EP2278169A2 - Hydraulic assembly with pressure relief means - Google Patents

Abstract

The assembly has a hydraulic source (18) and a hydraulic reservoir (20) connected with a control device (22). Over-pressure protectors (32, 34) are designed such that over pressure is generated by conveying hydraulic fluid between valve devices (28, 30) and operative connectors (24, 26). The protectors have over-pressure valves (42, 44) and an evocating part that is hydraulically connected upstream or downstream to the valves. The evocating part evocates the throttling volume flow of fluid conveyed through the over-pressure protectors.

Description

The invention relates to a hydraulic arrangement with a control unit, a hydraulic source and a hydraulic reservoir, which are each connected to the control unit, at least one hydraulic working connection for a hydraulic consumer, at least one controllable and a return of hydraulic fluid leak-free blocking valve means which between the at least one Working connection and the control unit is arranged, and at least one arranged between the at least one working port and the at least one valve device overpressure protection.

Mobile machines, such as agricultural machinery, such as tractors or harvesters, but also construction and forestry machines have hydraulic arrangements by means of which various hydraulic consumers are moved. Such hydraulic arrangements include functions in which the hydraulic consumers are kept in their last struck position. This holding function is important, inter alia, so that can be adjusted to the attached or attached to the mobile machine tools, not any hydraulic consumers (eg hydraulic cylinders), and open, for example, flaps for retaining bulk material or components while driving on the ground lower.

Such an adjustment of the hydraulic consumers (eg hydraulic cylinders) can be caused by technically induced leaks in the control devices of the hydraulic arrangement of the mobile machines by small amounts of hydraulic fluid flow through the valve slide these controllers to the hydraulic tank out. To such a To avoid draining the hydraulic fluid, leak-free check valves are used between the controllers and the driven by the controllers working ports of the hydraulic consumers, which can be controlled for the operation of the hydraulic consumer when needed to continue to ensure the function of the control units. Only in a neutral position of the control units, ie when no hydraulic fluid is to flow, close these check valves to the control unit off leakage. Various methods of designing such check valves are known in the art and will not be explained in detail here.

The working connections are often provided with so-called quick couplers, with which hydraulic consumers can be connected when needed. The quick couplers seal the working connection leak-tight to the environment when no hydraulic consumer is connected.

The leak-tight check valve located between the working connection and the control unit prevents leakage to the control unit, while the quick-coupler at the working connection prevents leakage to the working connection. Accordingly, hydraulic fluid which heats up due to heating of a surrounding metal shell can be trapped in a line section lying between the check valve and the quick-coupler. This can be done for example by solar radiation or by an operation heating of the hydraulic fluid. The result is an expansion of the hydraulic fluid volume. However, since the hydraulic fluid volume is leak-tightly locked and can not expand, there is an increase in pressure in the respective line section. Depending on physical property of the hydraulic fluid, the seals, the structural design of the line section, the pressure increase can also lead to failure of the affected components.

In order to prevent such thermally induced pressure increases, it is known to establish overpressure safety devices. It is known to form such overpressure safeguards by pressure relief valves, which are arranged in the correspondingly affected line sections. Typically, such overpressure valves, or thermal relief Valves called, pressure-controlled and connected via a drain line to the hydraulic tank, so that a presettable pressure in the affected line sections causes opening of these valves, whereupon the caged in the line sections hydraulic fluid through the drain line discharged to the hydraulic tank or relieved. This leads to a pressure decrease in the affected line section, whereupon the pressure relief valve closes again as soon as the presettable pressure limit is reached.

However, such overpressure safety devices can also pose problems when used in mobile machines. For example, if the pressure relief valve has too low a limit pressure, the hydraulic cylinder may sag as the pressure relief valve momentarily opens and the workport loaded with the hydraulic cylinder or the conduit portion connected thereto suddenly opens due to a working pressure spike is relieved in the hydraulic tank. That means a Hydraulic cylinder would increasingly retract at each occurring pressure peak or at each pressure surge. This is not in the sense of the operator of the mobile work machine, who usually wants to know fixed his fixed a hydraulic cylinder in its moved position.

