DE1759867A1 - Hydraulic actuation device for the working tools of earthworking machines - Google Patents

Description

Eisenwerk Gebr ,, Frisch KG Augsburg

Hydraulic actuator for the working tools of earthworking machines

The invention relates to a hydraulic operating device for the working tools of earthworking machines, preferably motor graders, with the work tools of two working pistons, each displaceable in a cylinder be operated.

In the previously known actuators this

Art, the control slides assigned to the two working pistons of a working tool are connected in parallel to a pump. If both control spools are actuated at the same time, the working piston moves first to adjust it the lower pump pressure is required while the other follows only afterwards. So that such an adjustment within takes place in a reasonable time, the pump must be designed for a relatively high delivery rate, which is then at Actuation of just one control knob is often too high and the associated working piston is not sufficiently sensitive disguise loudly.

The invention has therefore set itself the task of providing these Nacnteile while maintaining the advantages of the parallel connection to avoid and to be able to adjust the working pistons inevitably and independently of each other.

Lies succeeds according to the invention in that as a control member a control spool with one for each working piston upstream valve is used, which in a known manner with a valve piston which is under low spring force contains a throttle bore, which the pump pressure side with A barely on the back of the valve piston connects, whereby this space determines a desired maximum pressure Overpressure valve can be connected to the return flow, that furthermore the valve connected upstream in aem through the throttle bore in the valve piston into the space on its back

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flowing secondary oil flow through said control slide can flow freely into the return flow and thereby the valve piston of the upstream valve can be raised and the main oil flow releases the return and that finally for every cylinder with its working piston has the same performance Pump is provided, between the two pumps and the cylinders to be fed by them with the associated A directional control valve is interposed between the control slides, through which the two pressure medium flows generated by the pumps either routed separately to the respective assigned control spool and cylinder or connected together, this directional valve in the first-mentioned position releases each control slide its own secondary oil flow return and consequently also release its main oil flow return leaves and in the second-mentioned position the secondary oil flow return for a control slide and consequently also blocks its main oil flow return and at the same time the out of the other spool backflowing single lifting oil flow forces this one control spool to flow through

Bas the valve upstream of the control spool takes over in the invention in cooperation with the control slide and the directional control valve when the control slide is in the rest position Control of the oil flow delivered by the pumps and is used at the same time as a pressure relief valve. The invention thus allows the control slide to be made simpler and cheaper, since they do not need an idle in the usual sense. Through the directional control valve, in addition to the union of the two Pumps generated pressure medium flows for the purpose of the known parallel connection now, according to the invention, also the two Pressure medium flows are fed separately to the respective working piston via the control slide assigned to it, so that the working pistons move simultaneously and independently of each other, thanks to the same performance of the pumps at the same time by the same amount. The invention also allows the adjustment of a working piston in two speeds, which was not possible before through the directional valve either with the pressure medium conveyed by only one pump or with the pressure medium

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tel can be applied.

jjamit the equality of performance of the two pumps as possible is exactly realized, the invention prefers a double pump instead of two pumps of the same power.

Another simplification of the entire actuation device allows the invention to be achieved in that the control slide for several or all cylinders on an actuating side are connected to a control slide unit, whereby only one upstream valve is provided for each unit and the secondary oil flow branched into this valve through all the individual control spools of this unit lie Jd t.

An embodiment of the invention is shown in the drawing. It shows

Pig. 1 the control scheme of the actuator, Pig. 2 the directional control valve with control spools and them upstream valve in the position of the directional control valve separating the two pressure medium circuits,

Pigο 3 the representation corresponding to Pig, 2, however in the position of the directional control valve that switches the two pressure medium circuits in parallel.

The two pumps 1 and 2 with the same output suck from a common oil reservoir 6 via lines 4 and 5 Oil and promote it. via lines 7 and 1ü to the connections 8 and 11 of a directional valve 9.

