Viscous material pump with adjustable limitation of the delivery pressure

Abstract

A thick matter pump includes a hydraulically-driven two-cylinder piston-pump configured to generate a thick matter delivery pressure. The thick matter pump also includes a hydraulic pump configured to apply hydraulic fluid to the two-cylinder piston-pump via a drive line. The hydraulic pump includes a pressure regulator that is adjustable to a target value of pressure of the hydraulic fluid for limiting the thick matter delivery pressure, and the thick matter delivery pressure is adjustably limited. The pressure of the hydraulic fluid is limited in the drive line, via an adjustable pressure-limiting valve, to an adjustable maximum pressure. The target pressure of the pressure regulator and the maximum pressure of the hydraulic fluid are adjustable through a joint adjusting element.

Claims

1. A thick matter pump comprising: a hydraulically-driven two-cylinder piston-pump configured to generate a thick matter delivery pressure; and a hydraulic pump configured to apply hydraulic fluid to the two-cylinder piston-pump via a drive line, the hydraulic pump including a pressure regulator that is adjustable to a target value of a pressure of the hydraulic fluid for limiting the thick matter delivery pressure, wherein the thick matter delivery pressure is adjustably limited, wherein the pressure of the hydraulic fluid is limited in the drive line, via an adjustable pressure-limiting valve, to an adjustable maximum pressure, wherein the target value of the pressure of the hydraulic fluid of the pressure regulator and the maximum pressure of the hydraulic fluid are adjustable through a joint adjusting element.

2. The thick matter pump of claim 1, wherein the joint adjusting element is configured to set the target value of the pressure of the hydraulic fluid of the pressure regulator and the maximum pressure of the hydraulic fluid synchronously such that the maximum pressure always lies above the target pressure by a pre-specified differential pressure.

3. The thick matter pump of claim 1, wherein the joint adjusting element includes a first pilot valve adjustable to the target value of the pressure of the hydraulic fluid, wherein a first input side of the first pilot valve is connected with an adjusting slide of the pressure regulator of the hydraulic pump, and wherein a first output side of the first pilot valve is connected to a hydraulic reservoir, wherein the first pilot valve opens upon reaching the target pressure.

4. The thick matter pump of claim 3, wherein the joint adjusting element includes a second pilot valve, wherein a second input side of the second pilot valve is connected with a main stage of the pressure-limiting valve, wherein a second output side of the second pilot valve is connected with the first input side of the first pilot valve, wherein the second pilot valve opens as of a pre-specified differential pressure between the second input side and the second output side.

5. The thick matter pump of claim 4, wherein the second pilot valve is not adjustable.

6. The thick matter pump of claim 3, wherein the first pilot valve is adjustable via a handwheel.

7. The thick matter pump of claim 6, wherein the handwheel is lockable.

8. The thick matter pump of claim 3, wherein the joint adjusting element comprises a non-adjustable third pilot valve, connected in parallel with the first pilot valve, wherein the third pilot valve opens upon reaching a maximum-permissible pressure.

9. The thick matter pump of claim 8, further comprising: a switching valve located upstream from the first pilot valve such that the third pilot valve is connected in parallel to the arrangement of the first pilot valve and the switching valve, wherein the switching valve selectively establishes or breaks the connection of the first input side of the first pilot valve with the adjusting slide of the pressure regulator.

10. The thick matter pump of claim 9, wherein the switching valve is lockable.

11. The thick matter pump of claim 4, wherein the joint adjusting element comprises a non-adjustable third pilot valve, connected in parallel with the first pilot valve, wherein the third valve opens upon reaching a maximum-permissible pressure.

12. The thick matter pump of claim 11, further comprising: a switching valve located upstream from the first pilot valve such that the third pilot valve is connected in parallel to the arrangement of the first pilot valve and the switching valve, wherein the switching valve selectively establishes or breaks the connection of the input side of the first pilot valve with the adjusting slide of the pressure regulator.

13. The thick matter pump of claim 12, wherein the switching valve is lockable.

Description

(1) Further features, details and advantages of the invention result based on the below description, as well as by means of the drawings. Exemplary embodiments of the invention are represented purely schematically in the following illustrations and are described in greater detail below. Objects or elements corresponding to one another are provided with the same reference characters in all figures. Shown are in:

(2) FIG. 1 thick matter pump according to the prior art

(3) FIG. 2 thick matter pump according to the invention,

(4) FIG. 3 thick matter pump according to the invention with switching valve,

(5) FIG. 4 adjusting element according to the invention,

(6) FIG. 5 variant of the thick matter pump with remotely-controllable pilot valve.

