Method for controlling the operating state of a hydraulic actuator od a tamping unit of a track construction machine and arrangement for implementing the method

Abstract

Method for controlling the operating state of a hydraulic actuator (7), which as part of a working unit (4) of a construction machine (14) provides movable mechanical unit components, in particular a tool holder or a tool (6), and whose pressure chambers with their working ports (A, B) are connected to the piping system of a hydraulic circuit by means of at least one control valve (1, 12a, 12b, 12c, 12d, 12e), wherein on the one hand the operating state is maintained when the pressure chambers of the actuator (7) are completely separated from the piping system of the hydraulic circuit by means of the at least one control valve (12a, 12b, 12c, 12d, 12e) and on the other hand a change in the operating state is effected by means of a pulsed control of the at least one control valve (12a, 12b, 12c, 12d, 12e).

Description

[0001] The invention relates to a method for controlling the operating state of a hydraulic actuator which, as part of a working unit of a construction machine, in particular a tamping unit of a track construction machine, provides movable mechanical unit components, in particular a tool holder or a tamping tool, and whose pressure chambers are connected with their working connections to the line system of a hydraulic circuit by means of at least one control valve.

[0002] Hydraulic actuators are currently operated using proportional spool valves. Leakage oil losses cannot be avoided in this case. To maintain an operating state of the actuator, such as the piston stroke of a cylinder, in order to clamp a mechanical component, particularly a tamping tool or tamping pick, in a specific position, additional valves, typically pilot-operated check valves, must be provided in the connecting lines of the hydraulic actuator. Controlling these proportional valves requires a high level of control complexity, and their use is typically expensive.

[0003] The invention is based on the object of providing an improvement over the prior art for a method for controlling the operating state of a hydraulic actuator of the type mentioned above. Furthermore, it is an object of the invention to provide an arrangement suitable for implementing this method.

[0004] According to the invention, these objects are achieved by a method according to claim 1 and an arrangement for carrying out this method according to claim 10. Dependent claims specify advantageous embodiments of the invention.

[0005] In its basic form, the subject matter of the invention is a method for controlling the operating state of a hydraulic actuator which, as part of a working unit of a construction machine, in particular a tamping unit of a track-laying machine, provides movable mechanical unit components, in particular a tool holder or a tool, and whose pressure chambers are connected with their working connections to the line system of a hydraulic circuit by means of at least one control valve. On the one hand, the operating state is maintained with the pressure chambers of the actuator completely separated from the line system of the hydraulic circuit by means of the at least one control valve, and on the other hand, a change in the operating state occurs by means of a clocked control of the at least one control valve. In this way, no proportional valves with their associated disadvantages are required.Instead, seat valves are used, which are controlled in a timed manner and do not cause any leakage oil losses when disconnected from the hydraulic system.

[0006] An advantageous embodiment of the method according to the invention provides that the pressure fluctuations during the independent pressure controls of the working ports of the pressure chambers of the actuator are dampened by compensating movements of at least one hydraulic accumulator connected to the working ports of the actuator or to the hydraulic line system. It is advantageous for the method that the temporal rate of the operating state change is determined by the duty cycle of the control signal of at least one control valve.

[0007] The duty cycle is the ratio of the time duration TA of a signal level of the control signal, which switches a control valve from a passive basic position to an active position and leaves it in this position, to the time duration TP in which the signal level of the control signal does not result in any change in the passive basic position of the control valve.

[0008] Alternatively, the duty cycle is the ratio of the time duration TA of a signal level of the control signal, which switches a control valve from a passive basic position to an active position and leaves it in this position, to the sum of the total time duration TA +TP , which is composed of the above time duration TA and the time duration TP , in which the signal level of the control signal does not result in a change in the passive basic position of the control valve.

[0009] In a particularly advantageous embodiment of the method for controlling the operating state of the hydraulic actuator, the clock rate of the control signal of the control valves is set as a function of the characteristic variables of the working unit in such a way that the change in the operating state occurs quasi-continuously over time.

[0010] An example of a characteristic physical quantity of the working unit is the mass of the unit.

[0011] The clock rate f T is the inverse of the sum TA +TP , which is composed of the time period TA during which a control valve is in an active switching position and the time period TP during which the control valve is in the passive switching position.

[0012] For the method for controlling the operating state of a hydraulic actuator, it is advantageous if a control valve, which is connected to a first working connection of the hydraulic actuator via a connecting line, and another control valve, which is connected to a second working connection of the hydraulic actuator via a further connecting line, are controlled simultaneously.

