JP2006508311A - Hydraulic dual circuit system - Google Patents

Abstract

A hydraulic dual-circuit system for controlling consumer loads of a mobile appliance, in which each hydraulic circuit (2,4) is provided with an adjustment pump (6,7) depending on the highest load pressure and via which the associated load can be supplied with pressure and in which the two circuits (2,4) are interconnected via a summation valve arrangement (12), which is used to feed the pressure from one of the connected circuits via a summation line (24) downstream from the orifice plate (14) and from the pressure maintaining valve (16) of the summed consumer load.

Description

  The present invention relates to a hydraulic dual circuit system for controlling a mobile device, in particular a consumer of a crawler device according to the preambles of claims 1 and 13.

  U.S. Pat. No. 6,170,261 B1 discloses a hydraulic dual circuit system for mobile devices such as tracked and tracked devices. In such a crawler-type device, the running gear has two crawler plates, and each crawler plate can be controlled separately via one of the hydraulic circuits. Devices such as a turntable, a boom, an arm, and an excavator are connected to the two hydraulic circuits of the endless track device. Each of the two hydraulic circuits is supplied with a pressure medium by a variable displacement pump that is controlled according to the maximum load pressure of the consumer of each circuit. Other applications such as wheeled excavators and cranes are also conceivable for the hydraulic dual circuit system.

  In order to avoid an insufficient supply of pressure medium, it is conceivable to merge the two hydraulic circuits. In the solution disclosed in US Pat. No. 6,170,261 B1, two hydraulic circuits are merged via a merging valve, and a pressure line connected to two pumps and a load pressure transmission line of the two circuits are merged. Let The control of the junction valve is performed by supplying a pressure medium to another consumer. It is also possible for the operator to manually join the two circuits.

  German Patent Application Publication No. 102 52 241 by the present applicant discloses an improved solution over US Pat. No. 6,170,261 B1, where the merging valve requires less pressure medium when the circuits merge. It is designed so that a high load pressure is not sent to one of the circuits and not to the other circuit with a low load pressure.

  However, these solutions correspond to a proportional directional control valve having a throttle orifice and a pressure compensating valve downstream of each consumer in a load independent pressure distribution (LIPD) device by two circuits at the time of merging. There is a drawback in that it must be designed for the maximum flow rate sent to the consumer. That is, in the dual circuit operation of this apparatus, the proportional directional control valve provided on each main shaft, particularly the throttle orifice, has an extremely large size.

  Another disadvantage is that switching to a single circuit system is very difficult with known solutions, because the merging valve already merges the circuit when more pressure medium is needed than can be pumped. Occur early.

  The present invention is based on the object of providing a dual circuit system capable of optimally adapting the throttle orifice required for independent load pressure control of joined consumers to the dual circuit operating conditions and preventing premature joining. .

  This object is achieved by a dual circuit system having the features of claim 1 or claim 13.

  According to the present invention, the joining of the pressure medium flows is performed not only upstream of the throttle orifice of the main shaft provided corresponding to the consumer as in the prior art described above, but only downstream of the throttle orifice and the pressure compensation valve, The latter need only accept the pumping amount of the corresponding circuit. Since the merging is performed only downstream of the throttle orifice of the consumer to be merged, all the throttle orifices of the main shafts to be merged can match the pump amount of each pump. As a result, the controllability is greatly improved, and the saturation (Δp) between the pump pressure and the load pressure does not rapidly decrease when a plurality of consumers are operated simultaneously. As the control pressure decreases, the speed of each consumer increases with a higher gain, and the control signal predetermined by a setting device such as a joystick is quickly and accurately converted.

  Also, the control signal that activates the merging valve can be controlled by a dual circuit system consumer via the consumer valve stem, for example, by selecting that merging occurs only when it is accelerated. It is possible to prevent switching too early.

  In a preferred embodiment, a proportional directional control valve having a throttle orifice and a directional member is used on the main shaft corresponding to each consumer, and a LIPD pressure compensation valve is provided downstream of the throttle orifice. Thereby, the load pressure independent flow to the consumer can be maintained.

  In a preferred embodiment, the merging valve has a merging proportional valve that constitutes a merging throttle orifice, and a merging pressure compensation valve is provided downstream of the merging proportional valve. The control of the merging proportional valve can be performed electrically, mechanically, or hydraulically. By appropriately adjusting the control signal, the opening of the merging proportional valve and the connection of the dual circuit system to the single circuit system can be controlled so that the dual circuit operation is maintained in the operating range for as long as possible. Consumer controllability and energy balance are optimized.

  In the case of hydraulic control of the merging proportional valve, the control pressure can be designed as a function of the operation of a setting device in the merging proportional valve, for example a pilot control device.

  According to an advantageous feature of the invention, the merging valve has an LS (Load Sensing) signal valve, and each LS signal is sent to the LIPD pressure compensation valve of the merging shaft during merging. When the maximum load pressure of the pressure receiving side circuit is lower than the maximum load pressure of the pressure receiving side circuit, the pump pressure of the pressure receiving side circuit does not increase. When the pressure receiving side circuit has a higher load pressure than the pressure supplying side circuit, the pump pressure of the pressure supplying side circuit increases.

  The merging valve can have a control valve configured to be connected to a line that communicates pump pressure and load pressure. The operation of the control valve is performed, for example, via a control pressure output based on a predetermined manual control signal output by the operator. That is, the control valve allows the dual circuit system to be switched to a single circuit system independent of the circuit gap. This is necessary, for example, when the running gear of the crawler device is controlled simultaneously with other consumers.

