DE7413801U - Device for generating dry compressed air - Google Patents

Description

PATENT Attorney DIPL-iNG. GERD UTERjMANN

71 HEILBRONN POST BOX 1145 Mottkestr. 6 (Deutsche Bank building) Parking: Harmonie underground car park © (071 31) 82828 cable: PATU

Utility model registration

Deutsche Bank Hoilbronn: 354 364 Handelsbank Heiibronn: 23080 5 Kreissparkasse Heilbronn: 7001 6 Post check Stuttgart: 43016-704

D 12. 22 D April 19 / 3rd ^.

Applicant: Company

Dürr - Dental KG.

D-712 Bietighein

Etzelstrasse δ P.O. Box

Designation: Device for generating dry compressed air

Description:

The invention "relates to a device for generating dry compressed air with a Druckluitquelle, which übo; an adsorption filter feeds a compressed air container, and with return devices for returning dry compressed air through the adsorption filter to regenerate the same when the compressed air source is switched off.

./2

-6. Nov 1975

D 12. 2 D 23
3.4.74 / 6K

When compressed air is generated by sucking in and compressing air from the atmosphere, the known physical relationships result in compressed air which is oversaturated with water vapor, which leads to the formation of condensation which has to be removed from the system. After the condensation water has been discharged, however, compressed air still remains, which is saturated with water vapor, so that condensation water is produced again when the temperature drops slightly. Furthermore, with the usual systems for generating compressed air, as used in many companies, it is generally unavoidable that some of the grease and oil used to lubricate the compressor get into the compressed air, and that the compressed air also contains dust particles and microorganisms which are sucked in together with the atmospheric air by the compressor. In many cases it is acceptable for the compressed air to be relatively humid and dirty. This applies in particular where relatively robust compressed air units are to be driven or where the compressed air is used, for example in car repair shops, to clean machine parts. On the other hand, there is a whole range of applications in which dry, dust-free and germ-free compressed air is required. This applies primarily to the use of compressed air in the medical sector, for example to drive drilling turbines for dentists. The situation is similar with sensitive pneumatic controls, in which the formation of condensation water and the appearance of dust particles would cause malfunctions. The presence of oil and grease residues in the compressed air is also often not permissible, since such residues can lead to malfunctions or, for example, in the

• / 3

D 12. 2 D 23 / Jf)

3.4.74 / 6K / ^{/ c- /}

- 3 -

Dentistry, can become a nuisance to smell and taste for the patient.

In view of the frequent demand for very clean and, especially in the medical sector, also more sterile Dry compressed air systems have already been used to generate dry air developed, in which by combining at least one adsorption filter with other filter devices for filtering out solids and oil residue with regard to the quality of the dry compressed air very favorable results can be achieved.

Such a system is described, for example, in British patent specification 1 238 325, where the compressed air supplied by a compressor is fed to an adsorption filter after passing through an oil and water separator, in which further mechanical filtering and very intensive drying takes place. In the known Trockenluftanlagc a compressed air tank and an auxiliary tank are fed from the outlet of the adsorption filter. The auxiliary tank is used to hold a specified amount of compressed air, which is returned to the atmosphere immediately after the compressor has been shut down, depending on the reaching of a specified maximum pressure in the compressed air tank through the adsorption filter and a branch opening provided in the area of the oil and water separator. The dried air flowing out of the auxiliary tank regenerates the adsorption filter to such an extent that after the auxiliary tank has been emptied, the operating conditions are essentially the same as at the beginning of the previous working cycle of the compressor. The well-known system fails ever do Oh ₁ if the compressed air tank over a longer period of time

7413801 **** - ^{6 1 011 1975}

D 12. 2 D 23 . _A.

/ y / y

Time larger amounts of compressed air are taken, because In this case, the compressor runs for a very long time without the adsorption filter being regenerated in between would take place. In addition, the known system is very unfavorable insofar as it changes environmental conditions, such as fluctuations in temperature and humidity can not be taken into account, so that the amount of air in the Auxiliary tank too big for most cases, for some cases however, it is too small to bring about sufficient regeneration of the adsorption filter, which on the one hand leads to an unfavorable efficiency and on the other hand to fluctuations in the quality of the compressed air in the compressed air tank leads. Similar problems arise with those systems that work with two adsorption filters, which is generally used and regenerated alternately for filtering and drying with the help of a time control will. Such a system with two Adsorptionsfiü tern is described in German patent 1,282,608, for example.

