WO2010072201A1

WO2010072201A1 - Pilot-controlled valve and valve-controlled hydraulic machine

Info

Publication number: WO2010072201A1
Application number: PCT/DE2009/001775
Authority: WO
Inventors: Jörg Weingart; Peter Schwaderer
Original assignee: Robert Bosch Gmbh
Priority date: 2008-12-22
Filing date: 2009-12-16
Publication date: 2010-07-01
Also published as: DE102008064408A1

Abstract

The invention discloses a pilot-controlled valve having an electromagnetically actuated pilot control and a valve-controlled hydraulic machine having such a valve. In addition to an armature of the electromagnetically actuated pilot control, according to the invention a further main stage armature is provided, by way of which a valve body of the main stage can be moved into an open position in order to open a pressure medium flow path.

Description

description

Pilot operated valve and valve controlled hydraulic machine

The invention relates to a pilot-operated valve according to the preamble of claim 1 and a valve-controlled hydraulic machine with such a valve.

Such valve-controlled hydraulic machines are known, for example, from EP 1 537 333 B1. This document shows a hydraulic machine in axial or radial piston construction, which can be operated as a motor and as a pump, wherein the Förderbzw. Suction volume via the valve control is almost infinitely adjustable. In one embodiment, the hydraulic machine is designed as an axial piston machine, wherein a plurality of piston arranged in a cylinder is supported on a rotatably mounted swash plate. Each of these pistons defined with the associated cylinder chamber a working space, which is connectable via a low-pressure side valve and a high-pressure side valve with a pressure medium inlet or a pressure medium drain. In the known solution, the two valves are designed as electrically unlockable or lockable non-return valves, which can be controlled via the pump control and operated in the respective working space in "fill mode", "partial mode" or "idle mode" The delivery or displacement volume can be infinitely varied from a maximum value to 0. The hydraulic machine is operated via a control unit in accordance with a control algorithm in order to achieve a pulsation-free total displacement volume flow (pump) or total displacement volume flow (motor) This is often done according to a phase control, but it can also be performed after a Phasenabschnitts- or phase cut control.

Hydraulic machines with variable via the valve control displacement / delivery volume is also called Digital Displacement Units (DDU). In principle, all displacer principles are conceivable in such hydraulic machines. However, piston engines are advantageous, in particular in radial piston construction, since these make it possible to carry out the input and output separately for each displacer and thus to actively control it. It can make sense to switch between pump and motor operation. so that the control element for the low or high pressure connection can look different.

Such a control element is described for example in WO 2008/029073 A1. This document shows a high-pressure side valve, which is designed with a pilot control. This valve has a main stage with a valve body biased against a valve seat. The valve body is penetrated by a pilot control hole, which is closed in a basic position by a pilot valve body, which is also the armature of an electromagnetic pilot actuator. When energizing this actuator, the pilot valve body performs a stroke and opens the pilot hole, so that the valve body is relieved in the closing direction and can be lifted by the pressure at the entrance of his valve seat. The stroke of the valve body corresponds approximately to the stroke of the pilot valve body / armature.

At such a high-pressure side valve different, sometimes conflicting requirements are made. A minimized in terms of space hydraulic machine requires a small valve in its overall dimensions with the largest possible and thus low-resistance flow cross-section. However, such a large flow cross-section requires a larger valve lift, which contradicts the requirement for high valve dynamics with the lowest possible electrical power consumption. In addition, the requirements for the valve vary with different operating points of the hydraulic machine. For example, high flow rates result from high speeds, and demands for small switching times with low speeds are accompanied by long switch-on times for the solenoid coils.

In contrast, the invention has for its object to provide a pilot operated valve and a hydraulic machine designed so that is suitable for a minimum space for large volume flows while still ensuring a high valve dynamics for controlling the hydraulic machine.

This object is achieved by a pilot operated valve with the features of claim 1 and by a valve-controlled hydraulic machine with the features of the independent claim 11. According to the invention, the pilot-operated valve is designed with a main stage and an electromagnetically actuated pilot control, the main stage having a valve body which is traversed by a pilot control flow path. This can be closed by means of a pilot valve body of a pilot actuator, wherein a stroke of an armature of this pilot actuator is directly or indirectly transferable to the pilot valve body. According to the invention, a further main-stage armature is provided in addition to the pilot valve body associated with the armature, which comes after a partial stroke of the valve body in electromagnetic operative engagement to move this in a Endhubbereich and / or to keep there.

