DE19503943C2 - Brake valve arrangement for a reversible hydraulic consumer - Google Patents

Description

The invention relates to a brake valve arrangement for a reversible control valve hydraulic consumers, such as a hydraulic Traction motor or the like according to the preamble of the An saying 1.

Brake valves are usually between a hydrau arranged consumer and a control valve and serve if the delivery or inlet pressure is no longer present to reduce the backflow from the hydraulic consumer, so that the movement in the hydraulic consumer is slowed down,  but is not stopped abruptly. One use case is for example the hydraulic drive or traction motor of one Construction vehicle, such as an excavator.

Usually, slide valves are used as brake valves tile, where a spool from a middle working out on opposite sides in one position is adjustable in which he can return from Connects consumers with the tank for the hydraulic medium. To adjust the spool are ent opposing active surfaces provided with one inlet pressure each. In the The central position of the control spool is both the inlet as well as the rewind blocked. So there are additional ones Pressure relief valves to be provided at a pressure that is significantly above the maximum operating pressure, open to allow flow when the hydraulic ver high pressure due to mechanical adjustment is produced.

Such brake valve arrangements work satisfactorily lend and have proven themselves. However, they are relatively large building and therefore bulky when in the housing of one hydraulic consumer, for example a driving  motors to be integrated. In addition, at like valve arrangements can not be avoided that at first some oil flow to the brake valve flows around to put this in a working position. Such Oil losses mean energy loss and ver delayed response of the hydraulic consumer.

From DE 42 31 399 is a hydraulic control device for a hydraulic consumer, for example one Hydraulic cylinder in a construction machine. A main control valve is made up of a pilot valve or -Device controlled in a pilot control circuit. The tax The main valve spool has one of the pilot pressure dependent control characteristic, d. H. the standard cross section changes is proportional to the pilot pressure. Furthermore, a switching valve controlled by the pilot pressure provided, a check valve switches into the pilot control circuit, whereby the slide in the main valve is only damped or throttled. This has the advantage that a Operator cannot "overwhelm" the control process to Example not too fast the maximum speed he enough. This makes certain in unstable systems Stabilization of the movements at the beginning and at the end reached.

The invention has for its object a Bremsven tilanordnung of the type mentioned to that effect improve that it has favorable flow properties points and in the housing of a hydraulic Ver user, especially a hydraulic motor builds.

This object is achieved by the features of claim 1 solved.

The brake valve arrangement according to the invention sees two identically constructed separate valve units, each because switch to the hydraulic consumer if they are supplied with inlet pressure. You participate a third valve unit that throttles Shut-off device contains for throttling or blocking the Backflow when adjusting the switching valve in the  Neutral position. The valve units have a slide like first valve member, which has a perforation has, for example, of an annular cylindrical Body can be formed. The first valve member is from Inlet pressure in a second position in which it shuts off a first connection of the valve unit (nature are switching valve and hydraulic consumer on the valve unit "connected". With that in mind these "connections" in the explanations below are not mentioned). The first connections of the valve units are connected to the further valve unit, so that the each other valve unit with the first valve member in hydraulic medium returning to the first working position to the valve arrangement containing the shut-off device and via this can flow back to the tank or optionally to the entrance the valve unit connected to the inlet. In in the latter case, the hydraulic consumer can immediately "suck up" in a circuit, causing cavitation is avoided.

The valve units have a second valve member, that together with the perforation of the first valve member acts, with a spring closing the second valve member position preloaded. When applying one in the through  bore of the first valve member acting inlet pressure opens the second valve member after the first into the second working position has been adjusted to the flow release to the traction motor. In this way, one Loss-free switching guaranteed.

The described valve fulfilling the braking function units are separate parts attached to relatively any Place in the housing of a hydraulic consumer for example, a traction motor, can be accommodated. The individual valve units can be relatively small be so that a good use of space is possible.

