid. If the filling volume is greater, cleaning or replacement may be performed with another oil container or a larger oil container.

(18) The supply line 42 extends from G S/T to KC1. A filter 31 is arranged in the supply line. The filter in the supply line 42 has a filter indicator 33. A discharge 44, also referred to as a return, extends from KC2 to GT1. A filter 35 is arranged in the return 44. This filter 35 is also furnished with a filter indicator 37. A hose connection inlet 41 and a hose connection return 43 is furnished for connecting the flushing module 3 with the hydraulic drive 1. The hose connection inlet extends from fitting KM1 on the flushing module 3 to fitting K1 of the hydraulic drive 1. The hose connection return 43 extends from fitting KM2 on the flushing module to fitting K2 on the hydraulic drive. These hose connections may be firmly connected to KM1 and KM2 on the side of the flushing module. It may also be provided that the hose connections 41, 43 are detachably connected to the flushing module 3. In detachable connection, a required hose length of the hose connections 41, 43 is selected, and an accessory receptacle 59 is brought along that is provided in a housing 65 of the flushing module 3. In addition to the hose connections 41, 43, an adapter 57 may also be carried in the accessory receptacle 59. In addition, a check valve 39 is arranged in the supply line 42. In the illustrated embodiment, a connection is provided to the first hydraulic container 5 for new oil and to the second hydraulic container 7 for waste oil, by means of a flushing assembly—new oil 9 and a flushing assembly—waste oil 11. The flushing assemblies 5, 7 are fixedly connected to the flushing module 3.

(19) FIG. 2 and FIG. 3 show a three-dimensional representation of a flushing module that has a structure as shown in FIG. 1. The flushing module has two carrying handles, on both sides. The carrying handles 51 are part of a frame 63. A housing 65 is held by the carrying frame. However, a housing 65 may also be provided that is firmly connected to carrying handles, in which case a frame is dispensed with. The housing 65 comprises a housing base 67 and a cover 53. On one side of the flushing module, a main switch 55 is provided, for switching the flushing module 3 on and off. This main switch 55 could also be arranged on the upper cover 53. The shutoff valves 21, 23, 25 and the pressure adjustment valve 27 may be operated from the upper cover 53. The manometer 29 is arranged in the region of the upper cover so as to be visible. Thus, these controls are easily accessible and may be operated comfortably. In addition, these control elements are protected by the carrying handles 51. In the illustration of FIG. 3, the accessory compartment is visible, in which hose connections 41, 43 and an adapter 57 are mounted as accessories 61.

(20) Various operating modes of the flushing module shown in FIG. 1 will be described below.

(21) Process Step “Prepare Flushing Module”:

(22) Before the flushing module 3 is connected to a hydraulic drive 1, the flushing module 3 is prepared: The flushing module 3 is placed at a suitable location near the CLDP. It is important to ensure a safe placement of the flushing module 3 and sufficient room for operation. The shutoff valves 21, 23, 25 (red star grip) on the flushing module 3 are closed (screw in completely). Pressure valve 27 (black star grip) is opened (screw out completely). The flushing module 3 is equipped with the first hydraulic container 5, “fresh oil,” and the new oil flushing assembly 9 is connected to the hydraulic container 5 (GS/T). The flushing module 3 is equipped with the “waste oil” oil container 7, and the corresponding “return assembly” 11 is connected to the second hydraulic container 7 (GT1). A respective ventilation cover 8 is opened at both hydraulic containers. The existing connecting hoses 41, 43 are coupled to the flushing module 3 via the quick couplings KM1 and KM2. The connecting hoses 41, 43 are short-circuited; for this purpose, the two hose couplings KC1 and KC2 are connected to one another, FIG. 4. The power supply to the flushing module 3 is provided via a power plug.

