Fluid System

Abstract

The invention relates to a fluid system for a pump circuit (10), in particular a hydraulic high-pressure pump circuit, having a function block (12), in the housing of which fluid-conducting paths extend and to which valve components (32, 46) can be connected at least partially. The filter device is an at least partially integrated constituent part of the function block of the fluid system as a result of the fact that a filter device (46) with its filter housing (56) can be connected to the function block (12) in such a way that at least one filter element (70) is received in the installation space (72) of the function block.

Description

The invention relates to a fluid system for a pump circuit, in particular a hydraulic high pressure pump circuit, having a function block, in whose housing fluid-carrying paths extend and to which valve components can be at least partially connected.

DE 199 34 574 C2 discloses a generic fluid system, with flow paths for gases and/or liquids, with prismatic function units and structural units, which as fluid-carrying paths have flow channels and in the face surfaces have connection openings for adjacent function units and structural units. In addition, there can be a mounting plate for the attachment of the indicated function units and structural units. These units have a base surface which consists of a square with a standard edge length or which is composed of several: such squares. To build a modular building-block system consisting of the block-like function units and structural units as well as the valve components, the units on their base surface and the mounting plate have holes in a corresponding grid for definable fastening possibilities, the structural units in the respective fastening position adjoining one another with their side surfaces and the connection openings in the respective valve block as a unit being enclosed by ring-shaped depressions in which there is at least one respective gasket each which adjoins the wall of the depression and seals it.

With the known fluid system, a type of modular system is devised with which a plurality of fluidic tasks can be performed, in which, to trigger the fluid-carrying paths, valve components are used, such as directional valves, pressure limitation valves, throttle valves, etc; but it is also possible to connect sensors and other display devices such as, for example, pressure gauges or the like.

If the prior art function block is, however, to interact with other fluid components, such as, for example, hydraulic pumps, coolers, heat exchangers, filter units, etc., these additional components can be connected to the prior art function block separately via additional piping; this on the one hand leads to structurally large designs and on the other, due to the relatively long fluid transport paths, thermally inconsistent behavior occurs; this can adversely affect the efficiency of these fluid systems.

Proceeding from this prior art, the object of the invention is to further improve the known fluid system such that, in connection with the use of filter elements as additional fluid components, less installation space is necessary and such that improved efficiency is obtained especially when the most varied operating temperature ranges occur. This object is achieved by a fluid system with the features of claim 1 in its entirety.

In that, as specified in the characterizing part of claim 1, a filter device with its filter housing can be connected to the function block such that at least one filter element is held in the installation space of the function block, the filter device is at least a partially integrated component of the function block of the fluid system. This results in a fluid system of structurally small size, in which its individual components are compactly combined with the valve components in the region of the function block. Since relative to the function block moreover additional piping for connection of the respective filter element can be omitted, in terms of thermal operating conditions, a balanced operating situation for the fluid system according to the invention is achieved, to which the relatively thickly made wall parts of the function block can also contribute. Since, in addition, possible diversion paths for the fluid are shortened, efficiency for the fluid system according to the invention is also improved in this respect.

In one especially preferred embodiment of the fluid system according to the invention, the filter device is intended for the use of several filter elements through which flow can take place for filtration or backflushing in both directions, some filter elements undertaking filtration in one filtration position and at least one other filter element can be backflushed for cleaning its active filter surface in a backflushing position. In this way automatic operation for the fluid system is possible, and, by way of automatic monitoring of fouling, a backflushing process can be carried out, using a pivoting device with a motor for which the respective filter elements can be pivoted in succession into their filter position or backflushing position.

The fluid system according to the invention with its essential components, a function block with valve components and an inserted filter device, has proven especially effective in use in so-called high pressure pump circuits, in which a high pressure pump is coupled to the fluid outlet of the fluid system, the fluid system then ensuring that only highly cleaned fluid is made available for further transport to the high pressure pump in order in this way to ensure a smooth pumping process for the hydraulic circuit. It has been shown that otherwise even extremely small dirt particles can be enough, particularly for specially configured high pressure pumps, to endanger their operation.

