EP2236452B1 - Lifting module - Google Patents

Abstract

The module (M) has two main stage-elements (E1, E2) controlled by load pressure and connected in series in an outflow path (9), where the stage-elements are supplied with sealing pressure in a direction of a shut-off position. Pressure is derived from the load pressure by a throttle (16). The elements are commonly controlled in parallel by a magnetic servo valve (21) that is arranged in a sealing pressure-control line (20) that is shielded to a lifting hydraulic motor (Z), load pressure and a lifting section (1) by the throttle.

Description

The invention relates to a lifting module specified in the preamble of claim 1. Art.

For lifting modules e.g. of forklift trucks, or in masts, work vehicles or the like., strict safety regulations apply to ensure that a load stopped during lowering is actually stopped and then stops and in no case carries out uncontrolled lowering movements. It should be noted that after prolonged periods of use of the lifting module in the pressure unavoidable soiling or metal chips occur that circulate despite upstream filter devices in the main flow paths and settle in hydraulic elements and impair their function and / or can ruin, creating the required security against uncontrolled load lowering movements or a non-sustained load is not given.

Out EP 1 369 598 A is a lifting module known in which an additional redundancy switch z. B. in the sink control section, is arranged to produce when stuck a hydraulic element, such as a pressure compensator or a current regulator due to wear, contamination or a metal chip via an additional control routine pressure signals that make the stuck hydraulic element again passable. This is a structurally complex and expensive solution, requires additionally programmed control routines, and does not automatically have a high safety standard.

Furthermore, from practice a so-called LLSN controller for the sink control section of a lifting module is known, in which two throttles are connected in series in a connected to the working line to Hebehydromotor Neben-Abströmweg to the reservoir. The main outflow path to the reservoir passes through a 3/2-way valve with pressure pre-control, wherein the 3/2-way control valve is also part of the lifting control section. Since both pressure during lifting and lowering can flow off pressure medium, additional elements must be provided to ensure the necessary stacker tightness, d. H. a tightness in the system, in which a suspended load for a certain period of time does not fall or only over a certain small amount.

Further prior art is contained in: DE 42 39 321 A . DE 20 2004 014 029 U and DE 199 56 717 A ,

The invention has for its object to provide a lifting module of the type mentioned, which is structurally simple and inexpensive and ensures a high safety standard against malfunction, especially in the sink control section due to contamination or metal shavings.

The stated object is achieved with the features of claim 1.

Each of the two series-connected main stage elements in the outflow path is controlled by the common solenoid pilot valve as the load is lowered the same as the other, i. the actually desired function is carried out twice. Each element alone is capable of performing the sink function correctly. If one of the elements does not respond correctly due to a contamination or a metal chip, this does not affect the reaction of the other element, so that the load movement always remains controllable controllable. Should z. For example, if one of the elements fails to shut off properly as a result of contamination or metal chipping to stop and hold the load, then the load is reliably stopped and held by the other element in the series connection. An integrated redundancy function for a high safety standard is achieved, because the probability that both elements are simultaneously disturbed in their function can almost be ruled out. On the other hand, the desired function is properly controlled if one of the elements fails or is temporarily disturbed. Furthermore, the function of the solenoid pilot valve is not jeopardized by debris or metal shavings because the solenoid pilot valve is shielded by the restrictors from the main flow passages, in which case only very small pilot pressures need to be handled and the throttles act as additional filters. Additional redundancy is further provided by the fact that in a dirty throttle of an element, the necessary barrier pressure is built up quickly and in full on the still functional throttle of the other element for both elements and both elements thus reliably the leak-free shut-off for the outflow of the working pressure medium from the Take lifting hydraulic motor. It is achieved with simple components and without additional control routines a high safety standard that meets the applicable requirements.

In an expedient embodiment, both elements are loaded in the direction of the shut-off position parallel to the locking pressure by springs, to ensure that in a depressurized state, both elements first occupy their shut-off positions.

Structurally simple in a further embodiment, both elements are identical, possibly even identical, and similarly interconnected (common part principle).

