DE3639174C2 - Hydraulic control device - Google Patents

Description

The invention is based on a hydraulic control direction for a driven by a hydraulic motor, esp especially attached to an agricultural vehicle Tool according to the preamble of claim 1.

It is already such a proportionally working, hydraulic cal control device known from DE 34 41 946 A1, at the control spool to control a single-acting Power lift as a pressure compensation valve and as a pressure less working throttle valve is upstream and at which a hydraulically piloted blocking block the power lift secured. To actuate the locking block is in position Lower a control oil flow that is downstream from the Throttle valve is branched and via the control spool is led to the tank. In this control oil flow is a Dros sel or a pressure control valve switched, the or the necessary control pressure to actuate the push piston in Block builds up. This control device works together men with a variable pump in the load pressure sensing system, see above the variable displacement pump holds one when the consumer is not actuated relatively low outlet pressure ready. It can now be in one Chen cases be disadvantageous that this control oil flow in Lower position in connection with the relatively low off pressure leads to a power loss in the system. As long as in addition to the power lift, no additional, second consumer works, this power loss is relatively low. If however, in addition to the lowering process, a second consumer ar is working and its working pressure is close to the maximum pressure energy losses can become undesirably high. This is especially the case if the system is in a  Position clearance works, which is a constant sink gear corresponds, so that the control oil flow mentioned constantly flows.

It is unfavorable if the control device is not in one load-sensing system but in a constant pressure system is operated, the variable displacement pump constantly maintains the maximum pressure. In this case, the Power loss, which results from the maximum pressure and the because there is a significant amount of control oil flow pass. In contrast, there are energy-saving systems he wishes.

Furthermore, a hydraulic control is known from DE 33 34 094 A1 Device for a hydraulic motor on an agricultural Chen known tool that a three-axis total construction with locking block, spool and throttle valve. In this control device is located on the spool second working chamber directly next to a return chamber, so that no comparable control chambers between them available. The control device also works in sinks position with two parallel control oil flows, so the locking block is hydraulically operated and the throttle valve can work as a current regulator, reducing the energy losses are relatively large.

The object of the invention is based on the above State of the art mentioned the constant control oil flow in Avoid lowering position and thus the energy losses to reduce.

This task is solved with a generic tax establishment with the characteristic features of the An saying 1. This way you can keep  the previous advantages without any significant additional effort Reduce energy losses further. A constant tax there is no oil flow in the lower position; it will be little Control oil for the regulating movements of the pushing piston does. In addition, the pressure-increasing are also eliminated Means in the form of a throttle or a pressure maintenance valve tiles in the control line. The level of control pressure for the actuation of the push piston can be done in a simpler manner Be way by the design of the spring on the throttle valve voices.

By the measures listed in the subclaims advantageous training and improvements in the on saying 1 possible control device possible. Especially Formations according to claims 2 and 3 are expedient, which is a particularly simple, inexpensive and above all enable retrofittable construction of the control device. Further advantageous configurations result from the other claims.

An embodiment of the invention is shown in the drawing and Darge explained in more detail in the following description. Fig. 1 shows a longitudinal section through a hydraulic Steuerein direction in a simplified representation in the neutral position and FIGS. 2 and 3 each show a part of this control device in the lifting or lowering positions.

Fig. 1 shows a control device 10 with a Regelwegeven valve 11 , the tool for hoist control on an agricultural driving tool, in particular a tractor with articulated plow, is used.

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 hydraulically pilot-operated blocking block 15 , consisting of blocking valves 16 and associated push piston 17 , are arranged.

The throttle valve 13 has a throttle valve 18 , the housing 12 slides in a slide bore 19 in Ge. In the slide bore 19 are side by side, based on Fig. 1 seen from left to right, through annular extensions a pressure chamber 21 , an inlet chamber 22 , an outlet chamber 23 and a spring chamber 24 forms out. The throttle slide 18 is acted upon by a spring 25 arranged in the spring chamber 24 and by the pressures in the spring chamber 24 and in the pressure chamber 21 . For this purpose, the pressure chamber 21 is connected to the outlet chamber 23 via control channels 26 arranged in the throttle slide 18 . The spring 25 biases the throttle slide 18 in the direction of a starting position in which a formed at the throttle slide valve 18 Steuerfase 27 fully aufsteuert the connection from the inlet chamber 22 to outlet chamber 23rd

