Valve Block Arrangement and Method for a Valve Block Arrangement

Abstract

A valve block arrangement configured as a closed center system includes at least one main spool for controlling a hydraulic consumer. The main spool is configured to open and close at least one pressure medium connection between a hydraulic pump and the consumer in controlled, continuous fashion and, in at least one embodiment, is electrically activated. A bypass flow path with a cut valve branches off between the adjustable, hydraulic pump and the main spool. The cut valve is configured to open and close a pressure medium connection between the hydraulic pump and a tank in controlled, continuous fashion. The cut valve is electrically activatable.

Claims

1. A valve block arrangement, comprising: a closed center valve block having at least one main spool configured to control a hydraulic consumer, the at least one main spool assigned a pressure port and a working port; at least one hydraulic machine connected to the pressure port, a bypass flow path branching off fluidically between the pressure port and the at least one hydraulic machine; and an electrically activated cut valve configured to connect the bypass flow path to a tank, the bypass flow path throttlable via the cut valve.

2. The valve block arrangement according to claim 1, further comprising at least one further main spool, the main spools configured in each case to control a respective hydraulic consumer, wherein a respective main spool is assigned a respective pressure port and a respective working port, wherein the at least one hydraulic machine is connected to a respective pressure port, and wherein the bypass flow path with the cut valve branches off fluidically between the pressure ports and the at least one hydraulic machine.

3. The valve block arrangement according to claim 2, wherein a respective main spool is assigned an adjustable throttle disposed fluidically between the pressure port of the respective main spool and the hydraulic machine.

4. The valve block arrangement according to claim 2, wherein one or more of (i) at least one of the main spools is adjustable in continuous fashion, (ii) the cut valve is openable and closable in controlled, continuous fashion, and (iii) the hydraulic machine is adjustable in continuous fashion.

5. The valve block arrangement according to claim 3, wherein at least one throttle is configured such that a backflow of pressure medium from the associated consumer via the throttle is prevented.

6. The valve block arrangement according to claim 2, wherein the pressure port of at least one of the main spools is connected to at least two hydraulic machines arranged fluidically in parallel.

7. The valve block arrangement according to claim 2, further comprising a set of control electronics having an adaptation module in which, for a respective consumer, a respective preset value is configured to be input by an input unit, wherein the respective preset value is, by way of the adaptation module, changed into a respective adapted preset value.

8. The valve block arrangement according to claim 7, wherein the set of control electronics has a preset module configured to convert the respective adapted preset value into one or more of (i) a volume flow preset for the corresponding consumer, (ii) an item of load sensitivity information for the corresponding consumer, and (iii) a maximum pressure for the corresponding consumer.

9. The valve block arrangement according to claim 8, wherein the set of control electronics has an actuation module which generates one or more actuation signals on the basis of the converted preset values, wherein one or more of (i) a total volume flow preset for the hydraulic machine, (ii) a total throttling preset for the cut valve, (iii) a control variable or a respective control variable for the main spool or for a respective main spool, (iv) and a control variable or a respective control variable for the throttle or the throttles is provided as the one or more actuation signals.

10. The valve block arrangement according to claim 9, wherein, in the actuation module, a load pressure of a consumer or of some of the consumers or of all of the consumers is taken into consideration for generating the one or more actuation signals.

11. The valve block arrangement according to claim 9, wherein, in the actuation module, a rotational speed of the hydraulic machine is taken into consideration for generating the one or more actuation signals.

12. The valve block arrangement according to claim 9, wherein the adaptation module, the preset module, and the actuation module are software modules.

13. The valve block arrangement according to claim 9, wherein the actuation by the one or more actuation signals takes the form of non-feedback open-loop control.

