DE102012020580A1 - Valve arrangement has main stage with main piston which is designed such that quantity-way characteristic of switching-way valve is hop-free and steady - Google Patents

Abstract

The valve arrangement has a main stage (1) with a main piston (18), and control electronics through which shorter and longer electric pulses (26,28) can be generated by the main piston. An opening stroke with a short duration can be produced, due to the generation of electric pulses. The reversal position is spaced from an end position of the main piston. The main piston is designed such that a quantity-way characteristic of the switching-way valve is hop-free and steady.

Description

The invention relates to a valve arrangement according to the preamble of patent claim 1.

Proportional directional valves are known from the prior art, the valve body can occupy intermediate positions in addition to a closed position and an open position in which a flow cross-section is only partially opened. Thus, in such a directional control valve, a flow rate can be regulated. A disadvantage is the device-technical complexity of this way valves.

In the publication DE 10 2010 045 504 A1 is disclosed a controllable valve, the valve body can assume switching positions and can continue to be moved impulsively or jerkily, whereby the valve is opened at short notice. These opening movements or strokes are repeated several times. With this so-called ballistic mode, reduced flow rates are possible even compared to a complete opening, whereby the directly controlled valve can be regulated.

Furthermore, in the DE 10 2009 052 285 A1 discloses a digital hydraulic valve assembly having a plurality of mutually parallel switching valves of different sizes. These are opened simultaneously in different combinations, resulting in an accumulated opening cross section for the digital hydraulic valve assembly. In order to smooth the resulting gradation of the opening cross-section or the volume flow of the valve assembly, a directly controlled equalizing valve is proposed. This can be opened in a short time in a ballistic process in quick succession, without the valve body reaches its open end position.

A disadvantage of such ballistic valves is that they produce at their openings in each case a hydraulic opening shock, which generates a load of the connected hydraulic system by pressure peaks and further unpleasant operating noise by the continuous repetition of the opening and closing movement or lifting movement.

In contrast, the invention is based on the object to provide a valve assembly with a ballistic directional control valve, avoided in the pressure peaks and the operating noise are reduced.

This object is achieved by a valve arrangement having the features of patent claim 1 or by the features of patent claim 2.

A first variant of the claimed valve arrangement has a directly controlled switching directional valve, which is formed by a main stage with a main piston, and a control electronics, via which an electrical pulse can be generated. By means of the pulse, a partial stroke of short duration is generated on the main piston, the reverse position of which has a distance to an end position or to a stop of the main piston on a main housing. The main piston according to the invention is designed such that a quantity-path characteristic of the main stage is jump-free and continuous. This results in no shocks and a reduced load on the supplied system. The directional control valve and the system produce less noise.

A second variant of the claimed valve arrangement has a pilot-operated switching directional valve, which has a main stage with a main piston and a pilot stage with a pilot piston and a control electronics, via which an electrical pulse can be generated. By means of the pulse, a partial stroke of short duration is generated on the pilot piston and indirectly on the main piston, the respective reversal position being at a distance from a respective end position or to a stop of the respective piston against a respective housing (pilot housing or main housing). The main piston and / or the pilot piston is or are inventively designed such that a quantity-path characteristic of the respective stage is jump-free and continuous. If the pilot piston is designed according to the invention, there are no impacts and less stress in the main stage. The pilot operated directional control valve generates less noise. If the main piston is formed according to the invention, there are no shocks and a reduced load on the supplied system. The directional control valve and the system supplied produce less noise. Preferably, pilot and main stage are designed according to the invention, so that the pilot operated directional control valve generates no shocks and blows and develops minimal noise.

In both variants of the valve arrangement according to the invention "partial stroke" means that the piston does not reach its end position and the stage does not open completely. The "end position" is that position of the piston that causes the maximum opening of the stage. "Volume path characteristic" is the characteristic curve of the volume flow as a function of the stroke or travel of the piston.

Further advantageous embodiments of the invention are described in the dependent claims.

In a preferred embodiment, the main stage is a slide valve. The mass-path characteristic can then during the first opening a Increase from 0 and then steadily increase. This avoids shocks during the opening of the main stage and in the further course of the opening stroke.