In other words, by the armature of the pilot actuator, the pilot valve body is moved only with a comparatively small lift, which is required to control the Vorsteuerströmungspfad. After relieving the valve body of the main stage in the closing direction of the valve body also performs a corresponding to the stroke of the pilot valve body partial stroke. In this case, then the second main-stage armature comes into operative engagement, so that the valve body performs a further stroke and is kept open in Endhubbereich. That In this solution, two successive or overlapping effective anchor associated with a magnetic circuit, which cause the valve body performs a comparatively large stroke, so that the valve can be used even with relatively large pressure medium flow rates, without acting in the flow in the closing direction effective flow forces , As a result, the hydraulic machine embodied with the pilot-operated valve according to the invention can be operated with high dynamics during engine operation at higher rotational speeds than the conventional solution.

In a variant of the invention, the valve body of the main stage has a valve disk which is biased against a valve seat and in which the pilot valve body is guided at least in sections and biased against a pilot seat of Vorsteuerströmungs- path.

This bias can be done for example via a tension spring which is supported on the valve disk. In such a variant of the valve disk, for example, a guide bush, on which the tension spring is supported.

In one embodiment, in addition to the tension spring, a shift spring is provided which biases the pilot valve body against the pilot valve seat.

In a variant of the invention, the armature of the pilot actuator is penetrated by a guide rod of the pilot valve body, which carries at its end portion a spring plate on which the aforementioned shift spring is supported, which also biases main stage armature in the direction of its basic position.

In this case, the main-stage armature is then preferably attached to the valve body or integrally formed therewith.

In this case, the valve body may be designed, for example, with a rear hub projection on which the precursor armature is placed.

To adjust the characteristic curve, a projection extending toward the other armature can be formed on an armature, which protrusion dips into a corresponding recess of the other armature in the abovementioned end stroke range, so that the magnetic force on the armature is increased at a comparatively small stroke.

In order to avoid sticking of the second armature to the first-mentioned armature, an anticlip plate or a paramagnetic coating can be provided between them, so that the closing time of the valve is minimized. Likewise, a guide bush in the direction of the pilot control armature protrude from the valve body and thus act as Antiklebeplättchen. For this purpose, the guide bushing must be made of paramagnetic material.

Other advantageous developments of the invention are the subject of further subclaims. In the following, a preferred embodiment of the invention will be explained in more detail with reference to schematic drawings. Show it:

Figure 1 shows a longitudinal section through an inventive pilot-operated valve, which can be used as a high-pressure side valve of a valve-controlled hydraulic machine;

Figure 2 shows the pilot operated valve of Figure 1 with open pilot control and

FIG. 3 shows the valve from FIG. 1 with the main stage open.

Figure 1 shows a longitudinal section through a valve, which can be used for example as a fast-switching electrically unlockable high pressure valve of a DDU of the type described above. Such a high pressure valve 1 is used to control the high pressure side inlet and outlet of the DDU. During pump operation, the high pressure valve operates as a conventional spring-loaded check valve. During engine operation, it must be actively opened against the pending high pressure to release the pressure medium inflow to the displacement chamber.

The illustrated high pressure valve 1 is designed as a cartridge valve, which can be screwed into a receiving bore of the DDU or the hydrostatic displacer unit. Here, the radial port A with a high-pressure channel and the axial port B with a displacement of the hydraulic machine is in fluid communication.

The high-pressure valve 1 is designed as a pilot-operated valve and has a main stage 2, which is assigned to a pilot control 4.

The main stage 2 has a seat bushing 6, on which the radial port A formed by a radial bore star and the axial port B are executed. At an axial bore 8 of the seat sleeve 6, a valve seat 10 is formed by a radial shoulder, against which in the illustrated basic position of the high pressure valve 1, a valve body 12 is biased. This consists essentially of a valve plate 14, which is designed with a seat seat 16 at the end, the sealing in the basic position the valve seat 10 is applied. The valve disk 14 has a downwardly extending in Figure 1, from the axial bore 8 out projection 18 which is penetrated by a pilot hole 20, which widens in Figure 1 upwards to a pilot valve seat 22. Against this, a pilot valve body 24 is biased, the structure will be explained in more detail below.

According to FIG. 1, the valve disk 14 is stepped back on its side facing away from the valve seat 10 via a radial shoulder, so that the valve disk 14 merges into a rear hub projection 26 of the valve body 12. The pilot control bore 20 is extended in the radially expanded region of the valve disk 14 and the hub projection 26 in the radial direction to a guide bore 28, in the back of a guide bushing 30 is inserted. This may be made of paramagnetic material and protrude axially slightly beyond the back face of hub boss 26 to serve as anti-stick pads.