However, if one adjusts the pressure relief valve too high to prevent sagging of the loads, the problem may arise that a quick coupler, which is preferably used on tractors, must be designed for this high pressure, since it is thermally conditioned, correspondingly high pressures are to be expected in a certain regularity. The resulting thermally induced pressures or overpressures can assume values between 300 and 600 bar, whereas the maximum system pressure of a tractor is only 200 bar. An adaptation of the quick coupler to the expected overpressures or an improvement in their fatigue strength is inevitably associated with a high design effort and could also bring other disadvantages.

The object underlying the invention is seen to provide a hydraulic arrangement of the type mentioned, by which the aforementioned problems are overcome.

The object is achieved by the teaching of claim 1. Further advantageous embodiments and modifications of the invention will become apparent from the dependent claims.

According to the invention is in a hydraulic arrangement of the type mentioned at least one overpressure protection arranged and designed such that by discharging hydraulic fluid between the at least one controllable and a return of hydraulic fluid leak-free blocking valve means and the at least one working port a build-up pressure is degraded, the at least one overpressure a pressure relief valve and this hydraulically nach- or upstream means includes, which cause a throttling of the volume flow of the hydraulic fluid discharged through the at least one overpressure safety device. Preferably, the throttling of the volume flow takes place only after the pressure relief valve, in the same way, a throttling before the pressure relief valve with the same effect and equivalent function is conceivable.

The throttling is designed such that the discharged hydraulic fluid can flow out of a pressure-affected line section between the check valve and the working connection only in very small quantities, preferably dropwise, or is discharged into the hydraulic tank. The overpressure protection comprises a pressure-controlled overpressure valve, which opens upon reaching a presettable limit pressure value and depressurizes the affected line section in which it is arranged until the limit pressure value is fallen below again. The pressure relief valve can be opened by a control pressure line. However, a sensor-controlled electronic control is also conceivable. Thus, when a limit pressure value provided or presettable in the overpressure safety device is exceeded, a controlled leakage is generated, by which the overpressure in the affected line section between the check valve and Work connection is slowly dismantled. It is particularly avoided that the hydraulic fluid can flow freely or is discharged into the hydraulic tank and thus shock-like volume flow changes due to pressure peaks in the hydraulic arrangement, which can cause a sagging of the load on a hydraulic cylinder connected to the working port, are not to be expected. At the same time, it is made possible to design a quick coupler arranged at the working connection to a system pressure which is normal for a tractor, so that preventive overdimensioning of the quick coupler to avoid damage is not necessary since the overpressure safety device can be designed for a limit pressure value appropriate for the system pressure.

The means for throttling the discharged hydraulic fluid or for throttling the volume flow may comprise a discharge channel, through which the hydraulic fluid discharged through the at least one overpressure safety device is returned to the control unit, wherein the throttling of the volume flow of the discharged hydraulic fluid is effected by the control device associated with a technically caused leakage he follows. As already mentioned above, proportional control valves or control devices generally have a technically caused leakage. This can be used here to cause throttling of the hydraulic fluid discharged in excess pressure by the discharge channel leads the hydraulic fluid to the controller, in a line or hydraulic connection, which is located between the check valve and the control unit. The overpressure can then be reduced by dropwise discharge of the hydraulic fluid via the leakage of the control unit.

However, it is also conceivable that the means for throttling comprise a discharge channel, through which the hydraulic fluid discharged through the at least one overpressure safety device can be discharged to the hydraulic tank and the discharge channel comprises a device throttling the volume flow of the hydraulic fluid to the hydraulic tank. This device may for example be a conventional presettable or also controllable hydraulic throttle or orifice or any other device which reduces the volume flow in a hydraulic line.

The overpressure protection and the at least one check valve may be formed in a unitary hydraulic component or in a unitary component housing. This advantageously increases the compactness of the hydraulic arrangement. Pressure relief valve and discharge channel can then be accommodated together with the check valve in a component housing.

The hydraulic arrangement may comprise or be connected to a working connection to a so-called quick coupler with which a hydraulic consumer can be connected to the hydraulic arrangement. The work connection can directly include or represent such a quick coupler or even connecting lines between a working connection and a quick coupler can be arranged. Of course, the hydraulic arrangement can have multiple working ports and a corresponding number of quick couplers. The quick couplers allow a quick connection between the hydraulic consumer and the hydraulic arrangement and keep the working connection closed as soon as the consumer is removed or dismantled.