Alternatively or in addition, the pilot stage (the second variant) may be a spool valve. The mass-path characteristic may then have a slope of 0 during the first opening and then increase steadily thereafter. This avoids impacts during the opening of the pilot stage and in the further course of the opening stroke.

In a preferred embodiment, at least one control edge is formed on the pilot piston and / or on the main piston, on which a cone with - viewed against the opening direction of the piston - constantly decreasing cross-section is provided. The cone may be formed as a linear chamfer. The cone can also have a parabolic shape in sectional view, starting from the widest portion of the piston, the distance to the imaginary continuation of this section increases steadily increasing.

In a preferred embodiment, at least one control edge is formed on the pilot piston and / or on the main piston, which is interrupted by at least one recess. Starting from the control edge, viewed from a direction of displacement of the piston, the recess has a continuously decreasing cross-section. For changing the cross section, a width of the recess (approximately in the tangential direction of the piston) and a depth of the recess (in the radial direction of the piston) are available. Preferably, a plurality of recesses provided on the circumference of the control edge and thus on the circumference of the piston are provided.

If the partial stroke is smaller than a length of the recesses - viewed in the direction of displacement of the piston - no annular gap is created as the opening cross section even when the reverse position is reached, but the pressure medium must flow completely through the recesses throughout the opening stroke. Then the entire continuous quantity-path characteristic curve can be generated and determined via the above-described change in cross section.

If the invention according to the invention continuous flow path characteristic is to be maintained even at a Öffnungshube that releases a complete annular gap or ring as the opening cross-section, the recesses would have to be distributed so many at the periphery of the control edge and / or have such increasing width, that the recesses on touch the control edge or merge into each other.

Continuous cross-sectional changes can be realized in that the recesses are triangular notches or V-grooves.

In one application (both variants) of the valve arrangement according to the invention, the main stage is a 3/4-way valve, which has a pump connection, a tank connection, and two working connections. Between the pump port and each working port - more precisely between the associated pressure chambers - in each case a positive overlap is provided in a middle closed position of the main piston. Thus, the valve assembly according to the invention is low-leakage and particularly suitable for a position or position control of a consumer supplied by her.

In one application (the second variant) of the valve assembly according to the invention, the pilot stage is a 3/4-way valve having a pump port, a tank port, and two control ports, wherein between the pump port and each control port - more precisely between the associated pressure chambers - in one Middle closed position of the pilot piston is provided in each case a negative overlap.

Particularly preferred is a combination of the two last-mentioned applications. In this case, the control terminals of the pilot stage are connected to respective frontally arranged on the main piston control pressure chambers of the main stage. This results in a leakage from the pump port of the pilot stage to the control pressure chambers, so that a movement of the main piston (eg., A centering of the main piston in its normal position via springs) does not lead to an idling of the control channels.

Preferably, the quantity-way characteristic is a quadratic function z. B. Q (x) = x ² with Q = flow and x = stroke or way.

The main stage and / or the pilot stage may also be a seat slide valve.

The valve assembly is designed and adjusted so that a reproducible pulse duration leads to a partial lift up to a certain reversal point and with a certain duration of the pilot stage. As a result, such a large amount of control pressure fluid reaches the main stage that it performs a partial lift up to a certain reversal point and with a certain duration. As a result, the valve arrangement according to the invention allows a predetermined amount of pressure medium to be transmitted to a reproducible pulse duration. So z. B. by a partial stroke of the pilot piston, which is 70% of its complete stroke, reproducible partial stroke of the main piston are generated, which is 20% of its complete stroke.

In the following, an embodiment of the invention will be described in detail with reference to FIGS. Show it

1 a pilot-operated switching-way valve of the embodiment of the valve assembly according to the invention in a sectional view;

2 a diagram with the dependence of the stroke or travel of the pilot piston of the pulse duration of the valve assembly according to the invention;

3 a diagram with the stroke or travel of the pilot piston, the main piston and a cylinder supplied by the directional control valve in a time course;

4 a section of the pilot stage of the switching way valve;

5 a section of the main stage of the switching way valve; and

6 a diagram with a quantity-way characteristic of the main stage of the embodiment.

