DE102012208307A1 - Damping device for wheeled loader, has hydropneumatic accumulator discharged through discharging valve according to operation of control valve when pressure at storage terminal is larger than pressure at power port - Google Patents

Abstract

The device (14) has a discharging valve (38) formed such that a control valve (26), a power port (A) and a storage terminal (X2) connected to the unloading valve. A hydropneumatic accumulator (16) is discharged through the discharging valve according to an operation of the control valve when pressure at the storage terminal is larger than pressure at the power port. A main valve (18) is switchable between two switching positions (a, d). The main valve is switchable into one of the switching positions by the control valve. The discharging valve is designed as a 2/2-way solenoid valve or a 5/2-way valve.

Description

The invention relates to a damping device according to the preamble of patent claim 1.

Such damping devices are used, for example as a stabilization module in wheel loaders to dampen the pitching vibrations occurring during driving. For this purpose, a loaded blade is first lifted by a pump and a lifting cylinder, and the pressure chamber of the lifting cylinder, which is under load pressure, is separated from the pump by a control valve. During the loaded drive of the wheel loader, the pressure chamber under load pressure is connected via the stabilization module to a charged hydraulic accumulator in order to dampen the pitching oscillations.

In the publication EP 1 407 086 B1 discloses such a damping device having a (referred to as a control valve) main valve, via which the connection described between the pressure chamber of the lifting cylinder and the hydraulic accumulator is controlled when a control valve is switched. About the control valve, the moment is determined from which the damping is to take place.

If, upon activation of the damping by opening the main valve, the pressure of the previously charged hydraulic accumulator is higher than the pressure in the pressure chamber of the lifting cylinder, which is largely determined by the weight of the blade and its filling, disadvantageous discharge shocks occur in such damping devices.

In contrast, the invention is based on the object to provide a damping device in the activation of relief bumps are avoided.

This object is achieved by a damping device having the features of patent claim 1.

The damping device according to the invention has a first working connection for connecting a load (in particular a lifting cylinder) of a mobile working machine (in particular a wheel loader and a storage connection for connecting a hydraulic accumulator Switching position is a connection only from the first working port (and thus from the consumer) to the storage port (and thus to the hydraulic accumulator) is opened.Thus the damping is switched off.In the second switching position, the connection is open in both directions.Thus, the damping is switched on a control valve is provided with which the main valve can be hydraulically switched to the second switching position, that is, the damping can be switched on and off again il, which is so connected to the control valve and the first working port (and thus to the consumer) and to the storage port, that after the actuation of the control valve of the hydraulic accumulator via the discharge valve can be partially discharged when the pressure at the storage port (and thus in the hydraulic accumulator) is greater than at the first working port (and thus at the consumer). This avoids a discharge impact when connecting the hydraulic accumulator to the consumer, since any excessively high pressure of the hydraulic accumulator is previously reduced and adjusted. The discharge or pressure reduction takes place, in particular, in that the discharge valve opens a connection from the storage connection to a discharge connection or tank connection of the damping device.

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

It when the main valve can be switched only after completion of the partial discharge of the hydraulic accumulator via the control valve in the second switching position is particularly advantageous. As a result, relief bumps are further minimized.

In a particularly preferred embodiment, after the actuation of the control valve, the discharge valve initially remains open until the pressure at the first working connection (and thus at the consumer) is less than a predetermined pressure difference smaller than the pressure at the storage connection (and thus in the hydraulic accumulator).

Preferably, a valve body of the discharge valve is hydraulically loaded on the one hand via the control valve by the pressure at the storage port (and thus in the hydraulic accumulator), and on the other hand by the pressure at the first working port (and thus of the consumer) charged. The predetermined pressure difference (e.g., about 10 bar) is defined by a biased spring acting on the valve body. Thus, the switching time of the discharge valve is implemented concretely. The spring is preferably adjustable.

Preferably, the valve body of the discharge valve with open control valve with the pressure at the storage port in an open position for opening a discharge line is movable. Furthermore, the valve body of the discharge valve with the pressure at the first working port, together with the spring designed as a compression spring, can be moved into a closed position. The closed position is used for Shutting off the discharge line at least in the direction of the storage port to a tank connection.

In a first particularly preferred device-technically simple variant, the discharge valve is a leak-poor 2/2-way seat valve.

It is preferred if a current limiter is provided between an output of the control valve and acting in the opening direction of the main valve control, regardless of the pressure and viscosity of the control pressure medium always passes a predetermined amount of control fluid from the control valve to the control surface, so that an opening of the main valve and a beginning damping always takes a certain amount of time (eg 2 seconds).