With identical elements, each element has a lateral pressure feed into an annular chamber, an axial outlet through a valve seat, a barrier pressure control chamber on the side facing away from the valve seat side of a displaceable in the annular chamber stepped piston, and disposed between the annular chamber and the barrier pressure control chamber throttle , The lateral pressure feed of the outflow downstream element is connected to the axial outlet through the valve seat of the upstream element. The stepped piston cooperates with the valve seat in the manner of a seat valve, d. h., Closes leak-free in the shut-off position.

If, in another embodiment, both elements are structurally different or at least different interconnected, the one element has a lateral pressure feed into an annular chamber, an axial outlet through a valve seat, a barrier pressure control chamber on the side facing away from the valve seat of a movable in the annular chamber stage piston, and the throttle arranged between the annular chamber and the barrier pressure control chamber, while the other element an axial pressure feed through a valve seat, a lateral outlet of an annular chamber, and the here between the valve seat and the barrier pressure control chamber on the valve seat side facing away from Having in the annular chamber slidable stepped piston arranged throttle. The lateral or axial pressure feed of the downstream element is then connected to the axial or side outlet of the upstream element. Again, each element functions as a seat valve with leak-free shut-off position, which ensures the required stacker tightness and achieved by the integrated redundancy function high safety standard. Each of the two elements can be placed upstream or downstream of the other.

Structurally simple, the throttle is arranged in the stepped piston itself, in a bypass channel which connects either the annular chamber or the valve seat with the barrier pressure control chamber. Alternatively, however, the respective throttle could also be arranged in a housing of the element, namely there in a the annular chamber or the valve seat with the barrier pressure control chamber connecting bypass channel. Optionally, the respective bypass channel itself is designed as a throttle having a predetermined cross section at least in a section of the bypass channel.

In each element, the pressurizing surfaces of the stepped piston in the annular chamber and in the barrier pressure control chamber are at least substantially equal and larger than the pressurizing area of the stepped piston in the valve seat. The degree of opening of the element is controlled by the solenoid pilot valve to control or regulate the amount of outflow, which in turn determines the lowering speed of the load or lift hydraulic motor (under load, e.g., 0.6 m / s max.).

In an expedient embodiment, at least one element has a mechanical limitation of the maximum opening stroke of the stepped piston, preferably a stop screw arranged in the barrier pressure control chamber. In this way, the maximum lowering speed of the lifting hydraulic motor is limited at least under load, because the element can open only a passage cross section of limited size in Abströmweg (adjustable lowering brake function).

In a simple embodiment, the solenoid pilot valve is a 2/2-way magnetic seat valve, which is held in the de-energized state of its switching magnet pressure-dependent by a spring and the barrier pressure in the barrier pressure control chamber in the leak-free shut-off for Abströmweg.

In a further expedient embodiment, the solenoid pilot valve as the actuator to a proportional solenoid to operate as a proportional pressure control valve, which makes it possible to control the sink function proportionally.

In a further advantageous embodiment, downstream of the two elements connected in series, a pressure compensator can be arranged on the control side by a spring and a control pressure from the Abströmweg either between the elements or downstream of both elements, and closing control side of a control pressure from the load pressure Abströmweg upstream of both elements is acted upon. Thanks to the pressure compensator downstream of the two elements, load pressure independence is achieved in the lowering control.

Finally, it is expedient to secure the Hebehydromotor by a hose rupture valve that holds the load pressure at a hose break, and the proper function of switching and control technology is simple, for example, using the two series-connected elements from time to time verifiable.

Fig. 1

ein Blockschaltbild einer ersten Ausführungsform eines Hubmoduls,

Fig. 2

ein Blockschaltbild einer weiteren Ausführungsform eines Hubmoduls,

Fig. 3

eine Detailvariante des Hubmoduls von Fig. 1,

Fig. 4

eine weitere Detailvariante des Hubmoduls von Fig. 1, und

Fig. 5

eine Detailvariante des Hubmoduls von Fig. 4.

Embodiments of the subject invention will be explained with reference to the drawing. Show it:

Fig. 1

a block diagram of a first embodiment of a lifting module,

Fig. 2

a block diagram of another embodiment of a lifting module,

Fig. 3

a detail variant of the lifting module of Fig. 1 .

