DE2232857C2 - Control device for a hydraulically driven implement - Google Patents

Description

characterized,

JO

f) that the via the drainage channel (19) with a second, downstream consumer (20) in Communicating chamber (18) of the switching valve (12) as the control slide (13) associated annular chamber (18) is formed, whose pressure compared to the control slide (13) is pressure balanced,

g) that the control slide (13) connects the inlet channel (3) to an additional, «o associated annular chamber (21) controls,

h) that the check valve in series between the additional annular chamber (21) and the first Consumer (35) is switched and

i) that the means for throttling the effective cross section of the passage connection (29, 30, 40, 41 and 42) on an extension (37) of the closing body (36) of the check valve (32) are trained.

50

2. Control device according to claim 1, characterized in that the extension (37) of the closing body (36) is slidably guided in a blind hole and an annular groove (40) with a Has control edge that when the closing body (36) of the check valve (32) is lifted off an unthrottled connection connected in parallel to a throttled connection (41, 42) the port connection closes.

3. Control device according to claim 1 or 2, characterized in that the control slide (13) shortly before reaching its end position assigned to the stroke position in a pressure medium-filled, only through a throttling opening (25) cylinder (24) "5 immersed.

4. Control device according to one of claims 1 to 3, characterized in that the first Consumer (35) leading work channel (33) lowering position via a pilot operated, as a seat valve designed lowering valve (44) can be connected to the return channel (8), and the closing body (45) of the [ Lowering valve (44) at its end bearing a conical seat (59) one of the forward control! tion has associated throttle bore (46) and! with its other end into a pressure medium-filled j th cylinder (50) is immersed, from which the pressure medium! over on a spring-loaded non-return plate (53) | arranged throttle opening (51) can escape.

The invention relates to a control device for a hydraulically driven implement, in particular mounted on an agricultural vehicle, according to the type specified in the preamble of claim J.

Such a control device is known from DE-OS 20 34 214. This with a mechanical Moving pilot valve provided control device has a reversing valve, which in the lift position the Pressure medium flow to the consumer or in the neutral position or lowering position the pressure medium flow to the Rüclclauf leads. To prevent that when the pilot spool is switched to the lift position, the The entire flow of pressure medium reaches the consumer is a separate pressure-controlled valve arranged that relieves the control chamber of the switching valve in such a way to the return that with increasing Approaching the end position of the control slide assigned to the stroke position of the flow resistance is enlarged in the relief line. This variable damping of the control slide At first only a relatively small part of the flow rate reaches the consumer, so that pressure surges can be avoided. This leads to a relatively complex control device, which is also not suitable for the pressure medium flow in the neutral and the lowering division of the control device to a second consumer, since the switching valve controls only two ways and none Pressure loads allowed in the return.

Furthermore, from DE-AS 11 83 789 a control device known, in which two consumers are supplied with pressure medium via a 3-way flow regulator, a pressure-dependent switchover valve with 2 working connections in the preferred steering circuit is connected in parallel. A pilot valve and a check valve are missing; also plays the problem of Damping no comparable role.

Based on the prior art mentioned at the beginning, the object of the invention is to develop the known To improve control device with fast-switching pilot stage and dense mode of operation in such a way that that a preferred consumer can be smoothly supplied with pressure medium with little effort can.

This object is achieved according to the invention by the characterizing features specified in more detail in claim 1 Features solved.

In this way, a control device is obtained which bumps-free a first, preferred consumer can supply with pressure medium and the pressure medium in the neutral and lowered position of the control device a second, downstream consumer

The damping is achieved with simple, structural means by the functions of the check valve and integrating the cross-sectional control in the passage connection in a single component are.

Further advantageous refinements of the invention emerge from the remaining claims.

Embodiments of the invention are shown in the drawing. This shows in

F i g. 1 shows a first embodiment of a control device for tools, where the control is electrical,

F i g. 2 shows a second exemplary embodiment of a control device according to FIG. 1, the control happens mechanically,

F i g. 3 shows a third exemplary embodiment of a control device according to FIG. 1, the control happens hydraulically or pneumatically.

The in F i g. The control device shown in FIG. 1 consists essentially of two blocks connected to one another formed: the main part 1 and the pilot valve 2. In the housing of the main part 1 there is an inlet duct 3 arranged into which a pressure line 5 guided by a pump 4 opens. The pump 5 sucks pressure medium from a container 6. In a side channel 7 which branches off from the inlet channel 3 and which has a return channel 8 is connected to the tank 6, a pressure relief valve 9 is arranged as a safety valve.

The inlet channel 3 opens into an annular chamber 10 of a slide bore 11 of one in the main part 1 of the Housing of the control device arranged changeover valve 12. This has one in the slide bore 11 tightly and slidably guided control slide 13, which is controlled by one in the left end of the slide bore 11 arranged compression spring 14 is loaded. Between two arranged on the control slide 13 annular grooves 15 and 16, a control collar 17 is formed, the width of which is narrower than the width of the first annular chamber 10 in the Slide bore. In a second annular chamber 18 of the slide bore 11, which is on the right in the axial direction is arranged next to the first chamber 10, a drainage channel 19 opens, which is connected to a second, downstream Consumer 20 is connected.