14. A method for a valve block arrangement that includes a closed center valve block with at least one main spool configured to control a hydraulic consumer, the at least one main spool assigned a pressure port and a working port, at least one hydraulic machine connected to the pressure port, a bypass flow path branching off fluidically between the pressure port and the at least one hydraulic machine, and an electrically activated cut valve configured to connect the bypass flow path to a tank, the bypass flow path throttlable via the cut valve, the method comprising: one or more of (i) converting a preset value into a volume flow preset for the consumer, (ii) converting an adapted preset value into an item of load sensitivity information for the consumer, and (iii) converting the adapted preset value into a maximum pressure, and generating one or more actuation signals from the one or more converted preset values, wherein one or more of (i) a total volume preset for the hydraulic machine, (ii) a total throttling preset for the cut valve, (iii) a control variable for the main spool, and (iv) a control variable for the throttle is provided as the one more actuation signals.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Preferred exemplary embodiments of the disclosure will be discussed in more detail below on the basis of schematic drawings, in which:

[0047] FIG. 1 shows, in a hydraulic circuit diagram, a valve block arrangement according to a first exemplary embodiment,

[0048] FIG. 2 shows, in a schematic illustration, a set of control electronics of the valve block arrangement from FIG. 1,

[0049] FIGS. 3a and 3b each show a characteristic curve with regard to the signal conditioning,

[0050] FIG. 3c shows a time function with regard to the signal conditioning,

[0051] FIGS. 4a to 4c each show a characteristic curve with regard to the generation of different control variables from a preset value,

[0052] FIG. 5 shows, in a hydraulic circuit diagram, a valve block arrangement according to a further exemplary embodiment,

[0053] FIG. 6 shows, in a hydraulic circuit diagram, a main spool with an upstream throttle as per an embodiment,

[0054] FIG. 7 shows, in a schematic illustration, a set of control electronics of the valve block arrangement from FIG. 5 as per an embodiment,

[0055] FIG. 8 shows, in a schematic illustration, a set of control electronics for the valve block arrangement from FIG. 5 as per a further embodiment,

[0056] FIG. 9 shows, in a characteristic curve, a pressure loss in the case of the valve block arrangement from FIG. 5 as a function of the respective consumer volume flow,

[0057] FIG. 10 shows, in a schematic illustration, the valve block arrangement from FIG. 5 with exemplary pressure variables and volume flows,

[0058] FIG. 11 shows, in a hydraulic circuit diagram, a valve block arrangement according to a further exemplary embodiment,

[0059] FIG. 12 shows, in a hydraulic circuit diagram, a main spool with upstream throttle and upstream check valve as per an embodiment,

[0060] FIG. 13 shows, in a hydraulic circuit diagram, a main spool with two upstream throttles as per an embodiment, and

[0061] FIG. 14 shows, in a flow diagram, the method according to the disclosure as per an embodiment.

DETAILED DESCRIPTION

[0062] As per FIG. 1, a valve block arrangement 1 has a hydraulic machine in the form of a hydraulic pump 2. The latter is in particular electrically adjustable. To the outlet side of the hydraulic pump 2, there is connected a pressure sensor 4 for detecting an outlet pressure of the hydraulic pump 2. Three main valves or main spools 6, 8 and 10 arranged fluidically in parallel are fluidically connected to the hydraulic pump 2. Said main valves or main spools each have a pressure port P, which is connected in each case to the hydraulic pump 2, wherein, for the sake of simplicity, the alphabetic characters of the ports are shown only for the main spool 6. Furthermore, a respective main spool 6, 8 and 10 has a tank port T which is connected to a tank 12. Furthermore, a respective main spool 6 to 10 has a first and second working port A, B. In each case one consumer 14, 16 and 18 is connected to said working port. Thus, a respective main spool 6 to 10 serves for controlling a respective consumer 14 to 18 assigned thereto. The consumers 14 to 18 are each differential cylinders with a piston rod on one side.

[0063] A respective main spool 6 to 10 is spring-centered in its main position a. Proceeding from its main position a, a respective main spool 6 to 10 can be actuated in the direction of first switched positions b by means of actuators 20, 22. Here, the pressure port P is connected to the working port A, and the working port B is connected to the tank port T. Furthermore, a respective main spool 6 to 10 is displaceable from its main position a in the direction of switched positions c opposite to the switched positions b. Here, a respective pressure port P is connected to the second working port B, and the first working port A is connected to the tank port T. The main spools 6 to 10 are adjustable in continuous fashion.