[0013] In a further advantageous embodiment of the method, the actuator in the hydraulic line system can be bridged by a bypass circuit by controlling the control valves.

[0014] In one possible embodiment of the method for controlling the operating state of the actuator, the operating state is characterized by the angle that a movable part of a tamping tool, in particular a tamping pick, of a tamping unit of the track construction machine assumes with respect to a rest position.

[0015] In a further embodiment of the method for controlling the operating state of a hydraulic actuator, the operating state is characterized by the stroke that a piston of the auxiliary cylinder of a tamping unit of a track construction machine assumes with respect to an initial position.

[0016] In an alternative embodiment of the method for controlling the operating state of the hydraulic actuator, the operating state is characterized by a stroke that a piston of the translatory hydraulic cylinder of a lifting unit of a track construction machine assumes with respect to a basic position.

[0017] The control valves in the arrangement for carrying out the above-mentioned process are designed as seat valves to prevent leakage oil losses.

[0018] In one embodiment of the subject matter of the invention, at least one 4 / 3 way seat valve is used.

[0019] A 4 / 3-way seat valve is characterized by four ports each, which are arranged as two inlets and two outlets, and by the three defined switching positions: (1) no connections between both inlets and both outlets, (2) connection between the first inlet and the first outlet and the second inlet and the second outlet, and (3) connection between the first inlet and the second outlet and the second inlet and the first outlet.

[0020] It is particularly advantageous if at least two 2 / 2-way seat valves are used as valves per pressure chamber of the hydraulic actuator, since the control edge of the hydraulic actuator is decoupled from the control with at least one 4 / 3-way seat valve.

[0021] A 2 / 2-way seat valve is characterized by two ports each arranged as an inlet and an outlet, and by two defined switching positions: (1) no connection between inlet and outlet and (2) connection between inlet and outlet.

[0022] Both 4 / 3-way valves and 2 / 2-way valves in seat design are available from various valve manufacturers such as Parker, Rexroth, HAWE, Hydac or Bucher under the designations Parker GS02, Rexroth SEC, HAWE NBVP, Hydac WSM or Bucher WS22.

[0023] An alternative design of the control valve arrangement provides that each control valve consists of at least two valves connected in parallel in order to be able to control either larger volume flows of the hydraulic medium or to increase the reliability of the valve arrangement.

[0024] The invention is explained below by way of example with reference to the accompanying figures. They show schematically: Fig. 1A proportional slide valve with two pilot-operated check valves according to the state of the art; Fig. 2A side view of a switch tamping unit with upwardly pivoting tamping tools; Fig. 3A simplified detailed view of Fig. 2 ; Fig. 4A schematic representation of Fig. 3 , which illustrates the pivoting of the tamping tool; Fig. 5A tamping unit for the synchronous tamping of up to three sleepers, which comprises three individual units with pivoting tamping tools as in Fig. 2 comprises; Fig. 6aA schematic representation of the inventive control of a hydraulic actuator with four fast-switching on-off valves and two hydraulic accumulators; Fig. 6bAlternative 4 / 3 directional seat valve for the arrangement according to Fig. 6a ; Fig. 7A construction machine on a track with a tamping unit and a lifting and straightening unit; Fig. 8The top view of a switch arrangement as part of a track network.

[0025] Fig. 1 represents a valve arrangement according to the prior art which is suitable for maintaining the operating state of a hydraulic actuator over a definable period of time.

[0026] A proportional slide valve 1 with the three defined switching positions (1) no connections, (2) connection between the first inlet and the first output and the second inlet and the second output and (3) connection between the first inlet and the second output and the second inlet and the first output is connected on the inlet side to a hydraulic line system with a connection P and a connection T. A pilot-operated check valve 2a or 2b must be provided between the two outputs of the proportional slide valve upstream of the working connections A or B of a hydraulic actuator (not shown) in order to ensure the desired functionality. Without these check valves 2a, 2b, leakage oil losses would occur, which would cause the actuator to change its operating state when the pressure chambers are separated from the hydraulic system.

[0027] In Fig. 2 shows the application of the hydraulic actuator 7 in a tamping unit 4 for tamping a sleeper 9, which, together with rails 8, forms a track grid supported on a ballast bed 10. The tamping unit 4 is itself connected to the machine frame 3 of a track construction machine and comprises a tamping tool with a pair of pivot arms 5, to which a tamping pick is connected by means of the tamping pick holder 6. Via hydraulic actuators 7, which for this application are designed as translatory cylinders, the tamping picks, arranged in two rows with increasing distance from the rail, can be pivoted upwards via their tamping pick holders 6 in order to enable the tamping tools to be used in a way that is adapted to the position of the rails 8 at switches.