Proceeding from the problem set out above or from the prior art explained above The invention is based on the object, with the same or improved compressed air quality among the most varied Environmental and working conditions to adhere to tight tolerances for the moisture content of the compressed air and at the same time to reduce the technical effort and to improve the efficiency of the device.

This object is achieved by a device of the type described at the outset, which is characterized according to the invention in that the return devices are a function of the humidity of the compressed air, im

./5

7413801 t * «A-6. Nov, 1975

D 12. 2 D 23
3.4.74 / 6K

Compressed air tank include actuatable valve.

This has the advantage that a regeneration cycle is only initiated if this with regard to the already recorded by the adsorption filter Amount of moisture actually exists. Unnecessary regeneration cycles are avoided, which means the efficiency of the device is improved.

If the dry compressed air to regenerate the adsorption filter is taken from the compressed air tank in a further development of the invention, from which the working air is also taken, then there is the further advantage that an additional auxiliary tank can be dispensed with, which is costly and in terms of space requirements as well as in terms of the required Line and valve devices δχχ. leads to significant savings.

It has proven to be particularly favorable if the valve is operated via a sensing element, the dimensions of which change depending on the humidity, so that the changes in shape of the sensing element can be used more or less directly to open and close the valve without the interposition of electromechanical transducers or the like would be required. In this context, sensing elements in the form of plastic straps have proven to be very advantageous, since the change in length of such a plastic strap depending on the moisture content of the compressed air in the compressed air tank, especially when using a suitable lifting mechanism, can be used very easily to actuate one of the valve elements.

7413801t * "!" -6N0V. 1975

■ ^J3

- 5a -

Either a compressor can serve as the compressed air source for the device according to the invention a normal compressed air connection, which is already available at the workplace in question, but compressed air Inadequate quality supplies, which additionally have to be cleaned and dried in order to avoid the special features mentioned above Use cases to be used.

Further details and advantages of the invention are provided below explained in more detail with reference to a drawing and / or are the subject of the claims for protection. In the drawings show:

T shows a schematic representation of a device . for generating dry compressed air;

2 shows an enlarged illustration of a longitudinal section through the adsorption filter of the device according to FIG. 1 and through an associated valve arrangement and

5 shows a basic illustration of a valve for the device according to FIG. 1, which can be actuated via a moisture-sensitive sensing element.

The device shown in Fig. 1 comprises a compressor 10 with a motor 11 as a compressed air source, which is followed by a cooling device 12. It goes without saying that then _; if a conventional compressed air connection is used as the compressed air source, a cooling device can be dispensed with. Downstream behind the cooling device 12 is a valve arrangement 14, which usually comprises an oil and water separator and which has a branch opening 16. Behind the valve arrangement 14 is a filter 18 which, as is clear from FIG. 2, comprises an adsorption filter and additional mechanical filters. The filter 18 is connected to a compressed air tank 22 via a further valve arrangement 20. As long as the compressor 10 works or as long as it takes place

./6

II «· · · ♦ II«

■ ι ti * * ♦ · »·! I III «I ■. I · ·, ^f '

D 12. 2 D 25/24
3.4.74 / 6K

whose intended compressed air connection is open, the uncleaned compressed air flows after cooling and pre-cleaning in the valve assembly 14- through the filter 18 where they n'sitsr cleaned and dried, ülDsr the zv / eilie Valve arrangement 20 in the compressed air tank 22. During this operating phase, the device works according to Pig. 1 in The usual way and essentially using conventional components or assemblies, on their ins detailed explanations should therefore be dispensed with at this point. As soon as the compressed air tank 22 a corresponding pressure has built up, the compressor 10 is connected via a pressure switch 24 »the with the compressed air tank 22 is switched off.