1 shows the embodiment of the pilot-operated ballistic switching-way valve of the valve arrangement according to the invention in a sectional view. It has a main stage 1 and a pilot stage or pilot stage 2 , The pilot level 2 has a pilot piston or pilot piston 4 who in 1 is shown in its basic or closed position. The pilot piston 4 can along a longitudinal axis 6 be moved in both directions. This is the pilot piston 4 in a housing of the pilot stage or in a pilot housing 8th over two along the longitudinal axis 6 acting return springs 10a . 10b biased in its basic or closed position and can two pilot magnets 12a . 12b be shifted such that a pump port P 'either with a first control channel A' or with a second control channel B 'of the pilot stage 2 is connected. The respective other control channel A 'and B' is thereby relieved to a tank port T '.

The pilot level 2 is over her pilot case 8th on a main body 14 the main stage 1 attached, in which along a longitudinal axis 16 a main piston 18 slidably received. In 1 is the main piston 18 shown in its basic or closed position, in which a pump port P is shut off against two working ports A, B. Front side on the main piston 18 are two opposing control pressure chambers 20a . 20b formed, in each of which a return spring 22a . 22b is included, located on the main body 14 supports and the main piston 18 biased in the basic or closed position.

Every control pressure chamber 20a . 20b is via a control pressure channel 24a . 24b with one of the two control channels A ', B' of the pilot stage 2 connected. By one-sided admission of a control pressure chamber 20a . 20b with control pressure means can the main piston 18 be shifted so that the pump port P with one of the two working ports A, B is connected. The respective other working port A or B is thereby relieved to a tank port T.

During operation of the valve arrangement according to the invention, for example, the pump connection P should be connected to the working connection A of the main stage 1 get connected. This is the first pilot magnet 12a energized, so he the pilot piston 4 against the force of the second return spring 10b (in 1 ) moves to the right. Thereby, the pump port P 'is connected to the control channel B', so that via the second control pressure channel 24b Control pressure in the second control pressure chamber 20b arrives. As a result, the main piston against the force of the first return spring 22a (in 1 ) is moved to the left, so that the pump port P is connected to the working port A. At the same time the working port B is relieved to the tank port T.

The pilot operated switching directional control valve is pulsed or operated ballistically. This is done by an amplifier (not shown), which contains the two pilot magnets 12a . 12b subjected to a series of power surges. 2 shows a diagram with the dependence of the stroke and the path of the pilot piston 4 from the pulse duration sent by the amplifier to one of the two pilot magnets 12a . 12b is transmitted. Here are in 2 two examples shown. In the first example, the amplifier applies the pilot magnet 12a . 12b with a comparatively short current pulse 26 , This will be on the pilot piston 4 a comparatively small and short-lived stroke 30 generated. With a longer current pulse 28 at the pilot magnet 12a . 12b becomes a comparatively larger and longer-lasting hub 32 at the pilot piston 4 generated. The two strokes 30 . 32 begin and end in the 1 shown basic or closed position of the pilot piston 4 , Due to the temporarily short opening of the pilot stage 2 is via a corresponding short-term pressure medium thrust in one of the two control pressure chambers 20a . 20b the main piston 18 promoted, whereby this is deflected in the short term and the corresponding connection from the pressure port P to one of the working ports A, B is turned on.

3 shows an exemplary course of the stroke or path 34 of the pilot piston 4 and the stroke or path created thereby 36 of the main piston 18 , In the example, one of the pilot magnets becomes 12a . 12b initially energized comparatively long, so that the pilot piston 4 over a certain time in its final position is held (100% pilot piston). The answer of the main piston 18 is delayed and leads the main piston 18 also over a certain time in its final position (100% main piston).

Over time, the pilot magnet becomes 12a . 12b energized four times with decreasing duration, so that the pilot piston 4 four partial strokes 38 with (to a lesser extent) decreasing stroke. This is the stroke or path 36 of the main piston 18 also shows four time-shifted and (to a greater extent) decreasing partial strokes 40 performs. Every partial stroke 40 of the main piston 18 leads to pushing a certain amount of oil from the working port A, B of the main stage 1 ,

3 also shows a stroke or path 42 a piston of a (not shown) cylinder which is connected to the working port A, B. Due to the continuous current at the beginning of the time profile shown, the piston moves from a starting position 44 near a final position 46 and then becomes, by the four pulses of decreasing duration, four steps of decreasing magnitude in its final position 46 emotional. With the valve arrangement according to the invention, a position control is realized in this way.

