DE3334094C2 - - Google Patents

Description

The invention is based on a hydraulic control direction for a hydraulic motor driven ins particular to an agricultural vehicle built work tool according to the genus of the main claim.

Such a control device is already from the DE-OS 31 02 505 known that a throttle valve, one consisting of shut-off valve and associated unlocking piston Lock block and a spool, which affects the throttle valve and the release piston. At this control device is on Control spool serves as a control throttle edge formed, which is the throttle valve as pressure scale is assigned, so that in the lifting position closed hydraulic motor a load pressure dependent, pro proportional flow of pressure medium can be controlled there. At this control device that is for an open circuit is trained, it can now be disadvantageous that  the from the throttle valve via a flow chamber to Tank-guided pressure medium flow is not used to control a second, additional hydraulic motor can be used. In such a case, both hydraulic motors would pressed simultaneously and the downstream, second Hydraulic motor require a higher pressure than the first one, hydraulic motor operated by the control device, so step pressure medium ratios in the control device, which controls the first hydraulic motor in position Make lifting completely impossible. Even when lowering the The first hydraulic motor is created at higher pressure on the switched consumers this pressure even in the tax chamber of the unlocking piston and leads to an undesirable hard working of the control device. Furthermore, is with this control device also no load-independent Lowering of the first hydraulic motor possible. It also builds Control device expensive in that between Dros Selschieber and Steuererschieber a separate Steuerlei device with throttling point is required.

Furthermore, from DE-OS 30 25 949 a hydraulic Control device known, in addition to a locking block and a control slide has a throttle slide. This consist of a shut-off valve and an unlocking piston the locking block is a damping space on the unlocking piston connected in such a way with a return line that the Control spool in connection with the blocking block one load-compensated sink current regulation allowed, accordingly has a proportional sink area. Except of the fact that with this control device no load dependent lifting current control of the connected Hydromo tors is possible, it has the disadvantage that it bad for simultaneous control of a secondary switched, second hydraulic motor is suitable. Would namely  downstream hydraulic motor switched to pressure during the first hydraulic motor controlled simultaneously by the control device should lift, the downstream hydraulic motor receives none at all Pressure medium. It would especially when lowering the first hydraulic motor load-compensated, proportional control is no longer possible.

Based on this, there is a desire for a pressure-independent Supply of an upstream and a downstream hydraulic motor without mutual influence, including a load-independent lowering should be possible by means of the upstream hydraulic motor. The one here for intended control device should be as simple as possible in construction be.

This is a control device according to the features of the main fair.

The control device according to the invention has the front in part that it preceded a downstream, second hydraulic motor can be tet without their proportional mode of operation in any a shape is compromised. Both when lifting and when sen ken of the first hydraulic motor is independent of the pressure in the second Hy dromotor a load pressure compensated pressure medium flow to or from controlled the first hydraulic motor. In addition, the proposed solution builds simple and with little effort.

Advantageous further developments and improvements in the main claim specified control device result from the in the Unteran characteristics listed.

An embodiment of the invention is shown in the drawing represents, the only figure of a control device in simplified Representation in the lifting position shows.

The single figure shows a control device 10 with a control directional control valve 11 , which is used for hoist control on an agricultural vehicle, in particular a tractor with an articulated plow.

The control valve 11 has a housing 12 , in which in three mutually parallel axes a throttle valve 13 , a control valve 14 and a blocking block 15 , consisting of a blocking valve 16 and associated push piston 17 , are arranged.