  The functions of the control valve and the LS signal valve can be integrated into the merge proportional valve. In a preferred variant, the merging proportional valve is designed to have an additional switching position to which two lines communicating the pump pressures of the two circuits are connected. This can be achieved, for example, by a control spring that is designed so that the bias of the control spring decreases in one direction and biases the valve spool of the merging proportional valve to the basic position (blocking position), It moves to the switching position by the force reduced in one direction.

  In order to change the bias by the spring, the control spring of the merging proportional valve can be biased hydraulically via the control pressure, the control line conveying the control pressure is connected to the tank via the override valve, and the control pressure is reduced However, the bias of the control spring is reduced.

  When the two circuits merge and multiple consumers operate, the device operates under saturation, and each consumer's load pressure independent operation is not guaranteed. To mitigate these effects, a nozzle can be provided upstream of the confluence of consumers, usually with low load pressures, between consumers operating at low and high load pressures and the supply from the other circuit A desired distribution of quantities can be made.

  According to the present invention, the above-mentioned merging is performed in one direction of the pressure medium flow determined by the proportional valve of the consumer valve shaft, and the merging may not be performed in the opposite direction. It is particularly preferred that the pressure medium flow from the additional circuit is connected to the line section between the load holding valve of the consumer valve stem and the directional member of the proportional valve.

  Further advantages of the invention are the subject of other dependent claims.

  Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the schematic drawings.

  FIG. 1 shows a principle diagram of a power shovel control device realized as a dual circuit system having two hydraulic circuits 2 and 4. Power shovel consumers 8, 10 can be controlled via two circuits, for example, a driving drive mechanism of a traveling gear having two crawler plates, a power shovel device such as a turntable, an arm, an excavator, and a boom. . Supply of the pressure medium to the circuits 2 and 4 is preferably performed via variable displacement pumps 6 and 7 controlled according to the maximum load pressure of each circuit.

  If controlling the consumer 8 requires more pressure medium than the corresponding variable displacement pump 6 can supply, the consumer 8 will operate under a saturation defect. In order to avoid such a gap, a junction valve 12 is provided, and a predetermined amount of pressure medium can be supplied from the variable displacement pump 7 to the consumer 8.

  In a similar power shovel control device, independent supply of load pressure to consumers 8 and 10 is performed, and a variable throttle orifice 14 and a pressure compensation valve 16 downstream of the throttle orifice 14 are provided on each consumer valve shaft. The pressure compensation valve receives the pressure downstream of the throttle orifice 14 in the opening direction, and receives the maximum load pressure of each circuit 2, 4 in the closing direction. The maximum load pressure of each circuit 2, 4 exists in the LS lines 18, 20. The piston of the pressure compensation valve maintains a control position where the pressure drop across the orifice 14 is kept constant independently of the load pressure. A load holding valve 21 is provided between the pressure compensation valve and the consumer. Since such LS control devices are known, further description of the operation of the valve stem is omitted. In particular, it is known that the maximum load pressure is selected by an additional control edge in the pressure compensation valve 16 (eg, US Pat. No. 5,305,789).

  A merging line 24 to the merging valve 12 branches from a pump line 22 that transmits the pump pressure. The merge line 24 has a merge throttle orifice 26, and a LIPD merge pressure compensation valve 28 is provided downstream of the merge throttle orifice 26. Similar to the pressure compensation valve 16 of the consumer valve shaft, the merging pressure compensation valve 28 receives the pressure downstream of the throttle orifice 26 in the opening direction and the load pressure existing in the circuit 4 in the closing direction. This load pressure is in this case sent to the pressure compensation valve 28 via the LS line 18. A load holding valve 21 is also provided downstream of the pressure compensation valve 28.

  The merge line 24 is connected to the operation line 30 to the consumer 8 downstream of the consumer valve shaft corresponding to the pressure compensation valve 16, the load holding valve 21, and the consumer 8. That is, the merging is performed only downstream of the throttle orifice 14, the pressure compensation valve 16, and the load holding valve 21, and their cross-sections only need to be able to receive the medium flow of the highest pressure sent by the pump 6.

  Junction valve 12 further includes an LS signal valve 32. In the basic position biased by the spring, the LS signal valve 32 disconnects the connection between the LS line 18 and the pressure compensation valve 28. The LS line 18 is connected to the pressure compensation valve 28 by switching the LS signal valve 32 to the passing position. The switching of the LS signal valve 32 can be performed, for example, as a function of the operation of the variable throttle orifice 14. In the above-described embodiment, the pressure medium is described as being supplied from the circuit 4 only to the circuit 2. In such a one-way supply, the LS signal valve 32 can actually be omitted and one control surface of the pressure compensation valve 28 can be permanently connected to the LS line 18. Merging in the opposite direction can be achieved by suitably realizing the merging valve 12 so that the pressure medium is supplied from the circuit 2 to the circuit 4. In this case, since the LS signal valve is necessary, the LS signal valve is also included in FIG.

  Such an embodiment will be described with reference to FIGS.

