EP2062848B1 - Electro-hydraulic lifting module - Google Patents

Description

The invention relates to an electrohydraulic lifting module according to the preamble of patent claim 1.

At the EP-A-1067296 Known lifting module, the 3/2-way pressure compensator for the main consumer is combined with a proportional pressure control directional control valve to a 3-way flow regulator, which regulates the supply of secondary consumers. This concept is expensive and complicated because of the 3-way current regulator. Further, in the event that downstream of the 3-way flow regulator pressure should be present from a secondary consumer, an additional connection to the return required in order not to jeopardize the control function of the 3-way flow control.

At the EP-A-0936179 known lifting module is provided for auxiliary consumers own pressure source. In addition to a 3/2-way pressure compensator designed priority valve for a sub-consumer in the supply line, a 3-way current controller is provided which controls the supply of another secondary consumer. This concept is structurally complex and expensive. In addition, the 3-way flow control must be connected to an output to the return to perform the control function even with back pressure from the downstream auxiliary consumers. In both known lifting modules, each 3-way current regulator requires an expensive proportional magnet, which also has to be integrated into the electronics accordingly.

Further prior art is contained in: GB 21 59 779 A (Priority system for power steering), DE 20 2004 010 530 U1 (several priority valves).

Long-known, classic solutions of Hubmodulen with a main consumer and at least two secondary consumers work according to the so-called load-sensing principle (PSL) with multiple control valves for load-independent actuation of consumers, and with a control pump as a pressure source. This principle is structurally too expensive and too expensive for industrial trucks and requires a complicated load pressure pilot circuit.

The invention has for its object to provide an electro-hydraulic lifting module of the type mentioned, which is structurally simple and inexpensive to implement ensures the required supply priority for the main consumer, and possibly also ensures priority for each subordinate auxiliary to a priority secondary consumer supply priority.

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

The number of consumers corresponding number of 3/2-way pressure compensators as priority valves forms in Hubmodul a priority cascade that is structurally simple and cost-effective especially for industrial trucks and at least the main consumer supply priority guaranteed. This means that initially only the main consumer is supplied, as long as its needs are partially or completely covered by the pressure source. Only if the delivery rate of the pressure source exceeds the needs of the main consumer, at least one secondary consumer is also operable. If the capacity of the pressure source is sufficient to meet the needs of the main consumer and all secondary consumers, all auxiliary consumers can be operated together with the main consumer. In this priority cascade in each case the secondary consumer has priority, which is connected in the flow direction before another auxiliary consumer to the priority valve of the main consumer. The 3/2-way pressure compensators are cost-effective hydraulic elements that require no magnets or proportional solenoids for their function. Nevertheless, even a load pressure independent actuation of the main consumer and possibly the Nebenvertiraucher is possible via the 3/2-way pressure compensators.

Suitably, the lifting module is designed so that the secondary consumers in the row direction have decreasing flow rates. For example, the main consumer needs a delivery rate of at least 60 l / min, while the delivery rates of the secondary consumers are, for example, 40, 15 and 5 l / min. Although with sufficient delivery of the pressure source all consumers can be actuated simultaneously occurs in a material handling vehicle usually only the need to operate in addition to a main consumer one or more than two secondary consumers at the same time, or, without the main consumer to operate, only one or two secondary consumers at the same time actuate. Although in the priority cascade the accumulation pressures of the individual stages add up. However, this is insignificant in an industrial truck, since the control accuracy underneath sprübar does not suffer and the number of secondary consumers is limited anyway.

In an expedient embodiment, the 3/2-way pressure compensators of the priority cascade for the main consumer and for the secondary consumers are identical or even identical. At most, the biases differ from the control springs of the 3/2-way pressure compensators. This principle of equality is inexpensive.

The respective 3/2-way pressure compensator has in a settable by a control spring end position a direct flow path from the pressure source or the supply line (in the case of the auxiliary consumers) to the directional control valve and in a by control pressure of upstream the directional control valve and adjustable against the control spring, other end position a throttleable flow path from the pressure source or the supply line to the directional control valve and at the same time a direct second flow path from the pressure source or the supply line to another portion of the supply line. Only the direct second flow path of the rearmost auxiliary consumers in the series associated 3/2-way pressure compensator is connected to the return, so that the priority cascade, if the rearmost auxiliary consumer is not to operate, excess pressure fluid in the return leads.

Suitably, each 3/2-way pressure compensator is acted upon by the control pressure downstream of the respective directional control valve and the control spring in the direction of the end position, in which a second output of the 3/2-way pressure compensator is shut off to the subsequent supply line section. In this end position, the associated consumer (main consumer or secondary consumer) has supply priority with respect to each downstream consumer arranged in the flow direction.