The controllable valve arrangement having the shut-off element can be structured differently. A shape tion of the invention provides that the controllable valve arrangement has a pressure valve, the input of Check valves are connected to the first connections and its exit with the tank or via non-return valves Tile is connected to the input of both valve units and the control input of the pressure valve optionally with the outputs of the switching valve can be connected. Such The structure of pressure valves is generally known. They provide a flow cross section that ver  is changeable and is made dependent on a tax pressure. In the present case the control pressure is from depending on the respective inlet pressure, d. H. with high inflow pressure, a maximum flow cross-section is provided represents, so that about the respective other valve unit Check valve and the pressure valve a backflow in Operation of the hydraulic consumer is possible. Becomes meanwhile the inlet pressure is zero, the pressure valve goes in Closed position, but via a throttling intermediate state so that a suitable braking function is achieved. This braking function can be designed appropriately the pressure valve according to a desired characteristic. The control pressure can according to a further embodiment Invention to be derived from a shuttle valve, the Active inputs in a connection between the valve units lie.

Alternatively, a instead of the pressure valve mentioned Brake spool valve with a brake spool or Brake pistons are used, the opposite in two directed working positions the first connections of the Ver valve units with the outputs of the switching valve ver binds. Opposing active surfaces of the shooting bers with the respective pressure at an outlet of the  Switching valve acted to move the slide into one of to bring both working positions. In the middle or The connections are blocked in neutral position. It is in in this case it is necessary to provide a pressure relief valve, that shorts the hydraulic consumer when one flow pressure from the ver needs to be built up.

An alternative embodiment is based on a brake valve arrangement of the type mentioned. She sees also two identically constructed separate valve units before, each in a line between the switching valve and hydraulic consumer are arranged. You point also a first slide-like, a through-hole having valve member. Its peculiarity persists in that it is related to a valve seat in the housing acts to thereby block the first connection. The first valve member is closed by means of a spring biased. The axial drilling is done by a second valve member, which is also in the closed position is biased by a spring, locked. It will however opened by the inlet pressure. Like the one above described construction also acts here the second Valve element as a check valve. The first valve member  has an annular active surface of a size which is equal to the sum of the effective areas of the face of the first valve member and the effective area of the second Valve member facing the hydraulic consumer is. In addition, the connection of the hydraulic Ver user in a control room to which the first effective area facing the first valve member, preferably via a throttle. This control room is also under pressure valves connected to the tank, the control input of the pressure valves with the inlet pressure of the other Valve unit is acted on. By such an end the valve units can be designed simultaneously required braking function realize what at Construction described above by the pressure valve or done by the brake piston.

After a further design of the latter Embodiment, the valve units have a second Connection on that via a check valve with the off gear of the pressure valve or the first connection connected is. This first connection can work in the second position of the first valve member can be shut off. Find the valve member is in the first working position, the flow is guided via a check valve  in a circle when the switching valve is in its neutral position is and the consumer is still moved. To this Cavitation is avoided in this way.

The invention is described below with reference to drawings explained in more detail.

Fig. 1 shows schematically a brake valve assembly according to the invention.

Fig. 2 shows a modified from Fig. 1 Bremsven valve arrangement.

Fig. 3 shows schematically a pressure valve for the Bremsven valve arrangement according to FIG. 5th

Fig. 4 shows a second embodiment of a Druckven valve for the brake valve assembly of FIG. 5th

Fig. 5 illustrates another embodiment schematically shows a brake valve assembly according to the invention.

In Fig. 1, a traction motor 10 is controlled by a switching valve 12 which is connected to a hydraulic pressure source, not shown. The two outputs of the Schaltven valve 12 can be connected via lines 14 , 16 to the traction motor 10 , specifically via valve units 18 and 20 . The valve units 18 , 20 are constructed identically. Therefore, only the valve unit 18 will be described in detail ben.

In a housing 22 only indicated, a ring cylin drical valve member 24 is axially movable. In its lower end, it has a radially outwardly extending flange 26 which projects into an annular recess 28 . At an axial distance from it, the housing has a ring recess 30 . In the first working position of the valve member 24 shown , radial bores 32 are aligned with the annular groove 28 .

On the side facing the traction motor 10 , the first valve member 24 supports a second valve member 34 in the form of a plate which is biased by a spring 36 against the end face of the valve member 24 (the mounting of the valve plate and the attachment of the spring is con structive in detail not shown). As a result, the axial passage of the first valve member 24 is blocked.

The annular grooves 30 of both valve units 18 and 20 form a first connection; both first connections are connected to a common line 38 , in each case via a check valve 40 or 42 . Between the Rückschlagventi len 40 , 42 , the line 38 is connected to the input of a pressure valve 44 , the output of which is connected to a line 46, which is connected via a check valve 48 , 50 with the annular groove 28 of the valve unit 18 , 20 .