The throttle valve 13 has a throttle slide 18, which slides in the housing 12 in a slide bore 19th In the slide bore 19 , a pressure chamber 21 , a continuation chamber 22 , an inlet chamber 23 , an outlet chamber 24 and a spring chamber 25 are formed side by side, based on the figure from left to right, through annular extensions. The throttle valve 18 is opened by a spring 26 arranged in the spring chamber 25 and by the pressures in the spring chamber 25 and in the pressure chamber 21 be. For this purpose, the pressure chamber 21 is connected to the outlet chamber 24 via control channels 27 arranged in the throttle slide 18 . The spring 26 loads the throttle valve 18 to the left in the direction of a starting position, not shown, in which it blocks with egg nem piston portion 28 in connection from a laßraum 23 to the flow chamber 22 . In addition, a pilot throttle 30 is net angeord in the throttle valve 18 , which is connected between the control channels 27 and the spring chamber 25 , so that their pressure drop can load the throttle valve 18 against the spring 26 . At the piston portion 28 on the outlet chamber 24 th side a first control chamfer 29 is arranged, which in the initial position of the throttle valve 18, the connec tion from the inlet chamber 23 to the outlet chamber 24 fully opens. In addition, a second control chamfer 31 is formed on the other end face of the piston portion 28 , which serves to control the connection from the inlet space 23 to the further passage 22 . The inlet space 23 is connected via a first line section 32 to an input 33 of the control valve, from which a working line 34 leads to an output 35 , the throttle valve 13 , the control valve 14 and the check valve 16 being connected in series in the working line 34 . As part of this working line 34 , a second line section 36 leads from the outlet space 24 to the subsequent control valve 14 .

The control valve 14 has a control slide 37 , which serves in a second slide bore 38 and is slidably ge leads. In the latter ( 38 ) are again lying side by side and seen from left to right, based on the figure, a first return chamber 39 , an outflow chamber 41 , a control chamber 42 , a first ( 43 ) and a second working chamber 44 and a second return chamber 45 arranged. The two external return chambers 39, 45 are relieved to a tank 46 . In the first Ar beitskammer 43 opens the second portion 36 of the Ar beitsleitung 34th From the second working chamber 44 leads a third line section 47 as part of the working line 34 to the check valve 16 , from which a fourth line section 48 leads to the outlet 35 . A check valve 49 protecting the second working chamber 44 is connected in the third line section 47 . Furthermore, a Rücklauflei device 51 leads to the outlet chamber 41 and further via the first return chamber 39 to the tank 46 from the outlet 35 via the check valve 16 . Working line 34 and return line 51 are partially identical, namely in the area of the check valve 16 . From the control chamber 42 , a first control line 52 leads via a first ( 53 ) and egg ne second throttle 54 to the second return chamber 45 and thus further to the tank 46 . The first control line 52 has a branch 55 in the area between the two throttle points 53, 54 , which feeds the respective intermediate pressure to a pressure chamber 56 assigned to the pushing piston 17 . Furthermore, a second control line 57 connects the second working chamber 44 in the control valve 14 to the spring chamber 25 in the throttle valve 13 .

A first control edge 58 is formed on the control slide 37 itself in order to control the pressure medium flow to be flowed via the work output 34 in proportion to the deflection of the control slide 37 . While in the drawn lifting position the first control edge 58 opens the connection between the two working chambers 43, 44 , it interrupts this connection between the working chambers in a neutral position of the control slide 37, not shown. Furthermore, the control slide 37 has a second control edge 59 in order to control the pressure medium flow flowing off via the return line 51 to the tank 46 in a corresponding manner. In the depicted lifting position and in a New tralstellung this second control edge 59 interrupts the connection of the outlet chamber 41 to the first return flow chamber 39, while in a lowering position, this compound be proportional to the sliding probe deflection is controlled. The control slide 37 also has a third control edge 61 , with which it switches the connection between the first working chamber 43 and the control chamber 42 and thus influences a connection via the first control line 52 to the tank 46 . In the neutral and lifting positions, this third control edge 61 blocks the connection from the working line 34 to the first control line 52 , while it is opened in the lowering position. Further, the control slide has 37 controls a fourth control edge 62 with which it influ- striking the connection of the two ten working chamber 44 to the second return chamber 45 and thus the discharge of the spring chamber 25 in the throttle valve. 13 This fourth control edge 62 opens its associated connection in the neutral and lower positions.