The inlet space 22 is connected via a first line section 28 with egg nem input 29 of the control valve 11 , from which an Ar beitsleitung 31 one after the other via the throttle valve 13 , the control valve 14 and the blocking block 15 leads to an output 32 . As part of this working line 31 leads from the outlet space 23, a second line section 33 to the subsequent control valve 14 . At the throttle slide 18 , a second control chamfer 30 is also formed, which controls the connection from the outlet chamber 23 to the spring chamber 24 . The control chamfers 27 and 30 work in opposite directions to one another and are designed with a slightly positive overlap.

The control valve 14 has a control slide 34 which is guided tightly and slidably in a two-th slide bore 35 . In this slide bore 35 are again side by side and with reference to FIG. 1, seen from left to right, a first damping chamber 36 , a first return chamber 37 , an outlet chamber 38 , a first (39) and second working chamber 41 , a first ( 42 ) and second control chamber 43 , a second return chamber 44 and a second damping chamber 45 are arranged. The two outer damping chambers 36 , 45 are connected to each other via a compensation channel 46 , which has a throttling effect. Furthermore, the equalization channel 46 is connected to the second control chamber 43 via a check valve 47 opening towards it. Both return chambers 37 , 44 are relieved to a tank 48 . The second line section 33 of the working line 31 opens into the first working chamber 39 . From the second working chamber 41 , a third line section 49 leads as part of the working line 31 to the check valve 16 , from which a fourth line section 51 leads to the outlet 32 .

Furthermore, a return line 53 leads from the outlet 32 via the check valve 16 to the outlet chamber 38 and further via the first return chamber 37 to the tank 48 . This return line 53 is in the area of the check valve 16 with the fourth line section 51 and partially with the third line section 49 of the working line 31 identical.

A first control line 54 leads from the first control chamber 42 in the control valve 14 to the spring chamber 24 in the throttle valve 13 and further to a control pressure connection 55 in the control directional valve 11 . A control channel 56 leads from the second control chamber 43 in the control valve 14 into a pressure chamber 57 assigned to the pushing piston 17 . A first control edge 59 is formed on the control slide 34 on a first piston section 58 in order to influence the pressure medium flow flowing through the working line 31 in proportion to the deflection of the control slide 34 . Separated from the first piston section 58 by a recess 61 , there is a second piston section 62 with a second control edge 63 , which controls the pressure medium flow flowing through the return line 53 to the tank 48 proportionally in a corresponding manner. Separated from the first control edge 59 by a first ring groove 64 , a third piston section 65 is formed on the control slide 34 , to which a third ring groove 66 , a fourth piston section 67 , a fourth ring groove 68 and a fifth piston section 69 connect in the direction of the second damping chamber 45 . The annular groove 66 forms a third control edge 71 on the third piston section 65 and a fourth control edge 72 on the fourth piston section 67 . Correspondingly, the fourth annular groove 68 on the fourth piston section 67 forms a fifth control edge 73 and on the fifth piston section 69 a sixth control edge 74 .

The third piston section 65 is relatively long, its length being chosen to be greater than the width of the first control chamber 42 in the axial direction and the thickness of a housing web 75 between the first control chamber 42 and the second working chamber 41 . In this way, an axially extending first control notch 76 can be accommodated in the third piston section 65 , the length of which is greater than the thickness of the housing web 75 . At the same Kolbenab section 65 is offset from the first control notch 76 and approximately in the same radial plane a second control notch 77 is arranged. A first oblique channel 78 runs inside the control slide 34 , which connects the recess 61 with the third annular groove 66 and thereby penetrates the first piston section 58 , the first annular groove 64 and the third piston section 65 . Furthermore, the control slide 34 has a second inclined channel 79 , which connects the second control notch 77 with the fourth annular groove 68 and thereby partially penetrates the third piston section 65 , the third annular groove 66 and the fourth piston section 67 . For the sake of easier representation, the two control notches 76 , 77 and the associated inclined channels 78 , 79 in FIG. 1 in the drawing plane are Darge; in reality, the first and second control notches 76 and 77 are each arranged twice and opposite one another because of the pressure equalization, so that the first control notch 76 is rotated in the circumferential direction by approximately 90 ° to the second control notch 77 . The axial length of the fourth piston section 67 is selected to be smaller than the associated width of the second control chamber 43 , so that in the neutral position of the control slide 34 shown, the third annular groove 66 is connected to the fourth annular groove 68 via the second control chamber 43 .