[0064] A bypass flow path 24 branches off fluidically between the main spools 6 to 10 and the hydraulic pump 2, which bypass flow path is connected to the tank 12. A cut valve 26 which is electrically adjustable in continuous fashion is provided in said bypass flow path. A valve spool of the cut valve 26 is acted on in the direction of its opening positions by a spring force of a valve spring 28. The valve spool of the cut valve 26 can be acted on with a force in the direction of closing positions by an actuator 30, which is electrically activatable. It is thus possible for a pressure medium connection between the outlet side of the hydraulic pump 2 and the tank 12 to be controlled by means of the cut valve 26.

[0065] The valve block arrangement 1 is a closed center system, wherein, in the neutral position or main position a of the main spools 6 to 10, the pressure medium connections are closed. Owing to the adjustable hydraulic pump 2 and the cut valve 26, a load dependency or load sensitivity for a user of the valve block arrangement 1, as is provided in the case of an open center system, is nevertheless also made possible here, as will be discussed below.

[0066] FIG. 2 illustrates a set of control electronics 30 of the valve block arrangement 1 from FIG. 1. Here, for the control of a respective consumer 14 to 18, see FIG. 1, in each case one joystick 32, 34 and 36 is provided, which joysticks are connected in each case to the set of control electronics. A respective joystick 32 and 36 is in each case connected to a block 38, which blocks are part of an adaptation module or first module 40. Therein, a respective preset value a1 to a3 preset by the joysticks 32 to 36 is adapted. Subsequently, a respective adapted preset value b1 to b3 is output by the respective block 38. The adaptation is performed on the basis of characteristic curves as per FIGS. 3a and 3b and on the basis of a time function, such as for example PT1 or PT2, as per FIG. 3c.

[0067] The respectively adapted preset value b1 to b3 is fed into a respective block 42 of the set of control electronics 30. The blocks 42 form a preset module or second module 44. The preset values b1 to b3 are then, in their respective block 42, converted by means of a characteristic curve as per FIG. 4a into a maximum pressure p_max_1 to p_max_3. As per FIG. 4a, the maximum pressure p_max_i increases linearly with the respective increasing adapted preset value bi up to a particular value, beyond which the maximum pressure p_max_i then remains constant even if the respective adapted preset value b1 to b3 increases further. Thus, at the start of a respective deflection of a joystick 32 to 36, a respective preset for the maximum pressure p_max_1 to p_max_3 will increase in continuous fashion together with the deflection. Beyond a certain actuation travel of the respective joystick 32 to 36, the respective maximum pressure p_max_1 to p_max_3 then remains constant. Furthermore, in the second module, a respective adapted preset value b1 to b3 is converted into a respective volume flow preset Q1 to Q3 for the respective consumer 14 to 18, see FIG. 1. Said volume flow preset is adapted in each case in accordance with the characteristic curve in FIG. 4b. Accordingly, a respective volume flow preset Q1 to Q3 increases with the respective adapted preset value b1 to b3. Furthermore, a desired item of load sensitivity information A1 to A3 is generated in a respective block 42 of the second module 44. A respective item of load sensitivity information A1 to A3 is, as per the characteristic curve in FIG. 4c, likewise dependent in each case on the adapted preset value b1 to b3. The greater the preset value b1 to b3, the lower the respective item of load sensitivity information A1 to A3.

[0068] As per FIG. 2, the adapted preset values b1 to b3, the volume flow presets Q1 to Q3, the items of load sensitivity information A1 to A3 and the maximum pressures p_max_1 to p_max_3 are fed into a block 46 of the set of control electronics. Said block forms an actuation module or third module 48. Furthermore, load pressures p1 to p3 of a respective consumer 14 to 18 are fed into the block 46. From the fed-in calculation variables and load pressures p1 to p3, the control variables or actuation signals x1 to x3 for a respective main spool 6 to 10, see FIG. 1, are generated. Furthermore, a control signal x_cut for the cut valve 26 is generated as a total throttling preset. Furthermore, a total volume flow preset V_g for the hydraulic pump 2 is output.

