"Flexible pump device applied to drive a fan"

Abstract

Title: Flexible Pump Device Applied to Fan Drive. A pump device (10) whose discharge flow rate is continuously adjustable by a double-acting cylinder (20) having a first and a second chamber (21, 22), each associated with a first and a second receiving bore, respectively; one of the two receiving bores receives an integrated pressure regulating valve (30), and the other receives an integrated 3 / 2-way valve (32). The electrically actuated pressure regulating valve (30) and 3 / 2-way valve (32) are connected to a control device (80) that presets a differential discharge pressure setpoint (dp-cons). By controlling the pressure regulating valve (30) and the distributor (32) the control device (80) regulates the discharge flow rate so that the difference between the first and second actual pressure (pA; pB) approaches the difference in discharge pressure setpoint (dp-cons).Figure 1.

Description

Title of the invention: “Flexible pump device applied to the driving of a fan” FIELD OF THE INVENTION

[0001] The present invention relates to a flexible pump device applied to the driving of a fan. STATE OF THE ART

[0002] According to the technical notice “Axialkoben-Verstellpumpe A4VG Baureihe 35 » (adjustable axial piston pump 4AVG series 35) from Bosch Rexroth AG (order number RD92035 . edition 12.02.2020), we know an axial piston machine with inclined ice, the delivery flow of which is adjusted with a double-acting adjusting cylinder that moves to the zero position, so that for the same drive direction, the delivery direction is reversed by adjusting the rocker alone. In the ET adjustment, both adjustment chambers of the adjusting cylinder are connected to a pressure adjustment valve in the form of a pressure reducing valve. In the event of a failure of the electrical excitation, it is not unequivocally established which flow rate is adjusted.

[0003] This behavior is not desirable for hydraulic fan drives. The fan must generally rotate at its maximum rotation speed when the electrical control fails (integrated safety method).

[0004] Document DE 10 2010 020 528 A1 presents a fan drive having a closed hydraulic circuit which essentially comprises the axial piston machine described above. The control cylinder is controlled in this case by a pressure control valve in the form of a pressure reducing valve with an increasing or positive characteristic curve and with a 4 / 2-way slide valve, the two control valves each having an electrical adjustment. The circuit is designed so that in the event of failure of the electrical control, the axial piston machine automatically sets itself to a maximum amplitude delivery flow so that both fan rotors rotate at maximum speed.

[0005] Furthermore, the circuit is designed so that the current applied to the pressure adjustment valve does not abruptly change the adjustment pressure difference at the zero crossing. At the zero crossing, the corresponding adjustment current drops to zero and then rises again, and only the 4 / 2-way slide valve switches abruptly.

[0006] The disadvantage of this control is that it requires a special valve block for the adjustment valves which are specially adapted to drive fan. If instead of the above fail-safe behavior, another behavior is desired, then the damper block must be modified.

[0007] DISCLOSURE AND ADVANTAGES OF THE INVENTION

[0008] The invention aims to overcome these drawbacks and to this end relates to a pump device with a first and a second working connection to which a closed hydraulic circuit is connected by a fluid connection,

[0009] - the pump device having a motor shaft,

[0010] * a complete rotation of the motor shaft ensuring the transfer of a volume of discharge of pressurized fluid between the first and the other working connection,

[0011] * the discharge volume being continuously adjustable by an adjustment cylinder at double-acting having a first and a second adjustment chamber,

[0012] * the first and second adjustment chambers being associated respectively with a first and a second receiving bore connected respectively by a permanent fluid connection to the first and second adjustment chambers,

[0013] * the first and second receiving holes being identical, being made respectively for fixing an integrated valve,

[0014] * a first pressure sensor being provided to measure a first pressure actual at first working connection,

[0015] * a second pressure sensor being provided to measure a second actual pressure at the second working connection,

[0016] * a control device being connected to the first and second pressure sensors,

[0017] this pump device being characterized in that

[0018] a pressure adjustment valve in the form of an integrated valve is installed in the first or second receiving hole,

[0019] * the other drilling among the second or the first receiving drilling receiving a 3 / 2-way slide valve in the form of an integrated flap,

[0020] * the pressure adjustment valve and the 3 / 2-way distributor each being at electrical control, connected respectively to the control device,

[0021] * the control device pre-sets a pressure setpoint difference of repression,

[0022] * the control device controlling the pressure adjustment valve and the 3 / 2-way valve to adjust the discharge flow rate so that the difference between the first and second actual pressures approaches the discharge pressure setpoint difference.