(7) The illustration according to FIG. 1 shows, schematically and in detail, a thick matter pump 1 with a hydraulically driven two-cylinder piston pump 2 for producing a thick matter delivery pressure according to the prior art. The two hydraulic cylinders are indicated schematically and, via connecting lines and a switching controller 12, in this case e.g. an electro-hydraulically pilot-controlled 4/3-way valve, to a drive line 8, via which the two-cylinder piston pump 2 is applied hydraulic fluid by a hydraulic pump 3, for example an axial-piston variable-displacement pump. Via the switching controller 12, an alternating application of the two hydraulic cylinders of the two-cylinder piston pump occurs. Delivery pistons, not represented, are arranged at the upper ends of the schematically-indicated piston rods of the hydraulic cylinders, which project upwardly out of the hydraulic cylinders, which pistons are pushed back and forth by the hydraulic cylinders in delivery cylinders, thus generating the thick matter delivery pressure.

(8) The hydraulic lines represented by solid lines in the figures are so-called working lines, which are designed for high hydraulic fluid flows, whereas the hydraulic lines represented by dashed lines represent control or measuring lines, which are designed for smaller hydraulic fluid flows.

(9) A manometer 19 is coupled to the drive line 8, between the switching controller 12 and the hydraulic pump 3, at which the current pressure of the hydraulic fluid is directly readable.

(10) The thick matter delivery pressure can, via the ratio of the active piston surface of the hydraulic cylinder and the thick matter delivery cylinder to one another, be derived.

(11) The setting of the maximum target value of the pressure regulation means of the hydraulic pump is manually set by means of an adjusting slide 4 arranged on the hydraulic pump 3. As soon as the pressure of the hydraulic fluid in the drive line 8 reaches this target value, the pumping capacity of the hydraulic pump 3 is automatically reduced so that, upon reaching this threshold value, no losses result in the hydraulic system. This target value is, as a rule, factory and permanently pre-set at the initial entry into service, and should, as a rule, not be changed.

(12) If the pressure limiting at the hydraulic pump 3 e.g. due to a jammed adjusting slide 4, does not respond, another pressure limiting unit 5a is attached to the working line 8 for security. This pressure limiting unit 5a includes the main stage 15 of the pressure limiting valve, with a downstream pilot valve 18. The hydraulic pressure of the working line 8 is made to pass through the passage channel 17 equipped with a nozzle, through the main stage 15, through a further damping nozzle 20, to the pilot valve 18. Upon reaching a threshold pressure, which should lie somewhat above the target value of the target value set at the hydraulic pump 3, the pilot valve 18 and thus also the main stage 15 of the pressure limiting unit 5a opens, so that the drive line 8 is directly connected with the hydraulic reservoir 14, and the pressure built-up by the hydraulic pump 3 is thusly decreased. Because opening the pressure limiting unit 5a causes a high power loss, however, this should only take place in the event of failure of the pressure regulation means via the hydraulic pump 3. For this reason, the threshold pressure of the pressure limiting unit is to be set always somewhat higher, for example 20 bar, than the target value at the hydraulic pump 3.

(13) If a reduction of the maximum permissible thick matter delivery pressure is needed, for example if conveying lines are connected to the two-cylinder piston-pump 1, which can handle only lower delivery pressures, both threshold values would therefore have to be adjusted manually and independently, which, in practice, is only possible with great effort.

(14) The representation according to FIG. 2 schematically and in detail shows a thick matter pump 1 with a hydraulically-driven two-cylinder piston pump 2 for generating a thick matter delivery pressure according to the invention. The functioning substantially corresponds to the pump 1 represented in FIG. 1, which is why, in the following, only the setting of the thick matter delivery pressure according to the invention is explained.

(15) In the exemplary embodiment illustrated here, a so-called open hydraulic system is employed, in which the hydraulic pump 3 always pumps the hydraulic fluid in the same direction and suctions the hydraulic fluid from a hydraulic reservoir (tank) 14. The invention is, however, also applicable on known closed hydraulic systems in which the switching of the pumping direction of the hydraulic cylinders of the two-cylinder piston-pump 2 occurs in that the pump direction of the hydraulic pump 3 is reversed via a switching controller.

(16) In order to achieve the high volume flows in connection with the high pump pressure of the hydraulic fluid, often two hydraulic pumps 3 connected in parallel are also employed, which is not represented here for reasons of clarity.

