DE102019009254B3 - Proportional hydraulic valve - Google Patents

Abstract

Proportional hydraulic valve (1) with a valve housing (2), an actuating device (3) and a valve piston (5) which can be moved axially in a piston chamber (4) of the valve housing (2), the valve housing (2) having at least one pressure connection (P) and has at least one connection port (T), and the valve piston (5) blocks or proportionally opens a flow path between the pressure port (P) and the connection port (T), in that the valve piston (5) moves proportionally to a flow path generated by the actuating device (3). actuating force moves between a blocking position (SP) and an open position (OS) in the piston chamber (4), the valve piston (5) having a first slide area (6) and a second slide area (7), and the valve piston (5) in the axial Direction (AR) after the first slide area (6) and before the second slide area (7) has a circumferential depression (8), and the depression (8) together with the piston chamber (4) forms a pressure chamber (9), characterized in that that the pressure connection (P) opens into the pressure chamber (9), and a first diameter (D1) of the first spool area (6) is larger than a second diameter (D2) of the second spool area (7), so that a pressure-loaded differential area is affected by the difference between the Area of the first slide area (6) as a function of the first diameter (D1) and the area of the second slide area (7) as a function of the second diameter (D2) is formed.

Description

The present invention relates to a proportional hydraulic valve with a valve housing, an actuating device and a valve piston that can be moved axially in a piston chamber of the valve housing.

In such valves, the valve housing has at least one pressure port and at least one connection port. The valve piston blocks a flow path between the pressure port and the connection port or proportionally releases this flow path by the valve piston moving between a blocked position and an open position in the piston chamber proportional to an actuating force generated by the actuating device. The connection port is often a tank or return port. Such a proportional hydraulic valve is, for example, from DE 10 2005 022 693 A1 or the DE 10 2010 039 918 A1 known.

The known proportional hydraulic valves regularly fulfill the intended function very well, for example as a proportional pressure-limiting valve. The task of pressure relief valves is to limit the system pressure to a specific nominal pressure. As soon as the nominal pressure is reached, the pressure relief valve responds and the excess volume flow is routed from the pressure port to the connection or tank port. However, particularly at high nominal pressures of, for example, more than 300 bar, an increased dynamic pressure can occur on the valve piston. A dynamic pressure is to be understood here as the pressure difference between the pressure connection and the connection or tank connection.

In order to counter this problem, the seats are reduced in the proportional hydraulic valves designed as poppet valves in order to obtain a smaller pressurized area. The disadvantage here is that the volume flow also decreases, ie relatively little volume can flow when the valve is in the open position.

Against this background, the object of the present invention is to show a proportional hydraulic valve in which a low dynamic pressure can be achieved, particularly at high nominal pressures, while at the same time a sufficient volume flow can flow between the pressure port and the connection or tank port.

The object is achieved with a proportional hydraulic valve according to claim 1. Advantageous developments are described in the dependent claims.

The proportional hydraulic valve according to the invention is characterized in that the valve piston has a first slide area and a second slide area, and the valve piston has a circumferential recess in the axial direction after the first slide area and before the second slide area, and the recess together with the piston chamber a pressure chamber forms. The proportional hydraulic valve according to the invention is distinguished from the hydraulic valves known from the prior art in that the pressure connection opens into the pressure chamber. Furthermore, the proportional hydraulic valve according to the invention is characterized in that a first diameter of the first spool area is larger than a second diameter of the second spool area, so that a pressure-loaded differential area is determined by the difference in the area of the first spool area as a function of the first diameter and the area of the second spool area is formed as a function of the second diameter. The axial direction within the meaning of the invention is understood to mean the direction from the actuating device to the valve piston.

The construction of the valve piston according to the invention as a spool-like valve piston makes it possible for the dynamic pressure to be relatively small, although a relatively large flow cross section is available. This is because the effective or pressure-loaded differential area is formed by the difference between the area of the first slide area as a function of the first diameter and the area of the second slide area as a function of the second diameter. Depending on the nominal pressure and the area of application for which the proportional hydraulic valve is to be designed, a sufficiently large flow cross section and a correspondingly small differential area can be selected so that overall a low dynamic pressure is achieved despite a high maximum volume flow at particularly high nominal pressures.