The aufsteuerbare and a return of hydraulic fluid leak-free blocking valve device is preferably designed as a check valve and pressure controlled via a control pressure line aufsteuerbar. However, the control can also be done electronically or otherwise. Also, the valve device may be formed differently than in the form of a check valve. In particular, it is possible to arrange pressure-controlled switching valves, which switch by a corresponding control pressure lines from a closed position to an open position, wherein in the closed position, a leak-free blockage of the returning hydraulic fluid is given. Again, it is conceivable that the switching valves not pressure controlled but electrically or electromagnetically controlled. In the context of the present embodiments, the return of hydraulic fluid is understood as a flow of hydraulic fluid coming from the hydraulic consumer, flowing, for example, out of the chamber of a hydraulic cylinder, to the hydraulic tank. In principle, it should be ensured that a leakage of hydraulic fluid is avoided at the control unit by a leak-free valve device is arranged, which is permeable in the direction of the hydraulic consumer for hydraulic fluid and blocks a backflow leak-free. Furthermore, it should also be ensured that this valve device is aufsteuerbar, so it can be opened if operationally a backflow of hydraulic fluid, which is guided by the hydraulic consumer to the hydraulic tank, is required. This is the case every time, for example, the one chamber of a Hydraulic cylinder filled and the other chamber is emptied. Accordingly, then the valve means which is connected to the side of the chamber to be emptied, be turned on, whereas the valve means which is connected on the side of the chamber to be filled, is closed in the direction of the control unit and blocks a backflow leak-free.

In a particular embodiment, the hydraulic arrangement comprises two working connections for a hydraulic consumer, wherein in each case a controllable and a return of hydraulic fluid leakage blocking blocking valve means between the working ports and the control unit is arranged. Furthermore, an overpressure safety device is provided in each case between a working connection and the respective openable and a return of hydraulic fluid leak-free blocking valve device. The respective overpressure safety device is arranged and designed in such a way that an excess pressure which builds up can be broken down by discharging hydraulic fluid between the respective non-return valve and the respective working port. The respective overpressure protection comprises an overpressure valve and this hydraulically downstream means which, in accordance with the above embodiments, can cause a throttling of the volumetric flow of the hydraulic fluid discharged through the respective overpressure safety device.

The return of hydraulic fluid leakage-blocking valve devices are preferably each designed as a check valve and connected via a hydraulic line to the controller. Further, the line of a check valve via a control pressure line to the other Non-return valve and the line of the other non-return valve connected via a control pressure line to the other non-return valve, by means of the control pressure lines, the respective valve devices or check valves are hydraulically aufsteuerbar. Thus opens a control pressure line, which is connected to the lowering side of a hydraulic consumer, arranged on the lifting side check valve. The arranged on the lower side check valve is correspondingly hydraulically opened by a control pressure line which is connected to the lift side of the hydraulic consumer. This type of hydraulic cross-connection of control pressure lines between two arranged on different lines (hydraulic supply lines) check valves can be designed differently depending on the design of the return of hydraulic fluid leakage blocking valve devices as long as at a pressurization of a line (hydraulic supply line) an open (opening ) of the return of hydraulic fluid leak-free blocking valve device in the other line (hydraulic supply line) is initiated. Again, it is conceivable to control the leakage-free check valves electronically, mechanically, electromechanically, electro-hydraulically, electromagnetically, hydromechanically or in other ways to realize. The hydraulic arrangement described above is suitable both for two-sided and one-sided acting hydraulic cylinder. For the latter case, only one working port is provided, which is correspondingly connected to a return device of hydraulic fluid leak-free blocking valve device, such as a leak-free check valve. The control of the check valve can then, for example via a connectable to the hydraulic pump control pressure line. Should the chamber of the single-acting hydraulic cylinder be connected to the tank, for example because the hydraulic cylinder is to be lowered and the chamber has to be emptied, the non-return valve is simultaneously opened hydraulically by the control pressure line connected to the hydraulic pump. The connection to the control pressure line is interrupted as soon as the chamber of the hydraulic cylinder is refilled or closed (hydraulic cylinder is held in position). Alternatively, the check valve can also be opened electronically, mechanically, electromechanically, electrohydraulically, electromagnetically, hydromechanically or else in another way. Furthermore, another type of leak-free blocking valve device of the hydraulic fluid can be selected, which optionally also has one or more differently arranged control pressure lines.