The lines 14 , 16 are bridged by a line 52 in which a shuttle valve 54 is arranged, which is also connected via a line 56 to a control input of the pressure valve 44 .

In FIGS. 3 and 4 examples are shown schematically of a pilot valve, as shown in Fig. 5 as indicated, and as shown they can be used as pilot valves for the pressure valve 44 of FIG. 1. In Fig. 3, a valve piston 58 is axially movably mounted in a housing arranged at 55 , which has a radial collar 60 at one end, which forms a pressure chamber 62 with an extension in the bore of the housing 55 . The hollow piston 58 is biased downwards by a spring 64 , the tension of which is adjustable, and is supported by a further spring 66 on a spherical valve member 68 which cooperates with a valve seat 70 . The space 62 in which the spring 66 and the ball 68 are located is also connected to the tank 72 of the hydraulic system. The shuttle valve 54 according to FIG. 1 can also be seen in FIG. 3. The channel 76 opening into the valve seat 70 is connected to the line 38 when transferred to FIG. 1. As can be seen, the opening behavior of the ball valve is dependent on the pressure prevailing in the control chamber 62 , which is connected to the shuttle valve 54 via a check valve 78 and a throttle 80 connected in parallel. The space 74 is connected via a throttle 82 in the piston 60 to the inner space of the piston 58 , which is also connected to the tank 72 . When applied to FIG. 5, space 74 is connected to the tank line 130.

In the embodiment of Fig. 4, the ball valve is connected 68 'directly with the piston 58', which is biased by a spring 64 'downwards. In one Ver equal to the embodiments of FIGS. 3 and 4 is recognizable bar, that the pressure valve according to Fig. 3 operates damped, which is not the case in the embodiment of Fig. 4. The piston 58 'as well as the piston 58 has a ra dialen collar (not shown), which forms a control chamber like control chamber 62 in Fig. 3rd

The operation of the valve arrangement according to Fig. 1 is as follows. If with the help of the switching valve 12, for example, the line 14 is pressurized, the valve member 24 is moved axially upwards until the flange 26 bears against the upper edge of the annular space 28 . In this second position of the first valve member 24 , the annular space 30 (first connection) is shut off. Now the valve plate 34 opens (second valve member), so that a connection to the drive motor 10 is made and this is driven. The backflow takes place via the valve unit 20 , the annular space 30 , the check valve 42 and the pressure valve 44 to line 46 . The pressure valve 44 is acted upon by the inlet pressure via the shuttle valve 54 , and is therefore in the maximum open position. When considering Fig. 3, this would mean that the control chamber 62 is under the inlet pressure, the piston 58 is therefore maximum deflected upward, whereby the valve ball can easily open 68 at a low flow pressure in the channel 76, allowing the pressure in corresponds to line 38 . Via the check valve 50 and the annular recess 28, the fluid via the line 16 and the switching valve 12 may then (not shown) to the tank to flow back into the valve unit 20th If the switching valve 12 is brought into the neutral position, the line 14 is depressurized. However, the traction motor 10 continues to move and generates a return flow which can flow via the valve unit 20 , the pressure valve 44 to the line 46 and via the Rückschlagven valve 48 to the annular space 28 and via the check valve 34 to the motor 10 . However, there is an increasing throttling in the pressure valve 44 , since the pressure at the outlet of the shuttle valve 54 is zero, so that braking of the driving motor 10 occurs until it comes to a standstill. This can be done according to a predetermined characteristic.

The valve arrangement shown also represents a pressure valve. If a very high pressure is built up in the lines due to a movement on the drive motor 10 when the switching valve 12 is in the neutral position, the pressure valve 44 opens, so that a flow through the valve units 18 , 20 in the manner described takes place with sufficient after suction for the traction motor 10 . Cavitation does not occur.

In the embodiment according to FIG. 2, the traction motor and valve units are identical to those according to FIG. 1, so that the same reference numerals are used, to which only an "a" is added. As can be seen, the first connections 30 a to the valve units 18 a, 20 a are separately connected to a slide valve arrangement 84 , which, schematically indicated, has a slide 88 which, in a central position, blocks passages to a line 90 which connects to the line 52 a connected is. In the two working positions (left or right) one of the connections 30 a of the valve units 18 a, 20 a with the line 90 is connected ver. Via check valves 92 , 94 , the traction motor 10 a is bridged by a line 96 , to which the inlet of a pressure relief valve 98 is connected, the outlet of which leads to a tank 100 . The pressure relief valve 98 responds when caused by the traction motor 10 a, an operating pressure above loading occurs.