It is preferred if the main valve has a shut-off position, wherein the first switching position between the shut-off position and the second switching position is arranged. With an opening of the main valve thus the first switching position must be run over, so that a pressure equalization can be carried out from the higher pressure working port to pressure lower storage port, the current limiter for a predetermined time available.

In a second preferred variant, the discharge valve is a 5/2-way valve. In this case, a connection of an output of the control valve with a force acting in the opening direction of the main valve control surface is shut off via the open position of its valve body, at the same time the control surface is relieved. This ensures that the main valve does not open for damping when the unloading valve is still discharging. This ensures a temporal succession of the two states "unloading" and "damping".

In a preferred development of the second variant, a throttle arrangement is provided between the 5/2-way valve and the control surface acting in the opening direction of the main valve. This dampens and delays the opening and closing of the main valve.

In preferred applications of the damping device according to the invention of her dampable consumer is double acting, wherein the damping device has a tank port and a second working port for connecting the consumer (in particular an annular space of the lifting cylinder). In the first switching position of the main valve, a connection of the second working port to the tank port is shut off, and in the second switching position of the main valve, the connection is opened in both directions.

In the following, various embodiments of the invention will be described in detail with reference to FIGS. Show it:

1 a detail of a hydraulic circuit of a wheel loader with a first embodiment of the damping device according to the invention;

2 the detail of the hydraulic circuit of the wheel loader with a second embodiment of the damping device according to the invention;

3 a discharge valve of the first embodiment according to 1 in a sectional view;

4 a discharge valve of the second embodiment according to 2 in a first sectional view, and

and 5 the discharge valve of the second embodiment according to the 2 and 4 in a second sectional view.

1 shows a section of a hydraulic circuit of a wheel loader. This has two co-operating lift cylinders 1 , which are each formed as a differential cylinder and are used for lifting a (not shown) blade of the wheel loader. The lifting cylinders 1 each have a floor space 2 and an annulus 4 , where the two floor spaces 2 via a first working line 6 and the two annuli 4 over a second working line 10 with a control block 8th connected to the wheel loader. This controls the pressure medium supply of the two lifting cylinders 1 and thus a lifting movement of the blade. Furthermore, the wheel loader has a tank 12 ,

In particular with comparatively rapid travel (eg from 6 km / h) of the wheel loader and in particular with a filled blade, the first working line acting in the lifting force can act 6 via a damping device according to the invention 14 a hydraulic accumulator 16 be connected. This has the damping device 14 a first working connection A, over which it with the two floor spaces 2 connected, and a second working port B, over which they communicate with the two annular spaces 4 connected is. Furthermore, the damping device has a storage port X2, via which it communicates with the hydraulic accumulator 16 connected, and a tank connection T via which they are connected to the tank 12 connected is.

The damping device 14 has a designed as a 4/4-way valve main valve 18 , on the one hand with the two working ports A, B and on the other hand connected to the storage port X2 and the tank port T. A (not shown in detail) valve body of the main valve 18 has a first switching position a, in which a connection between the second working port B and the tank port T is shut off, while via a spring-biased check valve, a connection from the first working port A to the storage port X2 is given. Furthermore, the main valve has a shut-off position b, in which all four ports A, B, X2, P are shut off from each other. In an unloading position c of the main valve 18 is the storage port X2 via a throttle and the tank port T to the tank 12 relieved, while the two working ports A, B are shut off.

The first switching position a, the shut-off position b and the unloading position c are continuously interconvertible. Finally, the main valve 18 a second switching position d, in which the two floor spaces 2 via the first working port A and the storage port X2 with the hydraulic accumulator 16 are connected while the two annular spaces 4 via the second working port B to the tank 12 are relieved. The main valve 18 is switched to the second switching position d when pitching vibrations of the wheel loader to be damped or avoided by the blade.

The valve body of the main valve 18 is via a control line 20 and a control surface (not shown) 22 depending on a control valve 26 acted upon in the opening direction, while in the closing direction via a control line 28 and a control surface 30 is charged. Both control lines 20 . 28 are connected to the storage port X2. Furthermore, a spring acts 24 in the opening direction and a spring 32 in the closing direction of the main valve 18 , The force of the effective spring in the opening direction 24 can correspond to 120 bar, while the force of the spring acting in the closing direction 32 10 bar can correspond. The effective in the opening direction control surface 22 can have a diameter of 20 mm, while the closing direction effective control surface 30 can have a diameter of 4 mm.