According to the above embodiments, a hydraulic arrangement is provided which ensures protection against thermally induced overpressures, without that sagging of loads can take place at pressure peaks and without having to be oversized in terms of system pressure and construction of the quick coupler to their fatigue strength for high thermal To ensure pressures. It is ensured that at pressure peaks, the corresponding overpressure relief valve opens, but this has no negative impact in terms of sagging an application, since behind the pressure relief valves, the oil can flow only droplets. However, if a thermally induced pressure builds up slowly, the pressure relief valve would start at a certain presettable pressure value Open (limit pressure value) and the leakage, which can flow, for example via the valve spool of a control unit, would prevent further pressure build-up. The pressure which can be set on a pressure relief valve of an overpressure safety device can be set to a value slightly above the maximum system pressure of the hydraulic arrangement in order to be able to ensure that loads lifted with maximum pressure can not slowly lower again. The fact that this pressure setting is only slightly above the maximum pressure of the hydraulic arrangement, the risk of permanent overloading of the quick coupler is avoided and there is no adaptation of the quick coupler to higher pressures required. As already mentioned, the hydraulic arrangement can advantageously be made compact by the overpressure valves or the overpressure safety device being integrated in the unlockable or controllable valve devices (eg non-return valves) which block the return of hydraulic fluid so that no or only slight changes are made the housings of the control unit must be made. Thus, the advantages of a hydraulic arrangement according to the invention can be seen in particular in the fact that protection against thermal overpressures in relation to quick couplers and control devices with leak-tight check valves, no or only minimal adaptation of quick couplers or other components attached to the control units to thermally induced overpressures required is, a sagging of loads is prevented by pressure peaks and integration of the pressure relief valves in the leak-tight check valves no costly housing adaptation to the control units is required. The latter also makes it possible to provide a modular control device design concept by the corresponding parts of the overpressure protection in conjunction with the return of hydraulic fluid leak-free blocking valve devices or leak-free check valves can also be retrofitted integrated into an existing hydraulic arrangement.

With reference to the drawings, which show several embodiments of the invention, the invention and further advantages and advantageous developments and refinements of the invention are described and explained in more detail below.

Fig. 1

die schematische Seitenansicht eines landwirtschaftlichen Fahrzeugs mit einer erfindungsgemäßen hydraulischen Anordnung,

Fig. 2

einen schematischen Hydraulikschaltplan einer erfindungsgemäßen hydraulischen Anordnung,

Fig. 3

einen schematischen Hydraulikschaltplan einer weiteren Ausführungsform einer erfindungsgemäßen hydraulischen Anordnung und

Fig. 4

einen schematischen Hydraulikschaltplan einer weiteren Ausführungsform einer erfindungsgemäßen hydraulischen Anordnung.

It shows:

Fig. 1

the schematic side view of an agricultural vehicle with a hydraulic arrangement according to the invention,

Fig. 2

a schematic hydraulic circuit diagram of a hydraulic arrangement according to the invention,

Fig. 3

a schematic hydraulic circuit diagram of another embodiment of a hydraulic arrangement according to the invention and

Fig. 4

a schematic hydraulic circuit diagram of another embodiment of a hydraulic arrangement according to the invention.

FIG. 1 shows an agricultural vehicle 10 in the form of a tractor or tractor of a hydraulic arrangement 12, 14 according to the invention according to the Figures 2 and 3 includes. The in the Figures 2 and 3 shown schematically Hydraulic arrangements are described only as an example in connection with the tractor and can be found in the same way in other agricultural vehicles, such as harvesters, plant protection machines, planting and sowing machines but also in construction and forestry application.

The vehicle 10 comprises a frame 16 to which a three-point hitch (not shown) for operating attachments or implements (not shown) is disposed at a rear portion 17. The three-point hitch device can likewise be arranged at a front area of the vehicle 10. The three-point hitch has a hydraulic arrangement 12, 14, 15 according to the Figures 2 . 3 and 4 , The in the Figures 2 . 3 and 4 can also be used in conjunction with other hydraulically operated devices on the vehicle 10, such as a front loader or pulled by a puller implement application.

According to FIG. 2 The hydraulic arrangement 12 shown in the hydraulic circuit diagram comprises a hydraulic source 18 in the form of a variable hydraulic pump, a hydraulic reservoir 20 in the form of a hydraulic tank with hydraulic fluid, a hydraulic control unit 22 for controlling the hydraulic flow, a first and second working port 24, 26 for a hydraulic consumer first and second in the direction of the control unit leak-free closing or the return of hydraulic fluid leak-free blocking valve means 28, 30, in the form of a check valve, a first and second overpressure protection 32, 34 and a hydraulic consumer 36 in the form of a hydraulic cylinder.