The valve piston preferably has a closing element in the axial direction in front of the first slide area and the valve housing preferably has a valve seat, the closing element resting on the valve seat when the valve piston is in the blocking position. The closing element can in particular be a valve cone. This achieves particularly good tightness in the locked position and largely prevents leakage oil flow from the pressure connection to the connection or tank connection.

It is advantageous if the piston chamber has a first annular groove in the axial direction in front of the pressure connection, with the connection connection opening into the first annular groove and the valve seat being formed on a peripheral edge of the first annular groove, with the first slide region positively pressing the valve seat over a lifting movement path covered. The operational safety can thus be increased, since when the valve piston lifts off the valve seat from the blocked position in the direction of the open position, initially only a leakage oil flow flows from the pressure chamber to the first annular groove. Only when the valve piston has covered the lifting movement distance will a larger cross section be released, so that a larger volume flow can flow from the pressure chamber to the first annular groove.

It is expedient if the valve piston has at least one recess which extends axially from the recess into the first slide region, the at least one recess only partially encircling radially. In other words, the at least one recess is radially non-circular. The through-flow cross section can be increased by the recess, so that a larger volume flow can flow from the pressure connection to the connection or tank connection.

Preferably, the at least one recess at least partially has a cross-sectional area that increases in the axial direction. In this way it can be achieved that the flow cross section does not increase abruptly, but gradually. Overall, a better response of the proportional hydraulic valve is achieved.

It is advantageous if the valve piston has two or more recesses that are evenly distributed over the circumference. By providing two or more regularly arranged recesses, it can be prevented that the valve piston is subjected to a force on one side and therefore runs eccentrically.

It is expedient if the piston chamber has a damping chamber at one axial end, the valve piston having a circumferential damping groove which is in fluid communication with the connection port and a damping gap extending axially from the damping groove between the valve piston and the piston chamber, the Damping gap is in fluid communication with the damping chamber. As a result, the movement of the valve piston in the piston chamber is damped, which overall leads to a reduction or suppression of undesired vibrations. The damping gap is to be selected according to the desired damping.

The second slide area is preferably guided in a guide section of the piston chamber, with the damping chamber being arranged in the axial direction after the guide section and the damping groove being formed on the second slide area, so that the damping gap extends in the axial direction. This allows a particularly simple manufacture of the valve housing and simplified assembly of the proportional hydraulic valve.

It is advantageous if the valve piston has an axial blind bore, a first bore radially penetrating the valve piston and a second bore radially penetrating the valve piston, the first bore being in fluidic connection with the connection port and the second bore being in fluidic connection with the damping groove is. Consequently, the damping is arranged in the low-pressure area via the damping gap. When the valve piston moves from the blocking position (or an intermediate position) in the direction of the open position, hydraulic oil is sucked out of the connection or tank connection into the damping chamber via the first bore, the blind bore, the second bore and the damping gap. Accordingly, when moving from the open position (or an intermediate position) in the direction of the blocked position, hydraulic oil is pressed from the damping chamber into the connection or tank connection via the first bore, the blind bore, the second bore and the damping gap. This allows damping of the movement of the valve piston in a simple manner.

It is expedient if at least one circumferential second annular groove is arranged on the second slide area. The annular groove suppresses leakage oil flow from the pressure chamber via the second spool area. Of course, two or more second ring grooves can also be provided, care being taken to ensure that the axial length of the second ring grooves does not lead to an eccentric displacement of the valve piston.

The proportional hydraulic valve is preferably a proportional pressure relief valve. Depending on which actuation device is used, a proportional pressure relief valve can be implemented with a falling or rising characteristic. Alternatively, the proportional pressure relief valve can be a pilot operated check valve.

The solution to the problem is also achieved with a hydraulic system with an inventive ss proportional hydraulic valve. For example, the proportional hydraulic valve according to the invention can be used in a hydraulic system for pump control or for pressure limitation in an LS system.