(17) The thick matter delivery pressure generated by the thick matter pump 1 allows itself to be adjustably limited. To that end, the thick matter pump 1 comprises an adjusting element 6, via which the target pressure of a pressure regulation means and the maximum pressure of the hydraulic fluid, in the drive line 8, are jointly adjustable. Via the pressure regulation means, the hydraulic pump 3 can be regulated to cut off the thick matter delivery pressure, in that a target pressure of the hydraulic fluid is set in the pressure regulation means. To that end, the adjusting element 6 is connected to the adjusting slide 4 of the pressure regulation means, on the hydraulic pump 3, via the connection X. The pressure of the hydraulic fluid generated by the hydraulic pump 3 in the drive line 8 is limited to a maximum pressure adjustable by the pressure limiting valve 5. To that end, the adjusting element 6 is connected with the main stage 15 of the pressure limiting valve 5 via the connection X1. The adjusting element 6 is designed in such a manner that the target pressure of the pressure regulation means and the maximum pressure of the hydraulic fluid can be set synchronously. In this way, the maximum pressure of the hydraulic fluid in the drive line 8 always lies above the target pressure of the pressure regulation means by a pre-specified differential pressure. The adjusting element 6 comprises a first pilot valve 9 adjustable to the target pressure of the hydraulic fluid, which valve is input-sidedly connected with the adjusting slide 4 of the pressure regulation means of the hydraulic pump 3 and is output-sidedly relieved into a hydraulic reservoir 14. The first pilot valve 9 opens automatically upon reaching the set target pressure in the pressure regulation means and, in this way, very simply makes sure that the set target pressure is maintained. In the exemplary embodiment, the target pressure, in the pressure regulation means, can be set between 0 and 315 bar via the first pilot valve 9. A second pilot valve 7 of the adjusting element 6 is input-sidedly connected with the main stage 15 of the pressure limiting valve 5 and is output-sidedly connected with the input side of the first pilot valve 9. This second pilot valve 7 has the feature of adding up the backpressure from the downstream side directly onto the adjusting value set via the adjusting spring and opens as of a pre-specified differential pressure between input and output side and thusly ensures the limiting of the pressure fitting the set target value, in the drive line 8, via the pressure limiting valve 5. 20 bar are indicated as a pre-specified differential pressure in the exemplary embodiment. For reasons of operational reliability, the second pilot valve 7 adjustably represented here is preferably permanently factory-pre-set, i.e. the pre-specified pressure differential at which the pilot valve switches does not permit itself to be changed. In this way, the second pilot valve 7 acts upon the main stage 15 of the pressure limiting valve 5 to safeguard in such a way that the pressure limiting valve 5 pressure-relieves the drive line 8 as soon as the pressure of the hydraulic fluid, in the drive line 8, exceeds a value which lies above the target value of the pressure regulation means of the hydraulic pump 3 set at the first pilot valve 9. The adjusting element 6 further comprises an optional, non-adjustable third pilot valve 10, connected in parallel to the first pilot valve 9, which third valve, upon reaching a maximum permitted pressure, unloads into the hydraulic reservoir 14. The maximum-permissible pressure achievable here is, in the exemplary embodiment, specified with 320 bar. This maximum permitted system pressure is preset in the factory. This third pilot valve 10 makes sure that, in errors at the first pilot valve 9, am overloading of the entire system of the thick matter pump does not occur. In this way, the first pilot valve 9 and the third pilot valve 10 act directly upon the adjusting slide 4 for the pressure cut-off of the hydraulic pump of the hydraulic pump regulator. Through the parallel connection with the first pilot valve 9, the safeguard is continuously ensured through the third pilot valve 10.

(18) The nozzles 20 serve the purpose of limiting the through-flow volume of the hydraulic fluid in the simultaneous through-passing of the hydraulic pressure, so that the pilot valves 7, 9, 10 and the adjusting slide are only made to react in a damped manner.