This second, downstream consumer 20 can be, for example, an additional directional control valve act, with which a mower unit or a reel motor is controlled, for example.

In the axial direction to the left of the first annular chamber 10, the slide bore 11 has a third Annular chamber 21 into which a pressure channel 22 opens.

On the control collar 17 of the control slide 13 is at least one, in the direction of the annular groove 16 of the Control slide extending control chamfer 17 'arranged via which the connection to the second, downstream Consumer 20 is diverted. The one in front of the left, spring-loaded end of the control slide 13 Space is relieved from the return channel 8 to the container 6. The one in front of the other, the spring 14 facing away from the end face of the control slide 13 forms together with a fourth chamber the slide bore 11, the control chamber 23 of the switching valve 12. The rear, the bottom of the Part of the control chamber 2.5 facing the slide bore forms a closed cylinder 24 into which the piston-like end of the control slide 13 facing away from the spring 14 can dip. That in that Cylinder 24 then enclosed pressure medium can via one at the piston-like end of the control slide 13 arranged, groove-shaped throttle opening 25 escape.

A second pressure channel 29 which opens into the control chamber 23 and is provided with a fixed throttle, leads to a 3/2-way pilot valve 27 actuated by an electromagnet 26, depending on its Position can be the 3/2-way Voisteuervenril 27 second pressure channel 29 via a, second side channel 28 with the inlet channel 3 or one with the

ίο return channel 8 coupled second return channel 31 associate.

From the switching valve 12 from the third annular chamber 21 from its slide bore 11 emerging first pressure channel 22 is via a check valve 32 with a working channel 33 can be connected. The working channel 33 is continued in a working line 34, which leads to a Working cylinder 35 illustrated first consumer is performed. In the working cylinder 35 is a Working piston tightly and slidably guided, on the piston rod of a device, not shown, for example the cutting table of a combine harvester, on the chassis of which the working cylinder 35 is attached, is movably attached.

The check valve 32 has a conical design which is pressed onto its seat by a spring 38 Closing body 36, which extends on a side facing away from the spring 38, in a blind hole 39 tightly and slidably guided extension 37 is seated. On the periphery of the extension 37 of the check valve 32 an annular groove 40 is formed, which in the position shown of the extension 37 is an unthrottled, which in the second pressure channel 29 located throttle 30 releases the bridging passage connection 41,42.

Via a lowering valve 44, which is arranged in a lowering channel 43 and is designed as a seat valve, the The working channel can be connected to the return channel 8 in the lowered position of the control unit. In the closing body 45 of the lowering valve 44, a central throttle bore 46 is arranged, which via a pilot channel 47 arranged pressure-relieved, actuated by an electromagnet 48 shut-off valve 49 with the second return channel 31 can be connected. The one with a conical seat 59 provided side facing away from the end of the closing body

⁴ S 45 of the lowering valve 44 plunges into a closed, pressure medium-filled cylinder 50 when the closing body is lifted off, which cylinder 50 is formed by the end of the slide bore that receives the closing body and which is provided with the bottom of the bore. The pressure medium enclosed in the cylinder 50 can escape via a throttle opening 51 which is arranged on a non-return plate 53 loaded by a spring 52. The non-return plate 53 is held by the spring 52 against a shoulder 54 which is formed in a central stepped bore 54 within the closing body 45.

The electromagnets 26, 48 of the pilot valves 27, 49 can only be reproduced as an example Changeover switch 55 are connected to a power source and are thus excited.

The function of the control device is as follows: Is the hand lever of the changeover switch located 55 in the middle position, i.e. none of the When electromagnets 26, 48 are energized, the control device is in its neutral position. It occurs the pressure medium flow conveyed by the pump 4 via the line 5 via the inlet channel 3 of the control device a. Via the open control edge on the

Control collar 17 over the pressure medium flow is forwarded to the drainage channel 19, from where he the downstream consumer 20 can flow. The pressure that is now building up in the system is applied via the second side channel 28, the 3/2-way pilot valve 27, the second pressure channel 29, the throttle 30 and through the open passage connection 41, 42 in the control chamber 23 and acted there on the Control spool 13. This is so against the pressure of the Spring 14 pushed all the way to the left into its open position. The control device via the drainage channel 19 The pressure medium flow leaving again can therefore be used to operate the downstream consumer 20 be exploited. As already mentioned above, this downstream consumer can be about act a mower motor of a combine harvester.

