DE102020212201B4 - Separate hydraulic damping module and load holding valve with separate hydraulic damping module - Google Patents

Abstract

Separate hydraulic damping module (1) with a housing (2), a first hydraulic connection (3) and a second hydraulic connection (4), a first check valve (5) being arranged in a first hydraulic line (6) in the housing (2), a second check valve (7) is arranged in a second hydraulic line (8) and a throttle element (9) is arranged in a third hydraulic line (10), the first hydraulic line (6), the second hydraulic line (8) and the third hydraulic line ( 10) each connect the first hydraulic port (3) to the second hydraulic port (4), the first check valve (5) blocking the flow of hydraulic fluid in the direction of flow from the first hydraulic port (3) to the second hydraulic port (4) and the second check valve (7 ) blocks the flow of hydraulic fluid in the direction of flow from the second hydraulic port (4) to the first hydraulic port (3), and wherein the separate hydraulic damping module (1) is designed for detachable connection to a control pressure port (S) of a load-holding valve (LH), the throttle element (9) comprising a first throttle (19) and a fourth hydraulic line (25) connected in parallel with the third hydraulic line, the throttle element (9) also having a the fourth hydraulic line (25) blocking sealing screw (24) or a second throttle (27) which is arranged parallel to the first throttle (19) in the fourth hydraulic line (25).

Description

The present invention relates to a separate hydraulic damping module for a load-holding valve and a load-holding valve with a separate hydraulic damping module.

Load-holding valves are generally known in hydraulics and serve the purpose of preventing, for example in hydraulic lifting, swiveling or turning devices, that double-acting consumers such as hydraulic cylinders or hydraulic motors with an attached pulling or pushing load move uncontrollably and at greater speed when moving in the load direction or accelerate as specified on the pump side by the inflow of hydraulic fluid. The load-holding valve not only enables the eponymous, safe holding of a load, but also, for example, the safe and controlled lowering of the same load without endangering the environment or the hydraulic system.

Such load-holding valves regularly have a hydraulic connection on the pump side, a hydraulic connection on the consumer side and a control pressure connection. The hydraulic fluid can flow freely in the direction from the pump-side hydraulic connection to the consumer-side hydraulic connection via a check valve. The flow of hydraulic fluid in the opposite direction from the hydraulic connection on the consumer side to the hydraulic connection on the pump side, which in this case is relieved in the direction of the tank, for example, is throttled. For this purpose, a dynamic throttling resistance is generated, which is always slightly higher than the current load pressure. This is achieved in a generally known manner via a force balance between functional elements subjected to pressure on the outflow and inflow side on the one hand and a prestressing device, for example a spring, which loads these functional elements on the other. The opening of the load-holding valve for the flow of hydraulic fluid from the consumer-side hydraulic connection to the pump-side hydraulic connection is controlled via the control pressure connection of the load-holding valve.

For some applications in which such load-holding valves are used, it has proven to be useful, due to application-specific pressure fluctuations, to integrate damping elements into these load-holding valves on the control pressure side, for example to prevent pendulum movements triggered by starting and stopping processes or when there is a rapid transition from high-speed to crawler gear to effectively mitigate or, if possible, to suppress it completely. Such a load-holding valve is, for example, from EP 0 503 266 A1 known. Damping elements are also from the DE 10 2018 214 332 A1 and the DE 94 12 530 U1 known.

However, in other applications for which load-holding valves are used, such pressure fluctuations do not pose a problem during the flow of hydraulic fluid from the load-side hydraulic connection to the pump-side hydraulic connection of the load-holding valve.

Against this background, it is the object of the present invention to provide a cost-effective load-holding valve or load-holding valve system that can be used particularly flexibly.

The object is achieved with a separate hydraulic damping module for a load-holding valve according to claim 1. The separate hydraulic damping module according to the invention has a housing, a first hydraulic connection and a second hydraulic connection. A first check valve is arranged in a first hydraulic line in the housing, a second check valve is arranged in a second hydraulic line and a throttle element is arranged in a third hydraulic line. The first hydraulic line, the second hydraulic line and the third hydraulic line each connect the first hydraulic port to the second hydraulic port. In other words, the first hydraulic line, the second hydraulic line and the third hydraulic line are connected in parallel between the first hydraulic connection and the second hydraulic connection. The first check valve blocks flow of hydraulic fluid in the flow direction from the first hydraulic port to the second hydraulic port, and the second check valve blocks flow of hydraulic fluid in the flow direction from the second hydraulic port to the first hydraulic port. The separate hydraulic damping module is designed for a detachable connection to a control pressure connection of a load-holding valve. The throttle element comprises a first throttle and a fourth hydraulic line connected in parallel with the third hydraulic line. The throttle element also includes a sealing screw blocking the fourth hydraulic line or a second throttle which is arranged parallel to the first throttle in the fourth hydraulic line.