In the blocking block 15 is located on the push piston 17 of the pressure chamber 56 opposite a damping chamber 63 which receives a pushing piston 17 loading spring 64 . From the damping chamber 63 leads a third control line 65 in the return line 51 in the area between the check valve 16 and control slide 37th The confluence of the control line 65 in the return line 51 is also upstream of the check valve 49 based on the working line 34th

The single-acting hydraulic motor 66 connected to the outlet 35 of the control valve 11 is a power lift which can actuate a plow 71 articulated on the tractor frame 69 via a lifting arm 67 and a conventional three-point linkage 68 .

The input 33 of the control valve 11 is provided by a pump 72 via a supply line 73 with pressure medium ver. In the supply line 73 is an upstream t directional valve 74 , which can control an additional consumer 75 .

A drain line 76 leads from the flow chamber 22 in the throttle valve 13 to the tank 46 . A downstream directional control valve 77 is arranged in this discharge line 76 and controls pressure medium to a second hydraulic motor 79 in the raised position 78 shown . Corresponding to the upstream directional valve 74 , the downstream directional valve 77 also has a central position 81 which opens the drain line 76 , and a lower position 82 .

The control device 11 is accordingly designed for an open circuit.

The operation of the control device 10 is explained as follows: It should be assumed that the control slide 37 assumes a neutral position in the control valve 14 and the control slide of the upstream ( 74 ) and the downstream directional control valve 77 each take their central position 81 . The pump 72 promotes a constant pressure medium flow via the inlet line 73 into the inlet space 23rd From the inlet chamber 23 , a small control current flows past the throttling, first control chamfer 29 into the outlet chamber 24 and via the control channels 27 in the throttle slide 18 and via its pilot throttle 30 into the spring chamber 25 . From there, this control oil flow passes through the second control line 57 and the fourth control edge 62, which is open in neutral position, on the control slide 37 into the second return chamber 45 and on to the tank. The pilot oil flow causes a pressure drop at the pilot throttle 30 , which presses the throttle slide 18 against the force of the spring 26 to the right in the working position shown. The throttle valve 18 thus works as a flow control valve which keeps the control oil flow flowing to the tank 46 constant and as low as possible and controls most of the pressure medium delivered by the pump 72 largely unthrottled into the discharge line 76 and further to the tank 46 . The energy losses are therefore relatively low, as long as none of the hydraulic motors is operated.

As long as the control valve 11 remains in its neutral position, the consumer 75 can optionally be raised or lowered by means of the upstream directional valve 74 .

If the downstream directional control valve 77 is actuated when the control directional control valve 11 is in the neutral position, the drain line 76 is still controlled to in the lower position 82 . If, on the other hand, the directional control valve 77 is brought into its lifting position 78 , the drain line 76 is interrupted and the pressure medium delivered by the pump 72 largely rises on the second hydraulic motor 79 ann up to the maximum pressure of the pump 72 , the throttle valve working as a flow control valve 18 always keeps the control oil flow flowing to the tank constant.

It is now assumed that the upstream ( 74 ) and the downstream directional control valve 77 take their respective middle positions 81 and for lifting the plow 71 of the control slide 37 in the control directional control valve 11 is deflected to the left into its drawn lifting position. The fourth control edge 62 on the control slide 37 interrupts the relief of the second control line 57 to the second return line 45 and to the tank 46 . In Fe derraum 25 of the throttle valve 13 thus acts the spring 26 on the throttle valve 18 and in addition the pressure of the second working chamber 44 , which line 57 also builds up in the spring chamber 25 via the second control. By the first control edge 58 , the connection between the two working chambers 43 and 44 is now more or less turned open, so that a pressure medium flow via the work line 34 , the check valve 49 and the check valve 16 can flow to the outlet 35 and further to the hydraulic motor 66 . The pressure upstream of the first control edge 58 in the first working chamber 43 also prevails in the outlet space 24 of the throttle valve 13 and via the control channels 27 in the interior of the throttle slide 18 in the pressure space 21 . As long as the downstream directional control valve 77 is not actuated and the discharge line 76 to the tank 46 is relieved, the second control chamfer 31 , when the control path valve 11 is lifted, the connection from the inlet space 23 to the flow space 22 so strongly andros selen that that over the first control edge 58th available pressure drop corresponds to the force exerted by the spring 26 on the throttle slide 18 and is thus kept constant. The throttle slide 18 thus works as a pressure balance to the measuring throttle point serving first control edge 58 , so that a load-compensated, proportional lifting control of the hydraulic motor 66 is possible.