4 shows a section of the pilot stage 2 , These are the pilot housing 8th and the pilot piston 4 shown only in the region of a pressure chamber connected to the pump connection P 'and a pressure chamber connected to the control channel A' or B '. Between these two pressure chambers has the pilot stage 2 each a negative overlap, so that even in the basic or closed position of the pilot piston 4 Control pressure means for filling the two control pressure chambers 20a . 20b is available. The negative overlap is made by several at the periphery of a sealing section 48 distributed flattenings made by milling 50 educated. These extend from a groove 56 of the Pilotkobens 4 up to a control edge 58 and up to an adjoining cone 52 , As a result, from the pump connection P 'to the two control channels A', B 'always reach some control pressure medium.

For an opening stroke (partial or complete stroke) of the pilot piston 4 (in 4 ) to the right is over the cone 52 fully and steadily increasing a pressure fluid connection from the pump port P 'to the control channel A' and B 'opened and relieved the opposite side to T'. Through the cone 52 of the pilot piston 4 are a steady increase in volume flow and thus a smooth jerk-free control of the main piston 18 allows.

5 shows a section of the main level 1 with her main body 14 and her main butt 18 , Here is the main piston 18 in the region of a connected to the working port A and B pressure chamber, adjacent to this pressure chamber on the one hand a connected to the tank port T pressure chamber and on the other hand, a connected to the pump port P pressure chamber are arranged. In the (in 5 shown) basic or closed position of the main piston 18 is a positive overlap of the pressure chamber A / B on the one hand to the pressure chamber T and on the other hand to the pressure chamber P provided. As a result, the leakage is the main stage 1 minimized, so that a powered and position-controlled consumer via the working port A / B is not moved.

In order to achieve a smooth, shock-free start-up in the pulsed operation of the supplied consumer according to the invention with a continuous speed curve, on the one hand between the working port A / B and the tank port T and on the other hand between the working port A / B and the pump port P four evenly distributed around the circumference recesses arranged that of triangular grooves or V-grooves 54 are formed. Their cross-section increases toward a respective control edge 60 steadily.

6 shows the volume flow Q [in l / min] of the main stage 1 depending on the stroke or path of their main piston 18 [in mm]. The flow path characteristic shows an increasing volumetric flow for negative strokes 66 from the pump port P to the working port A or B, while they in positive strokes an increasing flow rate 68 from the working port A or B to the tank port T shows. Starting from the zero point, a short path is first of all without effect on the volume flow, since at the main stage 1 in each case a positive overlap for both compounds 62 respectively. 64 is realized (cf. 5 ). After this short stroke, the volume flow decreases 66 respectively. 68 square too. Thus, a continuous amount-way characteristic of the invention is the main stage 1 realized. In betreib the valve assembly according to the invention, the state of the main stage runs 1 repeated in rapid succession starting from the zero point along the quantity-way characteristic curve and back.

Disclosed is a valve arrangement with a ballistic switching directional valve, which is repeated by current pulses and briefly opened. The switching directional control valve is either directly controlled (according to a first variant) or pilot-controlled (according to a second variant). A main stage and in particular its main piston and / or a pilot stage and in particular its pilot piston are / is designed and movable in a respective housing of the respective stage that a crowd-way characteristic of the stage is continuous. This will be in ballistic operation Pressure surges within the switching way valve and / or avoided in a consumer supplied by this.