The detachable connection is to be understood here as a fluid-tight hydraulic connection that can be established and also released again. This detachable connection can exist directly between the load-holding valve and the damping module or can also be realized via an intermediate element, such as a piece of pipe or an intermediate block. By providing the separate hydraulic damping module, can be uniform provide designed, cost-optimized load-holding valves, which can be equipped with or without damping depending on the application. The separate hydraulic damping module is detachably connected to the control pressure connection of the load-holding valve as required and is thus interposed in the control-pressure line for controlling the load-holding valve. In this way, construction, production and process costs can be optimized and a simple, modular solution for providing damping for a load-holding valve is shown. With the optional parallel arrangement of the first throttle and the second throttle, the operating range of the throttle element can be adjusted particularly precisely.

The second hydraulic connection is preferably hydraulically connected to the control pressure connection of the load-holding valve when the separate hydraulic damping module is detachably connected to the control pressure connection of the load-holding valve. The hydraulic connection between the second hydraulic connection and the control pressure connection can exist directly between the two elements or can also be implemented via an intermediate element, such as a piece of pipe or an intermediate block. This ensures that the control pressure acting on the load-holding valve is dampened.

The separate hydraulic damping module expediently includes a thread for screwing into a counter-thread of the load-holding valve in order to implement the detachable connection to the control-pressure connection of the load-holding valve. In this way, a secure connection can be made between the separate hydraulic damping module and the load-holding valve, which can also be easily released again if necessary. Of course, any other type of hydraulic connection between the separate hydraulic damping module and the control pressure connection of the load-holding valve is also conceivable.

It is advantageous if the first check valve is a check valve that is preloaded with a first preload. In particular, the first prestress is in a range from 15 to 30 bar. In particular, the first preload is approximately 18 bar. In the direction of flow from the second hydraulic connection to the first hydraulic connection, the hydraulic fluid must therefore flow via the throttle element for smaller pressure differences between the second and first hydraulic connection. In this way, a higher damping effect is achieved for small pressure differences. Only in the case of higher pressure differences, in particular when the pressure at the second hydraulic connection is higher than the pressure at the first hydraulic connection by the amount of the first preload, does the first check valve open so that the main part of the hydraulic fluid no longer flows via the throttle element but via the first check valve.

Preferably, the second check valve is a check valve biased with a second bias, the second bias being less than the first bias. In particular, the second preload is in a range from 0.2 to 5 bar. In particular, the second preload is approximately 0.5 bar. The second check valve thus serves to enable a sufficient volume flow from the first hydraulic connection to the second hydraulic connection. Otherwise, for high pressure differences between the first hydraulic connection and the second hydraulic connection, the load-holding valve could not be opened quickly enough due to the resistance of the throttle element.

Furthermore, it is expedient if a filter is arranged in the flow direction from the first hydraulic connection to the second hydraulic connection in the second hydraulic line before the second check valve. The filter protects the separate hydraulic damping element from contamination.

The first throttle is preferably a threaded throttle. The threaded throttle is an effective throttle element that allows the throttle resistance to be adjusted even when installed. Furthermore, the threaded choke ensures strong damping of high frequencies and medium damping of low frequencies. It is of course conceivable to use any other type of throttle element.

The second throttle is expediently a screw-in nozzle which is screwed into an internal thread of the threaded throttle. The screw-in nozzle allows strong damping of high frequencies and low damping of low frequencies. Thanks to the combination of threaded throttle and screw-in nozzle, the working range of the throttle element can be adjusted particularly precisely. In particular, a diameter of the screw-in nozzle that is permeable to hydraulic fluid, which can only be replaced when the threaded throttle is removed, is used for rough adjustment and then fine adjustment of the damping properties of the separate hydraulic damping module via a screw-in depth of the threaded throttle when installed.

Furthermore, the object is achieved with a load-holding valve according to claim 9. The load-holding valve according to the invention has a valve housing in which a load-side hydraulic connection, a pump-side hydraulic connection and a Control pressure port are arranged, and a separate hydraulic damping module, as described above, which is detachably connected to the control pressure port of the load-holding valve.

