DE2756965A1 - Dissolved gases release system - with double acting piston in cylinder producing negative pressure - Google Patents

Abstract

Gases which are dissolved in liqs. e.g. the hydraulic systems of aircraft, are sepd. in a liq.-filled cylinder with a double-acting piston. When the volume of a cylinder side becomes grater than the volume occupied by the incoming liq., the inside pressure is reduced and dissolved gases are released for collection at a certain point. This removes dissolved gases continuously without requiring extraneous electric power. The satn. pressure lies below the lowest pressure during operation and standstill of the hydraulic system. It can be operated in a bypass to avoid interference with the continuous fluid flow.

Description

Method and device for separation in liquids

Dissolved Gases The invention relates to a method and an apparatus for separating gases dissolved in hydraulic fluids.

The pressure medium of Hydroulik-Anlogen basically contains air, namely either undissolved air in the form of bubbles or molecularly dissolved air. Undissolved air can cause damage to devices, incorrect switching, instability of Servo devices and premature oxidation of the pressure medium occur. Molecularly solved Air does not have a harmful effect, but can occur if low levels occur. pressure and at the same time existing shear rate from the molecular lattice and thus also form bubbles and lead to the damage described above. There are therefore, precautions must be taken to reduce the pressure medium in hydraulic systems as much as possible largely degassed.

Rotary flow vortices for separating media of different types are known Density, consisting of a rotationally symmetrical vortex chamber with an inlet pipe in a coaxial mouth for the media to be separated and the opposite Outlet for the media of lower density as well as with off-center and the inflowing Media obliquely oppositely directed inlets for an auxiliary medium to generate a Rotary flow in the form of an external, helical potential flow.

Centrifugal separators for gases or liquids are also known with tangential upper pipe medium inlet and axial clean medium outlet, whereby a ridged groove creates a spiral flow.

In the aerospace industry, it is known in engines, in particular Provide high-performance engines, air separators for the returning lubricating oil (DT-AS 18 06 854), because the lubricating oil can reach an air content of 70% and is no longer functional with this proportion of air. The lubricating oil is here Cascade-like transported to shell sets, whereby the air can escape.

The venting of hydraulic systems with closed containers (e.g.

of aircraft) is usually carried out manually. Most of time not all air collection points can be vented due to inaccessibility. Partially therefore air separators are used that remove the air via manually operated valves deposit. An automatic air separation device for aircraft is from US-PS 3,358,424 known. This device works with a diaphragm, a jet pump and Float valves.

The disadvantage here is in particular that the device after negative g-loads, as they can occur in aviation, no longer work.

The object of the invention is to provide a method and a device for the continuous removal of gases from hydraulic fluids, where the saturation pressure is below the lowest pressure occurring during operation and standstill of the hydraulic system and no external auxiliary energy (electrics) is required, the device can also be operated with bypass to ensure reliability of the Hydroulik systems during the separation of the gas not to be significantly impaired and to enable a continuous throughput of the hydraulic fluid, wherein however, the structure of the hydraulic fluid does not change.

This object is achieved according to the invention by a method in which the space inside a cylinder is enlarged by moving a piston and the pressure of a liquid flowing into the space is reduced, whereby Gases dissolved in the liquid are released and reach a collecting space.

A facility for carrying out the procedure is marked by a cylinder in which two separate spaces are formed by a piston and by working pistons connected to both sides of the piston, which control the movement of the piston cause by near the Piston dead center arranged inflow lines for the liquid medium as well as in the area of the dead center positions arranged valves for separating the gas separated from the pressure medium with reversal of movement of the piston.

To control the piston movement, it is particularly advantageous when the working pistons have different diameters and one working piston is designed as a control piston which is in communication with a control slide.

With the help of the automatic separation of the molecularly dissolved air from the hydraulic fluid and the removal of the bubble-shaped air from hydraulic Systems or sub-systems, the previously manually carried out ventilation is avoided, whereby floor downtimes and costs are reduced.

The automatic venting increases the service life of the system components increases, reduces the susceptibility of actuators to flutter and the reliability and flight safety of the components as well as the entire system increased.

