DE2136878C2 - Hydraulic system with two pressure medium sources and several hydraulic motors - Google Patents

Description

The invention relates to a hydraulic system of the type mentioned in the preamble of claim 1 Genus.

»Such a hydraulic system is known (US-PS 32 08 221). This hydraulic system is constructive Complicated and difficult to manufacture in terms of casting technology. It requires a valve body with a variety of holes and channels for the

ü Arrangement of the various gate valves and valves that can only be poured with great effort. The structurally intricate structure also complicates the Control and the sequence of the individual functions.

Quite generally it is with the simultaneous and / or

* o successive movement of several motors translational or rotaio. ical mode of action is often expedient. Supply pressure medium from at least two pressure medium pumps. The two pumps can then optionally jointly act on one or more motors, or the pressure medium flows can be conducted separately. This enables separate and partly load-independent movements. The pressure medium then no longer takes the path of least resistance, so that no more

so the least stressed movement becomes effective comes. A typical example of such a drive case is a hydraulic excavator with one each Chassis right and left, a rotatable slewing mechanism for the superstructure, a main boom, a articulated handle and a spoon, all of which are preferably hydraulic by means of, for example, two pumps are to be driven

(1) that the boom and the stick are independent can be driven from one another or at the same time as the trolleys.

(2) that the boom and the slewing gear can be driven at the same time independently of the load.

(3) that the bucket can be moved simultaneously with either the boom or the stick.

(4) that the spoon can be acted upon by both pumps and

(5) that the boom and stick can be driven by both pumps.

Of course, κ ^ · ΐι.- · η also have other priorities or combinations can be selected, which by type, design and function, for example an earthmoving machine, such as backhoe excavators, shovel excavators or front loaders are given.

It is known to assign a separate P'-mpe to each motor drive. Is disadvantageous in this In the event that (I) a large number of pumps are to be installed at a corresponding cost, that (2) a large number of them the thus available pressure medium flows remains unused and leads to increased idle friction losses Pressure medium flows and that (3) the power limitation of the main drive when using Constant pumping becomes difficult, that is, a "stall" of the main drive, ^ for example of a diesel engine, could be possible. It is also known to use at least two hydraulic pumps whose pressure medium flows controlled or throttled via directional valve blocks. The disadvantage in this case is that the Directional valves require a complex valve block construction in order to (1) perform the pure directional function (each 4/3-way valveJ to ensure (2) when idling to make a pressureless circulation of the pressure medium we'tgehe.id loss-free and to (3) additionally one to enable freely combinable combination and / or separation of the at least two pump flows. Through this a large number of control rooms in the valve housing was previously required. This leads in terms of casting technology likewise too complicated housing cores, too high in terms of production engineering and too much in terms of functionality Disadvantages (1) as a result of the control overlaps, which are difficult to match precisely for all operating conditions. (2) as a result of the increased leakage currents through a large number of control slide surfaces to be sealed off via sealing gaps and (3) as a result of the inevitably disproportionately long and insofar for clamping tilting valve spool.

To avoid these disadvantages, the aim is to find to design a hydraulic system with simple technical means so that the system is primarily based on a Function is designed as a directional control valve. Then they are simplified by the demand for freedom Circulation of the pressure medium and those caused by the requirement to combine / separate two pressure medium flows Complications of the directional control valves. This in turn allows the directional control valves themselves Throw in a structurally simple structure, especially briefly, without a large number of precisely coordinated Control edges and especially without complicated cast cores. Likewise, the hydraulic system should also with simple construction measures the requirement for unpressurized circulation of the pressure medium when idling of the working device and the requirement for a combinable combination / separation of two pressure medium flows meet, so allow a single or Doppelstrombcauf impact certain hydraulic cylinders.

Thus, the task arises for the invention, a Hydraulic system according to the preamble of claim I to be designed so that it is constructive and casting technical simplicity of their directional control valves an automatic effectiveness with regard to the merging tion and separation of functional processes together with an increase in control accuracy.

The solution to this problem arises according to the invention with the characterizing features of the patent claim I listed features.