(23) Process Step “Bleeding Flushing Module & Connecting Hoses” (FIG. 4): The “external flushing” shutoff valve 21 is opened. Shutoff valves 23, 25 remain closed. The pressure valve 27 for setting a preload pressure remains completely open. The flushing module 3 is switched on at the main switch. In this state, the flushing module 3 and the connecting hoses 41, 43 are flooded with new oil and bled. At the new oil flushing assembly 9 GS/T, it is checked whether hydraulic oil is flowing free of bubbles through the transparent suction and return lines. This flushing is provided over a predetermined period, preferably at least 5 minutes. The pressure valve 27 for adjusting a preload pressure is set to the preload pressure of the hydraulic drive. If this predetermined preload pressure is reached, the flushing module is operated at this pressure for at least one additional minute. The flushing module 3 is then turned off at the main switch 55. The shutoff valve 21 on the flushing module 3 is again closed.

(24) The “Bleeding flushing module & connecting hoses” process step has been completed.

(25) “Coupling Flushing Module” Process Step (FIG. 1):

(26) The flushing module is connected to the hydraulic drive. The shutoff valves 21, 23 and 25 on the flushing module 3 must be shut off. The connecting hoses 41, 43, which were short-circuited at the hose couplings KC1 and KC2, are separated. Hose coupling KC1 is connected to the hydraulic drive 1 with coupling K1 Hose coupling KC2 is connected to coupling K2 at the hydraulic drive. The preload pressure must be checked on the manometer. The preload pressure must be identical to the preload pressure of the hydraulic drive.

(27) The “Couple flushing module 3” process step is completed.

(28) Adapters may be necessary for the various models of hydraulic drives 1. For example, there are hydraulic drives that are equipped with a cooling module, with differing hydraulic connections. An intermediate adapter may be used for coupling the flushing module 3.

(29) “Bypass Filtering” Process Step (FIG. 6): The shutoff valve 23 (internal flushing) is opened on the flushing module 3. The preload pressure is checked on the manometer 29. The previously-set preload pressure should be maintained. The flushing module 3 is switched on via the main switch. The hydraulic circuit for bypass filtering—without new oil supply—is provided. In parallel with this, the hydraulic drive is activated and operated at a reduced speed with strokes that are as long as possible. Strokes are considered “as long as possible” that are in the range of 90% to 95% of the maximum stroke. This flushing and cleaning process runs for a predetermined period of time. Continuing this flushing and cleaning process for at least 20 minutes, preferably 30 minutes, has proven advantageous in the case of self-contained hydraulic drives with a maximum hydraulic volume of 2 liters. The hydraulic drive 1 is switched off in the retracted end position, approx. 0 to 5 mm before the end stop of the hydraulic drive. The flushing module 3 is switched off via the main switch 55. The shutoff valve 23 (internal flushing) of the flushing module 3 is closed. The process step of “bypass filtering” the hydraulic drive is completed.

(30) “Drain Waste Oil” Process Step, FIG. 7: The flushing module 3 and hydraulic drive must be switched off, and the shutoff valves 21, 23 and 25 on the flushing module 3 must be shut off. The connection of the flushing assembly 11 with the connection GT1 to the second hydraulic container 7 are checked. The ventilation cover 8 on the second hydraulic container 7 must be open. The third shutoff valve 25 on the flushing module 3, “oil change”, is opened slowly. Waste oil is drained into the second hydraulic container 7 via fitting T1. This relieves the system preload pressure. The system preload pressure is checked on the manometer 29. The system is depressurized by means of the flushing module. The third shutoff valve 25 on the flushing module, “oil change,” is closed again. The “drain waste oil” process step is completed.

(31) In this phase, the nitrogen preloading of the pressure accumulator may be checked using a correspondingly suitable test apparatus, and may be corrected if it deviates from the target pressure!