The control device 10 also has a variable displacement pump 81 with associated actuating device 82 , the output of the variable displacement pump 81 being connected to the input 29 of the control valve 11 . A piston rod chamber 83 of the actuating device 82 is acted upon by the output pressure of the variable pump 81 so that it is adjusted in the direction of the minimum delivery rate. A regulator spring 85 is arranged in a cylinder space 84 of the actuating device 82 and tries to adjust the variable displacement pump 81 in the direction of the maximum delivery quantity. As long as no pressure medium is required in the system by the hydraulic motors, this flow adjustment ends against the force of the regulator spring 85 close to zero, only the leakage losses being compensated for by the system. The relatively low pressure generated here by the variable displacement pump 81 and dependent on the force of the regulator spring 85 is referred to as the outlet pressure. Furthermore, the cylinder chamber 84 is connected to a change-over valve 86 as a maximum pressure selection device, which pressure line 87 communicates with the control pressure connection 55 via a first load line and with a load pressure connection of a second directional valve 89 via a second load pressure line 88 , which is a second Hydraulic motor 91 controls. The second directional control valve 89 is supplied with pressure medium from the variable displacement pump 81 parallel to the control directional control valve 11 and is also designed for a closed circuit.

The single-acting hydraulic motor connected to the outlet 32 of the control valve 11 is a power lift 92 , as is used in a manner not shown, to raise, hold or lower a plow articulated on a tractor frame via a lifting arm and a conventional three-point linkage.

The operation of the control device 10 is explained as follows, the basic function of the control directional valve 11 is assumed to be known per se, as well as in parallel operation with the second directional valve 89 , e.g. B. from the publication mentioned. In the following, therefore, the function of the control device 10 is only discussed as far as is necessary to understand the invention.

In the position shown in FIG. 1 neutral of the control valve 11 , the power line 31 leading to the power lift 92 is interrupted by the most control edge 59 . Simultaneously, the control relieved slide 34 the spring chamber 24 in the throttle valve 13 to the tank 48 and via the first control line 54, with the first Steuerkam mer 42 connected, second control groove 77, the second helical channel 79, past the opened sixth control edge 74 in second return chamber 44 and on to tank 48 . About the last schil dered connection is also relieved of the cylinder space 84 in the actuating device 82 to the tank, which has connection via the shuttle valve 86 and the control pressure connection 55 with the spring space 24 in the throttle valve 13 . The variable displacement pump 81 will therefore generate its low outlet pressure, also referred to as standby pressure, in order to compensate for leakage losses in the system and to keep the regulator spring 85 the same weight. This output pressure of the variable displacement pump 81 is higher than that provided by the throttle valve 13 in the outlet space 23 , regulated outlet pressure. The size of this pressure in the outlet space 23 is determined by the force of the spring 25 , which is accordingly out. The throttle valve 18 therefore assumes the position shown in the neutral position of the control valve 11 , its first control chamfer 27 throttling the connection between the inlet space 22 and the outlet space 23 to such an extent that the pressure prevailing in the outlet space 23 , which is also via the control channels 26 in the Pressure chamber 21 acts, keeps the throttle slide 18 in balance against the force of the spring 25 . The slight positive overlap of the control chamfers 27 , 30 ensures that the pressure in the outlet space 23 can be maintained. The throttle valve 13 thus acts as a pressure reducing valve which provides a pressure of constant size in the outlet space 23 which is lower than the outlet pressure of the adjusting pump 81 .

In the neutral position, the power lift 92 is also secured by the blocking block 15 , the pressure chamber 57 on the plunger 17 via the control channel 56 , the second control chamber 43 , the open fifth ( 73 ) or sixth control edge 74 and the return chamber 44 to the tank 48 is relieved, so that the locking block 15 cannot be opened unintentionally. From the first working chamber 39 leakage oil that may possibly get into the recess 61 is discharged via the first inclined channel 78 into the third annular groove 66 and further via the open fourth to sixth control edge 72 to 74 to the tank 48 .

