EP0717201B1 - Protection system in a pressure installation - Google Patents

Description

The invention relates to a protection system according to the preamble of claim 1.

Such a protection system is known from DE 34 34 884 A1. As overflow valves and associated consumer circuits in the sense of the preamble of the claim 1, for example, the positions there in FIG. 1 I and II or 1 and 10 are considered.

The overflow valves of a protection system of the type mentioned Kind usually have when filling the pressure medium system opening pressures different from atmospheric pressure, what inevitable manufacturing and adjustment tolerances is due. That can except for one uneven pressure build-up when filling the consumer circuit cause that in the event of a defect in the consumer circuit, whose overflow valve when filling the pressure medium system of atmospheric pressure the lower opening pressure, the total flow of Supply device in the defective consumer group and from this flows into the atmosphere and the intact Consumer group is not operational.

As detailed in DE 34 34 884 A1 already mentioned depends on the utility supplying inlet pressure at which an overflow valve opens, So his opening pressure, also from the pressure on his Output, so from the consumer circuit pressure of the downstream Consumer group, from. An overflow valve therefore requires a smaller one to open it opening pressure, the higher the consumer circuit pressure. With an empty consumer group, d. H. if there is atmospheric pressure prevails, has the assigned overflow valve its highest opening pressure.

This characteristic of an overflow valve evaluates that known protection system using the direct connections limited permeability to improve behavior of the protection system. To limit the transmission capacity serve as chokes in the direct connections.

Every direct connection is made while the utility is working even with the overflow valve closed past this pressure medium in the assigned consumer group promoted. This builds up in consumer circles Consumer circuit pressures to reduce the opening pressures of the overflow valves and thereby lead to a more even build-up of pressure when filling. If only one consumer group is intact, build in this a consumer circuit pressure to reduce the opening pressure of the assigned overflow valve under the value of the highest opening pressure and for safe opening of the relief valve leads while in the defective consumer circuit receives atmospheric pressure, with the result that the assigned overflow valve its maintains the highest opening pressure and does not open as long as until the pressure of the supply facility and thus also the consumer circuit pressure of the intact consumer group have accepted this value.

With a large delivery rate of the supply device and low The direct connections become more permeable the opening pressure very quickly in front of the overflow valves of the overflow valve with the lower opening pressure on. This overflow valve then opens for a long time before the other overflow valve. This has intact Consumer circles have a very uneven pressure build-up result. This can be achieved through the greatest possible permeability the direct connections are met. The has great permeability of the direct connections in In the event of a defect in a consumer group, the disadvantage that the total output of the supply facility in the defective consumer group and out of this in the atmosphere flows out and the intact consumer circuit does not become operational. This applies particularly to small delivery rate of the supply facility.

The invention has for its object a protection system of the type mentioned above with simple means to train that it is both large and small Flow rates of the supply facility when intact Consumer circles an even pressure build-up and good filling safety in the event of a defective consumer circuit of the intact consumer group guaranteed.

This object is achieved by that specified in claim 1 Invention solved. Advantageous further training and configurations are specified in the subclaims.

The invention enables a universally applicable Protection system and thereby a considerable rationalization effect.

The invention is for pressure medium systems of the type mentioned Type for use in all technical fields and in connection with all liquid and gaseous Suitable for pressure media. Compressed air is often used as a pressure medium used. An important area of application in connection with compressed air offer vehicle pressure systems.

The protection system mentioned at the beginning can be one or more additional overflow valves for one or more additional, compared to those in the preamble of the claim 1 mentioned original consumer groups subordinate, consumer groups are supplemented. this will below using the example of an additional overflow valve and an additional group of consumers. These statements apply to one or more further additional overflow valves and the assigned Consumer groups in full with.

For the arrangement of the additional consumer group there are two options. At the first option is the overflow valve of the subordinate consumer circuit to the overflow valves of the original consumer groups arranged in parallel. The second option is the overflow valve of the additional consumer circuit the relief valves and the assigned Direct connections from the original consumer groups each one towards the additional Subordinate consumer circuit permeable check valve.