While now in the known device of the type described above, which with a single adsorption filter work, after switching off the compressor 10 sivto— a regeneration cycle is automatically initiated, in the course of which a predetermined amount of dry compressed air is passed through the filter 18 and via the branch opening 16 of the valve arrangement H is blown off into the open, is the second in the device according to FIG. 1 Valve arrangement 20, as will be explained in more detail below, designed so that a regeneration cycle is only initiated when the humidity of the compressed air in the compressed air tank 22 a predetermined upper Limit value reached or exceeded. Furthermore, the compressed air required to regenerate the filter 18 is direct taken from the compressed air tank 22 and not from an auxiliary tank, as happens in the case of prior art devices.

The filter 18 and the valve arrangement 14 are in a preferred embodiment of a device according to

7413801 t «w» = - & Nov. 1975

fr I i

D 12. 2 D 23/24. '

3.4.74 / 6K IL

Pig. 1 combined into a structural unit, which in Pig. is shown _> which also shows the cooling device 12 and part of the second valve arrangement.

The unit according to Pig. 2, when the compressor 10 is working, compressed air is supplied via a supply line 26. The compressed air is relauiv hot due to the compression process and reaches temperatures C. Since the cleaning and drying can be carried out of the compressed air only from temperatures of about 60 ⁰ C, the compressed air must first be cooled to that temperature up to about 115 ^0th This takes place in a cooling coil 28 which wraps around the adsorption filter 30, which is interrupted in the drawing, over its entire length. The cooled compressed air passes from the cooling coil 28 to the inlet opening 32 of the valve arrangement 14. The valve arrangement H initially has a cyclone-like oil and water separator 34 in connection with the inlet opening, in which the compressed air, which after cooling in the cooling coil 28 is oversaturated with condensation products is cleaned, which collect at the lower end 36 of the pre-separator or the oil and water separator below a baffle plate 38.

The oil and water separator 34 is located in one Chamber which is closed at the top by a membrane 40. On the underside of the membrane facing the chamber a valve stem 42 is attached which cooperates with a valve seat 4-6 at the lower end 36 of the chamber. Valve tappet 42 and valve seat 46 together form the closable branch opening 16 of the device according to Pig. I.

./8th

-fcNov. 1975

D 12. 2 D23 / 24
5.4.74 / 6L

At the top. End of the chamber, which contains the oil and water separator 34 contains, an outlet channel 48 is provided, which via a filter screen 50 to various inlet valves the valve assembly 14 leads. A total of four individual valves 52 to 55 are provided, their function will be explained below.

The individual valves initially include a suction jet nozzle arrangement, which will hereinafter be referred to in the usual way as a Borda nozzle 52. The nozzle opening of the Borda nozzle 52 is surrounded by a chamber 55 'which is connected to a cavity 58 above the membrane 40 via a connecting line 56. When compressed air flows into the valve arrangement via the inlet opening 32, a negative pressure arises in the chamber 55 ', which acts on the upper side of the membrane 40 via the connecting line 56 and the cavity 58 and thus sees the valve tappet 42 against the valve seat 46. The compressed air supplied by the compressor 10 can therefore not escape through the branch opening 16. Parallel to the Borda nozzle 52, there is a second individual valve, a 3ypasn valve 53, which opens when a pressure drop of about 0.1 bar is reached, so that there is only a slight pressure loss even with larger quantities, while the Borda The nozzle 52 maintains a pressure difference of approximately 1 bar between the upper side of the membrane and the lower side of the membrane during the entire crater cycle. The further individual valves 54 and 55 normally remain closed while the compressed air tank 22 is being fed by the compressor 10. The outlet opening 60 of the valve arrangement 14 is located behind the individual valves 52 to 55.

D 12. 2 D 25/24
3.4.74 / 6K

The pre-cleaned ue saturated passes from the outlet opening 60 Compressed air through a further filter screen 62 into the adsorption filter 30. At the upper end of the adsorption filter 30, the dried compressed air passes a sintered filter 64 and a post-filter 66. Finally, the air passes out of the filter 18 via a line 68, in which a check valve 69 is provided to the compressed air tank 22. The check valve 69 is part of the further valve arrangement 20 in FIG. 1. A valve 70 is connected to the compressed air tank 22, which is shown in FIG. 3 and which is part of the second valve arrangement 20. The outcome of the Valve 70 is connected via a return line 72 to the filter 18, ur-.d with a filter to be described further below Filter head 74 of the same connected.

