EP1243799A2 - Hydraulic system for two fixed-volume pumps - Google Patents

Abstract

The system has a supply pipe (14) containing a preceding hydraulic module (27). This is positioned, so that the bypass channel (29) branches off the section (23) downstream of the module. This section is also connected to a secondary connections (40), which is charged with pressure medium by the second fixed displacement pump. The module is formed for attachment to a connection panel (16). The feed channel in the panel is interrupted in such a way, that its two sections (22,23) each form an intermediate connection (25,26) in a mounting surface (24), and are connected by the module.

Description

State of the art

The invention is based on a hydraulic system according to the Preamble of claim 1 specified genus.

It is such a hydraulic system with one Connection plate known from EP 0 190 431 B1, in which several consumer groups with LS directional control valves Flow adjustment of two constant pumps with each a pressure compensator can be supplied with pressure medium. The Connection plate itself takes only one of the first pumps assigned pressure compensator, while the second pump with the assigned second pressure compensator is arranged externally and is connected via lines; the two have Pressure compensators a different spring preload, so that they work with different control pressure differences to achieve a cascaded connection of the pumps. Such Connection plates often have a complex construction anyway, which is why they are poorly suited for design variants. Further no information is given here, as in the hydraulic system an additional group of consumers, e.g. a brake valve, can be connected upstream. Would with such a facility upstream of such a valve and thus the sum of the pressure medium flows of both pumps received, this could lead to undesirable energy losses to lead. This connection plate is also for the special one Use case provided and does not indicate any other application.

Furthermore, a hydraulic system is known from US Pat. No. 4,212,165 known, with several consumer groups of two Constant pumps are supplied with pressure medium, one first constant pump via a flow control valve privileged steering group with a constant current supplied while a residual current with the current of the second Constant pump is combined and several additional Consumer groups with LS directional control valves with pressure medium provided. The second is the constant pump, which has a Check valve is coupled to the residual current side, one Pressure compensator assigned, and the additional A brake valve is connected upstream of consumer circuits. On the formation of a connection plate is not described here received. This hydraulic system also builds relatively elaborate and can help with their flow power supply from flow control valve and pressure compensator to corresponding Lead energy losses, especially with regard to the upstream brake valve. Notes on a connection plate for flexible use in different There are no use cases here.

Advantages of the invention

The hydraulic system according to the invention with the characteristic Features of claim 1 has the advantage that flexible with a relatively simple design different applications is applicable and also at an operation with two constant pumps with one each assigned pressure compensator an energy-saving way of working especially allowed if an upstream hydromodule, such as. in the form of a brake valve. The Hydraulic system can be used if necessary without much effort an operation with two constant pumps on one with a constant pump. The hydraulic system with your Connection plate is particularly suitable for applications for those with a subsequent addition of a single-pump concept using a two-pump concept two constant pumps with assigned pressure compensators should be transferred.

By the measures listed in the subclaims advantageous developments and improvements in Main claim specified hydraulic system possible. Especially It is advantageous if the Hydromodule is executed as an add-on module, so that it can be attached directly to the connection plate, expedient this can be achieved according to claim 3 if the interrupted inlet channel in an acreage Forms intermediate connections, which is a connection of the Enable add-on module in a simple way. Most of all will thereby a simple and compact design and a flexible handling in different applications favored. Appropriate training courses also result the remaining claims; with regard to the multitude of too fulfilling functions build the connection plate relatively space-saving and inexpensive. More beneficial Refinements result from the description and the Drawing.

drawing

Three embodiments of the invention are in the Drawing shown and in the description below explained in more detail. 1 shows an inventive Hydraulic system with a connection plate in strong simplified representation, Figure 2 is an interchangeable Add-on module with integrated brake valve for attachment to the Connection plate according to Figure 1 and Figure 3, a second Embodiment of the hydraulic system with connection plate in simplified representation. Figure 4 shows a third Embodiment of the hydraulic system with the Connection plate separate hydromodule.

Description of the embodiments

FIG. 1 shows a hydraulic system in schematic form 10, in which with 11 a first constant pump and with 12 a second constant pump are designated, the pressure medium suck a tank 13 and each via a first Delivery line 14 or a second delivery line 15 to one Promote connection plate 16.

For this purpose, the connection plate 16 has one with the first feed line 14 connected inlet connection 17, of which an inlet channel 18 to a mouth 19 in one Flange surface 21 of the connecting plate 16 leads. The Inlet channel 18 is the section up to Mouth 19 reaching the first delivery line 14. This inlet channel 18 is in the connection plate 16 interrupted so that it was an upstream first Section 22 and a second downstream Section 23 forms. The connection plate 16 has a Cultivation area 24 in which the end of the first Section 22 a first intermediate connection 25 and the second section 23 a second intermediate connection 26 form. At this mounting surface 24 is on the connection plate 16 a hydromodule in the form of an add-on module 27 is attached, which has a connecting channel 28 in its interior, which the two intermediate connections 25 and 26 with each other connects, especially immediately and unthrottled.