The operation of the arrangement according to FIG. 2 is similar to that described according to FIG. 1, the position of the slide valve 88 being influenced by a control pressure at the control input which is connected via a line 102 or 104 to the first connection of the valve unit 18 a or 20 a is connected. When the slide 88 is returned to the neutral position, there is an increasing throttling, so that the back-flowing hydraulic medium is increasingly throttled when the switching valve is in a neutral position and a braking effect for the motor 10 a occurs.

In Fig. 5 again two identically constructed Ventilein units 18 b, 20 b are shown, which are in a line 14 b or 16 b to a traction motor 10 b and are connected to the outputs of a switching valve 12 b. Only the left valve unit 18 b, which has a housing 22 b, which is only indicated, is described again below. The housing has a first ring recess 30 b and a second ring recess 28 b. The ring-cylindrical first valve member 24 b has a radial collar 106 between the ends, which protrudes into the annular recess 28 b and is acted upon from below by a spring 108 , which tries to push the valve member 24 b upwards against a conical valve seat 110 , with which a conical surface 112 cooperates at the upper end of the valve member 24 b. In this Stel development, the annular recess 30 b is blocked by the bore of the valve member 24 b. A first chamber 114 and a second chamber 116 are formed by the annular collar 106 .

The second valve member 34 b acts with the inner upper edge of the passage of the valve member 24 b to seal and is biased by a spring 36 b in the closed position.

The first connections 30 b of the valve unit 18 b, 20 b are connected to one another via a line 118 , which are connected to the tank 124 via a line 120 and a throttle 122 . The control chamber 114 is connected via a pressure or pilot valve 126 or 128 to a line 130 which is connected to the tank 124 .

The housing 22 b has at the lower end a radial bore 132 which leads to the lower end of the valve unit 18 b in de ren passage and which is connected via a check valve 134 to a line 136 , which is also connected to the line 120 and thus leads via the throttle 122 to the tank 124 . The control inputs of the pressure valve 126 and 128 are each connected to the bore 132 via lines 138 and 140, respectively.

The control room 114 is also connected via a line 142 or 144 and a throttle 146 or 148 to the input or output of the traction motor 10 . The control room 116 , however, is connected to the tank 124 .

The size of the effective area of the collar 106 corresponds to the area facing the space 150 , namely the sum of the facing area of the second valve member 34 b and the area at the front end of the first valve member 24 b.

The operation of the valve arrangement according to FIG. 5 is as follows. When the switching valve 12 b is open, the first valve member 24 b is biased by the pressure acting from below into the position shown. The valve plate 34 b lifts off against the action of the spring 36 b and thus enables a flow to the traction motor 10 . The backflow pressure opens the valve unit 20 b, so that its valve member 24 b lifts off from the valve seat 110 . Characterized in that at the pressure valve 128, the pressure at the inlet of the first valve unit 18 is present b, the pressure valve 128 opens wide and thus relieves the control space 114th The backflow therefore takes place via line 118 and line 120 and via check valve 135 to bore 132 and tank 124 . If the switching valve 12 b is brought into the neutral position, the lines 14 b, 16 b are depressurized. The pressure valve 128 goes into the closed position, which can be done without damping, for example with the help of the pressure valve according to Fig. 4. The pressure build-up in the control chamber 114 is done only slowly by the throttle 148 , so that the first valve member 24 b only slowly in the Returns to the closed position and thus throttling and thus braking the driving motor 10 accomplished.

A pressure valve is in the arrangement of FIG. 5 if not necessary, since the valve unit concerned opens or a discharge can take place via the pressure valve 126 , 128 .