The valve 70 contains a plastic band 76 as an actuating element, for example made of a suitable polyamide, which expands as the humidity of the compressed air stored in the compressed air tank increases. The plastic band 76 is firmly connected at its one end 78 to the valve housing of the valve 70 and at its other end 80 to the free end of an angle lever 82 which can be pivoted about a pivot point 84. The upper leg of the angled lever 82, facing away from the plastic band 76 and running horizontally in the drawing, carries a seal, for example in the form of a rubber plate 86, through which a valve opening 88 can be closed. The leg of the angle lever 82 carrying the rubber plate 86 is plate-shaped in the case of the valve 70; it is acted upon by the pressure inside the compressed air tank 22. To compensate for these compressive forces, a compressive force acts on the upper side of the plate-shaped leg.

./10

7413801 * «** -6. Nov 1975

D 12. 2 D 23/24 ^

3.4.74 / 6K _ΊΟ

- 10 -

spring 90. The plastic ribbon 76, the length of the lever arms, the area of the gunnais plate 86.bearing The lever arm and the compression spring 90 are dimensioned so that the rubber plate 86 / m the compressed air tank 22 a Reached predetermined humidity, the valve opening 88 releases, so that now a regeneration cycle can be initiated as soon as the compressor 10 is switched off and the branch opening 16 is open.

When the compressor 10 is switched off, a first occurs Pressure equalization between the top and the bottom of the membrane 40, since the Borda nozzle 52 because of the lack a current no longer has a negative pressure over it Cavity 58 can be maintained. After pressure equalization has taken place, the valve tappet 42 lifts from the valve seat 46 from, so that the branch opening 16 is now open is. Through this opening, which is advantageous a silencer is connected downstream, flows first the oil-water mixture collected during the charging process to the outside. Then flows into the Filter remaining compressed air to the outside via the third individual valve, which is designed as a shut-off valve 54 is. If the valve 70 is closed at this time, that is, if the compressed air in the Compressed air tank 22 is still so dry that no regeneration of the adsorption filter 30 is required, then the pressure in deir adsorption filter 30 drops as well in the valve assembly 14 from about atmospheric pressure, and the system is at rest until the pressure im Compressed air tank 22 exceeds a lower limit value, whereupon the compressor 10 is started again by the pressure switch 24. As soon as air out of the Compressor flows into the oil-water separator 34,

./11

7413801 ⁶ * ¹¹⁹⁷⁵

D 12. 2 D 23 / 24-

3.4 «74 / 6K j Cj

- 11 -

the membrane 40 is suddenly raised and the branch opening closed, so that the compressed air after passing through the filter 18 finally via the line 68 is pumped back to the compressed air tank 22.

If, on the other hand, the valve 70 is open when the * compressor is switched off, there is a flow after the pressure equalization and the Open the branch opening 16 dry compressed air from the compressed air tank 22 into the adsorption filter 30, which this is regenerated. The regeneration cycle ends as soon as the compressor starts up again.

If the compressor 10 interrupts its operation only very briefly, for example for a time of less than 5 seconds, as is the case with short-term power interruptions in the control circuit of an electric motor driving the compressor the Pail can be, then there is a risk that the pressure in the valve arrangement H and in the filter 18 has not yet dropped to the atmospheric level Case, the compressed air conveyed by the compressor 10 cannot raise the membrane 40, so that without special Take precautions when the branch opening 16 would settle into a state of equilibrium in which practically all of the air conveyed by the compressor 10 would escape through the branch opening 16. To that to prevent a fourth individual valve in the form of a pneumatic against the pressure of a return spring b ^ - operable shut-off valve 55 is provided. The check valve can, as indicated in the drawing, in a housing a kind of piston ^ oesitz, which on its upper side over a connecting line 92 is connected to the outlet port 60 of the valve assembly 14 and thus from the Pressure in the filter 18 is applied. Against the bottom