From the second downstream section 23 of the Inlet channel 18 branches into the connecting plate 16 Bypass channel 29 from a first pressure compensator 31 Current regulator 32 and an additional control valve 33 to one Return line 34 is guided. The first pressure compensator 31 is assigned to the first constant pump 11 and has a four Path-controlling slide valve 35, which is also in a residual current channel 36 going out from the current regulator 32 which is connected downstream of the pressure compensator 31 also opens into the return line 34. The Constant current of the current regulator 32 becomes the additional control valve 33 supplied that in unspecified Way is mechanically actuated. In the connection plate 16 the second, downstream section 23 is furthermore via a branch channel 37 with a second connection 40 in Connection to which the second delivery line 15 is connected is. During the control slide 35 on one side of a first control spring 38 and a maximum Load pressure in the control line 39 is acted on the opposite side via a second control line 41 the respective inlet pressure in the branch duct 37.

At the flange surface 21 of the connection plate 16 are in known valve plates 42 and 43 flanged, of which the second valve plate 43 through an end plate 44 is closed. The valve plates 42, 43 have first and second 4/4-way valves 45 and 46 in LS technology, so that with each one load pressure-compensated control one not closer subscribed double-acting consumer is possible for what the directional valves have consumer connections A, B. each Directional control valve 45, 46 has a neutral position 0, two Working positions 1 and 2 and a free position F on, with one in each of working positions 1 and 2 Measuring throttle 47 is effective. The respective load pressures of the Consumers are in the conventional manner in the Directional control valves 45, 46 downstream of the measuring throttle 47 tapped and with control lines 48, 49 with Pressure selection valves in the form of shuttle valves 51 in Control circuit 52 selected and returned so that each the greatest prevailing load pressure over the first Control line 39 on the spring side 38 on the first Pressure compensator 31 takes effect.

The two directional control valves 45 and 46 are on one Supply channel 53 connected to the mouth 19 in the flange surface 21 communicates and which of the End plate 44 is shut off. Furthermore, both are directional valves 45, 46 crossed by a return channel 54, which also the Terminal plate 16 penetrates and with the return line 34th Has connection.

Around the additional control valve 33 also in the LS control technology the load pressure in the Current controller 32 tapped and via a in the Connection plate 16 arranged shuttle valve 55 in the Control circuit 52 fed. Branches in the connecting plate 16 also from the return channel 54 a drain channel 56, which in the mounting surface 24 opens and there from the add-on module 27 is cordoned off.

The via the second delivery line 15 in the connection plate 16 promoting second constant pump 12 is by a Check valve 57 in the delivery line 15 from the first Constant pump 11 decoupled. From the delivery line 15 in The area between pump 12 and check valve 57 branches a bypass line 58 to the tank 13, into which a second pressure compensator 59 is connected, that of the second Constant pump 12 is assigned. A control slide 61 second pressure compensator 59 is on one side of a second measuring spring 62 and via a fifth control line 63 acted upon by the maximum load pressure while on the other side of the second control slide 61 the pressure in the delivery line 15 via a sixth control line 64 takes effect. The fifth control line 63 is in the Control circuit 52 performed that on the spring sides of the two Pressure compensators 31 and 59 always have the same pressure. The sixth control line 64 takes the pressure from the second Delivery line 15 downstream from the check valve 57. The second pressure compensator 59 is a two-way, two-position valve performed; her second also shows Spring 62 has a lower preload than the first Spring 38 of the first pressure compensator 31. So can for example the first pressure compensator 31 with a Control pressure difference from 10 to 12 bar work while the second pressure compensator 59 to a control pressure difference of 8.5 is set to 9.5 bar, so that a total Cascade-like connection of the pressure medium flows takes place. To secure the pressure of the hydraulic system 10 is a Pressure relief valve 65 provided that as direct controlled valve from the pressure in the second delivery line 15 is applied.

FIG. 2 shows a second hydromodule in the form of a Add-on module 66, which instead of the first add-on module 27 the mounting surface 24 of the connection plate 16 is attachable. The second add-on module 66 has a simplified inside Hydraulic pilot-controlled trailer brake valve shown 67 on how it is principally from the beginning mentioned prior art is already known. The second Add-on module 66 has 68 connections in its mounting surface on to the intermediate connections 25 and 26 and to Drain channel 56 are arranged appropriately.

The operation of the hydraulic system 10 according to Figure 1 is explained as follows, the basic function Such hydraulic systems in LS technology with two constant pumps and two assigned pressure compensators as known per se is assumed.