As a result, on the one hand, every control line pressure leads to at least partial or complete closing

a release valve, and on the other hand, the flow rates of the pressure medium sources can be combined or separated in a definable combination via connecting valves. As a result, each directional control valve of the second valve block is available with individual actuation, the summed flow rates of both pressure medium sources, so that the controlled consumers work correspondingly quickly. On the other hand, the delivery flows of both pressure medium sources were separated in a definable combination so that load-independent movements are possible when several consumers are controlled. By separating the directional valve function, the function of pressureless pressure medium circulation, the delivery flow addition and separation and the control function, the directional valve blocks themselves can be easily constructed, especially short and without complicated cast core undercuts in the valve block housings, which are primarily price and production-related. The additional control elements and control line blocks are simple, relatively small and uncomplicated to create.

Relief valves in hydraulic system.! are already known, as for example CH-PS 4 44 601 and US-PS 34 65 519 illustrate. However, these are Systems have a different circuit structure than the subject of the invention

Appropriate refinements of the invention form the subject matter of the subclaims.

Embodiments of the invention are described in more detail below with reference to the figures. It shows 1 shows the hydraulic system according to the invention with a total of six directional control valves for controlling six consumers, such as required in earthmoving machines.

F i g. 2 shows a directional control valve as an exemplary embodiment according to section II-II in FIG. 1.

3 shows a relief valve as an exemplary embodiment according to section III-III in FIG. L.

F i g. 4 the common section through a directional control valve and a relief valve according to FIGS. 1 and 2 as an embodiment of a mountable together Unit and

F i g. 5 the connection of two sequence valves included in the system.

The system has two pressure medium sources 10 and 11 on. which suck pressure medium from a common collecting container 12. The plant is with six Directional control valves 13, 14, 15, 16, 17 and 18 are provided, each of which is assigned to a hydraulic cylinder. the Directional valves are divided into two groups of three each, each group is divided because that a directional control valve is separated from the other two by a control block. The first group is from valves 13 uni Ii on one side of a control block 100 and the Valve 15 formed on the other side. From the pressure medium source 10 pressure medium is via a Relief valve 21 supplied to valves 13 and 14. From the Druckmiitelquelle 11 pressure medium is via a Relief valve 22 is supplied to valve 15.

The / wide group of directional control valves comprises the valve 16 on one side of a switching device 23 and the valves 17 and 18 on the other side. That Pressure medium from the pressure medium source 10 reaches the valve 16 via a pressure relief valve 24. Das Pressure medium from the pressure medium source 11 passes over. a pressure relief valve 25 to the valves 17 and 18th

