DE2413060A1 - PRESSURE TRANSLATORS, ESPECIALLY FOR LOAD-DEPENDENT COMPRESSED AIR BRAKES OF RAIL VEHICLES - Google Patents

Description

Munich, B.3.7if

Fte ^8c

KNURR - BREMSE GmbH, B Munich 40, Moosacher Str. 80

"Pressure intensifiers, especially for load-dependent air brakes on rail vehicles."

The invention relates to a pressure intensifier according to the preamble of claim 1. Such pressure intensifiers are known, for example, from DP-AS 1 052 ITM and 1 137 kT5.

For lastsbhägige air brakes of rail vehicles animal exploitable pressure range is limited by the following criteria:

The maximum final pressure of the brake cylinder when the vehicle is fully loaded is to be selected so that there is still a sufficient pressure gradient from the air reservoir to the brake cylinder. According to international agreements, the highest pressure that occurs on the vehicle and therefore also the maximum pressure in the air reservoir is generally 5 bar . Of? _{Brake cylinder - maximum pressure is limited to 3 Γ} Θ bar without taking into account the pressure drop that occurs in the air reservoir when the brake cylinder is being filled. The smallest Brerns cylinder final pressure in an empty vehicle is to be ground in such a way that there is sufficient stepability for individual braking levels, according to international agreement

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must be controllable at least 5 braking levels is given. The known pressure intensifiers require a pressure step from brake stage to brake stage of at least translate pressure 0.2 bar; If these steps are selected smaller, the inevitable friction and hysteresis conditions cause the .Pressure intensifiers a / eruischen the individual braking levels, i.e., the successive pressure levels of the print to be translated do not result in pressure levels on the translated print, but rather only its gradual and creeping change. This is often not enough, the static friction in the pressure intensifier downstream parts, such as the brake cylinder and the brake linkage, to overcome; on the friction brake itself there are only a few, sudden and imprecise changes in force during the Go through the individual Brernsstufsn.

Taking these circumstances into account, the smallest brake cylinder with the known pressure intensifiers - final pressure of 1 bar C corresponding to 5 χ 0.2 bar) and the transmission ratio - The range of the pressure intensifier is limited to 1: 3.8. But this is not enough for modern vehicles; these require a gear ratio of approx. 0.55: 3, B.

The invention is based on the object of providing a pressure booster according to the preamble of the main claim, which _; even when its transmission ratio is set to low, translated output pressures and only minor changes are introduced

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causes the inlet pressure to be translated unique, appropriate modifications of the translated output pressure, these changes tjobei the output pressure to overcome hysteresis and friction phenomena in the pressure booster nachgsDrdnsten devices be suitable sills. The pressure booster should only require little construction and should only contain common, tried and tested components.

This object is achieved according to the invention by the features mentioned in the characterizing part of claim 1.

The inventive design results each time the translatable pressure an excessive change of the translated pressure, which then on the respective decays rapidly transmission ratio corresponding change, the pressure booster that has an over-· or understeer on. This control behavior of the pressure booster ensures that every change in the pressure to be translated is quickly and precisely followed by a change in the translated pressure which is sufficient to overcome resistances in devices downstream of the pressure booster and thus cause these devices to make appropriate changes.

There are already known pressure intensifiers according to the preamble of claim 1, the two on the side of the return piston Calf parts that can be coupled via a stop coupling if necessary

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have (DT-PS 1 279 710) and which among those for rail vehicles the described conditions in the final result related to the friction brake, with a sufficient transmission ratio range, always a good gradation of the actuation force of the friction brake ensure, but these intensifiers have one of the invention has different loading and a different work behavior without UbBr- or understeer phenomena. Additional equipment is also required.

Advantageous embodiments of the pressure booster according to the patent claim 1 aind can be found in the subclaims.

For pressure intensifiers with a balance beam as a transmission gear, at one end of which the control piston and the other end of which the return control piston is hinged, as is known from DT-AS 1 137 * »73, results from the features of claim k in conjunction with the features of the preceding claims, a particularly simple, compact structure of the pressure booster requiring few individual parts and operations.

Furthermore, the embodiment according to claim 5 grants the special The advantage is that, regardless of the absolute pressure level of the translated pressure, the level of the over or above pressure changes in the event of pressure changes. Understeering always remains constant, limited by the check valve.

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Finally, an embodiment according to claim 7 ensures that even when the transmission ratio is set to very low, translated output pressures at the beginning of a pressure control the pressure intensifier always controls a certain minimum pressure, which is necessary to overcome resistances in the pressure intensifier downstream devices bsi their conversion from the rest the working position serves. From the DT-PS 1 6Q5 25 <+ is one such low construction costs require two arrangements for one different types of pressure intensifiers known.