At a predetermined accumulator pressure of the hydraulic accumulator 16 from a wheel loader pump (not shown) via the control block 8th , the first working port A and the first switching position a of the main valve 18 is generated, the valve body of the main valve 18 moved to the blocking position b.

The control valve 26 which is used to shut off or open the control line 20 serves, is designed as a 3/2-way valve. In his biased by a spring basic position 0 relieves the control valve 26 the effective in the opening direction control surface 22 of the main valve 18 to the tank connection T. In an energized switching position e acts on the control valve 26 the control surface 22 with the pressure of the hydraulic accumulator 16 so that the main valve 18 can be switched to the second switching position d, and the damping of the blade can be turned on.

In the control line 20 between the control valve 26 and the control surface 22 of the main valve 18 is a current limiter 34 provided which, regardless of the viscosity and regardless of the pressure of the control pressure medium, a limited amount of it pass. This causes, upon movement of the valve body of the main valve 18 from the shut-off position b to the second switching position d, a movement over the first switching position a with a certain period of time (eg 2 seconds). This ensures that in the event that the pressure at the first working port A is higher than at the storage port X2, a discharge via the check valve of the first shift position A is possible.

According to the invention, a discharge line is located between the storage connection X2 and the tank connection T. 36 intended. In the unloading line 36 is a discharge valve 38 provided, which is designed as a 2/2-way seat valve. His (in 3 shown) valve body 40 can assume a closed position f and several opening positions g. The unloading valve 38 has at its input a storage port X2 and at its output a tank port T. The valve body 40 is via a pressure acting in the closing direction compression spring 42 and acted upon via a working port A in the closing direction, while it is acted upon via a control port Y1 in the opening direction. The control port Y1 is between the control valve 26 and the current limiter 34 to the control line 20 connected.

2 shows the section of the hydraulic circuit of the wheel loader according to 1 with a second embodiment of the damping device according to the invention 114 , The two essential differences from the first embodiment according to 1 to be seen in that on the one hand as a discharge valve 138 a 5/2-seat directional control valve is provided, and that on the other hand in the control line 20 instead of the current limiter 34 a throttle arrangement 134 is provided.

In both embodiments described above, the damping is switched on via the control valve 26 , This can be done automatically when a minimum speed (eg 6 km / h) is exceeded. When the pressure at the working port A is less than one over the spring 42 given pressure difference is smaller than on Storage port X2, the unloading valves remain 38 ; 138 both embodiments in their closed position f. The pressure at the storage port X2 is via the opened control valve 26 and over the current limiter 34 or the throttle arrangement 134 for comparatively large control surface 22 reported. In cooperation with the spring opens the main valve 18 in its second switching position d. If, however, the pressure at the first working port A and thus in the floor space 2 the lifting cylinder 1 significantly under the pressure of the storage port X2 and thus the hydraulic accumulator 16 is after opening the control valve 26 and before opening the main valve 18 the inventive lowering of the pressure of the hydraulic accumulator 16 , This suffices according to the first embodiment 1 the delay of the opening of the main valve 18 passing the current limiter 34 is reached. Before he gets the main valve 18 opens, opens the discharge valve 38 according to 1 because the pressure at the control port Y1 is more than the equivalent of the compression spring 42 is higher than the control pressure at the control terminal A. In the second embodiment according to 2 will open the main valve 18 forcibly prevented as long as the discharge valve 138 has completed the discharge process and returns from its open position g in the closed position f. Premature opening of the main valve 18 is thus prevented by the discharge valve 138 in its open position g the control surface 22 of the main valve 18 Relieved via a control port Y2 as long as the tank port T until the discharge is completed and the discharge valve 138 returns to its closed position f. Only then will the control line 20 released, leaving the main valve 18 can be opened.

3 shows the unloading valve 38 of the first embodiment of the damping device according to the invention 14 according to 1 in a cut view. In a housing 44 is the valve body 40 along its longitudinal axis 46 displaceable. It can over one on the housing 44 formed valve seat 48 and over a conical section 50 a connection from the storage port X2 to the tank port T is opened or shut off. become. This will discharge the hydraulic accumulator 16 (see. 1 ) initiated or terminated. 3 shows the valve body in its closed position f (see. 1 ). In this closed position f of the valve body 40 in particular via the compression spring 42 and pushed over the pressure of the first working port A. These both act on one end section 52 of the valve body 40 , The end section 42 is arranged in a pressure chamber, which is inserted into the housing 44 screwed in closure part 54 limited and over a hole star 60 connected to the first working port A. The compression spring 42 that have an intermediate piece 53 at the end section 52 of the valve body 40 rests, is based on the closure part 54 from.