[0069] The control variables or positioning variables x1 to x3 for the main spools 6 to 10 are obtained from the following formula: xi=k*bi, wherein i stands for a respective value 1 to 3. The control signal for the cut valve 26 can be determined from the smallest item of load sensitivity information A1 to A3: x_cut=min(A1, A2, A3). Alternatively, the control signal for the cut valve may be calculated from the physical relationship of the series-connected orifices: x_cut=1/(1/A1+1/A2+1/A3). The positioning variable for the pump activation means of the hydraulic pump 2, or the total volume flow preset V_g, arises from the individual consumer demands and from a factor k for the pump characteristic variable: V_g=(Q1+Q2+Q3)*k.

[0070] FIG. 5 illustrates a further embodiment of a valve block arrangement 50. By contrast to the embodiment in FIG. 1, an adjustable throttle 52, 54, 56 is connected upstream of the pressure port P of a respective main spool 6 to 10. The throttles 52 and 56 have the advantage that, in the case of an activation of a second consumer 14, 16, 18 in addition to a first consumer 14, 16, 18 and with different load pressure in relation to the first consumer 14, 16, 18, a change in speed of the first consumer 14, 16, 18 is prevented or is prevented as far as possible. The throttles 52 to 56 are arranged fluidically in parallel with respect one another and are jointly connected to the hydraulic pump 2. The bypass flow path 24 with the cut valve 26 then branches off fluidically between the hydraulic pump 2 and the throttles 52 to 56.

[0071] FIG. 6 illustrates an embodiment of the throttles 52 to 56. For more detailed information, reference is made to the explanations above and to the applicant's document DE 10 2014 204 070 A1. The throttles 52 to 56 are in this case designed so as to additionally be used as load-maintaining valves. Thus, the throttles 52 and 56 perform a dual function, in a manner which saves structural space.

[0072] FIG. 7 shows a set of control electronics 58 of the valve block arrangement 50 from FIG. 5. By contrast to FIG. 2, control variables y1 to y3 for the throttles 52 to 56 are generated in the block 46 of the third module 48.

[0073] FIG. 8 illustrates the set of control electronics 58 from FIG. 7, wherein a rotational speed n of the hydraulic pump 2, see FIG. 5, is additionally taken into consideration in the block 46.

[0074] In FIGS. 7 and 8, the control signals x1 to x3, the control signal x_cut and the total volume flow preset V_g are calculated in accordance with the formulae stated above. In FIG. 8, the total volume flow preset V_g may alternatively be calculated taking into consideration the rotational speed n: V_g=((Q1+Q2+Q3)/n)*1000. In FIGS. 7 and 8, the control variables for the throttles y1 to y3 are determined taking into consideration the adapted preset values b1 to b3, the volume flow presets Q1 to Q3 and the maximum pressures p_max_1 to p_max_3. In an intermediate step, it is the case here that a typical pump pressure of the hydraulic pump 2 is calculated as a function of the actuation of the consumers: p_pump=max(p1*sign(b1), p2*sign(b2), p3*sign(b3)). Here, to increase the accuracy, it is also possible for a pressure loss of the hydraulic system to be taken into consideration in the demanded volume flow, which may be realized in FIG. 9 in accordance with the illustrated characteristic curve. It can be seen here that, the higher a volume flow preset Q1 to Q3 is, the higher a pressure loss p_verlust_1 to p_verlust_3 is. The typical pump pressure of the hydraulic pump 2 is then obtained, in the case of a consumer actuation, from the following formula: p_pump=max((p1+p_verlust_1)*sign(b1), (p2+p_verlust_2)*sign(b2), (p3+p_verlust_3)*sign(b3)). The control variables for the throttles y1 to y3 may then be calculated, from the pressure drop dp1 to dp3 across the respective adjustable throttle 52 to 56 and the respective volume flow preset Q1 to Q3, by means of the following formula: y_i=Q_i/(*(2*dp_i/)). The pressure drop across each throttle 52 to 56 can then be calculated from the load pressures p1 to p3 and the typical pump pressure p_pump: dp_i=p_pumpp_i. To improve the calculation, it is also possible for the volume-flow-dependent losses to also be taken into consideration: dp_i=p_pumpp_ip_verlust_i. Thus, all of the variables for the calculation of the control variables y1 to y3 for the throttles are then known, and said control variables can be calculated in accordance with the following formula: y_i=Q_i/(*(2*dp_i/)).