  FIG. 2 shows a switching diagram of a dual circuit control device of a power shovel including a crawler belt drive device. The dual circuit control device includes two circuits 2, 4 connected via a junction valve 12. Each circuit 2, 4 supplies a pressure medium to a plurality of consumers. For example, circuit 2 supplies pressure media to the left footboard, excavator, and boom, and circuit 4 supplies pressure media to the right footboard, arm, turntable (not shown), and any consumer. Each circuit 2, 4 is provided with a variable displacement pump 6, 7 that is controlled according to the maximum load pressure of each circuit 2, 4. A consumer valve shaft is provided corresponding to each consumer (traveling gear, excavator, boom, arm, turntable, option), and each consumer valve shaft is proportional to embody a speed member (LIPD throttle orifice 14) and a direction member. A variable direction control valve 34 is included. A LIPD pressure compensation valve 16 is provided downstream of the speed member (LIPD throttle orifice 14). The LIPD pressure compensation valve 16 is a pressure downstream of the throttle orifice of the proportional valve 34 in the opening direction, as in the above-described embodiment. And receive the maximum load pressure of the circuit in the closing direction. Consumer valve stems provided for other consumers also have the same configuration.

  The merging shaft of the merging valve 12 has a merging proportional valve 36 that constitutes a merging throttle orifice 26. A merging pressure compensation valve 28 is provided downstream of the merging proportional valve 36, and the pressure drop of the merging throttle orifice 14 is kept constant independently of the load pressure.

  In the present embodiment, the merging valve 12 also has an LS signal valve 32, and the LS line 18 or the LS line 20 is connected to the pressure compensation valve 28.

  In special operating conditions, for example when driving an excavator or when operating several other consumers, a dual circuit manually is applied to ensure that the driving gear is supplied with a sufficient and constant pressure medium to ensure linear driving. It would be advantageous if the system could be switched to a single circuit system. In the embodiment according to FIG. 2, switching to a single circuit system connects the pump lines 40, 42 and the two LS lines 18, 20 carrying the pump pressure of the circuits 2, 4 in a basic position biased by a spring. This can be done via the control valve 38. The control valve 38 can be switched to the passing position by a control pressure, which is detected as a function of a control signal generated by the operator.

  In the solution shown in FIG. 2, the confluence proportional valve 36 of the confluence shaft is controlled by hydraulic pressure. The power shovel has various pilot control devices in the cab. In FIG. 2, for example, a manual pilot control device for operating an arm and turntable (pilot control device 44) and a boom and excavator (pilot control device 46). 44 and 46 are provided. The travel drive mechanism is controlled through two foot-operated pilot control devices 48, 50. The pilot control device 48 is provided for the left shoe, and the pilot control device 50 is provided for the right shoe. ing.

  The pilot controllers 44, 46, 48 and 50 operate based on a direct control pressure reducing valve. Regarding the functions of these control devices, for example, refer to the Bosch Rexroth data sheet RD 64 552.

  By operating the control lever of the pilot control device, a control pressure corresponding to the operation amount is output, and the control pressure is used to control the corresponding consumer. In the embodiment shown in FIG. 2, the control pressure output from the pilot control device 44 for controlling the arm is detected via the pilot control line 52 and transmitted to the control surface of the merging proportional valve 36. The highest pressure among the control pressures output from the pilot control device 46 for controlling the boom or the shovel is detected via the shuttle valve and the pilot control line 54 and transmitted to the other control surface of the merging proportional valve 36. .

  The highest control pressure output via the control devices 44, 46 is tapped by the shuttle valve assembly 56 and transmitted to the shuttle valve 64 via the control flow path 60 and the switching valve 62, and the other input of the shuttle valve 64. Is inputted with a relatively high control pressure manually selected in advance. These higher pressures are transmitted to the control surface of the control valve 38 acting in the opening direction.

  In the basic position, the switching valve 62 connects the control flow path 60 to the tank, and when the pilot control devices 48, 50 are not operating, the control valve 38 is input from the outside, for example, by operating a “single circuit system” switch. With the control pressure applied, it can only be switched to the switching position connecting the two circuits 2, 4. The operation of the switching valve 62 is performed by the highest control pressure output from the two foot-operated controllers 48, 50 and tapped through the shuttle valve assembly 58. That is, when the two travel drive mechanisms are operated via the control devices 48 and 50, and the devices are also operated simultaneously, the switching valve 62 causes the maximum control pressure output from the control devices 44 and 46 to reach the control flow path 60 and the shuttle valve. The control valve 38 is switched independently of the control pressure difference existing in the merging proportional valve 36 and connects the two circuits 2 and 4. Such switching can be performed under the operating conditions described above, and can also be performed manually by inputting a necessary control pressure from the outside.

  Further details of the confluence shaft and the consumer valve shaft will be described with reference to the enlarged view of FIG.

  The merge proportional valve 36 has two pressure ports P1, P2 connected to the pump lines 40, 42 of the circuits 2, 4, respectively. Two joining ports S1 and S2 are provided between the two pressure ports P1 and P2, and the joining ports S1 and S2 are connected to the joining line 24 of the circuit 2 and the joining line 66 of the circuit 4, respectively.

  The merging proportional valve 36 has an outlet port P ″ and a return port P ′. The outlet port P ″ is connected to the inlet port P, and the return port P ′ is connected to the outlet port A of the merging pressure compensation valve 28. The pressure in the flow path between the port P ″ and the port P is tapped via the control line and transmitted to the control surface acting in the opening direction of the merge pressure compensating valve 28. The merging pressure compensation valve 28 is normally biased but biased in the closing direction by a spring and a load pressure that are not always necessary. This load pressure is tapped via an LS signal valve 32 implemented as a proportional variable directional control valve. The LS signal valve 32 has two inlet ports LS1 and LS2 and an outlet port X. The two inlet ports LS1 and LS2 are connected to the LS line 20 of the circuit 2 and the LS line 18 of the circuit 4, respectively. The outlet port X is connected to the port LS of the merging pressure compensation valve 28 via the control flow path, and is also connected to the control surface of the pressure compensation valve acting in the closing direction. The control of the LS signal valve 32 can be performed by tapping a control pressure difference existing in the pilot control lines 52 and 54. That is, the LS signal valve 32 receives the same control pressure difference as the valve spool of the merging proportional valve 36.