The fluid system according to the invention is detailed below using one embodiment as shown in the drawings. The figures are schematic and not to scale.

FIG. 1 shows in the form of a hydraulic circuit diagram the use of the fluid system according to the invention for a so-called hydraulic high pressure pump circuit,

FIG. 2 shows in a perspective plan view the fluid system without the high pressure pump connected, and

FIG. 3 shows a longitudinal section through the fluid system as shown in FIG. 2.

FIG. 1 shows by way of example a fluid system for a pump circuit 10, in particular in the form of a hydraulic high pressure pump circuit. This pump circuit 10 has a function block which is designated as a whole as 12 and which is symbolized in the hydraulic circuit diagram as shown in FIG. 1 with a dot-dash frame. The indicated function block 12 has connection sites in the form of one pump inlet 14 and one pump outlet 16. The high pressure pump 18 which is connected to the connection sites in this way is shown with its drive motor 20 and otherwise is made as an intake pump. Furthermore, the function block 12 has one fluid outlet 22 to which there is connected a machine tool which requires a hydraulic medium which is not detailed and which in turn is connected with its fluid outlet to the fluid inlet 24 of the block 12. Furthermore there is a drain connection 26 which can lead, for example, to a chip conveyor of the indicated machine tool, which conveyor is not detailed. This application is only exemplary and instead of the machine tool there can be some other hydraulic consumer, for example, in the form of a hydraulic transmission, a hydraulically triggerable hoist, hydraulic motors of a fork lift and the like. Instead of the high pressure pump 18 there can be a low pressure pump or the function block 12 can be connected to the hydraulic circuit in another relation, for example, in a hydraulic heat exchanger circuit or hydraulic cooling circuit.

In this case, however, in the fluid-carrying path 28 to the machine tool, in addition to the high pressure switch 30, there are two high pressure 2/2-way valves 32, 34, on the input side of the directional valve 32 for safety reasons there being a pressure limitation valve 36 whose output discharges into the backflushing line 38. On the output side, the 2/2-way valve 32 is connected via an adjustable throttle valve 40 likewise to the backflush line 38 so that largely unpressurized circulation via the throttle valve 40 for the fluid is possible. Another fluid-carrying path 42 is a corresponding fluid line which leads from the fluid inlet 24 of the machine tool to the pump inlet 14 of the function block 12. Adjacent to the fluid inlet 24 in turn a pressure switch 44 is connected to the path 42, in this instance as a low pressure switch, and downstream in the direction of the inlet 14 a filter device 46 follows, the degree of whose fouling can be detected by way of an electrical differential pressure switch 48 which sits in the bypass line of the path 42 to the filter device 46. If in one preferred embodiment the filter device 46 is designed as a backflushing filter device, as in this case, the backflushing line 38 is connected to the filter device 46 and can be blocked by way of the backflushing valve 50. Furthermore, system values of the fluid circuit, such as, for example, the fluid pressure, can be retrieved by way of sensors, such as, for example, a pressure gauge 52.

Supply of the machine tool with fluid can be set via the indicated 2/2-way valves 32, 34 and, in the illustrated blocked state of the valves 32, 34, the high pressure pump 18 by way of the throttle valve 40 returns the quantity of fluid to the drain connection 26 of the function block 12. In this way the high pressure pump 18 can be made as a constant pump with a permanent pump capacity and for the corresponding demand for the machine tool, which is not detailed, the indicated directional valves 32, 34 are opened at discrete, definable time intervals. In this way it is possible to constantly ensure filtration operation, in which fluid coming from the fluid inlet 24 is filtered by means of the filter device 46 and conveyed by way of the pump 18 is discharged again into the hydraulic circuit 25 by way of the drain connection 26 from the function block 12. If the filter device 46 is made as a backflushing filter, the pertinent backflushing process can be manually triggered; but preferably automatic backflushing operation is envisaged, using a pivoting device for the individual filter elements, which device can be triggered by means of a motor 54; this will be detailed below. The filter device 46 in the simplest case of dismounting could, however, have only a single filter element which in the fouled state could be replaced by a new filter element.