[0075] FIG. 10 illustrates a valve block arrangement 60 in simplified form. Said figure serves for illustrating the control by means of the set of control electronics 58, see also FIG. 7. For the sake of simplicity, no cut valve is illustrated in the valve block arrangement 60. As consumers 62, 64, single-acting hydraulic cylinders are provided. The respective working chamber thereof is connected to a working port A of a respective main spool 66, 68. The consumer 62 serves for example for actuating an excavator bucket, and the consumer 64 serves for example for actuating an excavator boom. Then, to a pressure port P of a respective main spool 66, 68, there is connected in each case one throttle 70, 72, which throttles are designed correspondingly to FIGS. 5 and 6 respectively. The throttles 70, 72 are then connected to the hydraulic pump 2. By means of the set of control electronics 58, the main spools 66, 68, the throttles 70, 72 and the hydraulic pump 2 are adjustable, which is illustrated by the dashed lines shown in FIG. 10. Furthermore, the set of control electronics 58 is connected to the pressure sensor 4. Furthermore, in each case one joystick 32 and 34 for a respective consumer 62 and 64 is connected to the set of control electronics 58.

[0076] The consumer 62 is acted on with a typical load pressure (p_typ_Bkt) of 150 bar, and the consumer 64 is acted on with a typical load pressure (p_typ_Boom) of 200 bar.

[0077] The joysticks 32 and 34 are in this case actuated such that the consumer 62 should be supplied with a volume flow preset (Q_set) of 50 liters per minute and the consumer 64 should be supplied with a volume flow preset (Q_set) of 100 liters per minute. The pressure drop across the main spool is estimated, on the basis of the setpoint flow rate, as 20 bar.

[0078] An outlet-side pressure of the hydraulic pump 2, which can be detected by means of the pressure sensor 4, then amounts to 220 bar. Here, the throttle 72 is fully open, whereby said throttle is flowed through by a volume flow (Q_set_e-valve) of 100 liters per minute and no pressure loss (dp_set_e-valve) is provided. By contrast, the throttle 70 is throttled, such that a volume flow (Q_set_e-valve) of 50 liters per minute can flow through it. There is an estimated pressure drop of 10 bar across the main spool in the case of the demanded 50 l/min. Here, a pump pressure of 160 bar would typically take effect. The difference in pump pressure between the 220 bar of consumer 64 and 62 is now set at throttle 70.

[0079] In FIG. 11, a valve block arrangement 74 is provided. This has, by contrast to the valve block arrangement 50 from FIG. 5, a further hydraulic pump 76 in addition to the hydraulic pump 2. A pressure port P of a respective main spool 6, 8, 10 can then be supplied with pressure medium via both hydraulic pumps 2, 76. The hydraulic pump 2 is, correspondingly to the embodiment in FIG. 5, connected via the throttles 52, 54 and 56 to the respective pressure port P of the main spools 6 to 10. The hydraulic pump 76 is then likewise connected via a respective throttle 78, 80 and 82 to the pressure port P. The throttles 52, 78; 54, 80 and 56, 82 are then connected fluidically parallel to the respective pressure port P of the main spools 6, 8 and 10 respectively.

[0080] Correspondingly to FIG. 5, the bypass flow path 24 with the cut valve 26 branches off between the hydraulic pump 2 and the throttles 52, 54 and 56. Furthermore, a bypass flow path 84 is provided in which a cut valve 86 is arranged. Here, the bypass flow path 84 branches off, between the hydraulic pump 76 and the throttles 78, 80 and 82, to the tank 12. The consumers 14, 16 and 18 can thus be supplied with pressure medium in each case by means of two hydraulic pumps 2, 76, and the valve block arrangement 74 can advantageously be controlled in accordance with the designs in the preceding embodiments.