  As described above, the directional member 72 and the throttle orifice 14 are constituted by the proportional valve 34. The proportional valve 34 has a pressure port P and an outlet port P ′ connected to the inlet port P of the pressure compensation valve 16. The pressure present at the port P 'is transmitted via the control line to the control surface of the pressure compensation valve 16 acting in the opening direction. In the opposite direction, i.e. the closing direction, the pressure compensation valve 16 receives the spring force and the load pressure present in the LS line 20. The pressure compensation valve 16 has an outlet port A and a control port LS connected to the LS line 20. The outlet port A of the pressure compensation valve 16 is connected to two ports P ″ and P ″ ″ via a branch pressure flow path. The tank port T of the proportional valve 14 is connected to a tank flow path 74 common to the circuits 2 and 4. The proportional valve 34 is controlled by a control pressure transmitted to the control surface of the proportional valve 34 via the control ports a5 and b5. In the basic position shown, the ports A, B, P ', P "are connected to the tank port T and the ports P"', P are blocked.

  As shown in FIG. 3, the merging line 24 branches the connection channel 76 via a check valve 70 that also functions as the load holding valve 21 shown in FIG. 1 downstream of the merging channel 68 and the pressure compensation valve 28. Connected to the department. The connection flow path 76 branches into two partial flow paths 80 and 78 provided with load holding valves 82 and 84, respectively. The merge flow path 68 is connected to the branch flow path 80 between the load holding valve 82 and the corresponding port P ″.

  In order to control a consumer, for example, a boom of a power shovel, a control pressure higher than that of the port b5 is input to the port a5, and the valve spool of the proportional valve 84 moves upward in FIG. By this movement, the port P and the port P ′ are connected to each other, and the opening of the throttle orifice 14 is adjusted. Next, the pressure medium flows to the port P of the pressure compensation valve via the port P 'and acts on the latter in the opening direction. The pressure compensation valve 16 is adjusted to a control position where the pressure drop of the throttle orifice 14 is kept constant independently of the load pressure. That is, in this control position, the valve spool of the pressure compensation valve 16 moves upward in FIG. 3, and the connection between the ports P and A of the pressure compensation valve is opened. Next, the pressure medium flows to the port P ″ through the connection channel 76, the branch channel 80, and the load holding valve 82, and then flows from the port P ″ to the boom through the operation port A. The returned pressure medium is returned to the tank via the operation port B, the tank port T, and the tank flow path 74. In order to lower the boom, a high control pressure is input to the control port b5, the valve spool moves downward in FIG. 3, and the movement direction of the boom is changed correspondingly.

  The basic function of the LIPD consumer valve stem is well known and further description is omitted. Other consumer valve stems are similarly implemented, and in the embodiment shown in FIG. 2, the excavator and boom consumer valve stems are connected in circuit 2 to merging line 24, and the arm consumer valve stems in merging line 24 in circuit 4. 66. The consumer valve shaft is not connected to the merging lines 24 and 66 in the direction of action, but is connected only in the direction in which a high pressure medium is required, for example, in the case of a boom. In general, in the case of a consumer operating with a hydraulic cylinder, preferably only the pressure medium flow into the cylinder chamber is merged.

  For example, when operating the boom of a power shovel by operating the control device 46, the merging proportional valve 36 is moved to the position indicated by (b) by the higher control pressure in the pilot control line 54, and the process Thus, the confluence throttle orifice 26 is opened. The inlet port P2 of the merging proportional valve 36 connected to the pump line 42 of the circuit 4 is connected to the outlet port P ″ via the throttle orifice 26 and is connected to the inlet port P of the merging pressure compensation valve 28. The pressure downstream of the confluence throttle orifice 26 acts in an opening direction on the piston of the pressure compensation valve, the latter moving to a control position where the inlet port P is connected to the outlet port A. Next, the pressure medium flows from the outlet port A to the merging port S1 connected to the merging line 24 of the circuit 2 via the directional member of the port P ′ and the merging proportional valve 36, and is a consumer valve shaft to be merged, in this case The pressure medium is further supplied from the circuit 4 to the boom of the circuit 2. When the boom is operated, the piston of the LS signal valve 32 moves to the right in FIG. 3 by the higher control pressure in the pilot control line 54, and the control of the confluence pressure compensation valve 28 in which the LS pressure of the circuit 4 acts in the closing direction. Is transmitted to the surface via the LS signal valve 32.

  When the consumer of the circuit 4 joins, the spool of the joining proportional valve 36 moves to the position indicated by (a), and joining is performed toward the joining target axis in the circuit 4 as described above.

  When the pressure downstream of the merging restrictor orifice 26 is higher than the load pressure of the LS line 18 or 20, the pressure compensation valve piston of the merging pressure compensation valve 28 is supplied with the higher pressure to the LS line 18 or 20 ( It moves to the control position indicated by b) (the ports P and LS of the merging pressure compensation valve 28 are connected, the latter being connected to the port X of the LS signal valve 32).