[0023] The invention has the advantage of producing the pump device only with commercially available adjustment valves to have integrated safety. At the same time, the appropriate choice of the adjustment direction and the mounting location of the two adjustment valves allows a large number of drive variants without requiring special mechanical designs instead of catalog components. Simply adapt the program, or its variable settings of the control device to the selected control valves.

[0024] The pump device preferably operates with a pressurized fluid which is very preferably a liquid, in particular a hydraulic liquid. The pump device preferably comprises an axial piston ice machine whose rocker is adjusted with an adjustment cylinder around the rocker axis; the rocker is movably coupled to the piston of the adjustment cylinder and the adjustment piston delimits the first and second adjustment chambers. The rocker axis is coupled to the axis of rotation of the drive shaft, preferably at right angles. The two control ports of the axial piston machine are preferably plane-symmetrical with respect to each other and with respect to a plane containing the axis of rotation and the rocker axis. The hydraulically acting surfaces of the first and second adjustment chambers are preferably of the same dimensions.The hydraulic motor is preferably in direct drive connection with the associated fan rotor. The first and second receiving bores have an internal thread into which the pressure regulating valve or the 3 / 2-way valve is screwed, the two internal threads (threads) being identical; the thread diameter and the pitch are identical. The pressure regulating valve and / or the 3 / 2-way valve are preferably adjusted by an actuating solenoid. The pressure regulating valve is preferably a pressure reducing valve. The first and / or second receiving bore are preferably in a housing of the pump device.

[0025] According to a feature, in the control device, the two receiving bores are adjusted, namely the first and the second receiving bore receiving the pressure regulating valve or the 3 / 2-way distributor, the control device being designed to take this adjustment into account in the control of the pressure regulating valve or the control of the 3 / 2-way distributor. This taking into account is preferably done within the framework of the case decision and within the framework of the calculation of the different cases, namely the zero case, the positive case and the negative case; very preferably this is done only at this time. This is possible because, with reference to the calculation procedure described in connection with Figures 2 and 3, the difference in the set pressure setting is used as an intermediate value which is independent of the adjustable equipment with the regulating valves.

[0026] A rotation speed sensor can be provided to measure the actual rotation speed of the motor shaft,

[0027] * the control device being designed so that the control of the adjustment valve pressure and the 3 / 2-way distributor control take into account exclusively of the actual rotational speed and the first and second actual pressure in normal operation. This particularly economical sensor equipment is also possible because the control device predetermines the discharge pressure setpoint difference as a guide variable.

[0028] According to one feature, the control device implements a pre-control which is superimposed on the regulation. The pump device reacts on the one hand quickly in response to variations in the discharge pressure setpoint difference and this discharge pressure setpoint difference is nevertheless achieved very precisely.

[0029] According to one feature, in the control device it is set that the pressure regulating valve actually uses a curve with an increasing or decreasing characteristic, the control device being designed to take this setting into account for the control of the pressure regulating valve. For an increasing characteristic curve or positive characteristic curve, the pressure at the outlet of the pressure regulating valve increases substantially proportionally to the current supplied to the actuating electromagnet. In the case of a decreasing characteristic curve, i.e. a negative characteristic curve, the relationship is substantially inversely proportional. This taking into account is preferably done within the framework of the inverse model of the pressure regulating valve and very preferably only then. The inverse model of the pressure regulating valve is preferably selected as a function of the above setting.This is possible because, with reference to the calculation procedure described in Figures 2 and 3, the first and second adjustment pressures are used as intermediate values ​​and these are independent of the characteristic curve of the pressure adjustment valve.