Fig. 4

another detail variant of the lifting module of Fig. 1 , and

Fig. 5

a detail variant of the lifting module of Fig. 4 ,

The various embodiments of a lifting module M of Fig. 1 to 5 are for example for a material handling vehicle such as a forklift, a mast, a work vehicle and the like. For movement and speed control of a Hebehydromotors Z for lifting and lowering a load L determined, the Hebehydromotor Z, for example, a one-sided acted upon by the load plunger cylinder or differential cylinder ( Fig. 1 ), which, preferably, secured by a hose rupture valve 19 and connected via a working line 4 to the lifting module M. The Hebehydromotor Z could also be acted on double-sided.

The lifting module M in Fig. 1 is shown in simplified form and optionally contains other, not shown components. A lift control section 1 and a sink control section 2 communicate with each other via a node 3 in the working line 4. In the lifting control section 1, a pressure line 9 connected to a pressure source P is connected to a 2/2-way magnetic seat valve 7 from which a line branch 5 leads to the node 3 on the output side. The line branch 5 is secured by a check valve 6 in the flow direction to the pressure source P. From the node 3, a discharge path 9 for working pressure medium from the Hebehydromotor Z runs to a reservoir R. In the outflow 9 is connected to a branch 9a a lateral pressure feed 11 of a first main-stage element E1, of which a branch 9b to an axial pressure feed of a second Main stage element E2, which has a lateral outlet 11 ', from which a branch 9c leads to a reservoir line 24. The two elements E1, E2 in Fig. 1 are structurally different, differently interconnected, but connected in the outflow 9 in series so that they work the same, ie allow for the Hebehydromotor Z at least substantially the same control functions.

The two elements E1, E2 are 2/2-way seat valves with a pressure precontrol via a common control line 20 to the reservoir line 24. In the control line 20, a solenoid pilot valve 21 is included in the Fig. 1 a 2/2-way solenoid seat valve with a spring 22 and a black and white magnet 23 is. In de-energized state of the black-and-white magnet 23 takes the pilot solenoid valve 21 for the Abströmweg 9 the shut-off position shown (leak-proof seal) under the action of the spring 22 a. When energized black and white magnet 23, the control line 20 is connected to the reservoir line 24 to control a lowering movement of the load L via the two elements E1, E2 with disconnected or disconnected pressure source. In the in Fig. 1 shown switching position of the load pressure in the working line 4 via the check valve 6 and the two standing in their shut-off elements E1, E2 is held, or even only on the upstream main stage element E1.

The element E1 has in a ring chamber 10 a displaceably guided, sealed movable stepped piston 12 with a valve closure member defining a piston extension 17 which cooperates with an axial valve seat 13 in the valve seat design. On the side facing away from the valve seat 13 side of the stepped piston 12, a barrier pressure control chamber 14 is provided in which, preferably, a spring 15 is included, which acts on the stepped piston 12 in the direction of the shut-off position shown. The loading surfaces of the stepped piston 12 in the annular chamber 10 and in the barrier pressure control chamber 14 are at least substantially equal to and larger than the loading surface of the piston extension 17 on the valve seat 13. In the stepped piston 12 (or in a housing of the element E1) runs a bypass of the Ring chamber 10 to the barrier pressure control chamber 14, which includes a throttle 16.

The second element E2 is similar, d. H. a 2/2-way seat valve. However, the stepped piston 12, which is guided displaceably in the annular chamber 10, formed with a valve seat 13 with the barrier pressure control chamber 14 connecting bypass in which the throttle 16 is arranged, or which forms the throttle 16.

Alternatively, the respective throttle 16 could be housed in a bypass channel in the housing of the element E1, E2.

A manually operated cock 18 is provided to drain the system to the reservoir R, or to test, for example, the proper response of the hose rupture valve 19.