(32) “Flood Fresh Oil” Process Step (FIG. 8): The flushing module 3 and the hydraulic drive 1 must be switched off, and the shutoff valves 21, 23 and 25 must be shut off at the flushing module. The connection between the new oil flushing assembly 9 and the fitting GS/T on the first hydraulic container, which holds fresh oil, is checked. The ventilation cover 8 on the first hydraulic container 5 is open. The shutoff valve 21, “external flushing,” on the flushing module 3 is opened. The “preload pressure” pressure adjustment valve 27 “preload pressure” is completely open. The flushing module 3 is switched on at the main switch. Via the transparent suction and return lines at the flushing assembly 9 GS/T, it may be checked whether the hydraulic oil is flowing without bubbles. In a self-contained hydraulic drive with a total volume of 5 liters of hydraulic fluid, it has proven sufficient to operate in this operating mode for about 1-2 minutes.

(33) “Flush Fresh Oil” Process Step (FIG. 8): The pressure adjustment valve 27 is slowly set to a reduced “system pressure”. A reduced standard preload pressure, reduced by 1.5 bar, was generated. The standard preload pressure is predetermined in relation to the hydraulic drive. The hydraulic drive 1 is operated at a greatly reduced speed, about 10% V max., and with strokes that are as long as possible. The longest possible strokes are in the range of 80 to 90% of the maximum stroke of the hydraulic drive. In this case, the preload pressure will fluctuate. The duration of the flushing process is at least 10 minutes. The “Fresh oil—flush” process step is completed.

(34) Process Step “Adjustment of Preload Pressure”: the hydraulic drive 1 is moved to the retracted end position and switched off. The predetermined preload pressure of the hydraulic drive is set to the predetermined setpoint for preload pressure, at the “preload pressure” of the pressure adjustment valve 27. The flushing module 3 is switched off at the main switch. The shutoff valve 21 on the flushing module 3, “external flushing,” is closed. Process step “Adjustment of preload pressure” is completed.

(35) In the event that no oil change is intended and only the preload pressure must be corrected, the preload pressure may be adjusted directly in process step 4, “Bypass filtering”.

(36) “Decouple the Module” Process Step: Disconnect hose connections 41, 43 from the hydraulic drive 1 at connection points KC1 and KC2 (quick couplings). The coupling plug on the flushing module, and the coupling connections of the hydraulic hose connections 41, 43, are closed using dust caps. The system preload pressure at the hydraulic drive 1 is checked. The hydraulic drive 1 is checked for leaks.

(37) Process step 8, “Uncouple module”, is completed.

(38) “Prepare Flushing Module for Storage” Process Step:

(39) To properly store the flushing module or prepare it for the next use, two clean oil canisters are required. The “fresh oil” used for filling (including flushing) is mixed with “waste oil” to a certain extent. For this reason, this oil should not be used for further refillings. The waste oil should be disposed of appropriately. The power plug is disconnected from the power supply. The shutoff valves 21, 23 and 25 are closed, and the pressure adjustment valve 27 is opened. The hose connections 41, 43 are disconnected from the flushing module by means of the quick couplings KM1 and KM2, and the corresponding coupling plugs are closed with dust caps. Hoses are stored in the accessory receptacle of the flushing module. The second hydraulic container 7, “waste oil”, is removed from the flushing module and replaced with a clean empty container for waste oil. Inside this empty container, the flushing assembly 11 return GT1 is protected against contamination. The first hydraulic container 5 for “new oil” is removed from the flushing module and replaced with a clean empty container. The flushing assembly new oil with suction and return GS/T is protected from contamination inside the empty container.

(40) In FIGS. 9 to 11, variant embodiments of flushing modules are shown. In the flushing module 3 shown in FIG. 9, bypass filtering is not possible. This flushing module has only a first shutoff valve 21 and the third shutoff valve 25.

(41) FIG. 10 shows an embodiment of a flushing module in which a hose connection T of the new oil flushing assembly 9 must be connected with the second hydraulic container after GT1, for draining waste oil. This hose connection of the new oil flushing assembly must next be connected to the first hydraulic container 5 and fitting GS. Bypass filtering is also possible with this flushing module 3. This flushing module 3 has only the first shutoff valve 21 and the second shutoff valve 23.