It is now assumed that, during the lifting process with the control valve 11, the downstream directional valve 77 is brought into its lifting position 78 . The flow of pressure medium flowing from the throttle valve 13 via the drainage line 76 is now fed to the second hydraulic motor 79 . As long as the working pressure in the second hydraulic motor 79 is lower than the pressure in the power lift 66 , the first control chamfer 29 on the throttle slide 18 remains ineffective and the second control chamfer 31 throttles the connection from the inlet space 23 to the flow of power to the power lift 66 is retained unchanged. Now, on the other hand, the pressure in the second hydraulic motor 79 rises above the working pressure on the power lift 66 , so the second control chamfer 31 has, while in the opposite manner the first control chamfer 29 on the throttle slide 18 reinforces the connection from the inlet chamber 23 to the outlet chamber 24 throttled. This throttling is greater, the more the working pressure on the second hydraulic motor 79 exceeds the working pressure of the power lift 66 . It is therefore the pressure drop at the first control edge 58 of the spool 37 is always kept constant, namely accordingly the force of the spring 26 , so that the proportional lifting control of the power lift 66 is not affected.

In the present embodiment of the throttle valve 13 in connection with the control valve 14 , the control directional control valve 11 can thus be used as an upstream valve compared to the directional control valve 77 with a hydraulic motor 79 , the proportional operation of which is maintained when the two hydraulic motors are operated in parallel regardless of the ratio of the respective working pressures to one another.

If now with the aid of the control valve 11 of the plow 71 to be reduced, so the spool 37 to the right, relative to the figure, is deflected into a lowering position. The fourth control edge 62 on the control slide 37 opens the connection from the second control line 57 to the second return chamber 45 . The first control edge 58 interrupts the connection between the two working chambers 43, 44 . At the same time, the third control edge 61 opens a connection from the first working chamber 43 to the control chamber 42 , so that from the second line section 36 a control oil flow into the control chamber 42 and continues to flow via the first control line 52 with the two throttle points 53, 54 to the tank 46 can. In addition, by the second control edge 59 on the control slide 37, the dung Verbin from the discharge chamber 41 to the first return chamber 39 turned on is proportional to the deflection of the control slide 37th The intermediate pressure between the throttling points 53, 54 we pass through the branch 55 into the pressure chamber 56 , whereby the push piston 17 opens the check valve 16 via a tappet. Pressure fluid can then flow from the first hydraulic motor 66 via the opened shut-off valve 16 and the return line 51 and past the second control edge 59 to the tank 46 . The check valve 49 prevents the back flowing from the hydraulic motor 66 pressure medium in the second Ar beitskammer 44 can. Since the prevailing in the return line 51 load pressure on the third control line 65 in the damping chamber 63 wid and there acts on the plunger 17 , which is always struck in its pressure chamber 56 by a constant pressure can be with the help of the locking block 15th and the control valve 14 allow a load pressure-compensated lowering current control, as is known per se from the aforementioned DE-OS 30 25 949.

As long as the downstream directional control valve 77 assumes its central position 81 while lowering with the control directional valve 11 and the drain line 76 to the tank 46 is thereby relieved, the second control chamfer 31 on the throttle slide 18 will throttle the connection to the flow chamber 22 only to the extent that the outlet space 24 can build up a pressure that keeps the spring 26 in balance. The pressure in the outlet chamber 24 acts through the Steuerka channels 27 in the pressure chamber 21 , while the spring chamber 25 is relieved via the spool 37 to the tank 46 . The pressure drop available for the control oil flow via the first control line 52 is thus kept constant, namely in accordance with the force of the spring 26 . So that the pressure in the pressure chamber 56 on the pushing piston 17 is constant. Parallel to the control oil flow via the first control line 52 , a relatively small control oil flow can also be formed via the pilot throttle 30 and the second control line 57 to the tank 46 , which, however, does not influence the aforementioned function.