In the region of this guide bush 30, a main-stage armature 32 is placed on the outer circumference of the hub projection 26. In the illustrated embodiment, the material of the main stage anchor 32 is designed for optimal magnetic flux, while the spring plate 14 is designed in view of an optimized sealing effect and wear resistance.

The attachment of the main stage anchor 32 on the hub projection 26 can be done in any way, for example, by shrinking, welding, screwing or otherwise. In the illustrated embodiment, the main stage anchor 32 is plate-shaped with a in FIG. 1, which projects axially upwards in the circumferential direction.

The axial guidance of the valve body 12 in the seat sleeve 6 takes place along the outer circumferential surfaces of the main stage anchor 32 and the spring plate 14 - these sections are slidably guided along an inner guide 36 of the seat bushing 6.

According to Figure 1, the seat bushing 6 is inserted into a valve sleeve 38 which is screwed into the receiving bore of the hydraulic machine mentioned above. At a distance from the pilot valve seat 22 of the pilot valve body 24 of the pilot control 4 is extended to a guide collar 40 which is guided axially displaceably in the guide bore 28. Subsequent to the guide collar 40, the pilot valve body 24 is downgraded in the radial direction to a guide rod 42, which is guided over the guide bush 30.

A tensioning spring 44 engages the ring-shaped surface of the guide collar 40 at the top in FIG. 1, which in turn is supported on the adjacent annular end face of the guide bush 30, so that the pilot valve body 24 is preloaded in a sealing manner against the pilot valve seat 22 with its conical tip.

As shown in Figure 1, the guide rod 42 extends upward beyond the guide bushing 30 and passes through an armature 46 of the pilot control 4. On the out of this armature 46 extending end portion of the guide rod 42 is a bush-shaped, stepped spring plate 48 is placed on the a switching spring 50 attacks. An annular end face 52 of the spring plate 48, which lies at the bottom in FIG. 1, bears against a stop surface 54 of the armature 46 so that it is flush with the adjacent end face of the seat bush by the bias of the switching spring 50 with a radially projecting stop lug 56 on the outer circumference of the armature 46 6 patch washer 58 is biased. The armature 46 is embodied on its end face facing the main-stage armature 32 with an annular recess 57 whose geometry is adapted to the dimension of the projecting peripheral edge 34 of the main-stage armature 32.

In a receiving bore 60 of the valve sleeve 38, a bobbin 62, consisting of a coil carrier and a winding, is used, which can be energized by means of an electrical connection 64 to actuate the armature 46. The bobbin 62 is supported at the top on a pole ring 66 and at the bottom by a further, konifizizierten and non-magnetizable cone ring 68. The function of this conical ring 68 is to seal the high pressure area to the coil and further to the valve environment. Furthermore, the magnetic flux runs around the cone ring 68, so that the field line profile according to FIG. 3 is established. These construction Elements take on the function of a pole tube. In the interior defined by the pole ring 66 and the cone ring 68 and the bobbin 62 an axial pole piece 70 is inserted, which is flared at its lower end in Figure 1 end portion and rests flat against the correspondingly executed cone ring 68 and this engages in sections. The outer circumference of the cone ring 68 abuts with an inclined surface on a corresponding oblique shoulder 72 of the valve sleeve 38, so that the assembly consisting of the pole piece 70 and the cone ring 68 is secured upward (FIG. 1). The axial securing in the opposite direction is effected by a front plate 74, which is connected via a fastening screw 76 with the axial pole piece 70 and is supported in the axial direction on the adjacent annular end face of the pole ring 66. This is in turn supported by a support shoulder 80 on a shoulder 78 of the valve sleeve 68, so that the entire pilot control is clamped in the valve sleeve 38.

The pole piece 70 is designed with a blind hole 82, at the end face of the switching spring 50 is supported and dip into the illustrated in the basic position of the spring plate 48 and the end portion of the guide rod 42 sections.

In the illustrated basic position, in which the spring plate 14 is seated on the valve seat 10 and the armature 46 is biased against the washer 58, the peripheral edge 34 of the main step armature 32 is not or only slightly immersed in the annular recess 57 of the armature 46 so that a secondary working air gap 59 remains between the anchors 32, 46. Between the upper (Fig. 1) armature end face of the armature 46 and the adjacent end face of the pole piece 70 remains a Vorsteuerarbeits- air gap 21. In this case, the valve plate 14 is practically biased by the force of the switching spring 50 against the valve seat 10, wherein the force of the switching spring 50th is transmitted to the valve disk 14 via the pilot valve body 24.