Each directional control valve 13 to 18 has the in F i g. 2 and consists of a slide housing 30 with a I.angsbohrung31 with the slide 32. The housing contains the outlet chambers 33 and 34. which intersect the bore 31, and two 'working chambers 35 and 36. each of which with the two Connections of the hydraulic motor are connected. The inlet chambers 37 and 38 are located between the two working chambers at a distance from one another. The slide 32 is hollow at each end, and two chambers 39 and 40 are formed at a distance from one another 43 connected to each other on both sides. In the check valves there are freely movable balls 44 and 45, which form changeover valves and are held in place by threaded pieces 46 and 47. They have passages 46a and 47a, respectively 43 has yet a radial passage 42a and 43a of the slider 32 has in the 'chamber 4Ö two ^-:. "groups of radial bores 40a, 40b and the chamber 39 in respective sets of radial bores 39a, 39b. The bores 39a and 40a lie on a helical line, so that their center point lines are not on the same circumferential line. The ^r> bores 39b and 40b are separated from the bores 39a and 40a within the chambers 39 and 40 by check valves 39c and 40c, respectively, which by springs 39c / or. 40d are operated. Two spaced apart annular grooves 48, 49 surround the ^J0 slide 32 and are connected to the inlet chambers 37, 38 when the slide is in its neutral position. If it is moved in Fig. 2 to the right, the holes 40a are opened successively towards the working chamber 36, while the borings ^3S be opened gen 406 for Auslaßkainmer- 34th At the same time, the bores 39a to the inlet chamber 37 and the bores 496 to the working chamber 35 are opened. During the slide movement, the bores 39a and 40a are opened one after the other to the corresponding chamber in order to bring about a throttled pressure medium flow into the corresponding chamber. The pressure medium then opens the corresponding check valve 39c and 40c. which enables the pressure medium in the chamber 39 to flow into the working chamber 35 and from there to one side of the hydraulic motor, not shown. On the other hand, pressure medium is discharged from the other side of the hydraulic motor into the working chamber 36 and flows from there through the bores 40a and the check valve 40c into the ^{> 0 outlet chamber 34} Ball 44 of the shuttle valve closes the passage 41 and the corresponding radial bores 41 a. The radial channels 43a are then isolated. If the "slide is moved from the neutral position in the opposite direction, the pressure medium flow is reversed which are open to the radial channels 42a, 43a or radial bores 41a, ^M) when the slide is in the neutral position The groove 51 is connected to a radial channel 53 which extends to the outside of the housing 30 Grooves 50 and 52 are connected to channels 54 and 55, respectively, which run at an angle to the outside of the ⁿ¹ housing 30 and dor t open into a common housing opening 56.
The relief valve housing 60 (FIG. 3) has a bore 61. which is closed by caps 62 and 63 screwed into their ends. The bore 61 is cut at each end by the return 64, 65 which are connected to one another by a U-shaped channel 66. Pressure connections 67 and 68 also lead to the bore 61. A pressure sensing channel 69 cuts the bore 61 between the pressure connections 67 and 68. The cap 63 enters the return 65 and has a groove 63a which allows the pressure medium to flow freely through the return 65 enables. A control piston 70 is movable in de ^r bore 61 and is urged by a spring 71 against the cap 62nd The control piston 70 is hollow from its end adjacent to the cap 62 to a point spaced from its other end, and an inner axial chamber 72 is created. Radial bores 73, which are axially spaced from one another, pass through the circumferential wall of the Control piston 70 through and connect the chamber 72 with the Öruckanschiuo 65. Similar niduiie Buiirurigeri 74. which are also axially apart and pass through the wall of the control piston 70, connect the chamber 72 with the pressure connection 67. An annular groove 75 in the wall of the control piston 70 stands with the channel 69 in connection. The groove 75 is connected to the area between the cap 63 and the control piston 70 by an axial channel 76 which lies parallel to the chamber 72. If there is pressure in the pressure connection 67 or 68, it pushes the control piston to the left against the spring force. As a result, the pressure medium can escape largely without pressure via the return 64, 65 to the collecting container. If the control piston 70 receives pressure medium from any directional control valve, this reaches the spring chamber via groove 75 and bore 76, supports the spring force and thus closes the relief valve. This means that the required pressure is available to the hydraulic circuit concerned. A maximum limitation of the pressure is then given according to FIG. 1 by the pressure limiting valves 24, 25.

The directional control valve shown in FIG. 2 and in FIG. 3 The relief valve shown are selected according to FIG. 4 as an embodiment that can be flanged on.

The switching device 23 between the directional control valves 16 or 17 and 18 consists of a housing 80 with two connecting valves 81 and 82. to which the slide 83 and 84 belong. The sequence valves 81 and 82 are via lines 85 and 86 to the inlet chamber 38 of the next adjoining directional control valve, for example 16 and 17th connected. Lines 85 and 86 are in turn connected to the other bore through lines 87 and 88 connected so that the two connecting valves 81 and 82 are connected in parallel. The sequence valve 81 is on one end through a control line 89 with the channel 53 of the directional control valve 16, the sequence valve 82 on one The end is connected to the channel 53 of the directional control valve 17 via the control line 90. Both slides 83 and 84 are pressed by springs 91 and 92 in the direction of the lines 89 and 90 in the sequence valves 81 and 82 join.

