DE4414596B4 - Pressure medium system with at least two consumer circuits - Google Patents

Abstract

Pressure medium system with at least one first load circuit (I) and at least one second load circuit (II), between which arranged for a flow from the first load circuit (I) to the second load circuit (II) permeable and a flow blocking in the opposite direction check valve (2) is, characterized in that the check valve (2) has a predetermined opening pressure (p _ö ).

Description

The The invention relates to a pressure medium system with at least one first Consumer circuit and at least a second consumer circuit according to the preamble of claim 1

In Such a pressure medium system becomes the second consumer circuit fed from the first consumer circuit, so the first consumer circuit downstream or arranged to him in series. In such a pressure medium system are the pressure of the first consumer circuit - hereinafter the first consumer circuit pressure - and the Pressure of the second consumer circuit - hereinafter second consumer circuit pressure - up to one, through the flow resistance the check valve caused, negligible Equal pressure difference. The check valve causes that out the second consumer circuit no backflow into the first consumer circuit take place, thus serves to secure the second load circuit in the case of a pressure drop in the first consumer circuit.

Now are there any applications, where a priority filling of the first consumer circuit and a lower pressure level in the second consumer circuit as required in the first consumer circuit become. This means "priority Filling "- in short" priority "- that, starting from overpressure (i.e., at atmospheric pressure deflated) pressure medium system, the first consumer circuit to one filled up predetermined pressure have to be, before the filling of the second consumer circuit begins. "Lower pressure level ..." means that the second rated consumer circuit pressure less than the first rated consumer circuit pressure have to be.

In these cases it is usual, to give priority to the first consumer group between the check valve and the second load circuit to arrange a spill valve and the Achieving the required different pressure levels between the check valve and the overflow valve to provide a pressure relief valve. These components are with a considerable effort.

From the DE 39 33 551 A1 a hydraulic control circuit for parallel consumers is known, which has a hydraulic accumulator and a pilot operated check valve in a supply line which is loaded by a control pump with approximately constant normal pressure. The pilot-operated check valve is arranged between the hydraulic accumulator and the control pump and between at least one consumer with priority supply and at least one consumer with secondary supply. The pilot-operated check valve is unlocked at the normal pressure in the supply line and locked at a pressure lower than the normal pressure in the supply line.

Of the Invention is the object of a pressure medium system of The above-mentioned type so that they without additional Effort or with little additional Effort a priority filling of the first consumer circuit and a lower pressure level in the second load circuit than in the first load circuit guaranteed.

These The object is achieved by the invention specified in claim 1 solved. Advantageous embodiments and further developments are given in the dependent claims.

The Invention leaves to perform with any kind of pressure medium. Predominantly compressed air is used as the pressure medium used.

Further Advantages of the invention will become apparent in the following explanation called by means of drawings illustrated embodiments.

Under continuous use of the same reference numerals for components show with the same functions:

1 a pressure medium system,

2 to 4 Training of this pressure medium system,

5 in part, a training of the pressure medium after 4 ,

In the 1 shown pressure medium system has a first load circuit (I) and a second load circuit (II), which are each symbolized by a pressure medium memory.

The first consumer circuit (I) is a symbolized by a box pressure medium acquisition device ( 1 ) upstream, which contains a pressure generator in a conventional manner and may also contain in a conventional manner also means for pressure fluid preparation and plant safety such as pressure regulator, filters, coolers, dryers, pressure limiting devices, backflow preventer. The pressure-medium acquisition device ( 1 ) is capable of the first consumer circuit (I) to be filled up to a first nominal consumer circuit pressure (p _IN ).

The second consumer circuit (II) should be able to be filled to a second rated consumer circuit pressure (p _IIN ) which is less than the first rated consumer circuit pressure (p _IN ).