LIST OF REFERENCE NUMBERS

1

main stage

2

pilot stage

4

pilot piston

6

Longitudinal axis (pilot stage)

8th

pilot case

10a

first return spring (the pilot stage)

10b

second return spring (the pilot stage)

12a

first pilot magnet

12b

second pilot magnet

14

main body

16

Longitudinal axis (the main level)

18

main piston

20a

first control pressure chamber

20b

second control pressure chamber

22a

first return spring (the main stage)

22b

second return spring (the main stage)

24a

first control pressure channel

24b

second control pressure channel

26

shorter pulse

28

longer pulse

30

smaller shorter stroke

32

larger longer stroke

34

Stroke or path (of the pilot piston)

36

Stroke or path (of the main piston)

38

Partial lift (of the pilot piston)

40

Partial stroke (of the main piston)

42

Lift or path

44

starting position

46

End position (of the piston)

48

sealing portion

50

Flattening (of the pilot piston)

52

cone

54

V-groove

56

groove

58

Control edge (of the pilot piston)

60

Control edge (of the main piston)

62

positive coverage (of the main piston) between A / B and T

64

positive coverage (of the main piston) between P and A / B

66

flow

68

flow

P '

Pump connection (the pilot stage)

A ', B'

Control channel (pilot stage)

T '

Tank connection (the pilot stage)

P

Pump connection (the main stage)

A, B

Work connection (the main level)

T

Tank connection (the main stage)

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010045504 A1 [0003]
• DE 102009052285 A1 [0004]

Claims (15)

Valve arrangement with a directly controlled switching directional control valve, which is controlled by a main stage ( 1 ) with a main piston ( 18 ) is formed, and with a control electronics via which an electrical pulse ( 26 . 28 ) is generated by the on the main piston ( 18 ) an opening stroke ( 40 ) can be generated with a short duration whose reversing position is at a distance to an end position or to a stop of the main piston ( 18 ), characterized in that the main piston ( 18 ) Is designed such that a quantity-way characteristic of the switching-way valve is jump-free and continuous. Valve arrangement with a pilot-operated switching directional control valve, which is a main stage ( 1 ) with a main piston ( 18 ) and a pilot stage ( 2 ) with a pilot piston ( 4 ), and with a control electronics via which an electrical pulse ( 26 . 28 ) can be generated by the pilot piston ( 4 ) and indirectly on the main piston ( 18 ) an opening stroke ( 38 . 40 ) can be generated with a short duration whose reversing position is at a distance to an end position or to a stop of the respective piston ( 4 . 18 ), characterized in that the main piston ( 18 ) and / or the pilot piston ( 4 ) is or are designed such that a quantity-path characteristic ( 62 . 64 . 66 . 68 ) of the respective stage ( 1 . 2 ) is jump-free and steady. Valve arrangement according to claim 2, wherein the pilot stage ( 2 ) is a slide valve. Valve arrangement according to one of the preceding claims, wherein the main stage ( 1 ) is a slide valve. Valve arrangement according to one of claims 2 to 4, wherein at the pilot piston ( 4 ) at least one control edge ( 58 ) is formed, on which a cone ( 52 ) is provided with steadily decreasing cross-section. Valve arrangement according to one of the preceding claims, wherein at least one control edge is formed on the main piston, on which a cone is provided with continuously decreasing cross-section. Valve arrangement according to one of claims 2 to 4, wherein at least one control edge is formed on the pilot piston, is provided on the at least one recess with continuously decreasing cross-section. Valve arrangement according to one of the preceding claims, wherein on the main piston ( 18 ) at least one control edge ( 60 ) is formed on the at least one recess ( 54 ) is provided with steadily decreasing cross-section. Valve arrangement according to claim 7 or 8, wherein the opening stroke ( 40 ) smaller than a length of the recess ( 54 ). Valve arrangement according to one of claims 7 to 9, wherein the at least one recess a triangular notch or V-groove ( 54 ). Valve arrangement according to one of the preceding claims, wherein the main stage ( 1 ) is a 3/4-way valve having a pump port (P) and two working ports (A, B), and wherein between the pump port (P) and each working port (A, B) between the main piston ( 18 ) and a main housing ( 14 ) a positive overlap is provided. Valve arrangement according to one of claims 2 to 11, wherein the pilot stage ( 2 ) is a 3/4-way valve having a pump port (P ') and two control ports (A', B '), and wherein between the pump port (P) and each control port (A', B ') between the pilot piston ( 4 ) and a pilot housing ( 8th ) a negative overlap is provided. Valve arrangement according to one of the preceding claims, wherein the mass-path characteristic is a quadratic function. A valve assembly according to claim 2, wherein the pilot stage is a seat slide valve. Valve arrangement according to claim 1 or 2, wherein the main stage is a seat-slide valve.

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