FIG. 2 shows the function block 12 in a perspective side view and as shown the components specified in FIG. 1 are reproduced in their configuration in FIG. 2. As FIG. 2 shows, the entire function block 12 with the integrated filter device 46 is structurally small in the form of a cuboid and all components of the pump circuit 10 as shown in FIG. 1 can be analogously integrated in a space-saving manner into the function block 12.

Preferably, within the housing of the function block 12 the fluid-carrying paths, in particular the paths 28 and 42 with their secondary branch lines, are internally connected to one another such that a type of matrix structure of transverse and longitudinal rows of fluid-carrying lines is formed, with place-holders integrated in the function block 12 for installation of the respective, already addressed valve components. This place-holder solution, in addition to the matrix-like connecting structure by way of the respective connecting lines, makes it possible to manage a pronounced plurality of system tasks in which depending on the desired function other valve components can also be set on the place-holders. A basic system once in use can also be easily modified on site in the manner of a hydraulic module, in which other valve components replace the valve components used previously. In particular, in this way, when large amounts of fluid and fluid pressures arise, the system can be adapted on site. Valve components for the place-holders can be not only conventional pilot and directional valves, but also pressure limitation valves, nonreturn valves and other triggerable pilot valves. The function block 12 built in this way can also be integrated in this respect into other hydraulic function systems, for example, into the tank unit of a mobile hydraulic systems which is not detailed.

The filter device 46 which is shown in FIG. 3 is designed as a backflushing filter device and has a cylindrical housing part 56 as the filter housing. This filter housing part 56 viewed in the direction of looking at FIG. 3 is seated on the top of the function block 12 and engages the corresponding housing part of the function block 12 by way of a staggered projection 58. The housing part 56 widens to the outside over the flange piece 60 which in this respect on its underside has a receiving channel for a ring seal which is not detailed and with which the interior of the housing part 56 can be sealed relative to the exterior. In this way the housing part 56 is detachably connected to the housing of the function block 12 via the corresponding connecting screws 62 (cf. FIG. 2). For fluid supply of the filter device 46 the housing of the function block 12 has one fluid channel 64 which leads to the fluid input 24, and another fluid channel 66 which discharges into the backflushing line 38 with a backflushing valve 50 which, made as a screw-in cartridge as shown in FIG. 2, is inserted into the function block 12. Furthermore, the left half of the FIG. 3 shows the pump inlet 14 of the function block 12 which discharges by way of the fluid connection 68 into the interior of the function block 12 and into the interior of the housing part 56 of the filter device 46.

Filter elements 70 which taper conically toward the top are inserted into the filter device 46, for which instead of conical filter elements 70 there can also be at least partially cylindrical filter elements (not shown). The indicated conical filter elements 70 which consist preferably of so-called slotted hole screen filter elements are arranged at distances from one another along a cylindrical are within the filter housing part 56 and within the assignable housing part of the function block 12. For holding the individual filter elements 70 the function block 12 is provided with a cup-shaped recess 72 whose boundary wall ends flush with-the inside wall of the housing part 56.

The arrangement as shown in FIG. 3 with the filter elements 70 is chosen to be able to undertake backflushing; for function blocks of simple structure, however, it is also possible to integrate only a single filter element in the function block 12 such that viewed in its axial length it is more or less one half held in the function block 12, in particular in the cup-like recess 72, and the other half projects from the underside into the interior of the housing part 56. In this way the filter device 46 can be partially integrated in a very compact manner with its function elements in the function block 12 and otherwise the filter elements 70 are also protected against mechanical damage by means of the wall parts of the function block 12. Since the function block 12 in the region of the receiver of the filter elements 70 is provided with a relatively great wall thickness, in this respect reliable chambering of the active filter elements 70 is achieved in thermal terms; this results in a reduction in the loss of performance during filtration, especially if the medium to be filtered should be very different in terms of the temperature of use.