Further advantages, features and possible uses of the invention result from the single figure, which is described below.

1 shows an air separator according to the invention with an inflow line 2, the Uber lines 4 and 6 with a cylinder 8 in link stands. A check valve is located in each of the inflow lines 4 and 6 10, 12 and a throttle 14, 16. The lines 4 and 6 open into the cylinder 8 close to the dead center positions of a piston 18. Piston 18 can be in the cylinder move back and forth in the direction of the arrow; its drive will be explained later.

Opposite to the direction of gravity are located on the cylinder two outflow lines 20, 22, which in a common line 24 via check valves 26, 28 converge. Line 24 is in communication with an outflow line 30 which is shown in the upper part of FIG.

A piston 18 within the cylinder 8 is on the one hand with a working piston 32 connected, which is movable in a working cylinder 34. Working cylinder 34 system pressure pol is applied by means of a pressure medium line 36. At the other side is the piston 18 with a working piston designed as a control piston 40 connected, the cylinder 42 of which is connected via a line 44 to the line 36 stands. Working piston 40 is connected to a later by means of a line 46 to be explained switching valve 48 connected, with a line 50 via a throttle 52 both with the switching valve 48 and with a cylinder 42 of the piston 40 connected is. Finally, there is also a connecting line 56 between the cylinder 42 and the outflow line 30 are present.

The switching valve 48 is connected to the line 36 via a line 58 in connection and also has a connection to line 30. Of the Control piston 60 has different control edges and is on one side by means of a spring 62 biased. In line 46, which is in communication with switching valve 48, there is still a capacity 64. Finally, the switching valve 48 is about the Line 66 is provided with actuating piston 68, 70 for shut-off valves 72, 74. the Shut-off valves have lines 75, 76 that are free via check valves 78, 80 flow out.

Shut-off valves 72, 74 are provided via lines 82, 84 with vent valves 86, 88 in connection, which in turn are connected to lines 22, 20 already explained are.

In the following, the functionality of the air separation device will now be explained in more detail explained. The Luftabscheidegertit works on the principle of a bilateral effect Piston pump. Working piston 32 and control piston 40 are acted upon with high pressure oil and drive pistons 18 at an approximately constant speed. The area ratio of working piston 40 to working piston 32 is 2: 1. Since the working piston 32 always is connected to the system pressure po via line 36, with switching of the control piston 60 the piston 40 is pressurized and runs from left to right or not applied and then runs (pressed by piston 32) from right to left. Of the The sequence of the control cycle is described below.

The separation of the dissolved air from the pressure medium happens with Negative pressure in the ventilation space and shear gradient in the orifices 14 or 16. The controller. of the cycle is designed so that there is no dead center and the device in every position of the piston 18 starts up.

To explain how the air separator works, The following definition of terms is used: The discharge of the in the pressure medium is used as separation called dissolved air in the form of bubbles. As collecting is the guiding of the bubbles referred to as an air collection point and as excretion the process in which the collected air is expelled.

The separation takes place as follows: Between piston 18 and cylinder 8 working spaces 90, 92 are formed on both sides. The work area is considered 90 when the control piston 40 is driven at a constant speed. Pressure medium at a low pressure level now flows through the diaphragm 14 into the working space 90. The diaphragm is dimensioned in such a way that e.g. 11% less pressure medium enters the work area flows as volume is drawn up by the piston 18.

According to Hery's law, for weak solutions it is the gas uptake is proportional to the pressure at constant temperature.

The pressure medium, e.g. H 515, has 11% air at normal pressure (1 bar) solved. Is now in the working space 90 less pressure medium volume than Volume of work, this results in a vacuum (<1 bar), so that according to Henry's law, the Gas escapes and occupies the free volume. With 11% less pressure medium volume A pressure of 0.5 bar is established in the work area, as 5.5% air is from the pressure medium can escape and occupies the difference in volume of 11% at 0.5 bar.