The check valve 28 is arranged between the working port 24 and the control unit 22, wherein a hydraulic line 29 connects the control unit 22 and the check valve 28 with each other. The check valve 30 is arranged between the working port 26 and the control unit 22, wherein a hydraulic line 31 connects the control unit 22 and the check valve 30 with each other. The check valves 28, 30 can be opened via control pressure lines 38, 40. The arranged on the line 29 and the working port 24 associated check valve 28 is connected to the control pressure line 38, which in turn is in communication with the line 31. By pressurizing the line 31 and thus the control pressure line 38 can thus take place a control (opening) of the check valve 28. Analogously, the non-return valve 30 arranged on the line 31 or associated with the working port 26 is connected to the control pressure line 40, which in turn is connected to the line 29. By pressurizing the line 29 and thus the control pressure line 40 can thus take place a control (opening) of the check valve 30.

The working ports 24, 26 are designed as quick couplers, to which the hydraulic consumer 36 can be connected. The working ports 24, 26 each comprise a check valve (not shown) which closes leak-free in the direction of the hydraulic consumer 36, which is closed as soon as a connection of the working ports 24, 26 to the hydraulic consumer 36 is interrupted or the hydraulic consumer 36 is disconnected from the working ports is disconnected.

The overpressure safety devices 32, 34 each comprise a pressure relief valve 42, 44 and a device 46, 48 designed as a restrictor which throttles the volume flow. The device 46, 48 throttling the volume flow can also be designed as a diaphragm or as another hydraulic device throttling the volume flow.

The overpressure safety device 32 is arranged between the check valve 28 and the working connection 24, wherein a hydraulic line 50 branches off from a hydraulic line 52 connecting the check valve 28 and the working connection 24 and connects this to the pressure relief valve 42. A connected to the line 50 control pressure line 56 leads to the overpressure valve 42 and allows the control (opening) when exceeding an adjustable via a spring 58 limit pressure value in the line 50 and 52, wherein the spring 58 holds the pressure relief valve 42 in a closed position, as long the limit pressure value is not reached. The discharge side of the pressure relief valve 42 is followed by a discharge channel 60 in the form of a connected to the hydraulic tank 20 hydraulic line, the discharge channel 60 is equipped with the volume flow throttling device 46 and this includes, so that the flow of a flowing through the discharge channel 60 hydraulic fluid is throttled and this can flow slowly or throttled to the hydraulic tank 20 out. The device 46 throttling the volume flow may in this case also be arranged in front of the pressure relief valve 42, since it primarily serves only for volume flow reduction. This function or effect would also be achieved by arranging in front of the pressure relief valve.

In an analogous manner, the overpressure protection 34 is formed. The overpressure safety device 34 is arranged between the check valve 30 and the working port 26, wherein a hydraulic line 62 branches off from a hydraulic line 64 connecting the non-return valve 30 and the working port 26 and connects this to the pressure relief valve 44. A connected to the line 62 control pressure line 66 leads to the overpressure valve 44 and allows the control (opening) when exceeding an adjustable via a spring 68 limit pressure value in the line 62 and 64, the spring 68 holds the pressure relief valve 44 in a closed position, as long the limit pressure value is not reached. The discharge side of the pressure relief valve 44 is followed by a discharge channel 70 in the form of a connected to the hydraulic tank 20 hydraulic line, the discharge channel 60 is equipped with the volume flow throttling device 48 and this includes, so that the flow of a flowing through the discharge channel 70 hydraulic fluid is throttled and this can flow slowly or throttled to the hydraulic tank 20 out. Here, too, the device 48 throttling the volume flow can be arranged in an analogous manner in front of the pressure relief valve 44.

The drainage of the hydraulic fluids is preferably carried out only dropwise, so that only very small amounts can flow through which can indeed reduce an overpressure in the lines 50, 52, 62, 64, on the other hand, no sagging held by a consumer 36 or carried Load is to be expected.