In the lifting module are the directional control valves, preferably solenoid or proportional solenoid operated, 2/2-way pressure control poppet valves or multi-way spool valves. These valves allow very precise control of the speeds of the loads and also the control of clean ramps when going from standstill to motion or when moving from a motion to a standstill.

In an expedient embodiment, the directional valves are arranged in modular juxtaposed blocks, to which at the side of the pressure source in each case an input block is attached, at least the 3/2-way pressure compensator, each a portion of the supply line and a return and, preferably, a Contains pressure relief valve, the input blocks are also modular juxtaposed. This modular block design allows the optional design of differently designed electro-hydraulic lifting modules for different applications from individual components. In an alternative embodiment, each block and the input blocks could each form a block in which the directional control valve, the 3/2-way pressure compensator, a supply line section, a return section and the like are included.

In an expedient embodiment, the main consumer is a lifting cylinder which acts simply against load, a first secondary consumer is an initial lifting cylinder which acts simply against load, a second secondary consumer comprises a pair of single-acting rotary cylinders, and a third secondary consumer is a sliding hydraulic motor. The priority cascade with the 3/2-way pressure compensators is particularly well suited for this lifting module concept of a material handling vehicle.

Appropriately, a maximum of four auxiliary consumers are controlled by the electro-hydraulic lifting module.

It is also expedient to provide a check valve between at least two supply line sections, which blocks in the return flow direction to the pressure source. This check valve is expediently arranged in the transition between two blocks or input blocks and separates the supply line sections in the return flow direction.

Reference to the drawings, an embodiment of the subject invention will be explained. FIG. 1 shows a block diagram of an electro-hydraulic lifting module for supplying here a main consumer H and three auxiliary consumers N1 to N3, the working components of an unspecified forklift truck, such as a forklift or rack stacker, or the like .. are.

The electrohydraulic lifting module S in Fig. 1 is composed of four blocks 39, 40, 41 and 42, to each of which input blocks 43, 44, 45 and 46 are attached. In an alternative, not shown, the blocks and the input blocks may each be combined into a block.

A driven by a motor M pump P forms the common pressure source for all consumers H, N1 to N3. By way of example, the main consumer H is a lifting cylinder 1 which acts simply against load. The first secondary consumer N1 following the main consumer H is, for example, an initial stroke cylinder which acts simply against load. The next, second auxiliary consumer N2 consists for example of a pair of motion-coupled, single-acting rotary cylinder 3. The last or rearmost auxiliary consumer N3 is for example a sliding hydraulic motor. 4

A pump line 5 branches off at a node 6 in the input block 43 with a connecting line 8 to a return line 9 to the return line R, wherein in the connecting line 8, a system pressure relief valve 7 is included.

Downstream of the node 6, a first priority valve P1 is arranged in the pump line 5 for supplying the main consumer H, which is designed as a 3/2-way pressure compensator 10 and contains a control 11 which is connected between an inlet connection 12 and two outlet connections 14, 15 working regulates. Via a control line 19 upstream control valve 22 (lift valve, 2/2-way pressure control poppet valve with solenoid actuation) control pressure is tapped, which acts via a throttle 21, the control 11 of the 3/2-way pressure compensator in the direction of an end position. Downstream of the directional control valve 22 in the pump line 5 and upstream of a check valve 24 control pressure is tapped via a control line 20, the control element 11 via a throttle 21 towards another end position (together with a control spring 18) acted upon. In one, by the control pressure in the control line 20 and the control spring 18 adjustable end position leads a direct flow path 16 from the inlet port 12 to an outlet port 15, while the second outlet port 14 is shut off. To the second outlet port 14, a supply line 33 is connected, which consists of successive supply line sections 33a, 33b, 33c, wherein between the supply line sections further priority valves P2, P3, P4, each in the form of a 3/2-way Pressure compensator 10a, 10b, 10c are used. The priority valves P1 to P4 form in the electrohydraulic lifting module S a priority cascade and are, preferably, identical or even identical.

The pump line 5 leads downstream of the check valve 24 to a node 23 in a working line 25 of the main consumer H. The working line 25 branches off at node 23 in a drain line 26, in which another directional control valve 27 vertically (2/2-way pressure control Poppet valve with proportional solenoid operation) is arranged. Downstream of the directional valve 27, a 3/2-way pressure compensator 28 is arranged in the drain line 26, from which the drain line 26 into a Nutzsenkleitung 31 to the suction side of the pump P (hedged by a check valve 32) and into a drain line 30 to the return R. branched. In the drain line, 30 a 2/2-way pressure compensator 29 is included.