In such a supplemented protection system of the known type If there are irregularities in the pressure build-up in the original consumer circles that the Overflow valve of the additional consumer circuit an overflow valve or the overflow valves of the original Consumer circles open. This possibility eliminates the invention in that mentioned above universally applicable design.

One example of such a pressure medium system is given by a vehicle pressure medium system, the original (and priority) consumer circles service brake circuits and their additional (and subordinate) Consumer circuit a spring-loaded parking brake circuit is when filling the pressure medium system from atmospheric pressure a certain performance of the service brake circuits is requested before the spring-loaded parking brake circuit sufficient pressure to release the spring brake having.

Fig. 1

schematisch ein Schutzsystem für eine Druckmittelanlage,

Fig. 2

ausschnittsweise Einzelheiten einer Ausgestaltung,

Fig. 3

eine Fortbildung der Ausgestaltung nach Fig. 2,

Fig. 4

eine Fortbildung der Ausgestaltung nach Fig. 3.

Further advantages of the invention emerge from the explanation which now follows with reference to drawings. Use uniform reference numbers for elements with the same functions

Fig. 1

schematically a protection system for a pressure medium system,

Fig. 2

details of a configuration,

Fig. 3

a further development of the embodiment according to FIG. 2,

Fig. 4

a further development of the configuration according to FIG. 3.

Fig. 1 shows the solid lines schematically Basic version of a protection system for a pressure medium system with two consumer groups (10, 21), which by Storage containers are symbolized.

The protection system contains for one consumer group (10) an overflow valve (4), a direct connection (29) and a shut-off device (12). The overflow valve (4) is between a supply device (1) and the Consumer group (10) arranged.

The supply device (1) contains in a known manner a pressure generator and any necessary pressure treatment devices, Pressure control and pressure limiting devices.

The direct connection (29) is bypassing the protective valve (4), i.e. parallel to this, also between the supply facility (1) and the consumer group (10) arranged. The overflow valve (4) and the direct connection (29) are connected to the supply device (1) connected via a supply line (2, 28).

The shut-off device (12) is in the direct connection (29) arranged so that it controls their passage. The shut-off device (12) is not closer by means of two designated pressure-dependent control devices from two pressures controllable. Your is a control device via a control line (11) with one consumer circuit (10), their other control device is over one Control line (20) with the other consumer circuit (21) connected. The shut-off device (12) is designed that in the case of pressure equality, i.e. also at atmospheric pressure, the passage of the Direct connection (29) opens and this passage at one higher pressure in the control line (20) than in the Control line (11) closes. In other words: the shut-off device (12) is in favor of a pressure difference of the consumer group not assigned to it (21) into a direct connection passage (29) closing blocking position switched.

For the other consumer group (21) contains the protection system an overflow valve (23), a direct connection (26) and a shut-off device (19) with associated Control lines (22, 32). This applies to these components above for the corresponding components for one Consumer group (10) Executed accordingly.

The transmission capacity of the direct connections (26, 29) is so limited that in the event of a defect in one Consumer group (10 or 21) with every possible flow rate the supply device (1) in the defective Consumer circuit (10 or 21) flow rate in the assigned direct connection (29 or 26) one Back pressure creates the effect described below he brings. This limitation in transmission capacity by appropriate dimensioning of the direct connections, but also by throttling in the direct connections, such as they are indicated with the reference symbols (31 or 24), be achieved. Possible chokes can, like shown, upstream of the shut-off devices (12 or 19), but also arranged downstream of the same his.

The basic mode of operation of overflow valves and they bypass direct connections in a protection system is detailed in the already mentioned DE 34 34 884 A1 is described and is therefore known in the present case provided.