To a comparatively small extent, the pressure at the storage port X2 also acts via an annular differential area 55 in the closing direction. The opposite in the opening direction of the front side acts on the housing 44 provided control terminal Y1, with its pressure across an end face 56 the conical section 50 can be lifted from the valve seat and the discharge valve for discharging the hydraulic accumulator (see. 1 ) is opened. The storage port is X2 - along the longitudinal axis 46 considered - in the area of the conical section 50 and the difference surface 55 disposed while the tank port T between the conical section 50 and the face 56 is provided.

The valve body 40 is on the one hand between the face 56 and the tank connection T directly in the housing 44 stored and guided, and on the other hand between the differential area 55 and the end section 52 via a guide bush 58 stored and guided. The guide bush 58 is from the closure part 54 held and limits the connected to the first working port A pressure chamber. For this purpose, the guide bush 58 a seal on.

The 4 and 5 show the discharge valve 138 of the second embodiment of the damping device according to the invention 114 in two different cut representations. The unloading valve 138 has one - opposite the case 44 of the first embodiment - (in the 4 and 5 ) to the left extended housing 144 , in which the - opposite the valve body 40 of the first embodiment - extended valve body 140 along the longitudinal axis 46 slidably received. It corresponds to the in the 4 and 5 (right part) essentially the unloading valve 38 according to 3 , The in 5 shown first working port A, which over the radial hole star 60 with the inside of the closure part 54 formed pressure chamber is connected, also in the discharge valve according to 3 intended.

Notwithstanding the discharge valve 38 according to 3 has the unloading valve 138 another tank connection T1 (cf. 5 ), a control terminal Y2 and a control terminal Y1 (see FIG. 4 ) on. The pressure at the control port Y1 is via a channel 146 to the face 56 of the valve body 140 reported, in whose environment a pressure chamber is formed, which has a front-side closure part 148 is closed.

In 5 is shown that between the tank port T1 and the valve body 140 a check valve 150 is provided, whose Opening direction of the valve body 140 directed to the tank connection T1 (see. 2 ).

In the 4 and 5 is the unloading valve 138 according to the second embodiment in its closed position f (see. 2 ), in which the to the storage port X2 and to the tank port T (see. 4 ) connected discharge line 36 (see. 2 ) is locked. In this case, the control line connected to the control terminals Y1 and Y2 20 open. By an increase in the control pressure at the control port Y1 and / or by a decrease in the control pressure at the first working port A of the valve body 140 (in the 4 and 5 ) to the right in its open position g (cf. 2 ) postponed. In this case, the discharge from the storage port X2 to the tank port T, wherein the control port Y2 via the open check valve 150 is relieved to the tank port T1. Thus, the main valve remains 18 (see. 2 ), wherein the voltage applied to the control port Y1 pressure of the hydraulic accumulator 16 is locked. This is the discharge of the hydraulic accumulator 16 made sure before the main valve 18 (see. 2 ) is opened.

Notwithstanding the illustrated embodiments of the discharge valve 38 ; 138 this can also be in a common housing with some or all other components and valves of the damping device according to the invention 14 ; 114 be integrated.

Disclosed is a damping device with a first working port for connecting a consumer to be damped a mobile machine and with a storage port for connecting a hydraulic accumulator. Furthermore, a main valve with at least a first and a second switching position is provided. In the first switching position, a connection is opened exclusively from the first working connection to the storage connection. This deactivates the damping. In the second switching position, the connection is open in both directions. Thus the damping is switched on. Furthermore, a control valve is provided, with which the main valve can be hydraulically switched to the second switching position, so the damping on and off again. Finally, the damping device according to the invention has a discharge valve, which is connected to the control valve and to the first working port and to the storage port such that after actuation of the control valve the hydraulic accumulator can be partially discharged via the discharge valve when the pressure at the storage port is greater than at the first Work connection is. This avoids a discharge impact when connecting the hydraulic accumulator to the consumer, since any excessively high pressure of the hydraulic accumulator is previously reduced and adjusted.