Between the supply line sections 33a and 33b and 33b and 33c, there is arranged a respective non-return check valve 34, for example in the respective input block 43, 44. The supply line section 33a is in the input block 44 to the one inlet port of the 3/2-way pressure compensator 10a connected, one of whose outlet port a line 5a to two parallel directional control valves 34a, 34b of the first secondary consumer N1 (globe valve, 2/2-way Druckregelventille with magnetic actuation) and via check valves 24 leads to a working line 25b of the first auxiliary consumer N1. In a branched from the working line 25b drain line 36 of the first auxiliary consumer N1 another directional control valve 35 is included (lowering valve, 2/2-way pressure control poppet valve with solenoid actuation and pressure precontrol), of which the drain line 36 further to a portion 9b of the return line. 9 leads. The 3/2-way pressure compensator 10a is acted upon in one direction from a control line 20a with control pressure from the respective directional valve 34a, 34b and from a control spring, and in the opposite direction via a control line 19a with control pressure from upstream of the directional control valves 34a, 34b ,

In the input block 45, the input port 14 of the 3/2-way pressure compensator 10b is connected to the supply line section 33b. From one outlet port 15 of the 3/2-way pressure compensator 10b, a pressure line 5b leads to a directional control valve 37 (multi-way slide valve with solenoid actuation), from which a drain line via a pressure relief valve leads to the return line section 9c. The 3/2-way pressure compensator 10b is acted upon from a control line 19b with control pressure from upstream of the directional control valve 37 and in the opposite direction by a control spring and control pressure from a control line 20b downstream of the directional control valve 37. The one outlet port 14 of the 3/2-way pressure compensator 10b is connected to the last supply line section 33c to the last priority valve P4 arranged in the input block 46. The 3/2-way pressure compensator 10c of this priority valve P4 is acted upon from a control line 19c with control pressure from upstream of a directional control valve 38, and in the opposite direction via a control line 20c with control pressure from downstream of the directional control valve 38 and a control spring. The directional control valve 38 (a multi-way slide valve with magnetic actuation) is connected on the outlet side to the portion 9d of the return line 9, as well as the second outlet port 14 of the 3/2-way pressure compensator 10c.

Function:

As long as the capacity of the pump P does not exceed the demand of the main consumer H, the first priority valve P1 gives the main consumer H supply priority over the Nebenverbrauchem N1 to N3. The 3/2-way pressure compensator 10 takes the in Fig. 1 shown end position. The second outlet port 14 to the supply line section 33a is shut off.

Only when the directional control valve 22 in the in Fig. 1 shown position, or the capacity of the pump P exceeds the demand of the main consumer H, the 3/2-way pressure compensator 10 regulates a flow in the supply line section 33 a.

As long as the delivery flow in the supply line section 33a does not exceed the demand of the first auxiliary consumer N1 moved by activating a directional control valve 34a or 34b or both directional control valves, this supply priority has over the secondary consumption N2, N3. Only when the delivery rate in the supply line section 33a exceeds this requirement, or the first secondary consumer N1 is not actuated, pressure medium is controlled in the next supply line section 33b, with which the additional auxiliary consumer N2 can be actuated, which in turn has supply priority to the rearmost auxiliary consumer N3. In the same way, the rearmost auxiliary consumer N3 is actuated. If the rearmost auxiliary consumer N3 is not actuated (directional control valve 38), then the delivery flow in the last supply line section 33c is conducted directly into the section 9d of the return line 9.

In each 3/2-way pressure compensator 10, 10a, 10b, 10c, the flow path 16a in the end position caused by the control pressure in the control line 19, 19a, 19b, 19c to the outlet port 15 can be throttled, while the two other flow paths can be unthrottled, d. H. the flow path 16 in the other end position and the flow path leading from the inlet port 12 to the outlet port 14. In the intermediate positions it is regulated so that the 3/2-way pressure compensator keeps the pressure difference set at the respective directional control valve.

As an example of the electrohydraulic lifting module S for an industrial truck, the main consumer H has a maximum requirement of about 60 l / min, while the demand of the secondary consumers N1 - N3 is lower and in the direction of the row in which the auxiliary consumers N1 - N3 in the supply line 33 are gradually reduced, for example from about 40 to about 15 and finally about 5 l / min in the Nebenverbrauchem N1, N2 and N3.