If the operator of the agricultural vehicle, i. H. So about the combine harvester, now the one Working cylinder 35, so about the lifting cylinder of a mower table, lift, so he will the hand lever 56 of the Move changeover switch 55 into its right end position. As a result, the electromagnet 26 of the 3/2-way pilot valve 27 is energized and thus the valve 27 is switched over, whereby the control chamber 23 to the second return channel 31 is relieved. This creates the connection from the inlet channel 3 to the outlet channel 19 throttled quickly so that the pressure medium flow conveyed by the pump 4 via the first pressure channel 22 is fed to the check valve 32. When the pressure prevailing in the working channel 33 is reached the closing body 36 of the check valve 32 begins to open. During the movement of the closing body 36 is then immediately the existing via the annular groove 40 on the extension 37 of the check valve 32, unthrottled Passage connection 41, 42 closed in the second pressure channel 29 coming from the control chamber 23, so that the pressure medium flowing out of it must take the route via the throttle 30. This creates a strong damping of the movement of the control slide 13 of the switching valve 12 directed to the right causes. The connection from Zuiaufkana! 3 angry The drainage channel 19 is thus slowly and smoothly via the control bevels formed on the control collar 17 diverted. A further damping of the movement of the control slide 13 results when the right End of the control slide 13 into the cylinder 24 in the control chamber 23 formed by the bottom of the bore immersed. The pressure medium enclosed therein can only be piston-like on the circumference of the formed end of the control slide 13 formed throttle opening 25 escape very slowly. That I now the closing body 36 has completely lifted from its seat. exists via the check valve 32 an open connection for the pressure medium flow to the working duct! 33 and from there to the working cylinder 35. The working cylinder 35 is therefore a consumer 20 connected downstream privileged consumer.

If the lifting cylinder 35 now has the load moved by it, that is to say, for example, the cutting table at the desired height lifted, the operator will move the hand lever 56 of the toggle switch 55 back to its middle position Move position. This causes the solenoid 26 of the 3/2-way pilot valve 27 to be excited ends and the spring-loaded slide of the pilot valve is moved back to its starting position. Since the control chamber 23 is now pressurized again, the control slide moves 13 again to the left. The immediately falling pressure in the first pressure channel 22 then closes it immediately Check valve 32, so that a decrease in the load connected to the working cylinder 35 is prevented immediately will. The control device is thus again in the state described at the beginning in which the downstream consumer 20 can be operated.

If the operator now wants the load connected to the working cylinder 35, for example the Lower the mower table, it must bring the hand lever 56 of the changeover switch 55 to its left end position, whereby the solenoid 48 which serves as a pilot valve for the lowering valve 44 is relieved of pressure Shut-off valve 49 is energized, whereby the pilot valve opens. Since then the pilot control channel 47 to second return channel 31 is relieved, can be at the throttle bore 46 in the closing body 45 of the Lowering valve 44 form a pressure difference which ultimately leads to the lifting of the conical shape Seat provided closing body 45 leads. The pressure medium enclosed in the cylinder 50 can only slowly over the throttle opening 51, which is arranged on the spring-loaded non-return plate 53, escape, whereby a sudden, undamped movement of the closing body 45 is prevented. Above the now relieved to the return channel 8 working channel 33 flows the pressure medium contained therein so long to Container 6 from until the operator moves the hand lever 56 on the changeover switch 55 into his Middle position allows the pilot valve 49 to return to its closed position. That about the throttle bore 46 pressure medium reaching the interior of the closing body 45 now lifts the non-return plate 53 off their seat against the force of the spring 52, so that the cylinder 50 are immediately filled with liquid again can and the seat 59 of the closing body 45 comes to rest on its seat again.

The second exemplary embodiment of the control device according to FIG. 2 differs from the first Embodiment according to FIG. 1 only through a modified pilot control part 2. In the pilot control part 62 the pilot valves 49, 27, the hydraulic part of which corresponds exactly to that described first, controlled mechanically via a rotary shaft 64 provided with a cam 63. The operation of the rotating shaft 64 can be rotatably fixed on the shaft by means of a hand lever corresponding to the hand lever 56 64 is arranged. Otherwise, the function of the control device corresponds to FIG. 2 perfect that of the control device according to FIG. 1.

The control device according to FIG. 3 differs differs from the previously described ones only through the type of control of the pilot valves 49, 27 Embodiments. The one in the pilot part 72 of the third Embodiment housed pilot valves 49, 27 are each hydraulically or pneumatically Actuating pistons 73, 74 to be acted upon, which act on them via control lines 75, 76 with a pressure are operated

For this purpose 3 sheets of drawings

Claims (1)

Patent claims: 1. Control device for a first consumer for lifting and lowering hydraulically driven, in particular work equipment attached to an agricultural vehicle, a) with an inlet, a return and an outlet channel, b) with a pilot valve and one of them ι ο controlled, having a control slide Reversing valve, the control slide being different from that prevailing in a control chamber Pressure can be displaced against the force of a spring and one in neutral and in lowering position Establishes a connection from the Zulaiif Canal to the Abiaufkanal via a chamber, c) with a check valve in a line leading to the first consumer, d) with a passage connection leading from the control chamber to the pilot control valve, via which the control chamber can be optionally connected to the inlet channel or the return channel, and e) with means for throttling the effective cross section of the passage connection at Switching the control spool of the switchover valve to the lift position,