LIST OF REFERENCE NUMBERS

1

lifting cylinder

2

floor space

4

annulus

6

first line of work

8th

control block

10

second working line

12

tank

14; 114

damping device

16

hydraulic accumulator

18

main valve

20

control line

22

control surface

24

feather

26

Control valve

28

control line

30

control surface

32

feather

34

current limiter

36

discharge line

38; 138

unloader

40; 140

valve body

42; 142

compression spring

44; 144

casing

46

longitudinal axis

48

valve seat

50

conical section

52

end

53

connecting piece

54

closing part

55

differential area

56

face

58

guide bush

60

bore star

134

throttle arrangement

146

channel

148

closing part

150

check valve

A

first work connection, control connection

B

second work connection

X1

control connection

X2

memory connector

Y1

control connection

Y2

control connection

T

tank connection

T1

tank connection

0

initial position

a

first switching position

b

shut-off

c

unloading

d

second switch position

e

switch position

f

closed position

G

open position

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

• EP 1407086 B1 [0003]

Claims (11)

Damping device ( 14 ; 114 ) with a first working connection (A) for connecting a consumer to be damped ( 1 ) of a mobile working machine and with a storage port (X2) for connecting a hydraulic accumulator ( 16 ), whereby a main valve ( 18 ) is provided with at least a first switching position (a) and a second switching position (d), wherein in the first switching position (a) a connection is opened exclusively from the first working port (A) to the storage port (X2), and wherein in the second switching position (d) the connection is open in both directions, and with a control valve ( 26 ), with which the main valve ( 18 ) hydraulically in the second switching position (d) is switchable, characterized in that the damping device ( 14 ; 114 ) a discharge valve ( 38 ; 138 ), which in such a way with the control valve ( 26 ), the first working port (A) and the storage port (X2) is connected, that after the actuation of the control valve ( 26 ) the hydraulic accumulator ( 16 ) via the discharge valve ( 38 ; 138 ) is dischargeable when the pressure at the storage port (X2) is greater than at the first working port (A). Damping device according to claim 1, wherein after the discharge of the hydraulic accumulator ( 16 ) the main valve ( 18 ) via the control valve ( 26 ) in the second switching position (d) is switchable. Damping device according to one of the preceding claims, wherein after the actuation of the control valve ( 26 ) the unloading valve ( 38 ; 138 ) opens until the pressure at the first working port (A) is less than the pressure at the storage port (X2) by less than a predetermined pressure difference. Damping device according to claim 3, wherein a valve body ( 40 ; 140 ) of the unloading valve ( 38 ; 138 ) hydraulically via the control valve ( 26 ) is loadable by the pressure at the storage port (X2), and wherein the valve body ( 40 ; 140 ) is loaded by the pressure at the first working port (A), and wherein the predetermined pressure difference by a on the valve body ( 40 ; 140 ) acting prestressed spring ( 42 ; 142 ) is defined. Damping device according to claim 4, wherein when the control valve is open ( 26 ) the valve body ( 40 ; 140 ) with the pressure at the storage port (X2) in an open position (g) is movable, and wherein with the pressure at the first working port (A) together with the pressure spring ( 42 ; 142 ) formed spring of the valve body ( 40 ; 140 ) is movable in a closed position (f). Damping device according to one of the preceding claims, wherein the discharge valve ( 38 ) is a 2/2-way poppet valve. Damping device according to claim 6, wherein between an output of the control valve ( 26 ) and in the opening direction of the main valve ( 18 ) acting control surface ( 22 ) a current limiter ( 34 ) is provided. Damping device according to claim 7, wherein the main valve ( 18 ) has a shut-off position (b), and wherein the first switching position (a) between the shut-off position (b) and the second switching position (d) is arranged. Damping device according to claim 5, wherein the unloading valve ( 138 ) is a 5/2-way valve, wherein over the open position (g) of its valve body ( 140 ) a connection of an output of the control valve ( 26 ) with an opening direction of the main valve ( 18 ) acting control surface ( 22 ), whereby at the same time the control surface ( 22 ) is relieved. Damping device according to claim 9, wherein between the 5/2-way valve and the control surface ( 22 ) a throttle arrangement ( 134 ) is provided. Damping device according to one of the preceding claims, wherein the consumer ( 1 ) is double-acting, and wherein the damping device has a tank connection (T) and a second working connection (B) for connection of the consumer ( 1 ), and wherein in the first switching position (a) a connection of the second working port (B) to the tank port (T) is shut off, and wherein in the second switching position (d) the connection is open in both directions.

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