Although a filter device is optionally provided in the region of the pressure source P, it is unavoidable that in the main flow paths between the Hebehydromotor Z and the check valve 6 and the reservoir R dirt and possibly metal chips circulate, the proper functioning of the lifting module M especially at could jeopardize the lowering control of the load L or stopping and holding the load L. Since the solenoid pilot valve 21 in the control line 20 is isolated from the main flow paths by the throttles 16, with the throttles 16 retaining contaminants or functioning as filters, the risk of malfunction in the solenoid pilot valve 21 is negligible. However, contaminants or metal chips could affect the proper functioning of the two elements E1, E2. However, since both series-connected elements E1, E2 each perform the same function, controlled by the common solenoid pilot valve 21, it is precluded that an uncontrolled load movement (ie, faster and farther than controlled) occurs due to a malfunction in an element E1 or E2, or the load L to be stopped is not properly stopped and held. The probability that both elements E1, E2 are subject to a malfunction at the same time is extremely low.

Function:

In the Fig. 1 illustrated situation (pressure source P is switched off) is constructed from the load pressure in the annular chamber 10 of the element E1 via the throttle 16 blocking pressure in the barrier pressure control chamber 14 which holds in the element E1 the piston extension 17 on the valve seat 13 in the shut-off position. About the common connection to the control line 20 blocking pressure is built up in the barrier pressure control chamber 14 of the downstream element E2, so that the second element E2 as a precaution in the shut-off position. Should, for example, a metal chip be defined between the stepped piston 16 and the valve seat 13 of an element E1 or E2, then the outflow path 9 to the reservoir R is shut off leak-free, since the probability that a metal chip can obstruct the stepped piston of the second element is negligible , If a contamination or a metal chip in the throttle 16 of one of the elements E1, E2 set, so that the barrier pressure in the barrier pressure control chamber 14 of this element is not built up properly, then the barrier pressure from the other element forth via its continuous throttle 16th built reliably. Is, as soon as the solenoid pilot valve 21 goes into the shut-off position shown, taking the shut-off impeded in one of the elements E1, E2, for example, because the stepped piston 12 jammed, z. As the upstream element E1, then the other element E2 takes the shut-off reliably to block the outflow 9 to the reservoir R, and vice versa.

The two elements E1, E2 are structurally simple and cost-effective 2/2-way valves, which work very reliable, and in which it is expected that even with an entering by a pollution or by a metal chip disturbance this disorder automatically after several control cycles again washed out or eliminated, so that the full redundancy function for the lifting module M sooner or later sets again.

The embodiment of the Fig. 2 is different from that of Fig. 1 in that the two elements E1, E2 are identical in construction, ie in each case have a lateral load pressure feed 11, an axial outlet through the valve seat 13, and the bypass connecting the annular chamber 10 with the barrier pressure control chamber 14 with the throttle 16, wherein the both the elements E1, E2 connected in series are also connected in the same way, ie the axial outlet of the first element E1 is connected to the side load pressure feed 11 of the downstream element E2, while the axial outlet of the downstream element E2 is connected to the reservoir line 24 via the branch 9c is.

As an additional detail variant contains the embodiment in Fig. 2 an example, manually operable shut-off member 28 which is arranged in a cross-connection between a node 27 in the control line 20 and the control line 20 and the reservoir line 24, and serves, regardless of an actuation of the solenoid pilot valve 21 abruptly to clear a large outflow cross-section to the reservoir R. to do that in Fig. 1 Test shown hose rupture valve 19. When opening the shut-off member 28 both barrier pressure control chambers 14 of the elements E1, E2 abruptly and completely relieved so that both elements E1, E2 release a large cross-section Hauptabströmweg to the reservoir R, causing a momentary strong pressure drop in the working line 4, on which the hose rupture valve 19 so blocking responds that the load pressure of the Hebehydromotors Z is initially held as far as possible by the hose rupture valve. If system pressure is subsequently restored again, the blocking hose rupture-securing valve 19 also releases, so that the movement of the lifting-hydraulic motor Z can be controlled again via the lifting module M. The two barrier pressure control chambers 14 of the elements E1, E2 are incidentally via a node 26 in the control line 20 connected to each other, so that the solenoid pilot valve 21 controls both elements E1, E2 together.