The drawings serve to explain the function and structure of exemplary embodiments of pressure intensifiers designed according to the invention.

Show it:

Fig. 1 is a diagram of a known pressure intensifiers - constructions;

Fig. 2 is a pressure diagram of a pressure booster of the invention;

Figure 3 illustrates schematically a pressure intensifier with its classification in a brake system.

FIG. K shows a modified detail on an enlarged scale and FIG

Fig. 5 · schematically another embodiment of the pressure intensifier.

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In the diagrams according to FIGS. 1 and 2, the abscissa is Time t and on the ordinate, starting twice from idert zero, a pressure P is applied. The line C represents the stepped pressure curve of the vam pressure intensifier to be translated Pressure, the line C is the one supplied by the pressure intensifier, translated output pressure when setting the pressure intensifier to a lowest output pressure resulting transmission ratio From Figure 1 it can be clearly seen that with a clearly graded change in the pressure to be translated C, in eight steps from zero to 3.8 bar, the translated pressure C changes between zero and approx. 0.6 bar without any noticeable step formation. The known pressure intensifiers are not able to provide individual pressure levels specified in the line C of the pressure to be translated to recreate in the translated print C.

Through the training according to the invention it is, as already warned, an over or under control of the translated pressure is achieved. According to FIG. 2, the pressure curve C corresponds to the one to be translated Pressure the pressure curve according to Figure 1; from the line C of Figure 2 it can be seen that the over- or under-control of the translated pressure makes each pressure level appear very clearly. The at the beginning of each pressure stage, for example the Pressure stage C _, occurring in the course of the line C according to Figure 2, considerable pressure change quickly decays to the respective setpoint of the pressure stage, but it causes a clear delimitation of the individual pressure levels from one another and enables these devices to be overcome in the pressure intensifier adherent resistance to misrepresentation,

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so that these devices are also able to follow the individual pressure levels. At any pressure level with the total pressure height C " should denote the total pressure head during the override with C. be.

According to FIG. 3, a balance beam 2 is located in a housing i of the pressure intensifier, which is supported in its central area by means of a sliding block 3 as a pivot bearing. The sliding block 3 divides the balance beam 2 into zuei sections with dsn lengths a and b. In the housing 1 there is a fixed sliding track k on which the sliding block 3 can be adjusted by means of a rod 5 according to the arrow 6 in the longitudinal direction of the balance beam 2. At one end of the balance beam 2 sin control piston B is _{articulated with the effective piston area A 3} via a rod 7. The control piston θ delimits a pressure chamber 9, which is filled via a line 10 by the pressure C to be translated. Opposite to the control piston β engages the same At the end of the balance beam on the side of the sliding block 3, a valve tappet 11 of a Dappeiventiles 12, which comprises an EirilaBventilteil 13 and an outlet valve part 14. The inlet valve part 13 monitors the connection of a space 16, which is constantly connected to a compressed air source via a line 15, with a space 17 containing the translated pressure, and the outlet valve part 14 monitors a connection between the space 17 and the atmosphere. At the other end of the Uaagebalkens 2 is on this via a piston rod 18 Bin return piston 19 angslsnkt, in such a way that exercises control piston 8 and the return control piston

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act against each other via the balance beam 2.

The return control piston 19 comprises a desn balance beam 2 closer Piston part 21 and a coaxial, more distant piston part 22, with the piston part 21 being its larger effective piston area A and the piston part 22 has a smaller effective piston area A_ has. One between the two Koib parts The pressurization space 23 located in and 22 is at least virtually unthrottled with the space 17 via an air duct 24 tied together. The one with the smaller effective calving area A_ Calf part 22 is pierced by a nozzle 25 which defines the application space 23 connects to a further loading space 26 lying on the other side of the calf part 22.

BbI Classification of the pressure intensifier in a load-dependent controlled one The compressed air brake system of a rail vehicle is the line with a connection that carries a brake pilot pressure Brake control valves 27, the line 15 with an air storage tank and to connect the space 17 to a brake cylinder 30 via a line 29. The brake control valve 27 is also as usual with the supply air tank 28 and a main air line controlling it 31 in connection. The sliding block 3 is in this case by means of the rod 5 by devices not shown in one of the respective Vehicle load corresponding position set.