The escape of the air from the pressure medium is caused by the shear gradient supported in the aperture 14. If there is less dissolved air in the pressure medium, then there is a low pressure in the work area. The process described then runs when the piston 18 moves from left to right. In the same way will this process causes if the piston 18 moves from right to left, then stab pressure medium flows in via orifice 16 and the gas content contained in it is also separated out.

After the separation, the released gas is collected. Here rise the bubbles open against gravity and form one at the highest point Foam rising to vent valves 86,88.

The gas is now eliminated. For this purpose, the collected Air-foam mixture when reversing the piston 18 via one of the vent valves 86, 88, the respectively open shut-off valve 72, 74 and check valve 78, 80 displaced into the open, if vent valve 86 or 88 closes, this is vented Pressure medium via the check valve 26, 28 by means of the line 24 to the return 30 supplied again.

While the procedure was explained in the previous part, according to which the air separator works, the control of the air separator is now described. It happens with the help of the aperture 52, the control piston 40 and the Switching valve 48.

In the switching position shown in the figure, the piston 32 is Uber pol supplied with a pressure po from the pressure supply. On the switching valve 48 has with (not shown) right-hand dead center position of piston 60 po3 after B passage, whereby the shut-off valve 72 is closed and the shut-off valve 74 is opened. At the same time, the control piston 40 is acted upon via the throttle 52 and line 50. Control piston 40 pushes piston 32 back against pressure pol via piston 18. If control piston 40 reaches connection po2 with its control edge, the switchover takes place.

If the control piston 40 has passage from po2 to A, then it becomes a switching valve 48 switched against the spring force 62 and connects B with R, the capacitance 64 Loading. The connection B with R at switching valve 48 becomes a shut-off valve 72 opened while shut-off valve 74 is closed. Piston 32 pushes over piston 18 and control piston 40 the volume 54 of the control piston 40 via the throttle 52 and the connection B with R in the return. The pistons 32 and 18 and the control piston 40 leave the end position. Control piston 40 also interrupts the connection p02 A. Hold the stored volume 64 Control slide 48 and covers the leakage losses in control piston 40 from A to R. If control piston 40 reaches the other end position, then A is connected to R, and the capacitance 64 discharges in the return.

The control piston 60 is moved by the spring 62 into the right switching position pushed. This establishes the connection from po3 to B and the switchover brought about again.

Pistons can be used to start up the air separation device without system pressure 32, 18 and control piston 40 are in each position. The control piston 60 is through the spring 62 held in the right switching position. The shut-off valve 72 is open and shut-off valve 74 closed.

The starting of the piston 18 from any position with system pressure is also possible. When the pressure po is applied, the piston 32 becomes direct and the control piston 40 via the switching valve 48 and the throttle 52 with pressurized oil applied. Valve 72 closes and valve 74 opens. Because of the larger area of the control piston 40 with respect to the working piston 32 moves the control piston 40 Pistons 18 and 32.

Starting from the switching position shown in the figure. With the concern of the pressure po, the piston 32 is acted upon directly. Over the control edges of the Piston 40 is connected to A po2, switching valve 48 is pressurized and memory 64 is filled. Control piston 60 blocks the pressure at po3 and connects Connection B with R.

Stop valve 72 opens and stop valve 74 closes. Piston 32 moves pistons 18 and 40. Blank page

Claims (3)

Potential claims: J Process for separating dissolved liquids Gases, characterized in that the space within a cylinder (8) by movement of a piston (18) becomes larger than the volume occupying the space of an inflowing Liquid, which reduces the pressure in space (90 or 92) and in the liquid dissolved gases are released and collect in one place. 2. Device according to for performing the method according to claim 1, characterized by a cylinder (8) in which two separated by a piston (18) Spaces (90, 92) are formed and connected on both sides with the piston (18) Working piston (32, 40), which cause the movement of the piston (18) through in the Inflow lines (4, 6) arranged near the dead center positions of the piston (18) for the liquid medium and valves (86, 88) to remove the gas separated from the pressure medium when the movement is reversed of the piston (18). 3. Device according to claim 2, characterized in that the working piston (32, 40) have different diameters and a working piston (40) as a control piston is formed, which is in communication with a switching valve (48).