  The following are usually true: When the load pressure of the consumer of the first circuit supplied from the second circuit (that is, the consumer to be merged) is higher than the maximum load pressure of the second circuit, the merge pressure compensating valve 28 is completely opened. Then, the high load pressure of the consumers to be joined is sent to the LS line of the second circuit, and the pump pressure rises. As a result, merging is possible. The pump pressure increases only to the extent required by the load pressure of the consumers to be joined. In the first circuit, if another consumer with a load pressure higher than the merged consumer's load pressure is activated at the same time and cannot be merged, the high load pressure is not the second circuit but the first circuit. Will be present in the LS line of the circuit and will have no effect on the pump pressure of the second circuit. On the other hand, when the load pressure of the consumer to be merged in the first circuit is lower than the maximum load pressure in the second circuit, the pressure compensation valve 28 is in the control position and suppresses the merged flow. The LS pressure of the LS line of the first circuit is determined solely by the load pressure of the operating consumer of the first circuit and does not reach the level of the LS pressure of the second circuit, which may be higher. Therefore, unnecessary energy loss is avoided.

  By appropriately controlling the merging shaft 12, the merging can be performed at a phase different from that of each consumer valve shaft. Such a phase shift can be adjusted, for example, by adjusting the control range of the confluence axis to an upwardly shifted range (eg, 17-24 bar) by appropriate selection of the bias of the control spring, The control range of the consumer valve shaft is, for example, 6 to 24 bar. That is, the merge is performed only when the control pressure difference between the ports a4 and b4 exceeds 17 bar. Below this threshold, i.e. below a control pressure difference of less than 17 bar, the device operates as a dual circuit system and can only be switched to a single circuit system by actuating the control valve 38.

  In the embodiment described above, the control valve 38 and the LS signal valve 32 are formed separately from the merge proportional valve 36.

  In the embodiment shown in FIG. 4, the functions of the LS signal valve 32 and the control valve 38 are integrated into the merging proportional valve 36. In the embodiment shown in FIG. 4, the consumer valve stems are configured similarly to the embodiment described above, i.e., each shaft is configured with a LIPD throttle orifice 14 and a downstream LIPD pressure compensation valve 16, and several consumers. The valve shaft (travel gear, excavator, boom (circuit 2), arm) can be joined.

  The merge valve 12 includes a merge proportional valve 136 having a merge throttle orifice 26 and a downstream merge pressure compensation valve 28. The valve spool of the merging proportional valve 136 receives a control pressure difference via the control ports a4 and b4, the pilot control lines 52 and 54, and the control devices 44 and 46 in order to start merging. For the sake of clarity, FIG. 4a shows an enlarged switching code of the merging proportional valve 136. FIG. The merging proportional valve 136 has two pressure ports P1, P2, merging ports S1, S2, a port P ″ provided downstream of the throttle orifice, and a return port P ′ provided upstream of the direction member. Two LS ports LS1 and LS2 and a control port LS are provided. The two ports LS1, LS2 are connected to the LS lines 20, 18, respectively, the merging ports S1, S2 are connected to the merging lines 24, 66, respectively, and the two pump ports P1, P2 are connected to the pump lines 40, 42, respectively. ing.

  Similarly to the above-described embodiment, the port P ″ is connected to the inlet port P of the merging pressure compensation valve 28, and the outlet A of the merging pressure compensation valve 28 is connected to the return port P ′ via the connection flow path. Yes. The LS port LS of the merging proportional valve 136 is connected to the LS port LS of the merging pressure compensation valve 28, and acts in the closing direction with respect to the piston of the pressure compensation valve together with the spring force having a weak control pressure at the port LS. The pressure downstream of the throttle orifice 26 is transmitted via a separate control line to the control surface of the pressure compensating valve piston acting in the opening direction.

  The merging proportional valve 136 is biased to the basic position (0) by a control spring. In this basic position, all ports are blocked. By inputting the control pressure, the valve spool can be moved to the control positions indicated by (a) and (b), and the opening of the throttle orifice 26 and the direction of the pressure medium flow are determined. The function of the merging proportional valve 136 is the same as that of the embodiment described in detail with reference to FIG. In addition to these control positions, the merging proportional valve 136 has a fourth switching position (c) in which the two ports P1, P2 and LS1, LS2 are connected to each other and the other ports are blocked.

  As shown in FIG. 4, the valve spool of the merging proportional valve 136 is biased via two control springs 86 and 88. In order to adjust the basic position, these control springs are biased and the bias should be selected so that there is a phase shift between the consumer valve shaft and the merging shaft when the consumer and merging shaft are operating, as described above. Can do. The merge proportional valve 136 has a fourth position (c). The piston 90 is held against the stop by a control flow path 92 and an override valve 94 having a high control pressure of 30 bar, for example. In this stop position, the control spring 88 receives a basic bias with the valve spool positioned at the basic position (0). The override valve 94 is controlled by a shuttle valve 96 having a function corresponding to the shuttle valve 64 of FIG. That is, the inlet port of the shuttle valve 96 is connected to a control line to a control flow path 60 (see FIG. 2) and a control device (not shown), allowing the operator to manually generate control pressure. The higher of these two control pressures (the maximum control pressure output from the control devices 47, 46, 50, 48 or the manually set control pressure) is applied to the control surface of the override valve 94 via the shuttle valve 96. When input, the override valve 94 moves against the force of the reset spring to the switching position indicated by (a) where the control flow path 92 is connected to the tank T. In the switching position (a) of the override valve 94, a control line 98 for transmitting a high control pressure is connected to another control flow path 100 connected to the shuttle valve 102 as shown in the lower part of FIG. The other inlet port is connected to the pilot control line 52. That is, the higher of the two control pressures existing in the control flow path 100 or the pilot control line 52 is transmitted to the port a4 via the shuttle valve 102, and the fourth switching position ( Acts in the direction of c).