Are all directional control valves 45, 46 and control valve 33 in their basic positions, both pump constant pumps 11, 12 against relatively low pressure in the neutral circulation, whereby especially the first pressure compensator 31 and the first constant pump 11 and the second pressure compensator 59 the second constant pump 12 relieve.

If the first directional valve 45 is now actuated, the load pressure signal tapped downstream of the measuring throttle 47 the first pressure compensator 31 activated, which causes the pressure the first constant pump 11 throttled to the working level and the desired oil flow to the associated consumer ascribes. The second constant pump 12 operates for the time being in neutral circulation since they are controlled by the check valve 57 from the first constant pump 11 is decoupled and the second Pressure compensator 59 with one compared to the first pressure compensator 31 lower control pressure difference works. Only when the Control spool of the first directional valve 45 opened so far was that the first constant pump 11 the oil flow requirement who can no longer cover alone will also cover second pressure compensator 59 activated, throttling the pressure of the second constant pump 12 and feeds the other Oil flow requirement via the delivery line 15 at the second connection 40 into the connection plate 16. The pressure medium flows of both Pumps combine in the inlet channel 18 and supply over the first directional valve 45 connected consumers. The pressure medium flow is connected from the second constant pump 12 continuously and without Oil flow jump.

The maximum pressure in the hydraulic system 10 can be mastered by a single pressure relief valve 65, which is acted upon by the pressure in the second delivery line 15 and that as a directly controlled valve directly to the tank 13 relieved.

This cascade connection of the pressure medium flow second constant pump 12 can also be achieved when instead of the first directional valve 45, the second directional valve 46 or both directional control valves can be operated together. at joint actuation of both directional control valves 45, 46 is always the largest load pressure is selected via the control circuit 52 and forwarded to control both pressure compensators 31 and 59.

The hydraulic system 10 according to FIG upstream brake valve 67 are operated, so the first add-on module 27 removed from the connection plate 16 and for this, the second add-on module 66 is flanged. That’s it Brake valve 67 in the inlet channel 18, the directional valves 45 and 46 upstream. This arrangement of the second add-on module 66 allows an energy-saving way of working. Here only the Pressure medium flow of the first constant pump 11 over the Brake valve 67 to the first pressure compensator 31 or to the Directional control valves 45, 46 are guided so that the Flow resistance of the brake valve 67 is relatively low is held. The pressure medium flow of the second Constant pump 12 can, however, regardless of Flow resistance of the brake valve 67 on the Delivery line 15 and the second connection 40 unthrottled in the inlet channel 18 are fed; the second add-on module 66 therefore does not cause pressure losses in the second Pressure medium flow of the second constant pump 12, so that too with a total flow of both pumps to the directional control valves 45 or 46 overall the pressure fluid losses remain low.

The connection plate 16 also has the advantage that it has a high connection flexibility because it instead of the concept shown with two constant pumps 11 and 12 can also be used if only a single pump 11 for the pressure medium supply to the assigned consumers is used. With such a one-pump concept the connected via the second delivery line is omitted Constant pump 12 with assigned pressure compensator 59, the Second connection 40 shut off by a screw plug becomes. Accordingly, the fifth control line 63 is also on Output in the connection plate 16 blocked. This one-pump concept is both with the first add-on module 27 also with the second add-on module 66 with the brake valve 67 feasible. The connection plate 16 can thus without appreciable increase in their complexity as a result of the first Pressure compensator 31 in a variety of applications be used, especially when operating with two Constant pumps achieve an energy-saving way of working leaves.

The functions of the second pressure compensator 59, the Check valve 57 and the pressure relief 65 can be advantageously in a common housing accommodate that is assembled with the pump 12. In this case, the pressure compensator 59 can be expediently arrange easily in a cover of the pump housing. Alternatively, it is also advantageous to use pressure compensators 59 and Pressure relief valve 65 in a common housing to arrange that directly at the pressure connection of the Constant pump 12 is flanged, so that a special compact unit is created. The two can also Constant pumps 11 and 12 as a tandem pump assembly are carried out, for example, the Main pressure relief valve 65 in the pump cover of one Constant pump and the second pressure compensator 59 immediately on Pressure connection of the second constant pump 12 directly is flanged on.

FIG. 3 shows a second in a highly simplified form Embodiment of a second hydraulic system 70 with a Connection plate 71, which differs from that of Figure 1 like follows differs, being the same for the same components Reference numerals are used. The second Connection plate 71 is now the inlet port 17 on the Front 72 arranged so that it is opposite to Mouth 19 lies in the flange surface 21. The first Pressure compensator 31 is designed as a 2/2 control valve here the connection of an additional control valve 33 is omitted. in the remaining is clearly recognizable here that the control slide both pressure balances 31 and 59 of the same pressure difference are acted upon. Operation of hydraulic system 70 corresponds to that of the first hydraulic system 16 according to FIG. 1.