It is assumed that one group of consumers (10) is like this badly defective that when filling the pressure medium system of atmospheric pressure in this consumer circuit (10) despite the inflow of pressure medium through the assigned Direct connection (29) obtained the atmospheric pressure remains. Builds in the assigned direct connection (29) on the other hand, even with high transmission capacity the flow resistance caused by the inflow a back pressure on. This plants itself in the other Consumer group (21) assigned direct connection (26) and through this into the other consumer group (21), the yes is intact, gone. Print propagation also takes place into the control line assigned to the consumer circuit (21) (20) of the shut-off device (12). This is through the resulting pressure difference between the control lines (20) and (11) switched to their locked position. Now the total delivery rate of the supply facility via the direct connection (26) in the others, intact, flow consumer circuit (21). Consequently a consumer circuit pressure builds up in the other consumer circuit (21) on the opening pressure of the assigned Overflow valve (23) reduces and for safe opening it contributes. By blocking the direct connection (29) will further pressure medium escape via the now closed direct connection (26) and the defective consumer circuit (10) prevented until the assigned overflow valve (4) opens with the Result that the intact consumer group (21) at least up to the (undiminished) opening pressure of the defective consumer circuit (10) assigned overflow valve (4) is replenished. This opening pressure is called Security pressure of the consumer group (21) also held, if the defect in the consumer circuit (10) is filled Pressure fluid system occurs.

The switching of the defective consumer circuit just described (10) associated shut-off device (12) with practically everyone - no matter how small - the pressure difference can be disadvantageous if both consumer groups (10, 21) are intact. A certain unevenness of the Consumer pressure build-up when filling atmospheric pressure is namely inevitable, for example as a result unequal volumes of consumer groups (10, 21). The Switching a shut-off device (12 or 19) at virtually any pressure differential would lead to an interruption filling the consumer group (10 or 21) with lead to the lower consumer circuit pressure until the pressure in the supply line (2, 28) and thus the Consumer circuit pressure of the other consumer group (10 or 21) the opening pressure of the overflow valve (4 or 23) of the consumer group (10 or 21) with the lower Consumer circuit pressure reached. The inevitable unevenness of pressure build-up in consumer circles would be increased. This can be done through further training of the shut-off devices (12, 19) be that these only at a predetermined value of Pressure difference are switched into the blocking position. By this training will be pressure differences up to the predetermined one Value permitted, switching of the shut-off device (12 or 19) delayed accordingly, the one described Increase in the unevenness of the pressure build-up avoided.

However, the shut-off devices (12, 19) must this training be specially trained. Your switching must already be in the blocking position at the pressure difference insert that are caused by the dynamic pressure who - as described above - with a defective consumer group (10 or 21) in its direct connection (29 or 26) and in the intact consumer group (21 or 10) builds up. With increasing pressure difference the shut-off devices must be in the locked position continuously approach them until they reach the predetermined one Reach the pressure difference value. With others Words the shut-off devices (12, 19) in this Training for pressure differences below the predetermined Worth as continuously narrowing chokes be formed at the predetermined value of Pressure difference reach the (complete) blocking position. This training also builds up in this Case in the intact consumer group (26 or 29) to safely open the assigned overflow valve (23 or 4) leading consumer circuit pressure.

Of course, with a correspondingly restricted Result even one of the shut-off devices (12 or 19) are trained in this way.

The dashed line shows further developments of the Embodiment.

In the direct connection assigned to a consumer group or in the two consumer groups (10, 21) Direct connections (29 or 26) can have auxiliary check valves (30 or 27) may be arranged. This Secondary check valve or these secondary check valves prevent that via the respectively assigned direct connection from the assigned consumer group (10th or 21) pressure medium to the supply device (1) or in the other consumer group (21 or 10) can flow. The - albeit very low - flow resistance of the secondary check valve (s) (30 or 27) causes an increase in the above-mentioned dynamic pressure and therefore affects the behavior of the protection system advantageous in the event of a defective consumer circuit pressure.

The embodiment shows as further developments two arrangements of additional relief valves and these assigned additional consumer groups. These orders can exist alternatively, but also simultaneously his.

In the first arrangement, this is additional Overflow valve (8) via an additional branch (5) in this case with (2, 5, 28) supply line between the supply device (1) and the associated additional consumer circuit (9) arranged. The additional overflow valve (8) and the associated one additional consumer groups (9) are suitable Measures compared to the original overflow valves (4, 23) and the assigned consumer groups (10, 21) subordinate, for example by one opposite the opening pressures of the overflow valves (4, 23) of the original Consumer groups (10, 21) increased opening pressure.