  When the override valve 94 is switched to the switching position (a), the piston 90 is released from the load and moves toward the rear stop, and the bias of the control spring 88 is correspondingly reduced. The control pressure of the control line 98 is sent to the control flow path 100 by the override valve 94 and transmitted to the shuttle valve 102. As a result of releasing the control pressure present in control spring 88 and port a4 (control pressure in control flow path 100 or control pressure in pilot control line 52), the valve spool has two pump ports P1, P2, pump line 40, 42 and the ports LS1, LS2 move to the fourth switching position (c) where they are connected to each other. The device is then switched to a single circuit system, and this mode is required, for example, during travel and simultaneous operation of the device. That is, the function of the control valve 38 in FIG. 2 is integrated into the merge proportional valve by the switching position (c).

  In order to merge the consumer valve shafts, the merge proportional valve 136 moves to the position indicated by (a) or (b). For example, when a consumer valve shaft (see FIG. 2) provided for the arm is joined, a relatively high control pressure is input to the port a4 by operating the pilot controller 44, and the valve spool is (a) Move to the position indicated by. The opening of the throttle orifice 26 is determined by the axial movement of the valve spool, and the pump port P1 and the outlet port P '' are connected. The confluence pressure compensating valve 28 is moved to the control position by the pressure downstream of the throttle orifice, and the inlet port P is connected to the outlet port A. The pressure medium flows to the return port P ′ via the outlet port A of the merging pressure compensation valve, and flows from the port P ′ to the consumer (arm) to be merged via the merging port S <b> 2 of the merging line 66. As in the embodiment shown in FIG. 3, the supply of the pressure medium flow to be merged is performed by a merging channel 68 connected via a check valve 70 to a branch channel 78 or 80 to the directional member of the proportional valve 34. Again, merging is usually done only in the direction where a high pressure medium is required.

  At the position (a) of the merging proportional valve 136, the two ports LS1 and LS are connected, and the LS pressure of the merging circuit 2 exists in the pressure compensation valve 28. If the pressure downstream of the throttle orifice 26 is higher than the load pressure of the LS line 20, the pressure compensation valve 28 moves to the end position where the LS port is connected to the port P, and this high pressure is the new maximum load. The pressure is sent to the LS line 20.

  The confluence of the consumers of the circuit 2 is similarly performed by inputting a high control pressure to the port b4, and the confluence proportional valve moves to the control position indicated by (b).

  When multiple consumers of circuit 2 are activated, the corresponding pump flow from circuit 4 may not be distributed independently of the load pressure among the consumers to be merged. In order to ensure optimal operation of the confluenced consumer having a high load, a nozzle 138 or other throttling means is disposed in the confluence channel 68 of the proportional valve 34, usually upstream of the consumer having a low load. And a simpler oil distribution can be achieved by the directional groove of the proportional valve 34.

  Several operating conditions are described for further understanding of the valve assembly.

  It is assumed that the valve spool bias of the merging proportional valves 36, 136 is selected such that the control range is approximately 17-24 bar and the spindle control range is selected between 6-24 bar.

  1) In order to quickly level the extended excavator device, the maximum control pressure is input, i.e. the pilot control devices 44, 46 are armed so that the throttle orifice of the consumer valve shaft is fully opened. Operates to set functions on retract and boom pull. Since approximately the same control pressure exists in the two pilot control lines 52, 54, the merging axis remains at the center position. Because the two circuits 2 and 4 are disconnected, there is a dual circuit system, where each consumer cannot interact, which is particularly important during the critical operation of setting up the shovel. As both consumers (arm and boom) increase in speed, the boom lift must immediately and continuously decrease to zero because of the velocity kinematics of the arm. That is, there is a control pressure difference due to different adjustments of the pilot control devices 44 and 46 on the control surface of the merging proportional valves 36 and 136. Merge occurs due to the control pressure difference exceeding 17 bar, and the released pressure medium is transmitted from the boom circuit (circuit 2) via the merge shaft to the merge line 66, and from the merge line 66 to the arm, and the maximum arm speed. Is guaranteed.

  2) When the turntable is operated and the boom lifting function is set, there are two cases.

  a) The merging shaft receives the control pressure adjusted by the pilot controller 46, the control pressure difference acting on the merging proportional valve 36 is 17 bar or more, the merging shaft connects the circuit 4 to the circuit 2 and The pressure medium that is not preferentially absorbed is supplied downstream of the throttle orifice 34 of the boom shaft and the pressure compensation valve 16. This occurs even during the acceleration stage of the turntable. The LS line 18 is connected to the pressure compensation valve 28 via the LS signal valve 32 of the embodiment according to FIGS. 2 and 3 or the LS port of the merging proportional valve 136 of the embodiment according to FIG.

  b) If boom shaft merging is not desired, a turntable control pressure signal or another suitable control signal is tapped by dedicated logic (not shown) and input to merging shaft port a4, initially merging Therefore, the two circuits for operating the turntable and the boom can be operated independently of each other. Only when the control pressure difference between the ports a4 and b4 exceeds 17 bar, the two circuits are connected via the junction shaft. That is, in the last option, a control pressure signal that enables merging only when a predetermined control pressure difference is exceeded is output to the merging shaft via the logic.