Between the first consumer circuit (I) and the second consumer circuit (II) is a check valve ( 2 ) having a predetermined opening pressure (p _ö ) arranged such that it is permeable to a flow from the first load circuit (I) to the second load circuit (II) and blocks a flow in the opposite direction. This arrangement prevents the check valve ( 2 ) in the event of a pressure drop in the first consumer circuit, for example as a result of a defect in the first consumer circuit (I) and / or in the pressure medium acquisition system ( 1 ), a return flow from the second consumer circuit (II) to the first consumer circuit (I) and thus a pressure drop in the second consumer circuit (II). The check valve ( 2 ) thus secures the second consumer circuit (II) in the event of a pressure drop in the first consumer circuit (I).

As a check valve ( 2 ) can be used, for example, a type, as described in the WABCO Westinghouse document "check valve 434 014", August 1973 issue. The predetermined opening pressure (p _ö ) can be achieved, for example, by the fact that in this state of the art, only the safe closing serving spring on the valve body exerts a defined force. In this way, the predetermined opening pressure (p _ö ) can be achieved without additional effort or at least without significant additional expenditure.

Such a check valve opens at overpressure downstream side, that is, when at its downstream only the atmospheric pressure is present, whenever the predetermined opening pressure (p _ö ) occurs on its inflow side. If, after opening the check valve, the pressure on the inflow side thereof increases due to continued pressure medium delivery by the pressure medium acquisition system, the check valve maintains a pressure difference between the values of the opening pressure (p _ö ) between its inflow side and outflow side.

This characteristic of a check valve with a predetermined opening pressure (p _ö ) means in this case that the check valve ( 2 ) is then opened for a flow from the first consumer circuit (I) to the second consumer circuit (II) when the pressure difference between the first consumer circuit pressure (P _I ) and the second consumer circuit pressure (P _II ) is equal to the opening pressure (P _ö ) , as well as that, with continued supply of pressure medium, the non-return valve ( 2 ) always sets this pressure difference. The check valve ( 2 ) provides the first consumer circuit (I) so a priority filling in the amount of its opening pressure (p _ö ) and ensures that the second consumer circuit pressure (p _II ) after the first opening of the check valve ( 2 ) is always lower than the first consumer circuit pressure (p _I ) by the value of the opening pressure (p _ö ).

The opening pressure (p _ö ) of the check valve ( 2 ) is just set to the difference of the nominal consumer _{circuit pressures} (p _IN , P _IIN ), so p _ö = p _IN - p _IIN . Consequently, the check valve ( 2 ) in the second consumer circuit (II), the second rated consumer _{circuit pressure} (p _IIN ) when the first consumer circuit (I) to the first nominal consumer circuit pressure (p _IN ) is filled.

Pressure medium systems according to the type of embodiment, in which a first consumer circuit to be filled with a higher pressure level, a second consumer circuit is connected downstream with a lower pressure level, are common practice. As an example, a vehicle system may be mentioned in which the first consumer circuit with the higher pressure level may be a service brake system and the second consumer circuit with the lower pressure level may be an auxiliary brake circuit and / or a parking brake circuit and / or an auxiliary device circuit and / or a trailer supply and control circuit , Of particular importance may be the priority of the first consumer circuit when the second consumer circuit contains a pressure-releasable parking brake, for example a spring-loaded brake. With appropriate dimensioning of the first consumer circuit pressure (p _I ) to which the first load circuit (I) is primed, can be ensured in such a case that the parking brake is not solvable before the first consumer circuit (I) forming the service brake system full is operational.

Dashed is in 1 one more downstream of the check valve ( 2 ) parallel to the second load circuit (II) arranged further second load circuit (III). By its dashed line is indicated that the further second consumer circuit (III) represents an optional training. Such a training arises, for example, when in the above-mentioned vehicle system, the functions specified there for the second consumer group are grouped. So it is customary to assign the auxiliary device functions another consumer circuit. The previous versions apply to the other second consumer circuit (III) accordingly with. The same applies to the following statements, as far as nothing else results from them.

The pressure medium system in the previously described NEN extent has the disadvantage that in the case of a pressure drop, such as due to a defect in the second load circuit (II) the first load circuit (I) only up to a locking pressure of the value of the opening pressure (p _ö ) of the check valve ( 2 ) is secured. In other words, when the second consumer circuit pressure (p _II ) drops to atmospheric pressure, the first consumer circuit pressure (p _I ) drops to the value of the opening pressure (p _o ) of the check valve (FIG. 2 ).