In FIG. 2, a part of the control-way valve shown in the lift position 11, wherein the control slide is deflected 34 by electromagnetic actuation from its neutral position to the left. Here, the first control edge 59 opens the connection between the two working chambers 39 , 41 , so that a pressure medium flow can flow via the working line 31 to the power lift 92 in proportion to the deflection of the control slide 34 . The pressure drop available via the first control edge 59 is determined by the spring 25 , which allows the throttle slide 18 to operate as a pressure compensator and thus enables the power lift 92 to be controlled under load pressure. For this purpose, the pressure present in the second working chamber 41 is transferred in the lifting position via the first control notch 76 into the first control chamber 42 , which via the first control line 54 with the spring chamber 24 in the throttle valve 13 and further via the shuttle valve 86 with the cylinder chamber 84 the actuator 82 has connec tion. The variable displacement pump 81 will therefore build up a working pressure adapted to the respective load. In the raised position of the control slide 34 , the connection between the two control chambers 42 and 43 is interrupted by the third control edge 71 . Furthermore, the second control notch 77 is hydraulically blocked by the housing web 75 ; the two inclined channels 78 , 79 are thus without function. Furthermore, the pressure chamber 57 in the plunger 17 remains relieved via the control channel 56 and the opened control edges 73 and 74 to the second return chamber 44 and further to the tank 48 .

Fig. 3 shows part of the control valve 11 in a Sen kenstellung, the spool 34 is deflected from its neutral position to the right. As in the neutral position, the spring chamber 24 remains in the throttle valve 13 to the tank 48 in the lower position by the first control chamber 42 via the second control notch 77 and the second inclined channel 79 with the second return chamber 44 connection. With the help of the second inclined channel 79 , the second control chamber 43 is bridged, which is formed by the third control edge 71 and the fifth control edge 73 . is cordoned off. The throttle slide 18 in the throttle valve 13 therefore continues to work as a pressure reducer, which provides a relatively low, regulated outlet pressure in the outlet chamber 23 and thus also in the pressure chamber 21 . This output pressure passes through the second line section 33 into the first working chamber 39 , which has a connection with the recess 61 in the lowered position. From there, the regulated output pressure over the first helical channel 72 passes into the third annular groove 66 and further via the open fourth control edge 72 in the two-th control chamber 43rd From there, the outlet pressure builds up via the control channel 56 in the pressure chamber 57 of the pushing piston 17 . With the help of this output pressure, the pushing piston 17 can move against the spring force and the counterpressures acting on it in the spring chamber 93 to the left, so that the pilot operated check valve 16 opens. Finally, Druckmit tel can flow out of the power lift 92 via the return line 53 and the controlled second control edge 63 to the tank 48 via the opened shut-off valve 16 . The pressure upstream of the second control edge 63 is at the same time transmitted into the spring chamber 93 on the plunger 17 and thereby enables a lowering of the load pressure.

In this way, for actuating the poppet piston is Untitled 17 in lowering position of the control-way valve 11 no permanent control oil flow Benö; Via the first control chamfer 27 on the throttle slide 18 , only as much pressure medium is fed into the control circuit as is required for the control movements of the pushing piston 17 . During these re gel movements of the pushing piston 17 , excess pressure medium is discharged from the pressure chamber 57 via the aforementioned connection from the second control chamfer 30 on the throttle slide 18 into the spring chamber 24 , which in turn is connected to the tank 48 . The output pressure available in the lower position in the second control chamber 43 passes through the check valve 47 into the outer damping chambers 36 , 45 and also ensures that the damping device known per se functions properly. If in the lower position of the control valve 11, the variable pump 81 operates at maximum working pressure, because this z. B. the second hydraulic motor 91 requires, the energy losses occurring when actuating the locking block 15 are relatively small, since no constant control oil flow flows. So that the energy losses are kept extremely low in the free position of the control device 10 .