Claims (11)

1. Electrohydraulic lifting module (S) for an industrial truck, with at least one primary consumer (H) and at least one secondary consumer (N1 - N3), which can be acted upon from the same pressure source (P) via directional control valves (22, 27, 34a, 34b, 35, 37, 38), at least the primary consumer (H) attaining supply priority via at least one priority valve (P1), which is arranged between the pressure source (P), the directional control valve (22) of the primary consumer and a directional control valve (34a, 34b) of a secondary consumer (N1), and the priority valve (P1) being a 3/2-way pressure balance (10), to which control pressures can be applied which are tapped off upstream and downstream of the directional control valve of the primary consumer, and which 3/2-way pressure balance regulates, at one of two output connections (14, 15), the supply for the directional control valve of the respective secondary consumer depending on the requirement of the primary consumer (H) and on the delivery power of the pressure source (P), characterized in that a plurality of secondary consumers (N1 - N3) are connected in a row to a supply line (33), and in that arranged in the supply line (33) upstream of the directional control valve (34a, 34b, 37, 38) of each secondary consumer (N1 - N3) there is in each case a priority valve (P2 - P4) which is in the form of a 3/2-way pressure balance (10a, 10b, 10c) and to which control pressures can be applied which are tapped off upstream and downstream of the directional control valve of the associated secondary consumer.
2. Electrohydraulic lifting module according to Claim 1, characterized in that the plurality of secondary consumers (N1 - N3) are designed to have a delivery power requirement which reduces in the direction of the row.
3. Electrohydraulic lifting module according to Claim 1, characterized in that the pressure balance (10) of the primary consumer (H) and the pressure balances (10a, 10b, 10c) of the secondary consumers (N1 - N3) have an identical design.
4. Electrohydraulic lifting module according to Claim 1, characterized in that the respective 3/2-way pressure balance (10a, 10b, 10c) in the supply line (33) in an end position, which can be set by a regulating spring (18), has a direct flow path (16) from the pressure source (P) or the supply line (33) to the directional control valve (22, 34a, 34b, 37, 38) and in another end position, which can be set by control pressure from upstream of the directional control valve and counter to the regulating spring, has a flow path (16a) which can be throttled from the pressure source (P) or the supply line (33) to the directional control valve and a direct second flow path (15) from the pressure source (P) or the supply line (33) to a following section (33a, 33b, 33c) of the supply line (33).
5. Electrohydraulic lifting module according to Claim 4, characterized in that the direct second flow path (15) of the 3/2-way pressure balance (10c), which is associated with the rearmost secondary consumer (N3) in the row, can be connected to a return line (9).
6. Electrohydraulic lifting module according to Claim 1, characterized in that the control pressure from downstream of the directional control valve and the regulating spring can be applied to each 3/2-way pressure balance (10, 10a, 10b, 10c) so as to move it in the direction towards an end position, in which a second output (11) of the 3/2-way pressure balance to the following section (33a, 33b, 33c) of the supply line (33) is blocked off.
7. Electrohydraulic lifting module according to Claim 1, characterized in that the directional control valves (22, 27, 34a, 34b, 37, 38) are preferably magnet-actuated or proportional-magnet-actuated 2/2 pressure regulating seat valves or multi-directional sliding valves.
8. Electrohydraulic lifting module according to at least one of the preceding claims, characterized in that the directional control valves are arranged in blocks (39 - 42) which are arranged next to one another in modular fashion and on which in each case one inlet block (43 - 46) is fitted on the side of the pressure source (P), which inlet block contains at least the 3/2-way pressure balance (10, 10a, 10b, 10c), in each case one section (33a, 33b, 33c) of the supply line (33) and of the return line (9) and preferably a pressure-limiting valve (7), and in that the inlet blocks (43 - 46) are likewise arranged next to one another in modular fashion.
9. Electrohydraulic lifting module according to Claim 1, characterized in that the primary consumer (4) is a single-acting lifting cylinder (1) counter to the load, a first secondary consumer (N1) is a single-acting initial lifting cylinder (2) counter to the load, a second secondary consumer (N2) is a pair of single-acting rotary cylinders (3), and a third secondary consumer (N3) is a hydraulic shifting motor (4), in each case for a working component of an industrial truck.
10. Electrohydraulic lifting module according to at least one of the preceding claims, characterized in that at most four secondary consumers (N1 - N3) are provided in a row.
11. Electrohydraulic lifting module according to Claim 4, characterized in that a nonreturn valve (34), which shuts off in the return flow direction towards the pressure source (P), is arranged between at least two supply line connections (33a, 33b, 33c).

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