This disadvantage can be reduced by the in 2 illustrated arrangement of a spill valve ( 3 ) between the check valve ( 2 ) and the second consumer circuit (II).

An overflow valve opens, ie the passage between its inlet and outlet, when the inlet pressure assumes the value of an overflow pressure. The overflow pressure is also dependent on the outlet pressure, apart from the structural design and / or the setting of the overflow valve. An outlet pressure, more precisely: a higher outlet pressure than atmospheric pressure, may for example be present as residual pressure from a previous operation. The overflow pressure reaches its maximum value (p _ü ) when the outlet pressure is equal to the atmospheric pressure. After opening the spill valve equality between inlet and outlet pressure is established with continued pressure medium supply. An overflow valve closes again when the inlet and the outlet pressure has fallen back to a constructive and / or by setting predetermined closing pressure (p _s ).

The last-mentioned closing behavior is at the overflow valve ( 3 ) used to increase the securing pressure of the first consumer circuit (I). If the second consumer circuit pressure (P _II ) drops as outlet pressure of the overflow valve ( 3 ) to the value of the closing pressure (p _3s ) of the overflow valve ( 3 ), this concludes. Thereafter, no pressure fluid can flow out of the first consumer circuit (I) in the load circuit (II). This means that the first consumer circuit pressure (p _I ) is in no case below the sum of the opening pressure (p _ö ) of the check valve (FIG. 2 ) and closing pressure (p _3s ) of the overflow valve ( 3 ) can fall. The securing pressure of the first consumer circuit (I) is determined by the arrangement of the overflow valve ( 3 ) is thus increased by the value of its closing pressure (p _3s ) to the value p _ö + p _3s . Conversely, it can be said that the design of the check valve ( 2 ) with a predetermined opening pressure (p _ö ) the securing pressure of the first consumer circuit from the value of the closing pressure (p _3s ) of the overflow valve ( 3 ) is increased to the value p _3s + p _ö .

The overflow valve ( 3 ) also has a favorable effect on the precedence of the first consumer group (I). To open the overflow valve ( 3 ) and thus the beginning of the filling of the second consumer circuit is namely a first consumer circuit pressure (p _I ) equal to the sum of the opening pressure (p _ö ) of the check valve ( 2 ) and overflow _pressure (p _3ü ) of the overflow _valve ( 3 ), ie P _I = P _ö + P _3Ü , required. This means that due to the overflow valve ( 3 ) the priority of the first consumer _circuit (I) by the value of the opening _pressure (p _3ü ) of the overflow _valve ( 3 ) is increased to the value p _ö + p _3ü . Conversely, it can be said that the design of the check valve ( 2 ) with a predetermined opening _pressure (p _ö ) by the overflow _pressure (p _3ü ) of the overflow valve ( 3 ) has been increased to the value P ₃ + p _ö .

It is understood that the overpressure second consumer _circuit (II) occurring largest overflow (p _3ü ) of the _{spill valve} ( 3 ) must be less than the second nominal consumer _{circuit pressure} (p _IIN ). Otherwise, a filling of the second consumer circuit (II) would be impossible.

It should be mentioned that in order to secure the first consumer circuit (I) against a defect of the pressure medium procurement system ( 1 ) between the latter and the first load circuit (I) arranged an overflow valve, ie the first load circuit ( 1 ) upstream, can be. However, this is generally unnecessary, because a backflow preventer, as which can serve as an outlet valve of the pressure generator, the first load circuit (I) with respect to the pressure medium procurement facility secures.

As overflow valve For example, a type is considered, as in the WABCO Westinghouse publication "Overflow valve 434 100 ", edition August 1973, is described.

By dashed line is in 2 also indicated that also this embodiment can be further developed by a further second consumer circuit (III) and that also between this and the check valve ( 2 ) an overflow valve ( 4 ) can be arranged. In the latter case, every second consumer circuit (II or III) in the case of a pressure drop in the other second consumer circuit (III or II) by the associated overflow valve ( 4 respectively. 3 ) to its closing pressure (p _4s or P _3s ) secured.