The control line block 20 between the directional control valves 14 and 15 has two control lines 93 and 93a, each with the housing opening 56 of the valves 14 and 15 and with outlet openings 94 and 95 in Are connected, which in turn are connected to the shuttle valves 96, 97 in the control block 100. This has bores 101 and 102 in which the sequence valves 103 and 104 are arranged. the Sequence valves 103 and 104 are actuated by springs 105

and 106 as well as the slides 83 and 84 of the switching device 23. The line 89 of the switching device 23 is connected to the bore 101 through the line 110, with the bore! 02 through the line 111 and with one end of the shuttle valve% through the Line 112. The other end of the shuttle valve% is connected to the bore 101 through the line 113. The line 90 is connected to the bore 101 through the line 120, with the end of the bore 102 through the line 121 and with one end of the shuttle valve 97 through the line 122. The other end of the shuttle valve 97 through the line 122. The other end of the shuttle valve 97 is connected to the bore 102 through the line 123.

In Fig. 5, an embodiment of the connecting valve 81 or 82 is shown. Slides 152 and 153 are located in housing bores 150 and 151 and are pressed into the closed position by springs 154 and 155 . They are pressed into the open position by pressure medium, which acts through the cannula i52a and 1jj <<in the slides 152 and 153 on the end of the slider and is opposed to the springs 154, 155 and the pressure medium located in the lines 89 and 90 ( compare the description above / u Fig. I).

Some functional processes are described below:

With unpressurized circulation (idling), the pressure medium source 10 delivers according to FIG. 1 pressure medium largely Loss-free via the relief valve 21 to the collecting container 12, while the pressure medium source 11 Conveys largely loss-free via the relief valve 22 to the collecting container 12. The relief valves 21, 22 are hydraulically relieved on the spring side via the dashed lines leading to the collecting container Control lines 93, 94 which are connected to the housing opening 56. That is, the relief valves 21, 22 generate only a small dynamic pressure corresponding to the spring preload that loads their control piston.

If, in the simplest case, only the directional control valve 15 is activated, pressure medium flows from its right-hand dashed control line to the relief valve 22 and closes it in the direction of the spring force. Thus, work pressure can build up. All other control lines are unimportant since the pressure medium source 10 cannot deliver to the directional control valve 15 anyway. The same applies in reverse to the pressure medium source 10 when the directional control valves 13 and / or 14 are activated.

For example, if the directional control valve 13 (with reference to Fig. 1) is actuated downwards, that is, if the parallel flow arrows come into effect, the upper inlet arrow is provided with a little pressure medium via a shuttle valve located in the valve slide and the double-bent and dashed control line pointing to the left removed and passed to the spring surface of the relief valve 21 This now closes, since its inlet pressure and thus also the control pressure on the spring surface is greater than the discharge pressure to the collecting container corresponding to the spring preload. As a result, the pressure medium source 10 builds up pressure in the working line. The pressure build-up can take place steplessly according to the deflection of the directional control valve 13 or suddenly depending on the deflection. The same happens when the directional control valve 14 is activated, there

the control pressure taken from the supply arrow there acts through the housing opening 56 of the directional control valve 13 and the shuttle valves located therein on the spring surface of the venting valve 21 and closes it. Correspondingly, the control pressure taken from the work line by the directional control valve 15 closes the relief valve 22, so that the pressure medium source 11 also builds up pressure in its circuit. The pressure medium source 10 can act on the directional control valves 13, 14, but never the directional control valve 15, and conversely, the pressure medium source 11 can act on the directional control valve 15, but never the directional control valves 13, 14, since the check valves 160 and 162 both hydraulic circuits. insofar as they are permanently assigned to the pressure medium sources, disconnect.

Mad Here, however, the design example of a hydraulic circuit is to be an addition of currents for the directional control valves 16, 17 and 18. If, for example, the directional control valve 16 is actuated, the control pressure in the valve interior is doubly bent after actuation receives control pressure from the reversing valve in the directional control valve 16 on the working side . This control pressure is applied via line 112, shuttle valve 96, outlet opening 94, line 93 and through directional control valves 14, 13 to relief valve 2! on, which closes. As a result, the pressure medium source 10 promotes via the check valve 160 and the line 85 to the directional valve 16. At the same time, the control pressure emanating from the directional valve 16 is planted via the lines 112, 111, the connecting valve 104, the line 123, the shuttle valve 97, the outlet opening 95, the Line 93a and through the directional control valve 15 to the relief valve 22 , which closes. As a result, the pressure medium source 11 delivers via the check valve 162, the line 86, the opened connection valve 82 and finally via the line 87 to the directional valve 16. Both pump flows are added.