In pump operation, the above-described high pressure valve 1 operates as a check valve, which can be opened by the pressure in the displacement chamber (port B) against the force of the switching spring 50. In the engine operation described above, the higher pressure is applied to the radial port A, so that the high-pressure valve 1 must be opened against this high pressure. This case is described below on the basis of Figures 2 and 3 explained. The sections in FIGS. 2 and 3 are selected somewhat differently than in the illustration according to FIG. 1, but this is of no significance for the above explanations. From this other intersection, it is clear that the two armatures 46, 32 are each pressure-balanced by axially extending relief bores 86, 88.

When the magnet coil of the bobbin 62 is energized, the armature 46 is moved upward as shown in FIG. 2, so that the pilot working air gap 21 closes. In this case, the armature 46 takes over the spring plate 48 with the guide rod 42, so that in the valve plate 14 of the pilot valve body 24 lifts from the pilot valve seat 22.

By lifting the pilot valve body 24 from the pilot valve seat 22, a pilot control flow path between the two ports A, B is opened. This precontrol flow path is indicated by dashed lines in the illustration according to FIG. 1 and is identified by the reference numeral 82. Accordingly, bores are provided in the peripheral wall of the hub projection 26 and in the guide collar 40, which allow a control oil flow from port B through the open pilot valve seat, through the guide collar 40 and radially through the hub projection 26 to the port A.

By lifting the pilot valve body 24, the tension spring 44 is tensioned, whereby on the guide bush 30 in the opening direction on the valve plate 14 effective force is transmitted.

However, the valve disk 14 does not lift off its valve seat 10 immediately after opening the above-described pilot flow path, but only when the pressure level between the high pressure side and the low pressure side (displacement) is almost balanced, and thus in the closing direction due to the pressure difference across the valve Valve plate 14 effective force is smaller than the force acting in the opening direction of the tension spring 44th When the armature 46 abuts the pole piece 70, the magnetic circuit is split, where due to the not shown, running through the main stage armature 34 part of the magnetic circuit already has an opening force on the main stage armature 34 acts.

After the aforementioned pressure equalization of the valve plate 14 as shown in Figure 3, lifted by the force of the tension spring 44 from the valve seat 10, in which case the main stage armature 34 continues in operative engagement with the magnetic field of the solenoid, so that then the main stage armature 34 completely in the magnetic flux lies (see Figure 3). The stroke of the spring plate 14 is then electromagnetically supported, so that this performs a comparatively large stroke and in the illustrated position, in which the main-stage armature 34 bears against the armature 46, is held in its open position - the secondary air gap 59 is then closed. With variation of the regulated current level, the closing and holding force can be adapted to the operating point of the hydraulic machine. It is preferred if the axial length of the pilot air gap 74 is less than the opening stroke H of the valve disk 14. That the guide rod 42 is only so far moved in the inventive principle, as it requires the pilot control fluidically. The actual opening stroke is essentially due to the force of the electromagnet, wherein this opening stroke can in turn be adapted to the pressure and pressure medium volume flow conditions, so that closing of the high-pressure valve due to flow forces is virtually eliminated.

Depending on the design of the main stage armature 32, the valve body 12 may also be partially integrated into the magnetic flux even in the basic valve position. Thus, the beginning of the movement is already supported by the magnet. As a result, the tension spring 44 can be made weaker. However, this is at the expense of the magnetic force on the armature 46 and thus at the expense of the achievable opening force of the pilot control.

In principle, therefore, the magnetic force between pilot control and main stage can be distributed over the geometric design of the main stage anchor 32.

Since the valve disk 14 due to fluidic causes a larger stroke H than the guide rod 42, this must during the stroke of the valve disk 14 relative to Anchor 46 to be movable. During this relative movement, the switching spring 50 is compressed and thus holds the restoring force of the valve 1 in front. The compression work of the switching spring 10 essentially results from the magnetic circuit.

In the illustrated embodiment, the valve body 12 is constructed in two parts with the valve plate 14 and the main stage armature 34, the latter being made of a magnetically favorable material. In principle, however, the valve body can also be formed in one piece.