  3) When controlling only two footboards, the control signal is not output to the merging shaft via the pilot control devices 48 and 50 for operating the footwear. Even during cornering on difficult terrain, the two circuits 2, 4 remain disconnected.

  4) If other consumers must be added in addition to the travel drive mechanism, linear travel must be further ensured. In the embodiment according to FIG. 2, the switching valve 62 is switched by the control pressure output by the pilot control devices 48, 50 for operating the footwear, and the control valve 38 is switched via the line 60 to the pilot control device 44, By inputting the control pressure generated by 46 or an external control pressure, the circuits 2 and 4 are switched to the passing position where they are connected as a single circuit.

  In the embodiment according to FIG. 4, the connection as a single circuit is established by switching the override valve 94 by the control pressure output from the pilot control devices 44, 46 via the control flow path 60 and the shuttle valve 96. The piston 90 is released, and the valve spool of the merging proportional valve 136 moves to the fourth switching position indicated by (c) where the two circuits 2 and 4 are merged. As described above, the override valve 94 can be switched by inputting an external control signal.

  The embodiment according to FIG. 5 differs from the embodiments according to FIGS. 2 and 3 only in the design of the LS signal valve 32. The LS signal valve 32 according to FIG. 2 and FIG. 3 maintains the two LS lines 18 and 20 in a separated state at the time of merging, and controls the pressure compensation valve 28 according to the merging direction of the LS line 18 or LS line 20. Although connected to one of the surfaces, the LS signal valve 32 according to FIG. 5 is connected to the connection between the two LS lines 18 and 20 at the time of merging and between the lines 18 and 20 and one of the control surfaces of the pressure compensation valve 28. Establish a connection between. Thus, at the time of merging, the two circuits 2, 4 are always at the same pressure level determined by the maximum load pressure of all hydraulic consumers operating in the two circuits 2, 4. Since the pressure level of the pressure receiving circuit rises when the maximum load pressure of the pressure receiving circuit is lower than that of the pressure supplying circuit, the embodiment according to FIG. 5 is preferable in terms of energy balance than the embodiment according to FIGS. Absent.

  FIGS. 6a and 6b show one circuit in an embodiment where the selection of the maximum load pressure is made by, for example, a shuttle valve chain or a check valve 139 as shown, rather than by a pressure compensation valve with an additional control edge. Figure 2 shows two alternatives for delivering load pressure from one to the other circuit. Here, transmission of the maximum load pressure from the pressure receiving side first circuit to the pressure supply side second circuit is such that the maximum load pressure (= LS pressure) of the first circuit is higher than the maximum load pressure of the second circuit. Necessary when expensive. According to FIG. 6a, each check valve 140 is connected between two LS lines 18, 20 in two lateral switching positions of the LS signal valve 32, which check valves are connected to the LS line 18 of the second circuit. To LS line 20 of the first circuit. If the LS pressure in the first circuit is lower than that in the second circuit, the pressure in the first circuit is maintained at a low level. On the other hand, when the LS pressure of the first circuit is higher than that of the second circuit, this high LS pressure can be sent to the second circuit.

  In the alternative according to FIG. 6b, the function “connect one of the control surfaces of the pressure compensation valve 28 to the LS line of the second circuit” and “send the high LS pressure of the first circuit to the second circuit” It is divided between the two valves 32 and 33. The LS signal valve 32 is the same as the LS signal valve 32 of the embodiment according to FIGS. The LS passage connection valve 33 operates simultaneously with the LS signal valve 32 and connects one of the check valves 140 between the LS lines 18 and 20 according to the merging direction.

  In the two alternatives according to FIGS. 6a and 6b, the LS pressure of the first circuit is also sent to the second circuit when the load pressure of the joining consumer is low, but the LS pressure of the first circuit is It is higher than the LS pressure of the second circuit. However, if only the problem of comparison of the load pressure of the consumer to be merged with the LS pressure of the second circuit as in the embodiment according to FIGS. 2 to 4, the maximum load pressure of the consumer to be merged is determined separately. It must be possible to enter the selected pressure on lines 18, 20 in FIGS. 6a, 6b independently of the LS line to the variable displacement pump.

  A hydraulic dual circuit system for controlling a mobile device, in particular a consumer of a crawler device, is disclosed, where two circuits can be joined for a selected consumer by a merge valve. Supply of the pressure medium to the consumer is performed via a LIPD (load independent pressure distribution) throttle orifice and a LIPD pressure compensation valve. In the merging valve, the merging flow from the circuit to be merged to the other circuit is supplied at a position downstream of the throttle orifice, and / or the merging occurs only at a relatively late timing, that is, at a different phase from the consumer to be merged. Designed as such.

FIG. 1 is a schematic diagram of the basic functions of the dual circuit system of the present invention. FIG. 2 is a switching diagram of the dual circuit system of the present invention for a crawler device. FIG. 3 is an enlarged view of the junction valve of FIG. 4 and 4a show another embodiment of a merging valve. FIG. 5 shows a third embodiment, in which the LS pressures of the two circuits are always the same during merging. 6a and 6b show two alternatives of the fourth embodiment.