Claims (10)

1. Hydraulic control device for a driven by a Hydromo tor, in particular attached to an agricultural vehicle working implement, with a hydraulically pilot-controllable blocking block, with a blocking block controlling the control slide, which influences the pressure medium flow to the hydraulic motor during lifting, and the first control edge from the hydraulic motor to the tank flowing pressure medium flow during lowering influencing the second control edge, as with a control valve upstream, loaded by a spring throttle valve of a throttle valve, which in one of an input of the control device via the throttle valve, he ste control edge of the control valve and that Check valve to the hydraulic motor-guided working line is switched and enables a load pressure-independent control, the first control edge controlling the connection from a first working chamber to a second working chamber, to which then a first and two te control chamber and a return chamber, wherein in the raised position the pressure of the second working chamber is guided via the first control chamber to the spring chamber of the throttle valve and a pressure chamber of the locking block to the tank are relieved, characterized in that in the lower position ( Fig. 3) of the throttle valve ( 18 ) throttled pressure in its outlet chamber ( 23 ) via the second control chamber ( 43 ) of the spool ( 34 ) into the pressure chamber ( 57 ) on the push piston ( 17 ) of the locking block ( 15 ), which pressure chamber ( 57 ) is controlled exclusively with the is connected to the second control chamber ( 43 ) and that in the same position the spring chamber ( 24 ) of the throttle slide ( 18 ) is relieved via the second return chamber ( 44 ) of the control slide ( 34 ) to the tank ( 48 ). 2. Hydraulic control device according to claim 1, in which a piston section carrying the first control edge and a piston section of the control slide adjacent to the control chambers are penetrated by an inclined channel bridging the second working chamber, characterized in that the inclined channel ( 78 ) is in addition to the second Ar beitskammer ( 41 ) also bridges the first control chamber ( 42 ). 3. Hydraulic control device according to claim 1 or 2, characterized in that the control slide ( 34 ) has a second inclined channel ( 79 ) which, in the lowered position, the first control chamber ( 42 ) bypassing the second control chamber ( 43 ) with the return chamber ( 44 ) connects. 4. Hydraulic control device according to claim 2 or 3, characterized in that the adjacent piston section ( 65 ) is wider than the associated, between the second working chamber ( 41 ) and the first control chamber ( 42 ) formed housing web ( 75 ) and that this piston section ( 65 ) has a first control notch ( 76 ) which connects the second working chamber ( 41 ) to the first control chamber ( 42 ) in the lifting position, and has a second control notch ( 77 ) from which the second inclined channel ( 79 ) extends. 5. Hydraulic control device according to one of claims 2 to 4, characterized in that the adjacent Kolbenab section ( 65 ) on the verbun with the first inclined channel ( 78 ) which annular groove ( 66 ) forms control edges ( 71 , 72 ) which form the connection between Interrupt both control chambers ( 42 , 43 ) in the raise, neutral and lower positions. 6. Hydraulic control device according to one of claims 2 to 5, characterized in that the annular groove ( 66 ) connected to the first inclined channel ( 78 ) is hydraulically separated from the second control chamber ( 43 ) in the lifting position of the control slide ( 34 ) and in the Neutral and lower positions are connected to the second control chamber ( 43 ). 7. Hydraulic control device according to one of claims 4 to 6, characterized in that the two control notches ( 76 , 77 ) on the adjacent piston portion ( 65 ) are arranged in the same radial plane and in the circumferential direction ver sets to each other. 8. Hydraulic control device according to one of claims 1 to 7, characterized in that the throttle slide ( 18 ) of the throttle valve ( 13 ) has opposing control chamfers ( 27 , 30 ) which the connections of the outlet space ( 23 ) to the inlet space ( 22 ) or to the spring chamber ( 24 ). 9. Hydraulic control device according to one of claims 1 to 8, characterized in that a variable displacement pump ( 81 ) is connected to the input ( 29 ), the controller ( 82 ) of which forms a load pressure-sensing system with the spring chamber ( 24 ) of the throttle valve ( 13 ) is connected. 10. Hydraulic control device according to claim 9, characterized in that the spring ( 25 ) in the throttle valve ( 13 ) with the regulator spring ( 85 ) of the variable displacement pump ( 81 ) is matched so that the pressure associated therewith is lower than the output pressure of the Variable pump ( 81 ).