By using the separate hydraulic damping module according to the invention in the load-holding valve according to the invention, this can be used in a particularly versatile manner for applications with or without the need for damping, without load-holding valves having different designs having to be provided for this purpose.

• 1 einen Hydraulikschaltplan eines Lasthalteventils mit einem separaten hydraulischen Dämpfungsmodul gemäß einem ersten Ausführungsbeispiel;
• 2 einen Hydraulikschaltplan eines separaten hydraulischen Dämpfungsmoduls gemäß einem zweiten Ausführungsbeispiel;
• 3 eine Schnittansicht des separaten hydraulischen Dämpfungsmoduls aus 1;
• 4 eine Schnittansicht des separaten hydraulischen Dämpfungsmoduls aus 1 mit gedrehter erster Einschraubpatrone; und
• 5 eine teilgeschnittene Ansicht des Steuerdruckanschlusses des Lasthalteventils aus 1 mit daran angeschlossenem, separatem hydraulischen Dämpfungsmodul.

The invention is explained in more detail below with reference to exemplary embodiments shown in the figures. Here show schematically:

• 1 a hydraulic circuit diagram of a load-holding valve with a separate hydraulic damping module according to a first embodiment;
• 2 a hydraulic circuit diagram of a separate hydraulic damping module according to a second embodiment;
• 3 Figure 12 shows a sectional view of the separate hydraulic damping module 1 ;
• 4 Figure 12 shows a sectional view of the separate hydraulic damping module 1 with rotated first screw-in cartridge; and
• 5 Figure 12 shows a partially sectioned view of the control pressure port of the load holding valve 1 with a separate hydraulic damping module connected to it.

A first exemplary embodiment of a separate hydraulic damping module 1 will now be described with reference to FIG 1 and 3 until 5 described.

The separate hydraulic damping module 1 according to the first exemplary embodiment has a housing 2, a first hydraulic connection 3 and a second hydraulic connection 4. In the housing 2, a first check valve 5 is arranged in a first hydraulic line 6, and a second check valve 7 is in a second hydraulic line 8 arranged and a throttle element 9 is arranged in a third hydraulic line 10 . The first hydraulic line 6, the second hydraulic line 8 and the third hydraulic line 10 each connect the first hydraulic port 3 to the second hydraulic port 4. The first check valve 5 blocks the flow of hydraulic fluid in the direction of flow from the first hydraulic port 3 to the second hydraulic port 4 and the second check valve 7 blocks the flow of hydraulic fluid in the direction from the second hydraulic port 4 to the first hydraulic port 3. The separate hydraulic damping element 1 is detachably connected to a control pressure port S of a load-holding valve LH.

As in 1 can be seen, the load-holding valve LH also comprises, in a generally known manner, a hydraulic connection P on the pump side, a hydraulic connection V on the consumer side, a bypass check valve RV1 in a bypass line BL and a controlled, pilot-operated, spring-loaded check valve or a pilot-operated pressure relief valve RV2 in a throttle line DL. Furthermore, in the load-holding valve LH on the side of the control pressure connection S in a control line SL there is a control fluid inflow nozzle D1 and in an outflow line AL branching off the control line SL there is a control fluid outflow nozzle D2 and a spring-loaded outflow check valve RV3. Seen in the direction of flow from the control connection S, the outflow line AL branches off behind the control fluid inflow nozzle D1 and in the outflow line AL the control fluid outflow nozzle D2 is arranged in front of the outflow check valve RV3. The control ratio of the load holding valve LH can be set via the diameter ratio of the control fluid inflow nozzle D1 to the control fluid outflow nozzle D2.

The second hydraulic connection 4 is hydraulically connected to the control pressure connection S of the load-holding valve LH. The first hydraulic connection 3 in turn is hydraulically connected to a control pressure line of a superordinate hydraulic system (not shown) or can be connected to such a control pressure line.

As in the 3 and 4 shown, the separate hydraulic damping module 1 includes a first screw-in cartridge 11, in which the first check valve 5 and the throttle element 9 are arranged. The first screw-in cartridge 11 has various bores that form hydraulic lines. Among other things, sections of the first hydraulic line 6, the second hydraulic line 8 and the third hydraulic line 10 run through said bores in the first screw-in cartridge 11. In the sectional views of FIG 3 and 4 the first screw-in cartridge 11 is shown rotated in two different positions about its central axis A in order to make all fluid-carrying connections in the first screw-in cartridge 11 recognizable. In particular, the first screw-in cartridge 11 includes a connection channel 28 which opens into a hydraulic chamber 29 and connects it to the second hydraulic connection 4 . The second hydraulic line 8 opens into the connecting channel 28 via a radial bore in the first screw-in cartridge 11. The first check valve 5 in the first hydraulic line 6 and the throttle element 9 in the third hydraulic line 10.