In the second arrangement of the additional overflow valve (15) are the original overflow valve (4) and the associated direct connection (29) a check valve (14) and the other original overflow valve (23) and the assigned direct connection (26) downstream of a check valve (18). The additional Overflow valve (15) with the outputs of the Check valves (14, 18) connected, and consequently between each check valve (14, 18) and the additional one Consumer circuit (17) arranged. The check valves (14, 18) are arranged so that they are in the direction of additional overflow valve (15) or the additional Consumer group (17) are permeable. In this arrangement receives the additional consumer group (17) Pressure medium, which was previously one of the original overflow valves (4, 23) or one of them Direct connections (29, 26) has happened. Thereby the additional overflow valve also in this arrangement (15) and the associated additional consumer group (17) compared to the original overflow valves (4, 23) and the assigned consumer groups (10.21) secondary. In this arrangement, the opening pressure of the additional overflow valve (15) between the Pressure, which is at its entrance when filling atmospheric pressure only set via direct connections can always be up to full or nominal pressure. In this arrangement it is determined by considerations who are not interested in the present context.

The between the original overflow valves (4, 23) and the associated direct connections (29, 26) Check valves (14, 18) are responsible for one (Back) flow from the additional consumer group (17) into the original consumer groups (10, 21), but also a (cross) flow between the original ones To prevent consumer groups (10, 21).

In both arrangements of additional overflow valves (8, 15) and assigned additional consumer groups (9, 17), the overflow valves (8, 15) are direct connections not provided. Such direct connections but are possible in a manner not shown and can by appropriate design of their flow capacity for Interpretation of subordination.

In any arrangement, the additional overflow valve can (8 or 15) and the respective assigned consumer group (9 or 17) for several additional consumer groups stand. This is due to broken off and with (7) or (13) designated lines indicated. In this case it can be appropriate, a cross flow between the additional Consumer circles through the relevant overflow valves upstream or downstream check valves prevent. Such check valves are with the reference numerals (6 or 16). In the case of the first mentioned arrangement of the additional overflow valve (s), which is a parallel arrangement to the original Overflow valves (4, 23), this serves the additional Overflow valve (8) or the additional overflow valves upstream or downstream check valve (6) too preventing backflow to the utility (1) and the prevention of cross flow between the additional consumer group (9) and the additional consumer circles and the original Consumer groups (10, 21).

The original overflow valves (4, 23) can also Check valves (3, 25) are connected upstream or downstream, a backflow to the supply device (1) as well as a cross flow between the consumer circles, including roughly parallel additional ones, prevent.

The illustration shows the protection system in dissolved form Construction. This means that the existing overflow valves, the shutdown devices and the existing check valves are independent units and the associated ones Pressure medium lines and the existing direct connections, including the chokes, an open one Form line system. As an overflow valve comes in any known suitable type of construction, z. B. according to the WABCO Westinghouse publication "Overflow valve 434 100", August 1973 edition. The there shown version "without backflow" includes an approximately assigned check valve. As a shut-off device comes, for example, any suitable pressure difference controlled 2/2-way valve into consideration. The shut-off devices but must be linked so that one remains consistent when the other is in the locked position is.

All components of the protection system can also be in compact design combined into a "multi-circuit protection valve" be and then form an assembly similar of those already mentioned in Fig. 3 DE 34 34 884 A1 is shown.

Fig. 2 shows an embodiment of the shut-off devices (12 and 19).

Two consumer circuit chambers are located within a housing (42) (41, 46) arranged. The housing (42) can Specially provided for the shut-off devices (12 and 19) but it can, in the case of the compact design of the protection system, including that common to all components Housing.

In each consumer circuit chamber (46 or 41) opens out the viewer's point of view, from the right or from the left one of the direct connections (29 or 26). The mouths Valve seats are surrounding in the housing in a known manner arranged. The following are simplicity for the sake of this valve seats labeled "mouth (s)". The mouths (47 and 40) of the direct connections to be understood in this way (29 and 26) are coaxial with each other.