• 1 eine teilweise geschnittene Seitenansicht eines erfindungsgemäßen proportionalen Hydraulikventils in einer Offenstellung;
• 2 eine vergrößerte Ansicht des in 1 gezeigten proportionalen Hydraulikventils;
• 3 das in 2 gezeigte proportionale Hydraulikventil in einer Sperrstellung;
• 4 eine erste Seitenansicht eines Ventilkolbens des erfindungsgemäßen proportionalen Hydraulikventils;
• 5 einen Schnitt durch den in 4 gezeigten Ventilkolben entlang der Linie A - A;
• 6 eine zweite Seitenansicht des in 4 gezeigten Ventilkolbens; und
• 7 eine perspektivische Ansicht des in 4 gezeigten Ventilkolbens.

The invention is explained in more detail below using an exemplary embodiment shown in the figures. Here show schematically:

• 1 a partially sectioned side view of a proportional hydraulic valve according to the invention in an open position;
• 2 an enlarged view of the in 1 proportional hydraulic valve shown;
• 3 this in 2 proportional hydraulic valve shown in a blocking position;
• 4 a first side view of a valve piston of the proportional hydraulic valve according to the invention;
• 5 a cut through the in 4 shown valve piston along the line A - A;
• 6 a second side view of the in 4 shown valve piston; and
• 7 a perspective view of the in 4 shown valve piston.

In 1 an inventive proportional hydraulic valve 1 according to the present invention is shown in partial section. In this embodiment, the proportional hydraulic valve 1 is a proportional pressure relief valve. Of course, the hydraulic valve 1 can also be designed in such a way that it fulfills another hydraulic function, for example as a pilot-operated check valve. The proportional pressure relief valve 1 has a (in 1 section shown) valve housing 2 and an actuator 3 on. In addition, the valve housing 2 has a plurality of pressure connections P that are arranged radially circumferentially at regular intervals, as well as a plurality of connecting connections T that are axially spaced apart from the pressure connections and also run radially circumferentially at regular intervals. In this exemplary embodiment, the connection ports T represent tank ports. In this exemplary embodiment, the pressure ports P are inclined and the tank ports T are arranged perpendicular to the valve piston 5 . The inclination of the pressure ports P and tank ports T relative to the valve piston 5 can be adjusted as required.

The actuating device 3 can, in particular, comprise an electro-proportional magnet and possibly a spring unit, depending on whether the pressure-limiting valve 1 is to be designed with a rising or falling characteristic. A piston chamber 4 is formed in the valve housing 2, in which a valve piston 5 moves proportionally to the actuating force of the actuating unit 3 between a blocking position SP (cf. 3 ) and an open position OS (cf. 1 and 2 ) is arranged to be axially movable in order to block or proportionately open a flow path between the pressure ports P and the tank ports T.

The valve piston 5 is designed like a slide and has a first slide area 6 and a second slide area 7 . The second slide area 7 is guided in a guide section 17 of the piston chamber 4 . In an axial direction AR, ie in the direction from the actuating unit 3 to the valve housing 2 , a circumferential recess 8 is formed between the first slide area 6 and the second slide area 7 . How to get in particular 4 As can be seen, the recess 8 transitions into the corresponding slide area 6, 7 with a gently widening transition radially outward. The circumferential recess 8 forms a pressure chamber 9 together with an inner peripheral surface of the piston chamber 4. The pressure connections P open into the pressure chamber 9 as shown.

As in 4 shown, the first slide area 6 has a first diameter D1. The second slide area 7 has a second diameter D2, which is smaller than the first diameter D1. Consequently, the pressure-loaded differential area in the pressure chamber 9 is 0.25×π×(D1 ² −D2 ² ). It follows from this that relatively large flow cross sections can be realized with a relatively small differential area at the same time, which leads to a relatively low dynamic pressure overall.