The first screw-in cartridge 11 is accommodated in a recess 12 in the housing 2 and inserted through the housing 2 . On one side in relation to the central axis A (upper side in 3 and 4 ) the first screw-in cartridge 11 has a tool engagement head 13, which has a larger diameter than the recess 12 of the housing 2. On its side facing the housing 2, a sealing ring 14 lies between the tool engagement head 13 and the housing 2 in a sealing ring receptacle of the tool engagement head 13 , Which seals the fluid-carrying connections within the recess 12 to the outside when the separate hydraulic damping module 1 is mounted on the load-holding valve LH. On the other hand, with respect to the central axis A (lower side in Figs 3 and 4 ), the first screw-in cartridge 11 has a thread 15, which is screwed into a mating thread LHG of the load-holding valve LH (cf. 5 ) to implement the detachable connection of the separate hydraulic damping module 1 to the control port S of the load-holding valve LH. The first screw-in cartridge 11 is inserted through the housing 2 and screwed into the mating thread LHG of the load-holding valve LH in order to fasten the housing 2 to the load-holding valve LH, cf. 5 . The connection channel 28 is consequently in hydraulic connection with the control connection S of the load-holding valve LH.

The first check valve 5 is preloaded by a spring with a first preload of approximately 18 bar and the second check valve 7 is preloaded by a spring with a second preload of approximately 0.5 bar. The second bias is therefore smaller than the first bias. The second check valve 7 ensures a sufficiently large volume flow in the direction of flow from the first hydraulic port 3 to the second hydraulic port 4. The first check valve 5 only opens when the pressure difference is greater than 18 bar, so that the hydraulic fluid overflows in the event of smaller pressure differences in the direction of flow from the second hydraulic port 4 to the first hydraulic port 3 the throttle element 9 must flow and so the control pressure in the direction of the load-holding valve LH is maintained.

Furthermore, the separate hydraulic damping module 1 includes a filter 16 which is arranged in the direction of flow from the first hydraulic connection 3 to the second hydraulic connection 4 in the second hydraulic line 8 in front of the second check valve 7 . The filter 16 prevents dirt from entering the separate hydraulic damping element 1 via the second hydraulic line 8 from the first hydraulic connection 3 .

In the first screw-in cartridge 11, as in the 3 and 4 shown, a second screw-in cartridge 17 is screwed in through the internally hollow tool-engaging head 13 , which screw-in cartridge has a hollow tool-engaging head 30 , which is designed analogously to the tool-engaging head 13 of the first screw-in cartridge 11 . A sealing element 18 is arranged between the tool engagement head 30 of the second screw-in cartridge 17 and the tool engagement head 13 of the first screw-in cartridge 11 in order to ensure the tightness of the separate hydraulic damping module 1 to the outside.

The throttle element 9 includes in the first embodiment, as in the 3 and 4 shown, a threaded throttle 19. The threaded throttle 19 is screwed through the internally hollow tool engagement head 30 of the second screw-in cartridge 17. The screw-in depth of the threaded throttle 19 can be adjusted via a lock nut 20 . The engaged section of an external thread 21 of the threaded throttle 19 with an internal thread 22 of the second screw-in cartridge 17 forms the throttle path of the throttle element 9. Depending on the screw-in depth of the threaded throttle 19, this throttle path is longer or shorter and the throttle can be adjusted accordingly.

The threaded throttle 19 also has an internal thread 23 into which a sealing screw 24 is screwed in the first embodiment. This sealing screw 24 blocks a fourth hydraulic line 25 which would bridge the throttle path of the throttle element 9 via a radial bore 26 in the threaded throttle 19 , that is to say would be connected in parallel with this section of the third hydraulic line 10 .

In a second embodiment, the hydraulic circuit diagram in 2 is shown, the sealing screw 24 has been replaced by a screw-in nozzle 27 . In the second exemplary embodiment, the screw-in nozzle 27 is thus screwed into the internal thread 23 of the threaded throttle 19 and the fourth hydraulic line 25 is thus connected in parallel with the third hydraulic line 10 via the screw-in nozzle 27 . In the second exemplary embodiment, the throttle element 9 therefore includes the threaded throttle 19 and the screw-in nozzle 27.