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2A13060

In the steady state, the function of the pressure intensifier corresponds the one that is usual and known for pressure intensifiers with balance beams Functionality:

A corresponds to a certain pressure C in the application space S certain pressure C in the application space 23 and in space 17, where, if this pressure should change due to some influences ^ These changes in pressure C are counteracted via the double valve 12 will. The ratio of the two pressures C and C to one another is the ratio of the areas of application of the control piston and the reverse control piston 19 as well as the one set via the sliding block 3 The ratio of the lengths a and b of the balance beam (2) depends.

In the pressurization space 9, there is a pressure increase of a certain amount Pressure stage, as shown for example in Figure 2 in the line C, fed, the balance beam 2 is around the Slide block 3 swiveled to open the inlet valve part 13. the end Compressed air flows into space 17 and pressurization space 23 from space 16 and increases the pressure prevailing in these spaces, until this increase in pressure on the difference area between the two calving surfaces A. and A ^ of the two piston parts 21 and 22 acting on the total area A- of the control piston is sufficient to counteract the pressure increase in such a way that the balance beam 2 in its illustrated position with closing ι of the inlet valve part 14 returns. Builds with a time delay via the nozzle 25 the pressure increase thus fed into the loading space 23 also in the loading space 26; thus this becomes

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Pressure increase also for the piston area A "of the return piston Ultimately, the return control valve 19 exerts an increasing force on the Balance beam 2 and rotates it in the direction of opening the Outlet valve part 14 of the Deppelventlies 12. The pressure increase It is thus conveyed to the atmosphere through the air outlet from room 17 dismantled until the action of the return control piston 19 via dia Piston area A is just sufficient to act on the control piston β to keep the balance. At this moment, at one between the original pressure and the one immediately before excessive pressure lying pressure in the pressurization space 23 ^ the Itlaagebarken 2 rotates while closing the outlet valve part 14 back to its normal position, which is again a stationary position State reached in which the pressures prevailing in the admission spaces 9 and 23 in the aforementioned ratio to one another stand.

In detail, the following conditions arise during the above-described processes in the pressure intensifier: If a pressure increase to the final pressure C "is fed into the pressurization chamber 9, starting from a lower pressure, for example the preceding pressure stage of the C line according to FIG initially as a translated pressure a pressure altitude C ₁ , which can be derived from the equation

C _y . A ₃ . a - C ₁ . (A ₁ -A ₂ ). b

is calculable. After the pressure in the pressurization chamber is adjusted to the pressure in the pressurization chamber 23 via the nozzle 25

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there is an equilibrium when the translated pressure has decreased to a liiert C_ according to the following equation:

C β A_ ■ »B ~ C«. A _- ,. b «

the override can be calculated from the two equations given of the translated pressure when changing the pressure to be determined

The size of the override is thus determined by the bottle ratio ApSA ₁ and the print height of the translated print.

If the pressure drops in the admission space '9, corresponding reverse processes and relationships. A description of the function can therefore be omitted.

It can be desirable that the over or under control of the pressure booster at high pressures is not greater than at low pressures, and in particular remains limited to a certain value. Such a function can be achieved in accordance with FIG h by designing the return spool 19th The loading spaces 23 and 26 as well as the lever part 21 correspond to the embodiment according to FIG. 3. In the double-ended part 22 'of the return valve, next to the nozzle 25, two large cross-sectional openings 32 and 33 are provided 36 loaded check valve 3k or 35 is used. So as soon as a pressure difference occurs between the Beauf-SGhlagungaräume 23 and 2Q, which

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the retaining pressure of the check valves determined by the springs 36 34 and 35, one of the two non-return valves 34 and 35 opens and enables a rapid inflation of air. outflow in or out of the Aufufschlagungsraum 26 a limitation of the Pressure difference to the retention pressure of the check valves 34, 35 is referred to as the retention pressure of the check valves 34 and 35 with Δ G, the following conditions of equilibrium result for the pressure intensifier:

Before a pressure equalization between the sea impact rMumen 23 and 26 through the nozzle 25 applies

C _v . A ₃ . H = (C _1. A ₁ -AC A _? ). b and after pressure equalization

C _v . A ₃ . a = C ₂ . A ₁ . b The override is therefore

it is therefore because Δ C is in any case smaller than the smallest input The pressure level must be constant and independent of the prevailing application pressure level.

With the corresponding area ratio Ä.: A "of the retention pressure Δ. C and the QrSBe of the nozzle 25 can be the pressure booster the respectively desired oversteering or understeering behavior be adjusted.

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The piston parts 21 and 22 do not have to be attached coaxially sn to a piston rod 1ß; as seen in Figure 5, it is also possible to dissolve the reverse control calve in two separate piston rods 18 * and 18 * 'acting on different points of the scale beam 2 separate flask, 19' and 19 ^M. The air duct 2h opens into the one loading space 23 'of one piston 19' and the other loading space 26 'is connected to this via a nozzle 25 ¹ in a partition between the two loading spaces 23' and 26 '. The rest of the structure and the mode of operation of the pressure booster correspond to the embodiment according to FIG. 3.