In the position I of the Schieuers 12 of the directional control valve y (Pigc 2) happens that conveyed by the pump 1 and over Line 7 at 8 entering oil the directional control valve 9 via an annular channel 37 and arrives via a line 13 and a connection 15a in a pilot valve 15. In addition, the -Druckol arrives via a branch 33 to a hanging duct 34 of a first control valve 16 and to an annular channel 35 one second control slide 16a. The further way to the working piston (eg »B« 43) to operate the tools not shown is the DrucKÖl in the in Pig. 2 drawn rest position of the control spool piston 31 or »32 blocked. In the pilot valve 15, the pressure oil meets a valve

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Piston 20 which contains a throttle bore 19. That through her secondary oil flow branched off from the main oil flow impinging on the valve piston 20 arrives in a space 21 on the Back of the valve piston 20 and then flows from there practically without pressure via a connecting channel 39, two ring channels 22 and 23 in the control slide 16, two further ring channels 22a and 23a in the control slide 16a and via a connecting line 24 to the directional control valve 9, from where it has two interconnected annular channels 25 and 26 and one Line 27 can flow back into the tank 6. This practically pressureless outflow of the secondary oil flow leaves the main oil flow at the same time the valve piston 20 against the small force a spring 20 and flow back to the tank 6 via a return 29.

The pressure oil conveyed by the pump 2 and passing through the directional control valve 9 via line 10, connection 11 and ring channel 38 runs through an almost analogous circuit. The only difference to the above-described circuit of the pump 1 is that the secondary oil flow branched off from the main oil flow impinging on the valve piston 20 'through the throttle bore 19' flows from the space 21 'first via a line 30 to the directional valve 9, this via two with each other Connected ring channels 25 'and 26 passed and only then via a line 40 to the ring channels 22a' and 23a ^{1 of} the control slide 18a and further to the ring channels 22 'and 23' of the control slide 18, from where it finally arrives via connection 41 and line 42 flows back into tank b »line 14 corresponds to line 13 in the circuit of pump 1, connection 17a to connection 1:? a and control slide 18 or 18a to control slide 16 or 16a. Otherwise, the identical parts occurring in the two circuits are identified by the same reference numerals with the addition of the index.

The two circuits of pumps 1 and 2 can also be adjusted for each by an oei 45 or 45 ' Overpressure valve 36 or 3ö · secured.

vi 'is now in the position I of the previously described Slide 12 of the directional valve 9, for example, the control slide piston 31 of the control slide 16 actuated, then separates

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this control slide piston 31 separates the two annular channels 22 and 23 from one another and thus blocks the outflow of the secondary oil flow. The main oil flow impinging on the valve piston 20 is therefore no longer able to lift it and clear the return line via 29. The conveyed by the pump 1 The oil flow is therefore fully available to act on the working piston 43 available, depending on the direction of actuation of the control slide piston 31 starting from the annular channel 34 takes place either via A on the piston rod-free side or via B on the piston rod side and thus the not shown Work tool actuated according to the delivery rate of pump 1.

At the same time and independently of this, the control slide piston can also 31 'of the control slide 18 are actuated, with the pilot valve 17 as a result of the separation of the Annular channels 22 'and 23' play the processes described above accordingly, and thus the working piston 44 either via A 'or via B' according to the delivery rate the pump 2 are acted upon.

The two working pistons 43 and 44, which together make the Actuate working tool not shown, so can simultaneously and independently of one another in accordance with the The delivery rate of the pump assigned to them can be applied, which was previously not possible.

With the Deiden control spools 16a and 18a, by means of the associated control slide pistons 32 and 32 ', starting from the two ring channels 35 and 35' either via C and G ″ or via D and D ^1, two further working pistons (not shown) for another, not Depending on the number of working tools operated by two working pistons, any number of other similar control slides can be attached to the group of control slides 16 ... 16a or 18 ... 18a without the need for additional pilot valves. Care only has to be taken to ensure that the secondary oil flow of each control valve group flows in the same way through the control valve to be attached, so that the secondary oil flow return when any control valve piston is actuated

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175S867

and thereby also the main oil flow return of the relevant oil circuit is blocked.

In position II, the slide 12 of the directional valve 9 (Figo 3) are the two ring channels 37 and 38 with one another in connection, so that the two pumps 1 and 2 are connected are and together in the two lines 13 and 14 convey at the same time ο In this position of the slide 12 is in the annular channel 25 'of the directional control valve 9, the return for the blocked by the throttle bore 19 * branched off Neberiöl flow. As a result, the main oil flows through line 14 flows into the pilot valve 17, no return. To do this, all of the oil delivered by pumps 1 and 2 can be in the pilot valve 15 flow back over 29, because the branched off there Sidestream reaches the already described way to Ring channel 25 in the directional control valve 9 and from there via the ring channel 26 'and line 40 in FIG the secondary oil flow ring channels 22a ', 23a' and 22 ', 23' of the two control slides 18a and 18 and from there via connection socket 41 and line 42 finally into tank 6.