In order to largely prevent a possible flow of leakage oil, particularly in the blocking position SP, the valve piston has a closing element 10 in the form of a cone. The valve housing 2 has a valve seat 11 against which the cone rests in the blocking position SP, as in particular in 3 shown. The valve seat 11 is formed on a lower circumferential edge in the axial direction AR of a first annular groove 12 formed in the piston chamber 4 . As shown, the tank connections T open into this first annular groove 12.

As in the 4 until 7 shown, the valve piston 5 has a plurality of recesses 13 which extend axially from the depression 8 into the first slide area 6 . In this exemplary embodiment, the valve piston 5 has a total of three recesses 13 which are arranged circumferentially around the valve piston 5 at regular intervals. The recesses 13 are not radially circumferential and do not extend axially to the Cone 10. Rather, a positive overlap PÜ is provided between the cone 10 and the recesses 13 in the axial direction AR. In other words, the axial length of this positive overlap PÜ corresponds to a lifting movement distance by which the piston 5 must first be moved from the blocked position SP in the direction of the open position OS before the recesses 13 have a larger flow cross section as a flow path between the pressure chamber 9 and release the pressure connections P and the first ring groove 12 or the tank connections T. During the movement of the valve piston 5 along the lifting movement path PÜ, only leakage oil flows from the pressure chamber 9 to the first annular groove 12. As shown, the recesses 13 are designed such that the cross-sectional area of each recess 13 increases in the axial direction AR. Consequently, as the movement distance of the valve piston 5 increases from the blocked position SP to the open position OS, an ever increasing flow cross section is released.

At the axial end 14 seen in the axial direction AR, the piston chamber 4 has a damping chamber 15 which adjoins the guide section 17 or is arranged after the guide section 17 in the axial direction AR. A circumferential damping groove 16 is formed on the second slide area 7 and is fluidically connected to the first annular groove 12 or the tank connections T. For this purpose, the valve piston 5 has an axial blind bore 18 into which a first bore 19 radially penetrating the valve piston 5 opens. How in particular from a comparison of 2 and 3 As can be seen, the first bore 19 is in permanent fluidic connection with the first annular groove 12 and the tank connections T both in the open position OS and in the blocked position SP 5 penetrates radially and also opens into the blind bore 18. Furthermore, the second bore 20 opens out as in FIG 2 until 5 shown in the damping groove 16.

A damping gap S is formed after the damping groove 16 in the axial direction AR, which allows a relatively small volume flow of hydraulic oil between the damping groove 16 and the damping chamber 15 . When the valve piston 5 closes, i.e. when it moves in the axial direction AR, the hydraulic oil is pumped out of the damping chamber 15 via the damping gap S and via the damping groove 16 and the bores 18, 19, 20 into the first annular groove 12 or to the Tank connections T pressed. Due to the relatively small flow cross section of the damping gap S, this movement is therefore damped. Accordingly, when the valve piston 5 moves in the opposite direction, hydraulic oil is sucked out of the first annular groove 12 or the tank connections T via the bores 18, 19, 20, the damping groove 16 and the damping gap S into the damping chamber 15. Correspondingly, this opening movement of the valve piston 5 also results in damping due to the relatively small flow cross section of the damping gap S.

As shown in all figures, a total of three second annular grooves 21 are also formed on the second slide area 7 . The second annular grooves 21 are arranged in the axial direction AR after the depression 8 and before the damping groove 16 . These second annular grooves 21 suppress a leakage oil flow from the pressure chamber 9 to the damping chamber 15 or to the damping groove 16.

Reference List

1

proportional hydraulic valve/ pressure relief valve

2

valve body

3

actuating device

4

piston chamber

5

valve piston

6

first slider area

7

second slider area

8th

deepening

9

pressure chamber

10

closing element

11

valve seat

12

first ring groove

13

recess

14

axial end

15

damping chamber

16

cushioning groove

17

guide section

18

axial blind hole

19

first drilling

20

second hole

21

second ring groove

D1

first diameter

D2

second diameter

AR

axial direction

OS

open position

P

pressure connection

PU

positive overlap/lift off movement distance

T

Connection port/ tank port

S

damping gap

SP

locked position

Claims (13)