The control unit 22 is preferably, but only by way of example, designed as a proportional control valve and has continuously controllable control positions, which Both mechanically, in particular manually, or electronically or otherwise automated can be controlled. The control positions include a neutral position 72, in which all inlets and outlets of the control unit 22 are closed, a stroke position 74, in which the line 31 to the hydraulic pump 18 and the line 29 is connected to the hydraulic tank 20, and a lowered position 76, in the line 29 is connected to the hydraulic pump 18 and the line 31 to the hydraulic tank 20. The control unit 22 is subject to a technically caused (natural) leakage, which means that a (prevailing) hydraulic pressure built up in a line 29 connected to the control unit 22 is reduced via the proportional valve slide 78 by the hydraulic fluid in small quantities via the proportional valve spool to the hydraulic tank 20 flows out (technically caused leakage). To counteract the effect of such a technically induced leakage is the use of leak-free check valves 28, 30, as they are arranged between the lines 29, 52 and 31, 64, provided or required.

The operation of the hydraulic assembly 12 is as follows. If the vehicle 10 is operated with a connected hydraulic consumer 36, the hydraulic device 36 connected via the quick coupler to the working ports 24, 26 can be operated in accordance with a controlled position of the proportional valve slide 78 in a stroke position 74, depression position 76 or neutral position 72 ., In the lifting position 74, the leak-free check valve 28 via the control pressure line 38 and in the lowered position 76, the leak-free check valve 30 via the control pressure line 40th is opened or controlled. Should a load be present on the hydraulic consumer in one of the positions 72, 74, 76, an excess of the limit pressure value set in one of the two overpressure valves 42, 44 caused by pressure peaks results in the opening of the corresponding overpressure valve 42, 44 by the control pressure lines 56, 66. Pressure spikes may be caused by mass movements due to unevenness in the field or on the road or other resistors acting on the implement or hydraulic consumer 36 for a short time. However, due to the means provided in the overpressure safeguards 32, 34 for throttling the volumetric flow in the form of outflow-throttling devices 46, 48, the hydraulic fluid can not flow unhindered to the hydraulic tank 20, so that a pressure reduction is only very slow, preferably dropwise can be done. As a result, a sagging of the load on the hydraulic consumer 36 is effectively avoided, since usually the said pressure peak only lasts for a very short time and the overpressure valve 42, 44 is closed again before a substantial outflow of hydraulic fluid could be noticeable.

If the vehicle 10 is operated without a connected hydraulic consumer 36, the leakage-free check valves integrated in the quick coupler at the working connections 24, 26 close off the lines 52, 64 without leakage to the outside. At the same time, the check valves 28, 30 close off the lines 52, 64 in the direction of the control unit 22 without leakage. If there is now a temperature-related increase in pressure in one or both of the lines 52, 64, the pressure will increase until the Limit pressure value of the pressure relief valves 42, 44 is reached and this opens accordingly. At the same time, hydraulic fluid can flow to the hydraulic tank 20 through the respective means for throttling the volume flow or through the volume flow throttling devices 46, 48 and the discharge channels (discharge lines) 60 and 70 throttled, so that the pressure in one or both lines 52, 64 can slowly degrade until it has again taken a value below the set in the pressure relief valves 42, 44 limit pressure value. As a result, damage that may occur due to temperature-related pressure increases on the hydraulic assembly 12 can be effectively avoided. Preferably, the hydraulic arrangement 12 is dimensioned such that a thermally induced increase in pressure can take place only up to the level of the limiting pressure value of the pressure relief valves 42, 44, since in addition, due to the then throttled draining hydraulic fluid, a further increase in pressure is counteracted or a further pressure increase essentially absent.