If the downstream directional valve 77 is now brought into its raised position 78 while the directional control valve 11 is being lowered and the second hydraulic motor 79 requires a higher working pressure, then the control chamfer 29 on the throttle slide 18 is more strongly engaged and keeps the pressure in the outlet chamber 24 at the constant level limited by the force of the spring 26 . Regardless of the parallel actuation of the downstream hydraulic motor 79 and its respective working pressures, the proportional lowering control can thus be continued undisturbed with the aid of the control valve 11 .

In the proposed control device 10 , the control valve 11 can thus be used as an upstream valve, the proportional operation of which is maintained during lifting as well as lowering during parallel operation with an additional, downstream hydraulic motor. The func tion can be achieved with relatively simple means and accommodate in the available space.

The control slide 37 can be operated in any way. Although the cascade circuit is particularly advantageous for obtaining the control pressure for the push-up piston, this control pressure can also be obtained by a simple on-off circuit.

Claims (4)

1. Hydraulic control device for a driven by a hydraulic motor, in particular attached to an agricultural vehicle working device, with a blocking block consisting of a blocking valve and an unblocking piston, with a blocking valve controlling the blocking block, which influences the pressure medium flow to the hydraulic motor during lifting, first control edge and has a pressure medium flow flowing from the hydraulic motor to the tank when lowering, influencing the second control edge, and with a throttle valve, which is connected between the control valve and an input of the control device in a working line, which slide from the input via the throttle valve, the control valve and the check valve is guided to an output of the control device and that the throttle slide is by a spring in a stirnsei term spring chamber in the direction of a working line controlling way and before an edge occurring at the first control pressure difference in the opposite direction be openable, for which purpose the pressure chamber is opposite the spring chamber and the throttle valve is assigned to an inlet chamber connected to a pressure medium source, in addition to which on the one hand a switched into the working line device outlet space and on the other hand a further running space are arranged and the throttle valve two the connections between these Spaces in opposite directions control de control edges and that the position lowering the spring chamber to the tank can be relieved and with a branch line branching from the working position, influenceable by the control slide and guided to the ejection piston, characterized in that the pressure medium flow serving to control the opening piston ( 17 ) the section ( 36 ) of the working line ( 34 ) is branched, which is downstream of the throttle valve ( 18 ), that the pressure chamber ( 21 ) of the throttle valve ( 13 ) is acted upon by the pressure in its outlet chamber ( 24 ) and that in the Wei terlaufraum ( 22 ) an additional directional control valve ( 77 ) with hydraulic motor ( 79 ) can be switched on the throttle slide ( 18 ) outgoing discharge line ( 76 ) downstream of the further chamber ( 22 ). 2. Control device according to claim 1, with a damping space ( 63 ) on the push piston ( 17 ) of the locking block ( 15 ), characterized in that the damping space ( 63 ) with a region of the return line ( 51 ) has a connection between the control slide ( 37 ) on the one hand and on the other hand the blocking valve ( 16 ) and the valve means ( 49 ), which block the connection via the working line ( 34 ) to the throttle slide ( 18 ) when lowering. 3. Control device according to claim 1 or 2, characterized in that the first control line ( 52 ) via two series-connected throttle points ( 53, 54 ) to the tank ( 46 ) and the intermediate pressure between at the throttle points ( 53, 54 ) Pressure chamber ( 56 ) is fed to the push piston ( 17 ). 4. Control device according to one of claims 1 to 3, characterized in that the throttle slide ( 18 ) has the control piston ( 27 ) for the pressure transmission and a pilot throttle ( 30 ) connected between the outlet space ( 24 ) and the spring space ( 25 ).