Proportional hydraulic valve (1) with a valve housing (2), an actuating device (3) and a valve piston (5) which can be moved axially in a piston chamber (4) of the valve housing (2), the valve housing (2) having at least one pressure connection (P) and has at least one connection port (T), and the valve piston (5) blocks or proportionally opens a flow path between the pressure port (P) and the connection port (T), in that the valve piston (5) moves proportionally to a flow path generated by the actuating device (3). actuating force moves between a blocked position (SP) and an open position (OS) in the piston chamber (4), the valve piston (5) having a first slide area (6) and a second slide area (7), and the valve piston (5) in an axial Direction (AR) after the first slide area (6) and before the second slide area (7) has a circumferential depression (8), and the depression (8) together with the piston chamber (4) forms a pressure chamber (9), characterized in that that the pressure connection (P) opens into the pressure chamber (9), and a first diameter (D1) of the first spool area (6) is larger than a second diameter (D2) of the second spool area (7), so that a pressure-loaded differential area is caused by the difference the area of the first slide area (6) as a function of the first diameter (D1) and the area of the second slide area (7) as a function of the second diameter (D2). Proportional hydraulic valve (1) after claim 1 , characterized in that the valve piston (5) has a closing element (10), in particular a valve cone, in the axial direction (AR) in front of the first slide area (6), and in that the valve housing (2) has a valve seat (11), the Closing element (10) rests on the valve seat (11) when the valve piston (5) is in the blocked position (SP). Proportional hydraulic valve (1) after claim 2 , characterized in that the piston chamber (4) in the axial direction in front of the pressure port (P) has a first annular groove (12), the connecting port (T) opening into the first annular groove (12) and the valve seat (11) on a circumferential Edge of the first annular groove (12) is formed, wherein the first slide area (6) positively covers the valve seat (11) on a lifting movement distance (PÜ). Proportional hydraulic valve (1) according to one of the preceding claims, characterized in that the valve piston (5) has at least one recess (13) which extends axially from the depression (8) into the first slide area (6), the at least one Recess (13) is radially only partially circumferential. Proportional hydraulic valve (1) after claim 4 , characterized in that the at least one recess (13) at least partially has a cross-sectional area that increases in the axial direction (AR). Proportional hydraulic valve (1) after claim 4 or 5 , characterized in that the valve piston (5) has two or more recesses (13) which are evenly distributed over the circumference. Proportional hydraulic valve (1) according to one of the preceding claims, characterized in that the piston chamber (4) has a damping chamber (15) at one axial end (14), the valve piston (5) having a circumferential damping groove (16) which is fluidic is in communication with the connection port (T) and wherein a damping gap (S) extends axially from the damping groove (16) between the valve piston (5) and the piston chamber (4), the damping gap (S) being in fluid communication with the damping chamber ( 15) is. Proportional hydraulic valve (1) after claim 7 , characterized in that the second slide area (7) is guided in a guide section (17) of the piston chamber (4), the damping chamber (15) being arranged in the axial direction (AR) after the guide section (17) and the damping groove (16 ) on the second slide area (7), so that the damping gap (S) extends in the axial direction (AR). Proportional hydraulic valve (1) after claim 7 or 8th , characterized in that the valve piston (5) has an axial blind bore (18), a first bore (19) radially penetrating the valve piston (5) and a second bore (20) radially penetrating the valve piston (5), the first bore (19) is in fluid communication with the connection port (T) and the second bore (20) is in fluid communication with the damping groove (16). Proportional hydraulic valve (1) according to one of the preceding claims, characterized in that at least one circumferential second annular groove (21) is arranged on the second slide area (7). Proportional hydraulic valve (1) according to one of the preceding claims, characterized in that the hydraulic valve (1) is a proportional pressure relief valve Proportional hydraulic valve (1) according to any of the previous ones Claims 1 until 10 , characterized in that the hydraulic valve (1) is a pilot operated check valve. Hydraulic system with a proportional hydraulic valve (1) according to one of the preceding claims.

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