[0028] In Fig. 3 is the tamping unit of Fig. 2 simplified with the essential elements for understanding the swiveling process, i.e. the U-shaped swivel arm 5, the tamping pick holder 6 with tamping pick and the hydraulic actuator 7.

[0029] The process of pivoting is in Fig. 4 illustrated by two schematic diagrams showing the arrangement of Fig. 3 was replaced by a combination of basic geometric-kinematic elements. The tamping tine holder 6 and tamping tine are connected to the swivel arm 5 of the tamping unit 4 via a pivot bearing. The hydraulic actuator 7 is rotatably connected to the swivel arm 5 of the tamping unit 4 on the one hand and to the tamping tine holder 6 with tamping tine on the other. In an initial position of the piston of the actuator 7, the tamping tine holder 6 and tamping tine are aligned parallel to the swivel arm 5 and can thus participate in the tamping process when the tamping unit 4 is lowered.

[0030] If the piston of the hydraulic cylinder is moved by a working stroke h relative to this initial position, this results in a pivoting of the tamping tine holder 6 and the tamping tine by an angle ϕ due to the geometric arrangement of the components, whereby the tamping tine pivoted in this way is only available for use in the tamping process in this open position and from a certain opening angle ϕ n is no longer available at all.

[0031] Tamping with one or more tamping picks in the open position serves to achieve a significantly improved tamping result on switches, particularly in the case of a tamping machine whose tamping units 4 cannot be moved horizontally or can only be moved to a limited extent.

[0032] Fig. 5 represents a variant of the tamping unit 4, in which three identical tamping units 4A, 4B and 4C with individually pivotable tamping pick holders 6 with tamping picks for tamping one sleeper 9 each of a track grid with rails 8 mounted on a ballast bed 10 are arranged to form a combined unit 4 for the synchronous tamping of up to three sleepers 9. The hydraulic actuators 7A are used to pivot the tamping picks, the adjusting movement is carried out by means of the adjusting cylinders 7B and the lowering of each of the units is carried out via a hydraulic actuator 7C.

[0033] In Fig. 6a A variant of the valve arrangement 12a, 12b, 12c, and 12d is shown, which allows control of a hydraulic actuator 7, 7A, 7B, 7C according to the method according to the invention. The hydraulic actuator 7, 7A, 7B, 7C is a translatory actuator with a piston that divides the cylinder pressure chamber into a piston-side pressure chamber and a rod-side pressure chamber. The working port, designated A, of the piston-side pressure chamber of the hydraulic actuator 7, 7A, 7B, 7C is connected to port T of the hydraulic line system by means of the valve 12a. Valve 12c, on the other hand, connects A to port P of the hydraulic line system.

[0034] In contrast, valve 12b enables the establishment of a connection between the working port B of the rod-side pressure chamber of the hydraulic actuator 7 and the port T of the hydraulic line system, while valve 12d is arranged for the connection of the working port B to the port P.

[0035] In addition, hydraulic accumulators 13 are located between the pressure chamber connections A, B of the hydraulic actuator 7, 7A, 7B, 7C and the control valves 12a, 12b, 12c and 12d to reduce or avoid pressure fluctuations.

[0036] In Fig. 6a On-off valves, each with two connections and two different switching positions (1) and (2), are used as control valves 12a, 12b, 12c, and 12d. The passive basic position (1) of such an on-off control valve 12a, 12b, 12c, or 12d separates its output from its input. If the on-off control valve 12a, 12b, 12c, or 12d is activated against a spring force by an electromagnetic actuating device, in the active position (2) the valve output is connected to the valve input in such a way that the hydraulic medium can act either statically or dynamically both in the direction of the pressure chamber of the hydraulic actuator 7 and in the direction of the connections P and T of the hydraulic line system.

[0037] Fig. 6b shows a 4 / 3 way seat valve 12e as an alternative to the Fig. 6a shown 2 / 2 directional seat valves 12a-12d. Specifically, the 2 / 2 directional seat valves 12a-12d are replaced by a 4 / 3 directional seat valve 12e. However, the resulting coupling results in a loss of flexibility in controlling actuator 7. In particular, it is not possible to connect both working ports A and B of the pressure chambers simultaneously to either port P or port T of the hydraulic line system in order to implement functions such as positioning the actuator with both pressure chambers under pressure and moving the actuator without resistance in the floating position or flushing the pressure chambers. It is also not possible to connect port P and port T directly to one another in order to bypass the hydraulic medium past the actuator (bypass).