During the above-described stroke H of the valve disk 14, the peripheral edge 34 of the main stage armature 34 dips into the corresponding annular recess 57 of the pilot 46 of the pilot control, before the two facing end faces of the two armatures 46, 34 come into abutment. By the geometry of the peripheral edge 34 and the corresponding recess 57, the characteristic of the magnetic force acting on the main stage armature 34 can be adapted to the respective conditions. Of course, a projection on the armature 46 can be provided in kinematic reversal, which dips into a corresponding recess on the main stage armature 34. Depending on the characteristic curve adaptation, the projections may have different geometries. In principle, it is also possible to form an axial projection on one of the armatures, which dips into a corresponding axial recess of the other armature, this projection, for example, can be cylindrical or trapezoidal and the corresponding wall regions of the other armature can then be bevelled. Of course, other geometries, for example a peripheral edge with a triangular or trapezoidal cross-section, can be selected instead of the ring-cylindrical peripheral edge 34. In principle, the overlapping region can be chosen such that the characteristic curve is suitably adapted to the respective desired conditions.

In order to prevent sticking of the two anchors 46, 34 to each other or of the armature 46 on the pole piece 70, an anti-sticking plate can still be provided in the respective contact areas. Disclosed are a pilot-operated valve with an electromagnetically actuated pilot control and a valve-controlled hydraulic machine with such a valve. According to the invention, in addition to an armature of the electromagnetically actuated pilot control, a further main stage armature is provided, via which a valve body of the main stage for opening a pressure fluid flow path can be moved into an open position.

LIST OF REFERENCE NUMBERS

1 high pressure valve

2 main stage

4 pilot control

6 seat bush

8 axial bore

10 valve seat

12 valve body

14 valve plates

16 seat area

18 lead

20 pilot hole

22 pilot valve seat

24 pilot valve body

26 hub projection

28 pilot hole

30 guide bush

32 main level anchors

34 peripheral edge

36 inside guide

38 valve sleeve

40 Leadership Alliance

42 guide rod

44 tension spring

46 anchors

48 spring plate Switching spring Ring end face Stop face Stop lug Ring recess Washer Secondary air gap Mounting hole Bobbin body Connection Pole ring Cone ring Pole piece Inclined shoulder Face plate Fixing screw shoulder Support shoulder Pilot flow path Pilot air gap Relief bore Relief bore Field line

Claims

16 / 17Patent claims

1. Pilot operated valve with an electromagnetically actuated feedforward control (4), wherein a main stage (2) has a valve body (12) which is penetrated by a pilot control flow path (82) which is closable by means of a pilot valve body (24) by means of a Vorsteueraktors (62, 24) with an armature (46) from a closed position in an opening pitch can be brought, characterized by a main stage armature (32), which comes after a partial stroke of the valve body (12) in operative engagement with the pilot actuator to the valve body ( 12) to move and / or hold in a Endhubbereich.

2. Valve according to claim 1, wherein the valve body (12) has a valve plate (14) which is biased against a valve seat (10) and in which the Vorsteuerventilkör- by (12) is guided in sections and against a pilot valve seat (22) of the Pre-flow path (82) is biased.

3. Valve according to claim 2, wherein the bias of the pilot valve body (24) via a tension spring (44), which is supported on the valve body (12).

4. Valve according to claim 2 and 3, wherein the valve body (12) has a guide bush (30) on which the tension spring (44) is supported.

5. Valve according to one of the preceding claims, wherein the valve body (12) via a switching spring (50) is biased in the direction of its valve seat (10).

6. Valve according to claim 5, wherein the armature (46) of a guide rod (42) of the pilot valve body (24) is penetrated, which carries at its end portion a spring plate (48) on which the switching spring (50) engages, which also Anchor (46) biased towards a home position.

7. Valve according to one of the preceding claims, wherein the main stage armature (32) is attached to the valve body (12). 17/17

8. Valve according to claim 7, wherein the valve body (12) has a rear hub projection (26) on which the main-stage armature (32) is placed.

9. Valve according to claim 8, wherein on an armature (32, 46) for characteristic adaptation to the other armature (46, 32) extending towards projection (34) is formed in the Endhubbereich in a corresponding recess (57) of the other armature (46, 32) dips.

10. Valve according to claim 9, wherein in the contact region of the armature (32, 46) to each other or to other components a Antiklebeplättchen is provided.

11. Valve-controlled hydraulic machine with a plurality of actively controllable displacement units, each having a piston defining a displacement, which is connectable via a controllable by a control unit high pressure side valve with a high pressure line and a controllable low pressure side valve with a low pressure line, characterized by a high pressure valve according to one of the preceding claims.