If, in addition to the directional valve 16, the directional valve 18 (and / or the directional valve 17) is actuated, pressure medium is pressed from its working line (working arrow) via the control line, which is bent twice inside the valve, to the left and through the directional valve 17 into the control line 90 . This closes the connecting valve 82. Since the connecting valve 81 is already closed by control pressure from the directional valve 16 via the control line 89, the pressure medium flows from the pressure medium sources 10, 11 are now completely separated, and the separate pressure medium flows can also be completely independent, in particular load-independent Movements are driven. The control pressure medium from the line 90 also passes through the line 121 for sequence valve 104 which now also includes Accordingly, it can from among the pressure medium source 10 does not control fluid longer reach the discharge valve 22nd From the line 122 connected to the line 90, however, control pressure medium flows via the shuttle valve 97 into the control line 93a and further via the directional control valve 15 to the relief valve 22.

For this purpose 3 sheets of drawings

Claims (3)

Patent claims: I. Hydraulic system with two pressure medium cues and several hydraulic motors as consumers, each of which through a directional control valve assigned to it Is controllable, with certain consumers or directional control valves of one or the other pressure medium source permanently assigned and further consumers can be driven by both pressure medium sources, with one the connections of the pressure medium sources to the directional control valves of these additional consumers Switching device, characterized in that that each pressure medium source (10, 11) is assigned a relief valve (21, 22), via which the pressure medium flow of the assigned pressure medium source is discharged almost without pressure to the collecting container (12) when the directional control valves (13 to 18) are in the inactive neutral position,
that within each actuated directional control valve (13 to 18) a control pressure can be tapped from the respective line carrying the working pressure and this control pressure is applied to the area of the pressure medium source (10, 11) in question and thus the directional control valve / relieving valve (21, 21, acting in the closing direction) 22) is routed in such a way that when only one consumer intended for double current loading is actuated, the control pressure tapped at this directional valve (16 or 17 and 18) is routed to both relief valves (21, 22), that between two groups of directional control valves (16 and 17, 18) for the actuation of the double current charge device e'ihi switching device (23) with two connecting valves (81, 82) connected in parallel for the pressure medium! the control pressure branched off from one group of directional valves (16) acts on one connecting valve (81) and the control pressure branched off from the other group of directional valves (17, 18) acts on the other connecting valve (82) in such a way that, when actuated, only one group of directional valves one of the connecting valves (81, 82) connected in parallel for the pressure medium flow of the pressure medium source (11) of the other, non-actuated group of directional control valves (17, 18) is open and downstream of this connecting valve (82) a merging of the pressure medium flows takes place, while both are actuated at the same time Groups of directional control valves both connect valves (81, 82) close so that the pressure medium flows generated by the pressure medium sources (10, II) g are separated
and that between the switching device (23) and the groups of directional valves (15 and 13, 14) for the actuation of single-flow consumers, a control block (100) with changeover valves (96, 97) and with the control pressures that can be closed by the directional valve groups for double-pressurable consumers ( 103, 104) is arranged. whereby when only one group of directional control valves (16) is actuated / when the double-flow actuator is actuated, the relief valve (21) assigned to it is acted upon via the one shuttle valve (96) and the other relief valve (22) via a connecting valve (104) that can be closed by control pressure, and where when actuating both groups of directional control valves for actuation of double-flowcaufschlagbaren consumption cher both connecting valves (103,104) in the control block (100) are closed by control pressure, so that the control pressure of each group of directional control valves for the actuation of double-flow-loadable consumers only acts on an associated relief valve 2. Hydraulic system according to claim I, characterized in that the directional control valves (13, 14, 15; 16, 17, 18) are combined in two groups with three valves each and two voi these on one side and one on the other side of the switching device ( 23) or the control block (100) are arranged. 3. Hydraulic system according to claim I, characterized in that of the two control lines (89, 90) leading to the switching device (23) which extend from the two directional valve groups for consumers that can be acted upon by double action, the one control line (89) with one input of the one (96 ). the other control line (90) is connected to one input of the other shuttle valve (97) in the control block (100)