When the throttle element 9 is removed, the screw-in nozzle 27 can be changed and a rough adjustment of the damping behavior of the separate hydraulic damping module 1 can thus be made via different nozzle diameters. The fine adjustment is then made by screwing the threaded throttle 19 into the second screw-in cartridge 17 and specifying the throttle path via the lock nut 20.

Reference List

1

damping module

2

Housing

3

first hydraulic connection

4

second hydraulic connection

5

first check valve

6

first hydraulic line

7

second check valve

8th

second hydraulic line

9

throttle element

10

third hydraulic line

11

first screw-in cartridge

12

recess

13

Tool engaging head of the first screw-in cartridge

14

sealing ring

15

thread

16

filter

17

second screw-in cartridge

18

sealing element

19

threaded throttle

20

locknut

21

External thread of the threaded throttle

22

Internal thread of the second screw-in cartridge

23

Internal thread of the threaded throttle

24

sealing screw

25

fourth hydraulic line

26

radial bore

27

screw-in nozzle

28

connecting channel

29

hydraulic chamber

30

Tool engagement head of the second screw-in cartridge

A

Central axis of the first screw-in cartridge

AL

drain line

D1

Pilot Fluid Inflow Nozzle

D2

Pilot Fluid Drain Nozzle

DL

throttle line

LH

load holding valve

LHG

Counter thread of the load holding valve

P

pump-side hydraulic connection

RV1

Bypass check valve

RV2

piloted piloted spring-loaded check valve/piloted pressure relief valve

RV3

spring loaded drain check valve

S

control pressure port

SL

control line

V

hydraulic connection on consumer side

Claims (9)

Separate hydraulic damping module (1) with a housing (2), a first hydraulic connection (3) and a second hydraulic connection (4), a first check valve (5) being arranged in a first hydraulic line (6) in the housing (2), a second check valve (7) being arranged in a second hydraulic line (8) and a throttle element (9) being arranged in a third hydraulic line (10 ) is arranged wherein the first hydraulic line (6), the second hydraulic line (8) and the third hydraulic line (10) each connect the first hydraulic port (3) to the second hydraulic port (4), wherein the first check valve (5) blocks the flow of hydraulic fluid in the direction of flow from the first hydraulic port (3) to the second hydraulic port (4) and the second check valve (7) blocks the flow of hydraulic fluid in the direction of flow from the second hydraulic port (4) to the first hydraulic port (3 ) locks, and wherein the separate hydraulic damping module (1) is designed for detachable connection to a control pressure connection (S) of a load-holding valve (LH), wherein the throttle element (9) comprises a first throttle (19) and a fourth hydraulic line (25) connected in parallel to the third hydraulic line, wherein the throttle element (9) also has a sealing screw (24) blocking the fourth hydraulic line (25) or a second throttle (27 ) comprises, which is arranged parallel to the first throttle (19) in the fourth hydraulic line (25). Separate hydraulic damping module (1) according to claim 1 , characterized in that the second hydraulic connection (4) is hydraulically connected to the control pressure connection (S) of the load-holding valve (LH) when the separate hydraulic damping module (1) is detachably connected to the control pressure connection (S) of the load-holding valve (LH). Separate hydraulic damping module (1) according to claim 1 or 2 , characterized in that the separate hydraulic damping module (1) comprises a thread (15) for screwing into a counter-thread (LHG) of the load-holding valve (LH) in order to implement the detachable connection with the control pressure port (S) of the load-holding valve (LH). Separate hydraulic damping module (1) according to one of the preceding claims, characterized in that the first check valve (5) is a check valve which is preloaded with a first preload. Separate hydraulic damping module (1) according to claim 4 , characterized in that the second check valve (7) is a check valve preloaded with a second preload, the second preload being smaller than the first preload. Separate hydraulic damping module (1) according to one of the preceding claims, characterized in that a filter (16) is arranged in the flow direction from the first hydraulic connection (3) to the second hydraulic connection (4) in the second hydraulic line (8) before the second check valve (7). is. Separate hydraulic damping module (1) according to one of the preceding claims, characterized in that the first throttle is a threaded throttle (19). Separate hydraulic damping module (1) according to claim 7 , characterized in that the second throttle is a screw-in nozzle (27) which is screwed into an internal thread (23) of the threaded throttle (19). Load-holding valve (LH) with a valve housing in which a hydraulic connection (V) on the consumer side, a hydraulic connection (P) on the pump side and a control pressure connection (S) are arranged, and with a separate hydraulic damping module (1) according to one of the preceding claims, which is detachable with connected to the control pressure port (S) of the load-holding valve (LH).

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