(19) FIG. 3 schematically and in detail shows a thick matter pump 1 according to FIG. 1, wherein here, the adjusting element 6 comprises an additional switching valve 11. The switching valve 11 is connected upstream of the first pilot valve 9, in such a way that the third pilot valve 10 is connected in parallel to the arrangement of the first pilot valve 9 and switching valve 11, wherein the switching valve 11 selectively establishes or breaks the connection of the input side of the first pilot valve 9 with the adjusting slide 4 of the pressure regulation means. The switching valve 11 hereby makes the simple adjustment of the target pressure of the pressure regulation means between the target pressure set at the first pilot valve 9 and the maximum permitted system pressure at the third pilot valve 10 possible. In this way, the limiting of the thick matter delivery pressure can be adapted very quickly, without setting changes at the first adjustable pilot valve 9 being needed. Preferably, switching valve 11 is configured as a ball valve. The adjusting element 6 can thusly also simply be returned to the lower, set pressure via the switching valve 11. In FIG. 4, a constructive implementation of the adjusting element 6 according to FIG. 2 is shown schematically from the outside. The adjusting element 6 is configured as a special block and can be positioned at a location of the thick matter pump 1 (FIG. 1 or 2) easily reachable by the user. As can be discerned, the first pilot valve 9 allows itself to be set via a handwheel 13. In addition, the handwheel 13 is fixably and lockably configured. In this way, the setting value at the first pilot valve 9 allows itself to be secured. The shown switching valve 11 also allows itself to be simply managed and is latchingly as well as lockingly configured. The adjusting element 6 additionally has measurement terminals 16, with which information about the pressure ratios in the adjusting element 6 can be tapped.

(20) The operator of the machine can undertake the setting of the target value of the pressure limiting of the hydraulic pump 3 at the first pilot valve 9 in connection with the manometer 19. To that end, the two-cylinder piston-pump 2 is blocked, in that, for example, the switching controller 12 is placed in the central (locked) position and the hydraulic pump is set to full capacity. The pressure set at the first pilot valve 9 is then displayed on the manometer 19, because the capacity of the hydraulic pump 3, as described further above, is automatically limited to this pressure. In an error at the adjusting slide 4 on the hydraulic pump 3, a system pressure, which lies above the set target value by 20 bar, still results in the relief of the drive line 8 via the pressure limiting valve 5.

(21) Via a respective converting diagram, the operator can thereby easily adjust the hydraulic pressure in such a way, that the maximum thick-matter delivery pressure cannot be exceeded.

(22) The adjusting element 6 represented here as a structural unit can, for example, also be integrated in a hydraulic control block for the thick matter pump, as long as a simple settability and/or accessibility of the first pilot valve 9 is specified. The first pilot valve 9, but also the switching valve 11, could as well be electrically remotely-controllably adjustable. Furthermore, a spatially-separated arrangement of the valves of the adjusting element 6 is conceivable.

(23) A variant of the invention, in which the first pilot valve 9 is electrically remotely-controllably adjustable, is represented in FIG. 5. The first pilot valve 9 is embodied here as an electrically-controlled proportional pressure limiting valve and is actuated by a control electronics 23. The control electronics 23 measure the hydraulic drive pressure of the two-cylinder piston-pump 2 by means of the pressure sensor 21, and therefrom derives the thick matter delivery pressure via the ratio of the active piston surfaces of the hydraulic cylinders and the thick matter delivery cylinders to one another.

(24) By means of an operating unit 22, which is equipped with a keypad and a screen, as represented, or, for example, also with a touchscreen, the operator here just defines the desired maximum delivery pressure of the two-cylinder piston-pump 2. The control electronics 23 determines, from the hydraulic pressure measured by the pressure sensor 21 and from the maximum thick matter delivery pressure pre-specified by the operator, as already described further above, the correct setting of the first pilot valve 9, in a block two-cylinder piston-pump 2, and correspondingly sets it via the control line. Based on a pre-specified valve characteristic line, stored on behalf of the system, the control electronics 23 can set the first pilot valve 9, for example, also without the blocking of the two-cylinder piston-pump 2. With the help of the pressure sensor 21, the setting can be reviewed and, if necessary, readjusted.

(25) With the switching valve 11 represented in FIG. 5, the pre-set remotely-controlled reduction of the threshold pressure of the pressure cut-off can, when needed, simply be overridden. I.e., upon actuation of the switching valve 11, the maximum pressure, pre-specified via the third pilot valve 10, is set again for the pressure cut off, which, in the example represented here, lies 20 bar below the threshold pressure of the threshold pressure defined by the second pilot valve 7 and the pressure limiting valve 5.

LIST OF REFERENCE CHARACTERS

(26) 1. thick matter pump 2. two-cylinder piston pump 3. hydraulic pump 4. adjusting slide 5. pressure limiting valve (invention), 5a pressure limiting unit (prior art) 6. adjusting element 7. second pilot valve 8. drive line 9. first pilot valve 10, third pilot valve 11. switching valve 12. switching controller (4/3 directional valve) 13. handwheel 14. hydraulic reservoir 15. main stage 16. measurement terminal 17. throughput channel (from the prior art) 18. pilot valve (from the prior art) 19. manometer 20. nozzles 21. pressure sensor 22. operating unit 23. control electronics