[0081] FIG. 12 illustrates an embodiment for the connection of the hydraulic pumps 2, 76 from FIG. 11 to the pressure port P of the main spool 6. Here, a check valve 88 is provided instead of the throttle 52. Said check valve opens in this case in a flow direction from the hydraulic pump 2 toward the pressure port P, and closes in the opposite flow direction. The throttle 78 in FIG. 12 between the hydraulic pump 76 and the pressure port P is in this case designed correspondingly to FIG. 6. It is conceivable for the check valve 88 to also be used in place of the throttle 54 and/or 56, see FIG. 11. It is self-evidently also possible for the check valve 88 to be used as an alternative or in addition to the throttle 78 and/or to the throttle 80 and/or to the throttle 82, see FIG. 11.

[0082] In FIG. 13, the throttles 52 and 78 from FIG. 11 are illustrated together with the main spool 6. As already stated above, said throttles are designed correspondingly to the throttles 52 to 56, see FIG. 6.

[0083] FIG. 14 shows the method for controlling the valve block arrangements 1, 50, 60 and 74 with the set of control electronics 30 and 58. In a first step 90, the preset values a1 to a3 output by the joysticks 32 to 36, see for example FIG. 2, are converted into adapted preset values b1 to b3. Subsequently, the adapted preset values b1 to b3 are converted into a desired item of load sensitivity information A1, A2, A3, into a desired maximum pressure p_max_1, p_max_2, p_max_3 and into a respective volume flow preset Q1, Q2, Q3. In the next step, control variables for the activatable components are then generated from the converted values and from the adapted preset values together with load pressures p1 to p3.

[0084] A valve block arrangement is disclosed, which is designed as a closed center system. Said valve block arrangement has at least one main spool for controlling a hydraulic consumer. The main spool can open and close at least one pressure medium connection between a hydraulic pump and the consumer in controlled, continuous fashion, and is in particular electrically activated. A bypass flow path with a cut valve branches off between the, in particular adjustable, hydraulic pump and the main spool. Said cut valve can open and close a pressure medium connection between the hydraulic pump and a tank in controlled, continuous fashion, wherein said cut valve is electrically activatable.

LIST OF REFERENCE DESIGNATIONS

[0085] 1; 50; 60; 74 Valve block arrangement

[0086] 2, 76 Hydraulic pump

[0087] 4 Pressure sensor

[0088] 6, 8, 10; 66, 68 Main spool

[0089] 12 Tank

[0090] 14, 16, 18; 62, 64 Consumer

[0091] 20, 22 Actuator

[0092] 24, 84 Bypass flow path

[0093] 26, 86 Cut valve

[0094] 28 Valve spring

[0095] 30; 58 Control electronics

[0096] 32, 34, 36 Joystick

[0097] 38, 42, 46 Block

[0098] 40 First module

[0099] 44 Second module

[0100] 48 Third module

[0101] 52, 54, 56; 70, 72, 78, 80, 82 Throttle

[0102] 88 Check valve

[0103] 90, 92, 94 Step

[0104] P Pressure port

[0105] A, B Working port

[0106] T Tank port

[0107] a Main position

[0108] b, c Switched positions

[0109] a1, a2, a3 Preset value

[0110] b1, b2, b3 Adapted preset value

[0111] p_max_1, p_max_2, p_max_3 Maximum pressure

[0112] Q1, Q2, Q3 Volume flow preset

[0113] A1, A2, A3 Item of load sensitivity information

[0114] p1, p2, p3 Load pressure

[0115] x1, x2, x3 Control signal for main spool

[0116] y1, y2, y3 Control variable for throttle

[0117] dp_1, dp_2, dp_3 Pressure drop across throttle

[0118] x_cut Control signal for cut valve

[0119] V_g Total volume flow preset

[0120] n Rotational speed of the hydraulic pump