In 3 is between the check valve ( 2 ) and the second consumer circuit (II) a pressure relief valve ( 5 ) arranged such that its inlet with the check valve ( 2 ) and its outlet connected to the second load circuit (II).

A pressure relief valve keeps the through from its inlet to its outlet until its outlet pressure becomes the value of a predetermined limiting pressure (p _B ). Subsequently, the pressure limiting valve regulates its outlet pressure to the value of the limiting pressure (p _B ) by reopening the passage between its inlet and outlet when the outlet pressure falls below this value, and pressure medium from its outlet when the outlet pressure rises above this value escape a pressure relief opening.

In the present case, the limiting pressure (p _B ) of the pressure relief valve ( 5 ) is set to the value of the second rated consumer _{circuit pressure} (p _IIN ), that is, p _B = p _IIN .

The characteristic of a pressure relief valve in the present case has the advantageous consequence that the second nominal consumer _circuit pressure (p _IIN ) in the two th consumer circuit (II) can not be exceeded, which without the pressure relief valve ( 5 ), for example due to heating, is possible.

The opening pressure (p _ö ) of the check valve ( 2 ) Of the difference can in this embodiment is equal to the nominal load circuit pressures, so p _ö = P _IN - P _IIN be, but it can also be less than this difference, so p _ö <P _IN - P _IIN be.

When Pressure relief valve is for example a type into consideration, as stated in the WABCO Westinghouse publication "Pressure Relief Valve 475010", October issue 1975, is described.

As indicated by the dashed marking of the overflow valve ( 3 ) is indicated, the embodiment according to 3 with the embodiment after 2 be combined. In order to maintain the advantages of both embodiments, the pressure relief valve ( 5 ) between the check valve ( 2 ) and the overflow valve ( 3 ) can be arranged.

Also this embodiment can be, according to the dashed representation, to the downstream of the pressure relief valve ( 5 ) parallel to the second load circuit (II) arranged further second load circuit (III) and, if appropriate, to the associated overflow valve ( 4 ).

In 4 the pressure medium system is extended by a further first consumer circuit (IV) to which the pressure medium acquisition system ( 1 ) is also upstream and the downstream of the pressure medium procurement plant ( 1 ) is arranged parallel to the first load circuit (I). Between the further first consumer circuit (IV) and the second consumer circuit (II) is a parallel to the already mentioned check valve ( 2 ) lying second check valve ( 7 ) intended. The second check valve ( 7 ) has the same opening pressure (p _ö ) as the already mentioned check valve ( 2 ) and is arranged such that it is permeable to flow from the further first consumer circuit (IV) to the second consumer circuit (II) and blocked flow in the opposite direction.

With regard to the design of the second check valve ( 7 ) the same applies as for the already mentioned check valve ( 2 ). With regard to its mode of action in conjunction with the other first consumer circuit (IV) that applies to the already mentioned check valve ( 2 ) in connection with the first consumer circuit (I) said accordingly. By the arrangement of the second check valve ( 7 ) parallel to the already mentioned non-return valve ( 2 ) secure the check valves ( 2 and 7 ) not only the second consumer circuit (II) in the event of a pressure drop in a first consumer circuit (I or IV) and the first consumer circuits (I and IV) to the opening pressure (p _ö ) in the event of a pressure drop in the second consumer circuit (II), but also prevent a pressure medium exchange between the first consumer circuits (I and IV) and contribute as by their mutual protection in the event of a pressure drop in a first load circuit (I or IV).

Also Such pressure medium systems are common. For example arises such a pressure medium system, if in the above already mentioned Vehicle system acting as the first consumer circuit service brake system in two independent Service brake circuits is divided.

This pressure medium system can, according to the dashed representation, be further developed in that each first consumer circuit (I and IV) in each case an overflow valve ( 6 respectively. 8th ) is connected upstream. For the training and the mode of action of these overflow valves, the above applies to the overflow valve ( 3 ) Said accordingly. Each of these overflow valves ( 6 respectively. 8th ) secures in conjunction with the non-return valve associated with the respective other first consumer circuit (IV or I) ( 7 respectively. 2 ) the first consumer circuit (I or IV), which it is upstream, against a pressure drop in the other first consumer circuit (IV or I) from.