Another embodiment of a hydraulic arrangement 14 according to the invention is shown in FIG FIG. 3 shown. In the FIG. 3 illustrated hydraulic arrangement 14 differs only in the design of provided for the individual working ports 24, 26 overpressure fuses 32 ', 34', which are opposite to in FIG. 2 illustrated overpressure fuses 32, 34 as follows, with similar components and components with the same reference numerals as in the embodiment to FIG. 2 are named or provided. The overpressure fuses 32 ', 34' also have lines 50, 62, to each of which a pressure relief valve 42, 44 connected. The pressure relief valves 42, 44 are here also adjustable by respective adjusting springs 58, 68 and can be controlled via respective control pressure lines 56, 66. Each overpressure protection 32 ', 34' also has a discharge channel 60 'and 70', wherein the discharge channels 60 ', 70' here, in contrast to the embodiment in FIG. 2 , are not equipped with a volume flow throttling device 46, 48 or include any such and do not lead into the hydraulic tank 20, but rather directly into the connected to the control unit 22 and the check valves 28 and 30 lines 29 and 31 lead. In this case, the means for throttling the volume flow of the hydraulic fluid discharged in the discharge channels 60 'and 70' comprise no additional flow rate throttling devices 46, 48, but only the control device 22 itself, which is used as a means for throttling the flow rate, the throttling takes place via the previously mentioned technically conditioned (natural) leakage of the control device 22 and the proportional valve slide 78 contained therein. The effect and operation of the hydraulic assembly 14 according to FIG. 3 is comparable to that of the hydraulic arrangement 12 according to FIG FIG. 2 According to which the above-described embodiments also apply here: When hydraulic consumer 36 is connected, pressure peaks occurring that cause an override (opening) of the overpressure valves 42, 44 do not lead to a sagging of the load since the hydraulic fluid flowing out is throttled by the control unit 22 itself or prevented from flowing to the hydraulic tank 20 back without resistance. When not connected hydraulic consumer 36 is also ensured that a temperature-related pressure increase in one or both of the lines 52, 64, can slowly degrade again, since due to the technical (natural) Leakage of the controller 22 small amounts of hydraulic fluid via the control unit 22 to the hydraulic tank 20 can flow out throttled. As a result, damage that may occur due to temperature-related pressure increases on the hydraulic assembly 14 can also be effectively avoided. The effects or effects are thus with those of the previous embodiment according to FIG. 2 comparable. Of particular advantage in the hydraulic arrangement 14 according to FIG. 3 However, it is to be understood that the overpressure safeguards 32 ', 34' may each be formed together with the corresponding leak-free check valves 28 and 30 as a combined, unitary hydraulic component 80 and 82 respectively, thereby further enabling an existing hydraulic arrangement without overpressure protection 32, 34, Retrofit 32 ', 34' in a particularly simple manner.

Another embodiment of a hydraulic arrangement 15 according to the invention is shown in FIG FIG. 4 shown. In the FIG. 4 shown hydraulic assembly 15 differs essentially from the previous two embodiments of the hydraulic assemblies 12, 14 in that the hydraulic consumer is designed as a single-acting hydraulic consumer 36 'and thus only one working port 26 is acted upon. Accordingly, the in FIG. 4 illustrated hydraulic arrangement 15 only with the working port 26 in hydraulic operative connection components. Since only one chamber of the hydraulic consumer 36 'can be pressurized, only one working port 26 is required, which can be controlled via a control device 22'. By way of example, in this embodiment, the stroke side of the hydraulic consumer 36 'has been selected and correspondingly the working port 26 and the associated components. Equally significant, however, could also be the lowering side of the hydraulic consumer 36 'are selected and corresponding to the working port 24 and the associated components. The overpressure protection 34 is by way of example identical in construction to the exemplary embodiment of the hydraulic arrangement 12 according to FIG FIG. 2 educated. However, it could also be the same as in the embodiment of the hydraulic assembly 14 according to FIG. 3 be formed, that is, the discharge line 70 can leading to the hydraulic tank 20 leading with a flow rate throttling devices 48 according to FIG. 2 , or as a discharge line 70 'directly into the line 31 leader according to FIG. 3 be formed, with the formation of a combined, uniform hydraulic component 82 (or 80) is also possible here. It would be conceivable for the embodiment according to FIG. 2 also to arrange in an analogous manner, the flow rate throttling device 48 before the pressure relief valve 44.

The main difference, however, is that the control pressure line 40 is pressurized separately to aufzusteuern the check valve 30 (open), since no corresponding line 29 is present. For this purpose, the control pressure line 40 is connected directly to the control unit 22 '. With the switching position 76 as a lowering position for lowering the hydraulic consumer 36 'a connection between the pump 18 and control pressure line 40 is made, whereby the check valve 30 is opened (opened) and hydraulic fluid from the chamber of the hydraulic consumer 36' through the line 31 into the hydraulic tank 20 can drain. Furthermore, the control device 22 'comprises a switching position 74' as a stroke position instead of the switching position 74 from the preceding exemplary embodiments. in which only the line 31 is brought into communication with the pump 18 and at the same time the control pressure line 40 is interrupted or closed. The action and function of the overpressure protection 34 of the hydraulic arrangement 15 otherwise corresponds to the two preceding embodiments according to FIG Figures 2 and 3 , whereupon reference may be made to the preceding explanations, with the difference already mentioned above, that the hydraulic consumer 36 'arranged here requires only one working connection 26.