The consumer circuit chambers (41, 46) are through one Housing opening running coaxially to the mouths (40, 47) (43) connected to each other. Besides, they are Consumer circuit chambers (41, 46) each with one of the original consumer groups (10 or 21) and with the outlet of the assigned overflow valve (4th or 23) connected.

In the housing opening (43) is sealed and between two end positions axially displaceable a closing body (44) performed. In the exemplary embodiment, each has its own unspecified, sealing element more common Design for sealing against each consumer circuit chamber (41 and 46) are provided. This type of sealing secures the consumer groups (10, 21) against each other from, as a penetrating approximately on a sealing element Leakage not in the other consumer group can cross, but via an unspecified breathing opening the housing opening (43) to the atmosphere, or, depending on the type of pressure medium, in a collection container can escape with atmospheric pressure. With waiver the sealing of the closing body can be based on this advantage (44) but can also be carried out with only one sealing element.

The right end position of the Closing body (44) is by striking the Mouth (47) of the direct connection (29) determined. Corresponding is the left end position from the viewer's point of view of the closing body (44) is determined. The stop faces or stop lines of the closing body (44) are dimensional and formed from the material so that the closing body (44) over these areas or lines with the respective assigned mouth (47 or 40) of the direct connections (29 and 26) each form a valve (44, 47 or 44, 40), which is the passage between the respective direct connection (29 or 26) and the respective consumer circuit chamber (46 or 41) and thus the respective Consumer group (10 or 21) controlled. It's on hand that the mouths (47 and 40) of the material forth to form these valves (44, 47 and 44, 40) must be suitable.

As a result of the sealing of the closing body described (44) arise on this two piston surfaces, each with the in a consumer circuit chamber (46 or 41) prevailing consumer circuit pressure are applied.

The consumer circuit pressure predominates in a consumer circuit chamber (46 or 41) the consumer circuit pressure in the other consumer circuit chamber (41 or 46), so moves the higher consumer circuit pressure the closing body (44) into the end position, which is defined by the mouth (40 or 47) the other consumer group (10 or 21) assigned direct connection (29 or 26) is determined. If the pressure in the consumer circuit chambers (41, 46), also at atmospheric pressure in the same the shooting body (44) has a central position releasing both valves one, but not necessarily the geometric Must be middle position. Because of the above Operation of the closing body (44) and Mouths (47 or 40) shut-off devices (12 or 19) 1 in a general form Shut-off devices as two pressure difference controlled Designate 2/2-way valves that are linked so that one is in its open position when that other is in its locked position.

If the configuration according to FIG. 2 is to be developed further, that at least one shut-off device (12 or 19) only at a predetermined value of the pressure difference between the consumer circuit presses in their locked position, in which the relevant valve (44, 47 or 44, 40) is closed, is switched, for example by a switch spring (45). The switch spring (45) is supported on the one hand on the closing body (44) and on the other hand on the housing (42) and determined by their Force in the assigned end position of the closing body (44) the pressure difference at which the higher consumer circuit pressure the closing body against the force of the switching spring (45) has moved to this end position. The switch spring (45) is necessary to achieve the above-mentioned characteristic the continuously narrowing throttle in its spring characteristic be designed accordingly.

Switch springs (45) are in the configuration described shown on both sides, but it can, if the Use case this requires, even on one side only Switch spring (45) may be provided.

3 shows the example of, from the perspective of the viewer, on the right-hand side a training course on the design with switching spring (45) according to FIG. 2.

In this training is the secondary check valve (30) according to FIG. 1 integrated in the shut-off device (12). For this purpose, between the here with (52) designated closing body and the mouth (47) of the direct connection (29) a secondary valve member (54) is arranged. This forms the secondary check valve with the mouth (47) (30).