The embodiment of the lifting module M in Fig. 3 is different from that of Fig. 1 in that at least the upstream element E1 of the elements E1, E2 connected in series has a mechanical limit 25 for the maximum opening stroke of the stepped piston 12 when the control line 20 is relieved via the magnetic pilot valve 21. This mechanical limit 25 is for example a screwed into the locking pressure control chamber 14 stop screw, which makes it possible to adjust the maximum opening stroke. In this way, the upstream element E1 operates as a lowering brake, the maximum lowering speed of the Hebehydromotors Z limited, for example, to max. 0.6 m / s under load.

The embodiment of the lifting module in Fig. 4 is different from that of Fig. 1 in that the solenoid pilot valve 21 is designed as a proportional pressure control valve 29 which contains a proportional magnet 30 and an internal throttle 31. This allows the proportional electrical control of the sink function.

The embodiment of the lifting module M in Fig. 5 is different from the one in Fig. 4 in that the solenoid pilot control valve 21 designed as a proportional pressure control valve cooperates with a pressure compensator 31 which is arranged in the reservoir conduit 24. The pressure compensator 31 is acted upon, for example, by a control valve 35 tapped at a node 26 of the Abströmwegs 9, 9c via a throttle 35 in the up direction and parallel to a spring 32, however, in Schließsteuerrichtung via a control line 34, the control pressure from the Abströmweg 9 upstream of both elements E1 , E2 picks up. As a result, a 2-way flow control function is achieved, which also generates a load pressure independence in the proportional control of the sink function. Alternatively, the pressure compensator 31 could be acted upon in the opening direction by a pilot control pressure of a control line 33 'tapped between the two elements E1, E2 (in this case the node 36 is omitted and the control line 33' is connected to the control line 33). The further construction of the lifting module in Fig. 5 corresponds to that of Fig. 1 with the structurally different and unequal interconnected elements E1, E2 in Abströmweg 9. The pressure compensator 31 could also in the embodiments of Fig. 1 to 3 be provided.

The respective main stage element E1, E2 is structurally (not shown), for example realized by the fact that the stepped piston 12 in a stepped bore in a block housing is guided displaceably guided in a sealed manner, wherein the stepped bore contains the arranged between the annular chamber 10 and the axial outlet valve seat 13, and the barrier pressure control chamber 14 is closed by a screwed into the exposed end of the stepped bore final screw on which the spring 15 is supported. The bypass channel in the stepped piston 12 can then be composed of individual bore sections and form the throttle 16 or contain a throttle section corresponding to the throttle 16 between different bore sections. Optionally, a check valve is included in the bypass channel. Depending on whether in the stepped piston of the bypass channel connects the annular chamber with the barrier pressure control chamber, or the valve seat 13 with the barrier pressure control chamber, the bypass channel opens laterally in the piston extension 17 or axially in the end face of the piston extension 17th

Claims (15)