FIG. 4 shows a third in a simplified form Hydraulic system 80, which is different from the second hydraulic system 70 as shown in Fig. 3 differs as follows, being the same Components with the same reference numerals are used. The third hydraulic system 80 has a connecting plate 81, in which the inlet channel 18 is not interrupted and thus forms no intermediate connections; the hydromodule 82 that here is designed as a brake valve, is upstream of the Connection plate 81 switched into the first delivery line 14 and not attached to the connection plate 81.

The mode of operation of the third hydraulic system 80 corresponds analogous to that of the first hydraulic system 10 with the Brake valve 67 as add-on module 66; through the upstream Brake valves in the hydraulic module 82 are in the hydraulic system 80 the same energy savings possible.

Of course, the embodiments shown are Changes possible without the spirit of the invention departing. So the second pressure compensator 59 can also be used as run a 3/2 control valve that goes directly into the second Delivery line 15 is switched. Instead of directly controlled pressure relief valve 65 can also be a pilot operated pressure limitation are used, in which the Control slide of the second pressure compensator 59 as the main slide serves for the printing function. The selection and forwarding the maximum load pressure can also be with a control circuit take place instead of the shuttle valves with simple Check valves work as they do as well Pressure selection valves are known.

Claims (11)

Hydraulic system in which a constant working circuit with several consumers can be supplied with pressure medium from two constant pumps via an inlet channel in a connecting plate, with one directional control valve assigned to each consumer, which has a measuring orifice determining the flow rate in one working position, and with a control circuit, in which are assigned to each consumer circuit, via which the highest pressure prevailing at one of the consumers is selected, with each constant pump being assigned a pressure compensator which is acted upon on the one hand by the pressure prevailing in the joint working group and on the other hand by the highest consumer pressure and a control spring, wherein the control spring for the first pressure compensator has a greater bias than that for the second pressure compensator of the second constant pump, so that the second pressure compensator at a certain pressure drop on one of the orifice plates of the Wegeven Tile adjusts itself so that the second constant pump also conveys to the working group after it was previously connected to the return and that the first constant pump has a connection via a bypass channel branching off from the inlet channel to the return via the first pressure compensator, the inlet channel being a part of one Delivery line leading from the first constant pump into a flange surface of the connection plate, characterized in that an upstream hydraulic module (27, 66, 82) is arranged in the delivery line (14) in such a way that from the downstream of the hydraulic module (27, 66, 82) lying section (23) branches off the bypass channel (29) and that this section (23) also has a second connection (40) which can be acted upon by the second constant pump (12) with pressure medium. Hydraulic system according to claim 1, characterized in that the hydraulic module is designed as an add-on module (27, 66) which can be attached to the connecting plate (16, 71). Hydraulic system according to claim 2, characterized in that the inlet channel (18) in the connection plate (16, 71) is interrupted such that its two sections (22, 23) each form an intermediate connection (25, 26) in a mounting surface (24) which can be connected to one another by the assigned add-on module (27, 66). Hydraulic system according to claim 3, characterized in that the two intermediate connections (25, 26) on the one hand and the second connection (40) on the other hand are arranged on different end faces of the in particular cuboidal connection plate (16, 71). Hydraulic system according to claim 3 or 4, characterized in that the connecting plate (16, 71) is penetrated by at least one return channel (54) which is connected to a drain channel (56) leading into the mounting surface (24). Hydraulic system according to one of claims 1 to 5, characterized in that the second constant pump (12) is connected to the second connection (40) via a check valve (57) decoupling both pumps (11, 12) and in that the second pressure compensator (59) is one controls bypass line (58) branching between the second constant pump (12) and check valve (57) and leading to the tank (13). Hydraulic system according to one of claims 1 to 6, characterized in that both constant pumps (11, 12) are secured by a common pressure relief valve (65), which is designed in particular as a directly controlled valve (65). Hydraulic system according to one of claims 2 to 7, characterized in that the add-on module (66) has a hydraulic brake valve (67) which can be connected at least to the two intermediate connections (25, 26). Hydraulic system according to one of claims 2 to 7, characterized in that the add-on module (27) has a through channel (28) connecting both intermediate connections (25, 26). Hydraulic system according to one of claims 1 to 9, characterized in that the inlet connection (17) for the first constant pump (11) on the one hand and on the other hand the mouth (19) of the inlet channel (18) in the flange surface (21) on different sides of the connection plate ( 71). Hydraulic system according to one of claims 1 to 10, characterized in that a downstream valve (33) is connected in the bypass channel (29) downstream of the first pressure compensator (31), which valve is designed in particular in OC technology.

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