Claims (8)

1. Brake valve assembly for a reversible hydraulic valve controlled by a switching valve, such as a hydraulic traction motor or the like, in which a shut-off element acts in the respective return flow path, which can bring the return flow path increasingly throttling into the closed position and its open position or adjustment in the closed position from the inlet pressure is influenced, characterized in that two identically constructed separate valve units ( 18 , 20 , 18 a, 20 a) are provided, each in a line ( 14 , 16 , 14 a, 16 a) between the switching valve ( 12 ) and hydraulic consumption cher ( 10 , 10 a) are arranged and which contains a first in the housing ( 22 ) limited displaceable, having a through-bore slide-like first valve member which blocks a first connection ( 30 , 30 a) when acted upon by inlet pressure and one on the first Ven valve member ( 24 , 24 a) movably mounted second valve member ( 34 ), which with the Du rchbohrung of the first valve member ( 24 , 24 a) cooperates and is biased by a spring ( 36 ) in the closed position, in which it blocks the through hole and can be brought into the open position by the inlet pressure for the purpose of connecting the consumer ( 10 , 10 a) with the inlet line ( 14 , 16 , 14 a, 16 a) and the first connections ( 30 ) of both Ventilein units ( 18 , 20 , 18 a, 20 a) with a controlled valve arrangement having the shut-off device ( 44 , 84 ) are connected , whose variable flow cross-section depends in each case on the pressure in the feed line ( 14 , 16 , 14 a, 16 a). 2. Valve arrangement according to claim 1, characterized in that the controllable valve arrangement has a pressure valve ( 44 ), the input of which is connected via check valves ( 40 , 42 ) to the first connections ( 30 ) and the output of which is connected to the tank or via check valves ( 48 , 50 ) is connected to the input of both valve units ( 18 , 20 ) and the control input of the pressure valve ( 44 ) can optionally be connected to one of the two outputs of the switching valve ( 12 ). 3. Valve arrangement according to claim 2, characterized in that both outputs of the switching valve ( 12 ) via the active inputs of a shuttle valve ( 54 ) can be connected and the shuttle valve ( 54 ) is connected to the control input of the pressure valve ( 44 ). 4. Valve arrangement according to claim 1, characterized in that the controllable valve arrangement has a two-input brake slide valve ( 84 ), the inputs being connected to the first connection ( 30 a) of a valve unit ( 18 a, 20 a) and the brake slide in one of two oppositely directed working positions, a connection ( 30 a) with the tank via check valves ( 48 , 50 ) connects to the input of both adjustment units and blocks the other input and opposing active surfaces of the slide ( 88 ) with the pressure at the outlet of the Schaltven tils are applied. 5. Brake valve assembly for a reversible hydraulic valve controlled by a switching valve, such as a hydraulic traction motor or the like, in which a shut-off device acts in the respective return flow path, which brings the return flow path increasingly throttling into the closed position and whose open position is influenced by the inlet pressure when adjusted to the closed position , characterized in that two identical ge separate valve units ( 18 b, 20 b) are provided, each in a line ( 14 b, 16 b) between Schaltven valve ( 12 b) and hydraulic consumer ( 10 b) are angeord net and which contains a first in the housing ( 22 b) displaceable, a through-bore, slide-like first valve member ( 24 b) which, when in contact with a valve seat ( 110 ) in the housing ( 22 b), has a first connected to the tank ( 124 ) Connection ( 30 b) blocks, the first valve member ( 24 b) by a spring ( 108 ) against the valve seat ( 110 ) is biased and on the first valve member ( 24 b) movably mounted second valve member ( 34 b), which is biased by a spring ( 36 b) in the closed position, in which it blocks the axial bore of the first valve member ( 24 b), that a first annular active surface ( 106 ) is provided on the first valve member ( 24 b), the size of which corresponds to the sum of the active surfaces of the end face of the first valve member ( 24 b) and the second valve member ( 34 b), the first active surface ( 106 ) preferably a Dros sel the pressure at the input of the load (10 b) being set and the pressure on the active surface (106) by a pressure valve (126, 128) is controlled, the control pressure of the inlet pressure of the respective other Ven tileinheit (18 b, 20 b) is determined. 6. Valve arrangement according to one of claims 1 to 5, characterized in that the valve units ( 18 , 20 , 18 b, 20 b) have a second connection ( 28 , 132 ) which via a check valve ( 48 , 50 , 134 , 135 ) with the output of the pressure valve ( 44 ) or the first circuit ( 30 , 30 b) is connected. 7. Valve arrangement according to one of claims 1 to 6, characterized in that the second valve member ( 34 , 34 b) is a valve plate which on the consumer ( 10 , 10 b) facing the end face of the first valve member ( 24 , 24 b) is arranged. 8. Valve arrangement according to one of claims 5 to 7, characterized in that the first effective surface of a radial collar ( 106 ) of the slide-like first valve member ( 24 b) is formed.