In the selected arrangement as shown in FIG. 3, in addition to the two illustrated filter elements 70, seen in the viewing direction and at radially equal distances to the indicated two filter elements 70, there is another pair of filter elements 70 which on the one hand project out of the plane of the figure and on the other lie in the plane of the figure which lies behind. Altogether therefore there are four filter elements 70 which are located diametrically to one another to the longitudinal axis 74 of the filter device 46 and which are arranged in pairs opposite one another to the longitudinal axis 74. Other configurations are conceivable here. Viewed in the direction of looking at FIG. 3 the right-hand filter element 70 is located over the other fluid channel 66 and is backflushed by means of the filtrate which is found in the housing part 5. In doing so the filtrate from the outside to the inside penetrates the filter element 70 which is to be backflushed and dirt which has been removed by way of the backflushing quantity travels via the other fluid channel 66 and the backflushing valve 50 which is then opened to the drain connection 26 of the function block 12, for example, in this way then the fouled backflush quantity can be delivered to the chip conveyor of a machine tool which is not detailed.

The other three filter elements 70 are connected annularly with their respective underside to the fluid channel 64 via which the unfiltered material originating from the machine tool via the fluid input 24 is supplied to the filter device 46. Therefore filtration takes place via the individual filter elements 70 from the inside to the outside and the filtrate travels via the fluid connection 68 to the high pressure pump 18 which is not detailed, as shown in FIG. 1. Since this high pressure pump 18 can implement very high intake capacities, according to the invention care must be taken that the fluid connection 68 discharges in the lower base region of the conical filter elements 70 so that it can offer a corresponding resistance to a strong fluid flow. In the region of the widened base support for the individual filter elements 70 effective filtration takes place to an especially high degree; this in turn benefits the operation of the fluid system in terms of the overall energy balance.

By means of a pivoting device 76 it is possible to move the individual filter element 70 in succession from their filtration position into the backflushing position and again into the filtration position, and peripheral motion for the individual filter elements 70 can take place both clockwise and also counterclockwise. The pivoting means 76 itself has a receiving part 78 for end-side accommodation of the individual filter elements 70, the receiving part 78 by means of the motor 54 being pivotable within the filter housing 56 around the pivoting axis 80. This pivoting axis 80 is essentially congruent with the longitudinal axis 74 of the filter device 46.

The receiving part 78 has two opposite end parts 82, 84, between which the individual filter elements 70 extend, the lower end part 84 having passages for fluid transport and the upper end part 82 being sealed fluid-tight to the exterior, that is, into the interior of the housing part 56. If the housing part 56 is removed from the function block 12, via the upper end part 82 the filter elements 70 here can also be lifted out of the function block 12 for replacement by new elements.

The motor 54 of the filter device 46 can be an electric motor; but preferably it is designed as a pneumatic motor. This pneumatic motor is characterized in that its cog-like driven part, depending on the pump motion of the piston parts of the pneumatic motor, executes alternating back and forth motion, and this back and forth motion then can be converted by means of a free-wheeling device 88 into a constant drive motion in one drive direction for the pivoting axle 80 of the filter device 46. These free-wheeling devices for pneumatic motors are conventional so that they will no longer be detailed here. With the indicated drive concept it is, however, possible to convert the alternating back and forth motion of the pneumatic motor 54 as driving into pivoting motion by 90° at a time for the filter elements 70 by means of the pivoting device 76 in order in this way to always clean one filter element 70 in the backflushing position in succession and to maintain conventional filtration operation with the other three filter elements. The respective backflushing process for a filter element 70 can therefore take place at more or less continuous time intervals; but it is also possible by way of difference pressure measurements, for example, by means of an electrical differential pressure switch 48, to determine on the respective filter elements 70 themselves when they are ready to be backflushed.