1. Hoist module (M), in particular for industrial trucks like forklift trucks, lifting bridge vehicles, mobile hydraulic appliances, working vehicles or the like, comprising a lifting control section (1) and a lowering control section (2) both connected with at least one single acting or double acting hoisting hydromotor (Z), wherein a discharge flow path (9) for pressure medium under load pressure and leading to a reservoir (R) is arranged in the lowering control section (2) and a hydraulic element in the discharge flow path (9) for controlling the hydromotor lowering speed between zero and a predetermined value, characterised in that two main stage elements (E1, E2) controlled to open under load pressure are switched in series in the discharge flow path (9), each main stage element (E1, E2) being actuable in a direction towards a blocking position by a blocking pressure derived via a respective aperture (16) from the load pressure, and that both main stage elements (E1, E2) are controlled in parallel and commonly by a solenoid pilot control valve (21) arranged in a blocking pressure pilot line (20) which is shielded by the apertures (16) versus the hoist hydromotor (Z), the load pressure and the lifting control section (1).
2. Hoist module according to claim 1, characterised in that both main stage elements (E1, E2) are spring loaded parallel to the blocking pressure actuation and in a direction towards a leakage-free blocking position.
3. Hoist module according to claim 1, characterised in that both main stage elements (E1, E2) are equally structured and are equally switched in the series.
4. Hoist module according to claim 3, characterised in that both equally structured main stage elements (E1, E2) respectively comprise a sideward pressure supply port (11) leading to a ring chamber (10), and axial outlet port through a valve seat (13), a blocking pressure control chamber (14) at a side of a stepped piston (12) remote from the valve seat (13) the stepped piston (12) being displaceably accommodated in the ring chamber (10), and the respective aperture (16) arranged between the ring chamber (12) and the blocking pressure control chamber (14), and that the sideward pressure inlet port (11) of the main stage element (E2) which is positioned downstream in the discharge flow path (9) is connected with the axial outlet port of the valve seat (13) of the upstream main stage element (E1).
5. Hoist module according to claim 1, characterised in that both main stage elements (E1, E2) are structurally different but are equally switched in the series.
6. Hoist module according to claim 5, characterised in that among the differently structured main stage elements (E1, E2) one main stage element (E1) comprises a sideward pressure inlet port (11) leading to a ring chamber (10), and an axial outlet port through a valve seat (13), a blocking pressure control chamber (14) at a side of a stepped piston (12) remote from the valve seat (13), the stepped piston (12) being displaceably accommodated in the ring chamber (10), and the respective aperture (16) which is arranged between the ring chamber (10) and the blocking pressure control chamber (14), and that the other main stage element (E2) comprises an axial pressure inlet port through the valve seat (13), a sideward outlet port (11') leading outwardly from the ring chamber (10), and the respective aperture (16) arranged between the valve seat (13) and the blocking pressure control chamber (14) at a side of the stepped piston (12) remote from the valve seat (13), the stepped piston (12) being displaceably accommodated in the ring chamber (10), and that the sideward or the axial pressure inlet port (11) of the main stage element (E2) positioned downstream in the series is connected with the axial or sideward outlet port of the upstream main stage element (E1).
7. Hoist module according to claim 4 or 6, characterised in that the aperture (16) is arranged in the stepped piston (12) in a bypass channel arranged within the stepped piston (12).
8. Hoist module according to claim 4 or 6m, characterised in that the aperture (16) is arranged in a bypass channel of a housing of the main stage element (E1, E2), the bypass channel interconnecting the ring chamber (10) respectively the valve seat (13) and the blocking pressure control chamber (14)
9. Hoist module according to claim 4 or 6, characterised in that pressure receiving areas of the stepped piston (12) in the ring chamber (10) and in the blocking pressure control chamber (14) are at least substantially equally sized and are larger than the pressure receiving area of the stepped piston (12) in the valve seat (13).
10. Hoist module according to at least one of the preceding claims, characterised in that at least one of both main stage elements (E1, E2) comprises a mechanical limit (25) of the maximum opening stroke of the stepped piston (12) in lifting direction of the stepped piston (12) from the valve seat (13), preferably an abutment screw arranged in the blocking pressure control chamber (14).
11. Hoist module according to at least one of the preceding claims, characterised in that a testing exit port (28) is arranged in the blocking pressure discharge line (20) between both main stage elements (E1, E2) and the solenoid pilot control valve (21), which testing exit port can be opened selectively.
12. Hoist module according to claim 1, characterised in that the solenoid pilot control valve (21) is a 2/2-way solenoid seat valve which is held in current-free condition by a spring (22) in a leakage-free blocking position.
13. Hoist module according to claim 12, characterised in that the 2/2-way solenoid seat valve is a proportional pressure regulating valve (29) comprising a proportional solenoid (30).
14. Hoist module according to at least one of the preceding claims, characterised in that a pressure compensator (31) is arranged in the discharge flow path (9) downstream of both serially switched main stage elements (E1, E2), the pressure compensator (31) being actuated in opening direction by a spring (32) and by a pilot pressure derived from the discharge flow path (9, 9b, 9c) either between both main stage elements (E1, E2) or downstream of both main stage elements (E1, E2), and being actuated in closing direction by a pilot pressure derived from the discharge flow path (9) upstream of both main stage elements (E1, E2).
15. Hoist module according to at least one of the preceding claims, characterised in that the lifting hydromotor (Z) is protected by a hose breakage safety valve (19).

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