If the pressures in the consumer circuit chamber are equal (46) and in the direct connection (29) the secondary valve member (54) from a closing spring (51) under closing of the secondary check valve (30) against the mouth (47) pressed. Only if the pressure in the direct connection (29) the consumer circuit pressure and the force of the closing spring (51) predominates, the pressure in the direct connection increases (29) the auxiliary valve member (54) while opening the auxiliary check valve (30) from the mouth (47). The Auxiliary check valve (30) is therefore (only) in the direction the consumer circuit chamber (46) and thus in the direction of the assigned consumer group (10) permeable. The force of the closing spring (51) was the above For completeness mentioned with. It is through appropriate Design of the closing spring (51) so low that their effect in practice with the exception of those mentioned above Increase of the dynamic pressure if the consumer circuit is defective is negligible.

The closing body (52) is favored by a pressure difference the consumer circuit pressure in the, not shown, connected to the other consumer group (21), Consumer circuit chamber (41) from the perspective of the beholder shifted to the right, shifts end facing the secondary valve member (54) against the secondary valve member (54), press this against the muzzle (47), thereby closes the auxiliary check valve (30) and keep it closed regardless of the pressures in the direct connection (29) and in the consumer circuit chamber (46).

The closing spring (51) can be in a not shown Support way directly on the housing (42). In the illustration but is between the closing spring (51) and the housing (42) a spring plate (50) is arranged. The spring plate (50) is due to the switching spring (45). He offers a simple solution for simultaneous arrangement the closing spring (51) and the switching spring (45). is the closing body (52), as shown, in one Middle position, support both springs (45) and (51) on the spring plate (50) on the housing (42). Becomes the closing body (52), from the perspective of the beholder shifted to the right, one grips the closing body (52) arranged driving shoulder (53) the spring plate (50), so that then both over the spring plate (50) Support springs (45) and (51) on the closing body (52) and determine the characteristic of the shut-off device (12).

From the participation of the closing spring (51) in the determination the characteristic of the shut-off device (12) follows the advantage that the switching spring (45) is correspondingly weaker and thus be made cheaper and smaller can.

The aforementioned gripping of the spring plate (50) by the Carrying shoulder (53) of the valve body (52) takes place, after doing an empty shift (x) Has. The empty shift (x) serves to compensate for any Manufacturing tolerances between the closing body (52) and Housing (42).

The above for those from the viewer's perspective The statements made on the right apply accordingly Way for the not shown, from the point of view of the viewer, left side with.

In FIG. 4, the configuration according to FIG. 3 is a configuration trained, in which the for subordination of the additional overflow valve (15) and the associated one additional consumer group (17) required Check valves (14, 18) are integrated.

Regarding identical on both sides Components and functions are described again based on the, from the perspective of the viewer, right Side of the illustration.

In this case, the housing opening (43) in FIG. 2 and 3 to an additional consumer circuit chamber (64) trained. To form the additional consumer circuit chamber (64) is between the consumer circuit chamber (46) and the interior of the housing opening in the here with (65) designated housing the inside of the Breakthrough opening facing the valve seat (62) arranged, namely coaxial to the mouth (47) of the Direct connection (29) and thus also coaxial to the mouth (40) on the left, from the perspective of the beholder Page.

The additional consumer circuit chamber (64) is one unspecified connection with the additional Additional consumer group (17) Overflow valve (15) connected to the inlet.

Within the additional consumer circuit chamber (64) an axially displaceable valve body (60) is arranged. This forms with the valve seat fixed to the housing (62) the check valve (14) of FIG. 1, with its output - About the additional consumer circuit chamber (64) - that additional overflow valve (15), namely its inlet, connected is.

The valve body (60) has a not designated Cavity that extends axially through the valve body (60) extends through and coaxial to the mouth (47) of the Direct connection (29) and to the valve seat (62). This cavity is sealed and axially displaceable the closing body (52) guided.

The valve body (60) is one in the additional Consumer circuit chamber (64) arranged closing spring (63) against the valve seat (62) and thus in the closing direction of the check valve (14) biased. The closing spring (63), on the other hand, is based on the corresponding valve body from the viewer's perspective, the left Side off and therefore also serves as a closing spring check valve (18) on the left.