This now existing only secondary oil circuit This means that when any control spool is actuated, it becomes »piston locked, so that the delivery rate of both pumps is available together to act on the associated working piston stands. If, for example, the control slide piston 31 'is actuated, the secondary oil flow is interrupted between 22 * and 23' and the main oil flow return is shut off at 29. The total oil flow delivered by pumps 1 and 2 therefore flows - the return sound at 29 'is yes due to the position of the blow 12 at the üingkanal 25 'blocked from the start - only Via line 14 and annular channel 34 'to working piston 44.

.When two control slide pistons are actuated at the same time, for example from 31 and 31 ' _f , of the two associated working pistons 43 and 44, as before, that one moves first, for the adjustment of which the lower pump pressure is required.

In the case of a performance design preferred by the association of the two pumps 1 and 2, in which both pumps together have approximately the same or a slightly higher delivery rate.

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perform better than the only known pump, ergiot in position I of the slide 12 of the directional control valve 9, apart from the option already mentioned, the two Working colony at the same time and independently of each other actuate, the further possibility, the working piston only with about half the speed, so much finer and more adaptable to adjust.

After the invention, the compulsory and independent actuation of the two working pistons for a work tool can be used in all cases in which the work tool is only at three points, e.g. on the piston rods of the two working pistons and on a frame-mounted bearing, is suspended, additional devices for parallel guidance the work tools are omitted.

The three-point suspension mentioned is a necessary prerequisite for the triangular swivel chair to hold the overhead bunch of a motor grader. The invention allows an advantageous simplification of the suspension while expanding the operating options _e

Claims (1)

- 8 claims ® Hydraulic actuating device for the working tools of earthworking machines, preferably motor graders, the working tools being actuated by two working pistons, each displaceable in a cylinder »characterized in that a control slide (16, 18) with a upstream valve (15, 17) is used, which in a known manner contains a valve piston (20, 20 ') under low spring force (28, 28') with a throttle bore (19, 19 ') which connects the pump pressure side with a space (£ i, 21 ·) on the rear side of the valve piston (20, 20 ·) connects, this space (21, 21 ') being connectable to the return via a pressure relief valve (36, 36') which determines the desired maximum pressure the secondary oil flow flowing in the upstream valve (15, 17) through the throttle bore (19, 19 ') in the valve piston (20, 20') into the space (21, 21 ') on its rear side through the said control slide (16, 18) fr egg can flow off into the return and thereby raise the valve piston (20, 20) of the upstream valve (15, 17) and release the return (at 29, 29 ') for the main oil flow and that finally for each cylinder with its working piston (43 , 44) a pump (1, 2) of the same power is provided, a directional valve (y) being interposed between the two pumps (1, 2) and the cylinders to be fed by them with the associated control slides (16, 18), a through the the two pressurized medium flows generated by the pumps (1, 2) are either routed separately to the respectively assigned control slide (16, 18) and cylinder or are connected together, whereby this directional valve (9) in the first-mentioned position (I) of each control slide (1, 1b, 1ö) its own secondary oil flow return (19, 21, 39, 22, 23, 24, 25, 26, 27 / or, iy ·, 21 ·, 30, 25 ', 2b', 40, * 2 ' , 23 ^f , 41, 42, 6) releases (at 25-26 or 25'-26 ·) and consequently also releases its main oil flow-üücklaui '(at 29, 29') en fed and in the second-mentioned position (II) the secondary oil flow (at 25 ')
uf / for a control spool (1o) and consequently also 1098 ^ 2/0430 whose main oil flow return ^ at 29 ') blocks and at the same time the one flowing back from the other control slide (16) IMebenülstrom to flow through this one control valve (18) forces (at 25-26 '). 2 "Actuating device according to claim 1, characterized in that that a double pump is provided for the two pumps of the same power. 3. Actuating device according to claim 1, characterized in that the control slide (16, 16a or 18, 18a) for several or all cylinders on an actuating side are combined to form a control slide unit, with only one upstream valve (15 or » 17) is provided and the secondary oil flow branched off in this valve (15 or 17) (at 19 or 19 ¹ ) flows through all the individual control spools (16, 16a or 18, 10a) of this unit. 109842 / (K3Q L β e r s e i t e