(42) FIG. 11 shows a flushing module with only one shutoff valve. In this flushing module, as in the flushing module shown in FIG. 10, it is only possible to dispose of waste oil by changing the connection of the new oil flushing assembly 9 to the second hydraulic container 7. Bypass filtering is not possible. The process steps of bleeding, supplying fresh oil, flooding, flushing the fresh oil, and adjusting preload pressure may be carried out without restriction.

(43) The process steps of preparing the flushing module, bleeding, coupling, uncoupling, preparing for storage and preparing the flushing module for transport and storage, relate to all the flushing module variants shown.

(44) Flushing assemblies 9 and 11 have check valves 45 on their ends that protrude into the hydraulic container ends. These check valves are provided so that the flushing module, in particular the hydraulic lines of the flushing module, remain filled with hydraulic fluid during transport and also during container replacement and during storage. As a result, the process step of bleeding is limited, and the handling of the flushing module is more pleasant, because hydraulic fluid is prevented from leaking out.

(45) FIGS. 12 to 14 show an additional embodiment. This flushing module 3 has a directional control valve 20 serving as shutoff valve 21, 23, 25. Specifically, a 4/3-way valve is used. The directional control valve 20 has three switching positions 22, 24, 26. In the case of switching into the first switching position 22, the process step “drain waste oil” is provided. “Drain waste oil” has already been described with reference to FIG. 7.

(46) With the second switching position 24, the “bypass filtering” function is provided. The “bypass filtering” function has already been described with reference to FIG. 6,

(47) With the third switching position 26, the functions “flooding fresh oil” as described with reference to FIG. 8, and “bleeding” as described with reference to FIG. 4, are provided.

(48) FIGS. 13 and 14 depict a variant embodiment of the flushing module 3. In this embodiment, the housing 65 comprises foldable receptacles 66 that serve as a recess 4 for accommodating hydraulic containers 5, 7. The advantage of this variant is that the flushing module 3 is even more compact and easier to transport, due to its reduced external dimensions. Carrying handles 51 are formed on both sides of the housing 65. This makes carrying particularly straightforward. The hydraulic containers 5, 7 may only be put in place shortly before switching on the flushing module 3. In the exemplary embodiment shown, the hose connections for the inlet 41 and the return 43 are fixedly connected to the flushing module. The return 43 and inlet 41 are accommodated in a folded position within the foldable receptacles 66.

LIST OF REFERENCE SIGNS

(49) 1 Self-contained linear actuator 3 Flushing module 4 Recess for hydraulic container 5 First hydraulic container, new oil 7 Second hydraulic container, waste oil 8 Ventilation cover 9 Flushing assembly—new oil 11 Flushing assembly—waste oil 13 Motor-pump assembly 14 Valve, pressure protection 15 Motor 17 Pump 19 Valve-filter unit 20 Directional control valve 21 First shutoff valve, shutoff valve for external flush 22 First switching position of the directional control valve 20 23 Second shutoff valve, shutoff valve for internal flush 24 Second switching position of the directional control valve 20 25 Third shutoff valve, shutoff valve for oil change 26 Third switching position of the directional control valve 20 27 Pressure adjustment valve, pressure adjusting unit 28 Lever for adjusting the directional control valve 29 Pressure gauge, manometer 31 Filter in inlet 33 Inlet filter indicator 35 Return filter 37 Return filter indicator 39 Check valve 41 Inlet hose connection 42 Supply line 43 Return hose connection 44 Discharge 45 Check valves 51 Carrying handles 53 Cover 55 Main switch 57 Adapter 59 Accessory compartment 61 Accessories 63 Frame 65 Housing 66 Foldable receptacle 67 Housing base