./12

D 12. 2 D 23/24
3.4.74 / 6K

- 12 -

the piston acts a compression spring 9 ^ As soon as the pressure at the top of the piston falls below a certain lower limit value, 94 the spring pushes the piston SC upward and thereby gives a connection between the cavity 58 on top of the diaphragm 40 and a throttle valve 98 free , which opens into the open. This ensures that when the compressor 10 starts up again after a short interruption, the necessary pressure difference between the two sides of the membrane 40 is created very quickly, so that the branch opening 16 is safely closed after a short start-up phase, whereupon the delivery of compressed air to the Compressed air tank 22 can be done. On the other hand, the shut-off valve 55 in no way hampers the return of compressed air from the tank 22 through the adsorption filter 30, since only small amounts of air at low pressure flow through the valve arrangement during the regeneration phase, so that pressure equalization between the two sides of the membrane 40 is always ensured . It has also proven to be favorable if the shut-off valve 55 contains a membrane instead of a piston which, when the pressure at the outlet opening 60 of the valve arrangement 14 is sufficiently high, closes a valve opening that leads to the throttle valve 98 and releases this valve opening as soon as it decreases Pressure is lifted from the valve opening by a compression spring.

As already mentioned · _v of the adsorption filter 30 is provided a special filter head 74 at the upper end, which has in its inside a cavity in which the Nachfiliür is 66, at which the sintered filter is arranged 64th Through this filter-

7413801 <ΜΒΘΓ - Nov. 6, 1975

D 12. 2 D 23/24
3.4.74 / 6K

- 13 -

The feed line 26, through which the hot compressed air from the compressor 10 flows, is passed through the head 74. This viuuuxuu ιια «uuii ΐνχ vw ^. ^., Νιο» üS · I ^. »« Uiuv ^. j; τ- v: ^

running compressor 10 is heated, so that the incoming via the return line 72 compressed air is heated during the regeneration phases and thus has an improved drying effect. From the above it becomes clear that FIG. 2 with respect to the arrangement of the lines 26 and 72 in the pilter head 74 only is very schematic, and that in practice the lines mentioned are laid in such a way that calibration a optimal heating of the pilter head 74 and optimal heat transfer to the return line 72 results.

Another advantage of the construction according to the invention it is to be seen therein that parts of the valve arrangement are säiat-liGiie 14 are housed in a single block, which is preferably made of a material that conducts heat well, such as aluminum, so that there is practically no Temperature gradient results. This is essential as adsorption filters are very effective against oversaturated compressed air are sensitive. The construction of the filter H under consideration means that it is behind the oil-water separator 34 practically no further cooling of the compressed air occurs, so that the adsorption filter 30, which is directly connected to the housing block of the filter arrangement H, saturated and none oversaturated compressed air is supplied. The compact structure of the filter 18 and the valve assembly 14 in shape a single structural unit thus relieves the load on the adsorption filter 30 or reduces it Regeneration times and an overall higher

./14

-6. N nv. 1975

D 12. 2 1) 25/24
3.4.74 / 6K 19.4.1

Life expectancy of the adsorption filter. Moreover, brings the considered construction of the valve arrangement H den YoT-tei? r "it- itself. that with the existing pneumatic Pressure or with the pressures derived therefrom, all valve functions can be controlled, so that additional Control devices, in particular electrical ones Control devices, can be dispensed with. Especially the waiver of additional electrical ones Control devices prove to be very advantageous, since the device is now regardless of the different national and international regulations with regard to electrical safety and independent of the different mains voltages and -frequencies can be shipped fully assembled to a wide variety of countries * Must be on the spot only a suitable compressor "or a suitable drive motor for the compressor or another compressed air source to be available.

Finally, it should be noted that it is cheap is to provide a throttle valve in the return devices, with the help of which the return into the adsorption filter Air can be largely relaxed in order to make optimal use of the regeneration air and thus a to achieve high efficiency. The effect of a Dr.sselventiles has, in the exemplary embodiment under consideration, the valve opening 88, which is so narrow and, for example, only has a diameter of 0.75 mci that the pressure in the Adsorption filter 30 during the regeneration phases Atmospheric pressure only slightly exceeds.

Furthermore, it is advantageous in devices with and, above all, without a compressor, directly at the inlet opening to provide a connection piece for a compressed air connection, because when supplying compressed air from a compressed air network, the Compressed air does not have to be cooled.