The overflow pressures at overpressure-free outlet (p _6ü or p _8ü ) and the closing pressures (p _6s or p _8s ) of the overflow valves ( 6 and 8th ) may be different but are normally nominally the same. But even in the latter case, the _{Überströmdrücke} (p _6ü or p _8ü ) due to unavoidable manufacturing and assembly tolerances may be different within certain limits. That can be have a share in the priority of the first consumer groups (I and IV). For example, assume that the overflow _pressure (p _8ü ) of the overflow _valve ( 8th ) is lower than the overflow _pressure (p _6ü ) of the overflow _valve ( 6 ). Then it may happen during filling of the initially pressureless pressure medium system, that in the further first consumer circuit (IV) even the opening pressure (p _ö ) of the associated check valve ( 7 ) has built up before the overflow valve ( 6 ) opens at all, with the result that the filling of the second consumer circuit (II) begins before the filling of the first consumer circuit (I). In this case, therefore, the first consumer circuit (I) loses its precedence over the second consumer circuit (II).

This means for the already mentioned Vehicle system, in the full operational readiness of the service brake system - so both Service brake circuits - before solubility the parking brake is sought, that this advantage only for the another first consumer circuit (IV) forming service brake circuit achievable is.

The arrangement of the overflow valve ( 3 ) between the check valves ( 2 ) and ( 7 ) on the one hand and the second consumer circuit (II) on the other hand, as it is indicated by dashed lines as optional training, remedies this situation. Analogous to the above related to 2 What is said by the overflow valve ( 3 ) the first consumer _{circuit pressure} required at the beginning of the filling of the second consumer _circuit (II) is raised to the value p _I = P _IV = P _ö + P _{3 u} , and this value can be set by appropriate definition of the overflow _pressure (p _{3 u} ) of the overflow _valve ( 3 ) are dimensioned at non-pressurized outlet so that both the first consumer circuits (I and IV) associated overflow valves ( 6 and 8th ) certainly before opening the second load circuit (II). Conversely, it can be said that the design of the check valves ( 2 and 7 ) with predetermined opening _pressure (p _ö ) by the overflow _pressure (p _3ü ) of the overflow _valve ( 3 ) priority of one or both of the first consumer groups (I and / or IV) by the value of the opening _pressure (p _ö ) increased to the value p _3ü + p _ö .

Dashed line of the pressure relief valve ( 5 ) is indicated that this training with their advantages in the pressure medium system according to 4 is possible, wherein the pressure relief valve ( 5 ) between the first consumer circuits (I and IV) associated check valves ( 2 and 7 ) on the one hand and the second consumer circuit (II) or, if appropriate, the overflow valve ( 3 ) must be arranged.

From the dashed representation it is further apparent that, in accordance with the above with the advantages mentioned there, the further second consumer circuit (III) and, if appropriate, the associated overflow valve ( 4 ) can be provided.

5 clarified in a section of a pressure medium system, for the rest of the explanations to 4 that the non-return valves associated with the first consumer circuits ( 2 and 7 ) to a multiple check valve ( 9 ) can be combined. As indicated in the drawing, in this case, the predetermination of the opening pressure (p _ö ) of the individual non-return valves ( 2 and 7 ) serving spring between the valve bodies of both check valves ( 2 and 7 ), whereby they are both on the valve body of the first-mentioned check valve ( 2 ) as well as on the valve body of the second check valve ( 7 ) exerts the same defined force and tolerances of the opening pressure (p _ö ) of both check valves ( 2 and 7 ) and one from it. the following uneven opening of the check valves ( 2 and 7 ) excludes.

In not shown, the pressure medium system to more first and / or second consumer groups are trained, for which the above statements apply accordingly.