Only if the consumer circuit pressure in the consumer circuit chamber (46) that in the additional consumer circuit chamber (64) prevailing pressure as well as the power of Closing spring (63) predominates, the consumer circuit pressure lifts the valve body (60) while opening the Check valve (14) from the valve seat (62). Otherwise presses the closing spring (63), if necessary in connection with an excess pressure in the additional consumer pressure chamber (64), the valve body (60) under Close the check valve (14) against the valve seat (62). The check valve (14) is therefore (only) in Permeable direction of the additional consumer circuit (17).

In this embodiment, as shown, that too Auxiliary check valve (30) and the switching spring (45) are provided so it is expedient, as shown, this one assigned spring plate (61) on the valve body (60). A support for the valve plate, such as in Fig. 3, on the housing could impair the Inflow or throughflow of the check valve (14) have as a consequence. However, with this arrangement the Spring plates (61) designed the closing spring (63) so strong be that they are also against the forces of the closing spring (51) and the switching spring (45) at atmospheric pressure or a low pressure in the additional consumer circuit chamber (64) one for securely closing the check valve (14) has sufficient closing force.

In this embodiment too, the empty displacement is to be carried out (x) of the closing body (52) may be possible, so how shown within the cavity of the valve body (60) to be provided.

When filling the pressure medium system from atmospheric pressure the overflow valve (14) opens when the Direct connection (29) in the consumer circuit chamber (46) and thus in the assigned consumer group (10) Consumer circuit pressure has built up that of the Closing spring (63) exerted on the valve body (62) Closing force overcomes. By the now possible Pressure medium flow through the check valve (14) builds over the additional consumer circuit chamber (64) to the entrance of the additional overflow valve (15) a print on. However, this pressure is not enough to open the additional overflow valve (15).

Only when the overflow valve assigned to the consumer circuit (10) (4) has opened, can be in the consumer group (10) and thus in the assigned consumer circuit chamber (46) Build up pressure across the relief valve (4) and the additional consumer circuit chamber (64) the build-up of the opening pressure when filling Atmospheric pressure at the inlet of the additional overflow valve (15) and thus open it. Thereby is the priority of the consumer group (10) and the assigned overflow valve (4) compared to the additional Consumer group (17) and the associated Overflow valve (15) secured.

In a further training, the closing spring (63) are designed so strongly that they are one over the one to perfect Closing the check valve (14) required Closing force force exerted on the valve body (60) exercises. This is when filling the pressure medium system of atmospheric pressure the value of the consumer circuit pressure in the consumer group (10) and in the assigned consumer circuit chamber (46) which can be opened of the overflow valve (4) is raised. As a result, the priority of the consumer group (10) compared to the additional consumer group (17) and the associated additional overflow valve (15), measured in pressure units, is enlarged.

A participation of, from the perspective of the beholder, left illustrated parts of the pressure medium system is to be achieved the effects described above are not required. That means that this functional description also applies in the event that the other consumer group (21) is defective. But, as is normal, both are Consumer groups (10) and (21) intact, so apply above for those from the viewer's perspective, right Explanations given for the, from the point of view of Viewer, left side in a corresponding manner.

In the case of a parallel arrangement of the additional consumer group 1 can between the assigned Overflow valve (8) and the supply device (1) other facilities such as a pressure limiting device, be arranged in In the event of subordination of the additional consumer group (17) such additional facilities can be set up between the Check valves (14) and (18) and the associated additional Overflow valve (15) can be arranged without the above statements would be affected.

Otherwise apply, insofar as is clear from the above nothing else results from the statements made for a FIG for the other figures directly or in a corresponding manner Application with.

Those skilled in the art recognize that the scope of the invention not in the above embodiments or configurations exhausted, but that he rather all configurations covered, the characteristics of which are the claims subordinate.