[0038] In Fig. 7 A construction machine 14 is shown on a track, the machine frame of which is connected to a tamping unit 4 and a lifting and straightening unit 15. Analogous to the tamping unit 4, the lifting and straightening unit 15 also contains various hydraulic actuators 7 for executing mostly translational movements.

[0039] Fig. 8 finally shows a switch arrangement consisting of rails 8 and sleepers 9 of a track as a section of a track network in plan view, wherein the switch is set by means of the switch setting device 16.

[0040] The subject matter of the invention is not limited to the illustrated embodiments. In particular, arrangements with at least one 4 / 3-way valve in seat configurations per hydraulic actuator, as well as those with parallel valves per valve position, are encompassed by the claims.

Claims

1. Method for controlling the operating state of a hydraulic actuator (7) which, as part of a tamping unit (4) of a track-laying machine (14), provides movable mechanical unit components, in particular a tool holder or a tool (6), and whose pressure chambers with their working connections (A, B) are connected to the line system of a hydraulic circuit via at least one control valve (1, 12a, 12b, 12c, 12d, 12e), characterized in that on the one hand, the operating state is maintained with complete separation of the pressure chambers of the actuator (7) from the line system of the hydraulic circuit by the at least one control valve (12a, 12b, 12c, 12d, 12e) and, on the other hand, a change in the operating state takes place by means of a clocked control of the at least one control valve (12a, 12b, 12c, 12d, 12e).

2. Method according to claim 1, characterized in thatthe pressure fluctuations during the independent pressure control of the working connections (A, B) of the pressure chambers of the actuator (7) are damped by at least one hydraulic accumulator (13) connected to the connecting lines of the actuator (7) or to the hydraulic line system.

3. Method according to claim 1 or 2, characterized in that the temporal rate of the operating state change is determined by a clock ratio of a control signal of at least one control valve (12a, 12b, 12c, 12d, 12e).

4. Method according to claim 3, characterized in that a clock rate of the control signal of the control valves (12a, 12b, 12c, 12d, 12e) is set as a function of characteristic variables of the tamping unit (4), such as its mass, in such a way that the change in the operating state occurs quasi-continuously over time.

5. Method according to one of claims 1 to 4, characterized in thatthe control valve (12a, 12c, 12e) connected via a connecting line to a first working connection (A) of the hydraulic actuator (7) and the control valve (12b, 12d, 12e) connected via a further connecting line to a second working connection (B) of the hydraulic actuator (7) are controlled simultaneously.

6. Method according to one of claims 1 to 4, characterized in that by controlling the control valves (12a, 12b, 12c, 12d) the actuator (7) in the hydraulic line system is bridged by a bypass circuit.

7. Method according to one of claims 1 to 6, characterized in that the operating state is characterized by an angle (ϕ) which a movable part of a tamping tool (6) of the tamping unit (4) of the track construction machine (14) assumes with respect to a rest position.

8. Method according to one of claims 1 to 6, characterized in thatthe operating state is characterized by a stroke (h) which a piston of an auxiliary cylinder (7B) of the tamping unit (4) of the track construction machine (14) assumes in relation to an initial position.

9. Method according to one of claims 1 to 6, characterized in that the operating state is characterized by a stroke (h) which a piston of the translatory hydraulic actuator (7C) of the lifting unit (15) of the track construction machine (14) assumes in relation to an initial position.

10. Arrangement for carrying out a method according to one of claims 1 to 9, characterized in that each of the control valves (12a, 12b, 12c, 12d, 12e) is designed as a seat valve.

11. Arrangement according to claim 10, characterized in thateach pressure chamber is controlled by at least two control valves (12a, 12b, 12c, 12d), which are characterized by two connections each arranged as an input and as an output, and by two defined switching positions: - no connection between input and output and - connection between input and output.

12. Arrangement according to claim 10, characterized in that the pressure chambers are controlled by at least one control valve (12e), which is characterized by four connections each, which are arranged as two inlets and two outlets, and by the three defined switching positions: - no connections between both inlets and both outlets, - connection between the first inlet and the first outlet and the second inlet and the second outlet and - connection between the first inlet and the second outlet and the second inlet and the first outlet.

13. Arrangement according to one of claims 10 to 12, characterized in that each control valve (12a, 12b, 12c, 12d, 12e) consists of at least two valves connected in parallel.

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