As a result of the conical structure of the individual filter elements 70, including the configuration of the cavity for the housing part 56, this arrangement has proven especially favorable in terms of energy in filtration operation, since the resistance offered in flow through the filter elements 70 in conventional filtration operation, formed by the resistance of the parts of the housing 56, is distinctly reduced in this way. Based on this configuration essentially laminar flow behavior occurs; this helps reduce outflow resistance in conventional filtration operation and ensures that the filtered amount can be removed at the fluid connection 68 to the high pressure pump 18.

The already indicated slotted hole screen filter elements which are preferably used, in the direction of the longitudinal axis 74 of the filter device have tilted support rods around which a wire section is wound in individual turns, leaving gaps through which fluid can pass, there being a weld spot in the region of each contact point of the wire section with the support rod. The gap size which is provided for free fluid passage, that is, the distance between two gaps, prevents passage of dirt if the particle size exceeds this gap width. Dirt which has, however, settled in the gaps can be reliably removed from the filter device by way of the described backflushing operation. The filter element 70 which has been cleaned in this way then moves from the backflushing position back into the filtration position and can be directly used there for further filtration operation.

For stable support of the filter elements 70, a configuration is also used in which the pivoting axle 80 on the end side is guided both in the function block 12 and also in the region of the upper wall parts of the filter housing 56 of the filter device 46. The vibrations which occur at the pneumatic motor 54 thus can be reliably diverted into the base structure of the function block 12 both via the housing part 56 and also via the pivoting axle 80; this helps reduce the damaging portion of the vibration. The tightly packed coaxial arrangement of filter elements 70, relative to the pivoting axle 80, in this respect also ensures reliably operation in which the filter elements 70 as a whole are moved into the illustrated backflushing position.

Claims

1. A fluid system for a pump circuit (10), in particular a hydraulic high pressure pump circuit, having a function block (12), in whose housing fluid-carrying paths (28, 42) extend and to which valve components (32, 34, 46) can be at least partially connected, characterized in that a filter device (46) with its filter housing (56) can be connected to the function block (12) such that at least one filter element (70) is held in the installation space (72) of the function block.

2. The fluid system according to claim 1, characterized in that the filter device (46) is intended for the use of several filter elements (70) through which flow can take place for filtration or backflushing in both directions, and that some filter elements (70) undertake filtration in one filtration position and at least one other filter element (70) can be backflushed for cleaning its active filter surface in a backflushing position.

3. The fluid system according to claim 1, characterized in that the respective filter element (70) is held more or less over half its axial installation length in the installation space (72) of the function block (12) and that the fluid-carrying paths (64, 68) which form the filter inlet and the filter outlet are integrated in the function block (12).

4. The fluid system according to claim 1, characterized in that by means of a pivoting device (76) the respective filter element (70) can be moved from its filtration position into the backflushing position and back into the filtration position, and that the pivoting device (76) has a receiving part (78) for holding the filter elements (70), which part is pivotable within the filter housing (56) around the pivoting axle (80) by means of a drive (54).

5. The fluid system according to one of claim 1, characterized in that the filter housing (56) of the filter device (46) is seated on the function block (12) and holds more or less the top half of the installation length of the respective filter element (70).

6. The fluid system according to claim 4, characterized in that the drive (54) acts by means of a free-wheeling device (88) on the pivoting axle (80) of the pivoting device (76) around which the individual filter elements (70) are coaxially located and which is guided to be rotatable on the end side in the filter housing (56) and in the function block (12).

7. The fluid system according to claim 6, characterized in that the drive (54) with its drive housing is seated on the housing of the free-wheeling device (88) which is in turn seated on the filter housing (56).

8. The fluid system according to claim 1, characterized in that the respective filter element (70) is made as a conical slotted hole screen filter element.

9. The fluid system according to claim 1, characterized in that the function block (12) in addition to valve components such as directional valves (32, 34) and pressure limitation valves (36) has pressure switches (30, 44) and at least one pressure gauge (52).

10. The fluid system according to claim 1, characterized in that the hydraulic pump, in particular a high pressure pump (18), can be connected from the exterior to the function block (12) to carry fluid.