Although the invention has been described with reference to selected embodiments, many of the various alternatives, modifications, and variations that fall within the scope of the present invention will become apparent to those skilled in the art in light of the foregoing description and the drawings.

Claims (8)

Hydraulic arrangement (12, 14, 15) with a control device (22, 22 '), a hydraulic source (18) and a hydraulic reservoir (20) which are each connected to the control device (22, 22'), at least one hydraulic working connection ( 24, 26) for a hydraulic consumer (36, 36 '), at least one controllable and a return of hydraulic fluid leak-free blocking valve means (28, 30) which between the at least one working port (24, 26) and the control unit (22, 22 ') is arranged, and at least one between the at least one working port (24, 26) and the at least one valve means (28, 30) arranged overpressure protection (32, 34, 32', 34 '), characterized in that the at least one overpressure protection (32, 34, 32 ', 34') is arranged and designed such that by discharging hydraulic fluid between the at least one valve device (28, 30) and the at least one working port (24, 26 ) is a degradable overpressure, wherein the at least one pressure relief (32, 34, 32 ', 34') comprises a pressure relief valve (42, 44) and with this hydraulically nach- or upstream means, the throttling of the flow through the cause at least one overpressure (32, 34, 32 ', 34') discharged hydraulic fluid. Hydraulic arrangement (14, 15) according to claim 1, characterized in that the means comprise a discharge channel (60 ', 70 '), by means of which the hydraulic fluid discharged through the at least one overpressure safety device (32', 34 ') is returned to the control device (22), the throttling of the volume flow of the discharged hydraulic fluid through the control device (22) which is subject to a technical leakage. he follows. Hydraulic arrangement (12, 15) according to claim 1, characterized in that the means comprise a discharge channel (60, 70) through which the through the at least one pressure relief (32, 34) discharged hydraulic fluid to the hydraulic tank (20) can be discharged and the Discharge channel (60, 70) comprises a flow of hydraulic fluid to the hydraulic tank (20) down throttling device (46, 48). Hydraulic arrangement (14) according to one of the preceding claims, characterized in that the at least one overpressure safety device (32 ', 34') and the at least one controllable and a return of hydraulic fluid leak-free blocking valve means (28, 30) in a single hydraulic component (80 , 82) are formed. Hydraulic arrangement (12, 14, 15) according to one of the preceding claims, characterized in that the at least one working port (24, 26) comprises a quick coupler, or is connected to such, with which a hydraulic consumer (36, 36 ') to the hydraulic arrangement (12, 14, 15) can be connected. Hydraulic arrangement (12, 14, 15) according to one of the preceding claims, characterized in that the at least one aufsteuerbare and a return of hydraulic fluid leak-free blocking valve means (28, 30) is designed as a check valve and via a control pressure line (38, 40) aufsteuerbar is. Hydraulic arrangement (12, 14) according to one of the preceding claims, characterized in that the hydraulic arrangement (12, 14) comprises at least two working connections (24, 26) for a hydraulic consumer (36), per working connection (24, 26) openable and a return of hydraulic fluid leakage blocking valve device (28, 30) between the working port (24, 26) and the control unit (22) and arranged per working port (24, 26) between the working port (24, 26) and the respective valve means (28, 30) arranged overpressure protection (32, 34, 32 ', 34') is provided, wherein the respective overpressure protection (32, 34, 32 ', 34') is arranged and designed such that by discharging hydraulic fluid between the respective Valve means (28, 30) and the respective working port (24, 26) is a build-up pressure is degradable, wherein the respective overpressure protection (32, 34, 32 ', 34') an exercise rdruckventil (42, 44) and this hydraulically downstream means comprising a throttling of the flow through the respective Overpressure (32, 34, 32 ', 34') cause hydraulic fluid discharged. Hydraulic arrangement (12, 14) according to claim 7, characterized in that the aufsteuerbare and a return of hydraulic fluid leak-free blocking valve means (28, 30) each formed as a check valve and via a line (29, 31) to the control unit (22) and furthermore the line (29) of one valve device (28) via a control pressure line (40) with the other valve device (30) and the line (31) of the other valve device (30) via a control pressure line (38) with the one valve device ( 30), wherein by means of the control pressure lines (38, 40), the respective valve means (28, 30) are aufsteuerbar.

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