Explanation of symbols

2 First circuit 4 Second circuit 6 Variable displacement pump 7 Variable displacement pump 8 Consumer 10 Consumer 12 Merge valve 14 Throttle orifice 16 Pressure compensation valve 18 LS line 20 LS line 21 Load holding valve 22 Pump line 24 Merge line 26 Joint orifice 28 Joint pressure compensation valve 30 Actuation line 32 LS signal valve 33 LS passage connection valve 34 Proportional valve 36 Joint proportional valve 38 Control valve 40 Pump line 42 Pump line 44 Manual pilot control device 46 Manual pilot control device 48 Foot Type pilot control device 50 foot type pilot control device 52 pilot control line 54 pilot control line 56 shuttle valve assembly 58 shuttle valve assembly 60 control flow path 62 switching valve 66 merging line 68 merging flow path 70 check valve 72 directional member 74 Flow path 76 Connection flow path 78 Branch flow path 80 Branch flow path 82 Load holding valve 84 Load holding valve 86 Control spring 88 Control spring 90 Piston 92 Control flow path 94 Override valve 96 Shuttle valve 98 Control line 100 Additional control flow path 136 Merge proportional valve 138 Nozzle 139 Check valve 140 Check valve

Claims (14)

A hydraulic dual circuit system for controlling a mobile device, in particular a consumer of a crawler device, and
A variable displacement pump (6, 7) that operates according to the maximum load pressure is provided for each hydraulic circuit (2, 4),
Each hydraulic circuit (2, 4) supplies a pressure medium to the corresponding consumer,
At least one consumer connected to the other (4,2) of the circuit, with the pump (6,7) of one (2,4) of the circuit sending pressure medium to the other (4,2) of the circuit The circuit (2, 4) is connected via a merging valve (12) such that a pressure medium is supplied by the pump (6) and the pump (7).
A hydraulic dual circuit system in which a load independent pressure distribution (LIPD) valve assembly having a throttle orifice (14) and a pressure compensation valve (16) is provided for the consumer,
The merging valve (12) causes the pressure medium to flow from one of the circuits (2, 4) via the merging line (24, 66) to the constricting orifice (14) of the consumer to be merged and the pressure compensation. Hydraulic dual circuit system, characterized in that it is supplied downstream of the valve (16). In claim 1,
The merge line (24, 66) is branched downstream of the throttle orifice (14) and upstream of the directional member of the proportional valve (34) forming the throttle orifice (14). A characteristic dual circuit system. In claim 1 or claim 2,
The said merging valve (12) has a merging proportional valve (36) provided with the downstream merging pressure compensation valve (28), The dual circuit system characterized by the above-mentioned. In claim 3,
The dual proportional circuit system is characterized in that the operation of the merging proportional valve (36) is performed hydraulically by the action of a control pressure. In claim 4,
The dual circuit system, wherein the control pressure is input to the merging proportional valve (36) according to operation of a pilot controller (44, 46, 48, 50) or other logic. In any one of Claims 3-5,
The junction valve (12) has an LS signal valve (32),
The dual circuit system, wherein the maximum load pressure of the circuit (2, 4) is input to the control side of the merging pressure compensation valve (28) by the LS signal valve (32). In any one of Claims 3-6,
The merging valve (12) has a control valve (38) in addition to the merging proportional valve (36),
A dual circuit characterized in that the lines (40, 42; 18, 20) of the circuit (2, 4) conveying the pump pressure and the load pressure are connected to each other by a control valve (38) according to a control signal system. In claim 6 or claim 7,
A dual circuit system, wherein at least one function of the LS signal valve (32) and the control valve (38) is integrated into a confluence proportional valve (136). In any one of Claims 3-8,
The main spools of the proportional valve (34) and the merging proportional valve (36) provided corresponding to the consumer are biased to a basic position by a control spring,
The dual circuit system, wherein a bias of the control spring provided corresponding to the merging proportional valve (36) is larger than a bias of the proportional valve (34) provided corresponding to the consumer. In any one of Claims 1-9,
A dual circuit system, characterized in that the supply to at least one joining target consumer (8, 10) is effected via a throttling means (138). In claim 8,
An override valve (24),
A control signal is sent to the merge proportional valve (136) by the override valve so that the valve spool of the merge proportional valve (136) moves to a predetermined end position (c) to which the circuits (2, 4) are connected. Dual circuit system characterized by being input. In any one of Claims 3-11,
A load holding valve (82, 84) is provided upstream of the consumer;
The dual circuit system, wherein the merging line (24, 66) branches between the load holding valve (82, 84) and the directional member of the proportional valve (34). A hydraulic dual circuit system for controlling a mobile device, in particular a consumer of a crawler device, and
A variable displacement pump (6, 7) that operates according to the maximum load pressure is provided for each hydraulic circuit (2, 4),
Each hydraulic circuit (2, 4) supplies a pressure medium to the corresponding consumer,
At least one consumer connected to the other (4,2) of the circuit, with the pump (6,7) of one (2,4) of the circuit sending pressure medium to the other (4,2) of the circuit The circuit (2, 4) is connected via a merging valve (12) such that a pressure medium is supplied by the pump (6) and the pump (7).
A hydraulic dual circuit system in which a load independent pressure distribution (LIPD) valve assembly having a throttle orifice (14) and a pressure compensation valve (16) is provided for the consumer,
The merging valve (12) is operated according to a control signal generated by a control device (44, 46; 50, 48) for operating the consumer, and is optionally operated according to logic. Type dual circuit system. In claim 13,
The merging valve (12) includes a merging throttle orifice (26) and a merging pressure compensation valve (28),
The dual circuit system according to claim 1, characterized in that the confluence throttle orifice (26) is moved to an open position to initiate a confluence by a control pressure or a control pressure difference.

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