It may be useful to equip the pressure intensifier with a device to equip which at the beginning of a loading of the loading area 9 with a pressure to be translated a rapid achievement of a certain minimum pressure at the output of the pressure intensifier guaranteed, in order to ensure that the pressure intensifier downstream devices by this certain minimum pressure surely reversed from their rest to a working position will. In a simple way, as in FIG Indicated by dash-dotted lines, a further piston 37 can be provided, which via a line 38 in the direction of action of the return control piston 19 ', 19 "from the pressure prevailing in the loading space 9 the force of a spring 39 is applied. By means of a stop coupling * »D the piston 37 is able to move against the return control piston part 19 'to be supported. The piston 37 has a smaller area than

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the control piston 8 on. With this arrangement, the control piston 8 with its entire area of action is effective against the action of the return control piston 1SH, 19 ″ by the converted pressure If the pressure to be translated reaches and exceeds a certain level at the knee 37, which is sufficient to overcome the spring 39, the piston 37 is pressed against the spring 39 via the stop coupling UQ against the return control piston part 19 ' Force is thus absorbed by the piston, so that the return piston 19 ', 19 ^M only has to counteract the remaining force component. When pressure increases in the pressure chamber 9 above the specific pressure value, there is thus a slowed increase in the translated pressure.

To reduce friction, it can be advantageous to use the BinzelnBn The piston of the pressure booster differs from the illustrated embodiments to be designed as a diaphragm piston.

A further embodiment to the sensitivity of the pressure booster, especially when setting its transmission ratio To bring to low, translated output pressures very high, consists in the arrangement of the double valve 12 at that end of the Balance beam 2, on which also the pressure to be translated C ^ acted upon control piston 8 engages. This ensures that changes in the application of the control piston 8 of this outgoing adjustment forces directly, i.e. not via the balance beam 2 unfavorably reduced in their power, on the double valve 12 over-

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wear uierden; The double valve 12 can be sGrnit at very minor changes in the pressurization of the control piston 8 to open one or the other valve part 13 or 1 * f sufficient Adjusting forces act.

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Claims (1)

Claim e 1.! Pneumatic pressure intensifier, especially for load-dependent ^v - ^ controllable compressed air brakes of rail vehicles, with a control piston loaded by the pressure to be translated, a reverse control piston loaded by the translated pressure, a transmission gear with an adjustable pivot bearing, on which the control and return pistons are articulated to counteract each other and a u-valve device which controls the translated pressure and is actuated by a part coupled to the transmission gear, characterized in that the return piston (19), known per se, is designed as a double caliper, one of which is not throttled and the one of which is known per se differently, the lever part (22) is acted upon in a throttled manner by the increased pressure in a counteracting manner to the control piston (8) via a nozzle (25) connected upstream of its application space (2S). 2. Pressure booster according to claim 1, characterized in that the two piston parts (19, 22) have different, effective hollow surfaces (A, A), the hollow portion (22) with a smaller hollow surface (A-) counteracting the pressure in the impact space (26 ) is unthrottled by the geared pressure (C). 3. Pressure booster according to claim 2, with a balance beam as a transmission gear, at one end of which the control and the other end of the return control piston is hinged, characterized in that the two piston parts (21, 22), coaxially an- 509840/0867 are ordered and that a between the two piston parts the pressurization space (23) located on opposite sides, unrestricted by the increased pressure (C) is burdened. k. Pressure intensifier according to claim 3, characterized in that the piston part (22) facing away from the balance beam has the smaller piston area (A ₂ ) and that the nozzle (25) is arranged in this piston element to counteract it. 5. Pressure booster according to claim 1, characterized in that the nozzle (25) is bridged in at least one flow direction by a large-cross-section, spring-loaded check valve (3if, 35). 6. Pressure booster according to claims k and 5, characterized geksnnzeichnat that the check valve (3 ^, 35) in the piston part (22) is arranged with a smaller piston area. 7. Pressure booster according to claim 1, characterized in that, as known per se, one with the return control piston (19) can be coupled further calves (37) with, based on the control piston (8), smaller effective piston surface is provided, which is in the direction of action of the Return piston is loaded by the pressure to be translated (C) and on the other hand by a spring (39). 8. Pressure booster according to claim 3, characterized in that the U-valve device (12) and the control piston (8) at the same end de3 Uaagebolzens (2) are hinged. 509840/086 7 4 * Blank page