For the sake of completeness, it should be mentioned that the arrangement of one or more overflow valves in a multi-circuit pressure medium system, optionally in connection with backup tasks receiving check valves, as mentioned above, is often referred to as a "protection system", and that such in its construction and in its mode of action in the DE 34 34 884 A1 is described in detail.

Otherwise apply the above for an embodiment made statements, as far as nothing else results from them for the other embodiments accordingly with.

Claims (18)

Pressure medium system with at least one first consumer circuit (I) and at least one second consumer circuit (II), between which a for a flow from the first load circuit (I) to the second load circuit (II) permeable and a flow blocking in the opposite direction check valve ( 2 ), characterized in that the check valve ( 2 ) has a predetermined opening pressure (p _ö ). Pressure medium system according to claim 1, characterized in that parallel to the first load circuit (I) at least one further first load circuit (IV) is arranged between the and the second consumer circuit (II) parallel to the other non-return valve (II) 2 ) lying, for a flow from the other first consumer circuit (IV) to the second load circuit (II) permeable and a flow in the opposite direction blocking second check valve ( 7 ) is arranged at the predetermined opening pressure (p _ö ). Pressure medium system according to claim 2, characterized in that the check valves ( 2 and 7 ) to a multiple check valve ( 9 ) are combined. Pressure medium system according to claim 1, characterized in that between the check valve ( 2 ) and the second consumer circuit (II) a pressure relief valve ( 5 ) is arranged. Pressure medium system according to claim 2, characterized in that between the check valves ( 2 and 7 ) and the second consumer circuit (II) a pressure relief valve ( 5 ) is arranged. Pressure medium system according to claim 3, characterized in that between the multiple check valve ( 9 ) and the second consumer circuit (II) a pressure relief valve ( 5 ) is arranged. Pressure medium system according to claim 1, characterized in that between the check valve ( 2 ) and the second consumer circuit (II) an overflow valve ( 3 ) is arranged. Pressure medium system according to claim 7, characterized in that between the check valve ( 2 ) and the overflow valve ( 3 ) a pressure relief valve ( 5 ) is arranged. Pressure medium system according to one of claims 2 or 3, characterized in that between the check valves ( 2 and 7 ) or a multiple check valve ( 9 ) and the second consumer circuit (II) an overflow valve ( 3 ) is arranged. Pressure medium system according to one of claims 5 or 6, characterized in that between the pressure relief valve ( 5 ) and the second consumer circuit (II) an overflow valve ( 3 ) is arranged. Pressure medium system according to one of claims 2 to 3, 5 to 6 or 9 to 10, characterized in that each first consumer circuit (I or IV) in each case an overflow valve ( 6 respectively. 8th ) is connected upstream. Pressure medium system according to claim 1, characterized in that downstream of the check valve ( 2 ) is arranged parallel to the second load circuit (II), a further second load circuit (III). Pressure medium system according to claim 4, characterized in that downstream of the pressure relief valve ( 5 ) is arranged parallel to the second load circuit (II), a further second load circuit (III). Pressure medium system according to claim 12, characterized in that between the check valve ( 2 ) and each second consumer circuit (II or III) in each case an overflow valve ( 3 respectively. 4 ) is arranged. Pressure medium system according to claim 13, characterized in that between the pressure relief valve ( 5 ) and each second consumer circuit (II or III) in each case an overflow valve ( 3 respectively. 4 ) is arranged. Pressure medium system according to one of claims 2, 3 or 11, characterized in that downstream of the check valves ( 2 and 7 ) or a multiple check valve ( 9 ) is arranged parallel to the second load circuit (II), a further second load circuit (III). Pressure medium system according to claim 16, characterized in that between the check valves ( 2 and 7 ) or the multiple check valve ( 9 ) and each second consumer circuit (II or III) in each case an overflow valve ( 3 respectively. 4 ) is arranged. Pressure medium system according to one of claims 10 or 11, characterized in that downstream of a pressure relief valve ( 5 ) is arranged parallel to the second load circuit (II), a further second load circuit (III), between the and the pressure relief valve ( 5 ) parallel to a second consumer circuit (II) associated overflow valve ( 3 ) an overflow valve ( 4 ) is arranged.