Claims (10)

1. A protective system for a pressure medium installation comprising two load circuits (10, 21), having a spill valve (4, 23, respectively) for each load circuit (10, 21, respectively), which spill valve is arranged between a supply device (1) and the respective associated load circuit (10, 21, respectively), wherein for each load circuit (10, 21, respectively) a direct connection (29, 26, respectively) of limited transmission capacity by-passing the respective spill valve (4, 23,respectively) is provided, characterised in that in each of the direct connections (29, 26, respectively) there is arranged a shut-off device (12, 19, respectively) controlled by the pressures of the two load circuits (10, 21), which shut-off device is switched into a blocking position when the pressure in the load circuit (21,10, respectively) not associated with it is higher than in the load circuit (10, 21, respectively) associated with it.
2. A protective system according to claim 1, characterised in that an auxiliary non-return valve (30, 27, respectively) allowing passage in the direction of the respective associated load circuit (10, 21, respectively) is arranged in at least one of the direct connections (29, 26, respectively).
3. A protective system according to one of the preceding claims, characterised in that at least one of the shut-off devices (12, 19) is not switched into the blocking position until the pressure difference has a predetermined value.
4. A protective system according to one of claims 1 and 2, characterised in that for forming the shut-off devices (12, 19) it comprises the following features:

   a) within a housing (42) each direct connection (29, 26, respectively) opens out coaxially with respect to the respective other direct connection (26, 29, respectively) into a respective load circuit chamber (46, 41, respectively) connected at least to the output of the respective associated spill valve (4, 23, respectively);

   b) the load circuit chambers (46, 41) are connected by a break-through (43) in the housing arranged coaxially with respect to the orifices (47, 40, respectively) of the direct connections (29, 26, respectively);

   c) a closing member (44) is guided so as to slide axially and in sealed manner in the housing break-through (43), which closing member in an end position closes the orifice (47, 40, respectively) of a direct connection (29, 26, respectively).
5. A protective system according to any one of the preceding claims, characterised in that it comprises at least one additional spill valve (8) arranged between the supply device (1) and an additional load circuit (9) and having a higher opening pressure than the opening pressures of the first-named spill valves (4, 23).
6. A protective system according to any one of the preceding claims, characterised in that a non-return valve (14, 18, respectively) is arranged downstream of each direct connection (29, 26, respectively) and the associated spill valve (4, 23, respectively) and the protective system comprises an additional spill valve (15) arranged between the non-return valves (14, 18) and an additional load circuit (17) towards which the non-return valves (14, 18) allow passage.
7. A protective system according to any one of claims 1 to 3 and 6 or 5 and 6, characterised in that to form the shut-off devices (12, 19) it comprises the following features:

   a) within a housing (65) each direct connection (29, 26, respectively) opens out coaxially with respect to the respective other direct connection (26, 29, respectively) into a respective load circuit chamber (46, 41, respectively) connected at least to the output of the respective associated spill valve (4, 23, respectively);

   b) valve seats (62) built into the housing are arranged coaxially with respect to the orifices (47, 40, respectively) of the direct connections (29, 26, respectively), the valve seats each separating a load circuit chamber (46, 41, respectively) from an additional load circuit chamber (64) connected to the additional spill valve (15);

   c) the non-return valves (14, 18) each arranged downstream of a respective direct connection (29, 26, respectively) and the associated spill valve (4, 23, respectively) are each formed by one of the valve seats (62) built into the housing and by a valve body (60);

   d) the valve bodies (60) comprise cavities coaxial with respect to the orifices (47, 40, respectively) of the direct connections (29, 26, respectively);

   e) a closing member (52) passing through the additional load circuit chamber (64) is guided so as to slide axially and in sealed manner in the cavities of the valve bodies (60), which closing member in its end positions closes the orifice (47, 40, respectively) of a direct connection (29, 26, respectively).
8. A protective system according to claims 2 and 4 or 2 and 7, characterised in that to form the auxiliary non-return valve (30, 27, respectively) between the orifice (47, 40, respectively) of the associated direct connection (29, 26, respectively) and the closure member (44; 52), an axially slidable auxiliary valve member (54) is arranged coaxially to this orifice (47, 40, respectively) and the closure member (52).
9. A protective system according to claims 3 and 4 or 3 and one of claims 7 and 8, characterised in that the closure member (44; 52) is biased in at least one displacement direction with respect to the housing (42; 65).
10. A protective system according to claim 9, characterised in that, to create the bias, there is provided a switching spring (45), which, viewed in the displacement direction of the closure member (44; 52), acts at one end on the closure member (44; 52) and at the other end on the housing (42; 65).

Images