.ß Μην

Claims (1)

1 * Device for generating dry compressed air with a compressed air source which feeds a compressed air tank via an adsorption filter, and with return devices for returning dry compressed air through the adsorption filter to regenerate the same when the compressed air source is switched off, characterized in that the return devices are a function of the Moisture of the compressed air in the compressed air tank (22) comprise actuatable valve (70). 2. Apparatus according to claim 1, characterized in that the valve (70) over a sensing element (76) can be actuated, the dimensions of which change as a function of humidity. ./2 -6. N ov, 1975 D 12. 2 D 23
19-4-.74 / 16K 3. Apparatus according to claim. 2, characterized ^e ~ g denotes that the i;? Hlelernent a plastic tape (76) whose County ^ e increases with increasing moisture. 4. Apparatus according to claim 3, characterized. marked calibrates that the plastic band (76) on a lever mechanism ·. (82, 84-) acts, with the help of which a seal; selement (rubber plate 86) with regard to a valve opening (88) to close and open the same is possible. 5 · Device according to one or more of the claims 1 to 4, characterized in that the compressed air to regenerate the adsorption filter (30) comes from the compressed air tank (22). 6. Device according to one or more of the claims 1 to 5, characterized in that the valve (70) between the compressed air tank (22) and the adsorption filter ¹ (18, 30) is arranged. 7. Device according to one or more of the claims 1 to 6, characterized in that that the valve contains a compression spring (90) which acts on the sealing element (rubber plate 86) or the parts connected to it v / irkenden pressure of the compressed air from the compressed air tank (22) at least partially offsets. 8. Device after einir. or more of the claims 1 to 7, characterized in that the compressed air source is a compressor (10). ./3 D 12. 2 D 23 19.4.74 / 16K -C - 3 - 9. Device according to one or more of claims 1 to 7, characterized in that that a connection piece for connecting a normal compressed air connection for relatively humid and / or polluted Compressed air is provided as a compressed air source. 10. Device according to one or more of the claims 1 to 9 »characterized by that between the compressed air source and the compressed air tank (22) at least one mechanical filter (50, 62, 641 66) is provided. 11. Device according to claim 10, characterized in that that a mechanical filter in the form of a sintered filter (64) is provided. 12. The device according to claim IG, characterized in that that mechanical filters in the form of filter screens (50, 62) are provided. 13. Device according to one or more of the claims 1 to 12, characterized in that between the output of the compressed air source and the The inlet of the adsorption filter (30) is provided with a valve arrangement (14) with an oil / water separator (34) is. 14. Device according to one or more of the preceding claims, characterized in that that the Druckluitquelle is a compressor (10), and that zv / ischen the output of the Compressor (10) and the Singang of the adsorption filter (30) a cooling coil (^ 8) is provided. ./4 D 12. 2 D 23 Γ 3.4.74 / 6K 19.4. \ j 15. The device according to claim 14, characterized in that that the cooling coil is filled by a heat sink (Filttrkuyx 74) is, and that the return means comprise a return line (72), which also through the Heat exchanger (PiIterkopf 74) is led * to the to heat the regeneration of the adsorption filter (30) serving compressed air. 16. Device according to one or more of the preceding claims, characterized in that that a valve assembly (14) is provided which is pneumatically operated by the Compressed air source generated pressure and derived therefrom Pressures is controllable. 17 · Device according to claim 16, characterized in that the valve arrangement (14) an oil-water separator (34) and several individual valves in a common housing block (52 to 55). 18. The apparatus according to claim 17, characterized in that the housing block of the Valve arrangement (14) is mounted in the immediate vicinity of the adsorption filter (30). 19. Device according to one or more of the claims 1 to 18, characterized in that that the return devices have a throttle valve for releasing the pressure returned to the adsorption filter (30) Contain air at a pressure close to atmospheric pressure. ■ / 5 D 12. 2 D 23 19.4.74 / 16K - ■ τ 20. The device according to claim 19, d a d u r c h characterized, that the throttle valve through the 'very narrow valve opening (88) of the moisture-dependent controlled valve (γη) is formed. 21. Device according to one or more of the preceding claims, characterized in that that a valve housing with an interior space is attached to the compressed air tank (22), which communicates with the interior of the compressed air tank via a channel and in which a sensing element (76) is arranged, whose dimensions change depending on the moisture and due to its changes in shape a Opening and closing a valve opening (88) in the Valve housing can be guided. , 1975