[0030] According to a feature, the 3 / 2-way valve is pre-stressed by a return spring in a first adjustment position and with the associated actuating electromagnet and it switches into a second position, the corresponding first or second adjustment chamber being connected by a fluid connection by the switching of the 3 / 2-way valve either to the control input or to the control output and in the control device it is set that the 3 / 2-way valve actually used, in the first setting, creates a fluid connection between the associated adjustment chamber, namely the first or second adjustment chamber and the control input or the control return, the control device being designed to take this setting into account for the control of the 3 / 2-way valve.This consideration is preferably done within the framework of the inverse model of the 3 / 2-way distributor and very preferably it is done only then. The inverse model of the 3 / 2-way distributor is preferably chosen according to the indicated setting. This is possible because in the calculation procedure described in . relation to figures 2 and 3, the first and second setting pressure are used as intermediate values ​​and these are independent of the switching function of the 3 / 2-way valve.

[0031] According to a characteristic, the pressure control valve has an increasing characteristic curve and the 3 / 2-way valve in the first setting makes a connection with the control input. This is a possibility to have a fail-safe behavior for the fan drive.

[0032] According to one characteristic, the pressure regulating valve has a decreasing characteristic curve and the 3 / 2-way distributor, in the first setting, makes a connection with the control feedback. This is another possibility to have the fail-safe behavior of the fan drive.

[0033] According to a feature, a feed pump is in driving connection with the drive shaft and is fluidically connected, on the output side, to the control inlet, a feed pressure limiting valve regulating the pressure at the control inlet and the control device is designed to take into account the setting of the feed pressure limiting valve for controlling the pressure regulating valve and for controlling the 3 / 2-way valve. The feed pressure limiting valve can be fixedly adjusted, for example with a locking adjusting screw and this adjustment is taken into account as a set parameter in the control device. The feed pressure limiting valve can be adjusted with an actuating solenoid connected to the control device which takes into account the actually carried out electrical adjustment of the feed pressure limiting valve.This consideration is preferably done within the framework of the inverse model of the pressure adjustment valve and within the framework of the inverse model of the 3 / 2-way distributor and very preferably this is only done in this case.

[0034] According to one feature, the first and / or the second adjustment chamber are permanently connected by a fluid connection with a first or a second throttle member respectively associated with the first or the second receiving bore. The first throttle member or the second throttle member allow the speed with which the discharge flow rate is adjusted to be adjusted, being limited upwards in confidence to protect the hydraulic motor and the fan against damage. The first and / or the second throttle member preferably respectively have a fixed fluid resistance. It is preferably a particular insert fixed in the fluid channel of the housing of the pump device in particular by screwing.

[0035] According to one characteristic, the discharge flow rate is continuously adjusted so that the reversal of the direction of flow between the first and second working connections for a direction of rotation remaining the same for the motor shaft, is done solely by the displacement of the adjustment cylinder. The pump device according to the technical data sheet cited in the preamble has this operating behavior. Within the scope of the invention this can be used to reverse the direction of delivery in the absence of current, by exchanging the pressure regulating valve and 3 / 2-way distributor, by adapting the setting in the control device accordingly. Brief description of the drawings

[0036] The present invention will be described below in more detail with the aid of embodiments shown in the accompanying drawings in which:

[0037] [Fig-1] hydraulic diagram of an axial pump device according to the invention,

[0038] [Fig.2] part of a regulation diagram implemented by the method of the invention,

[0039] [Fig.3] another part of the regulation diagram of [Fig.2], and

[0040] [Fig.4] diagram explaining the inverse model of the pressure adjustment valve.

[0041] [Fig.5] hydraulic diagram corresponding to [Fig.l] for a second mode of production of a pump device according to the invention,

[0042] [Fig.6] Sectional view of the pressure adjustment valve and the receiving bore partner.

[0043] DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0044] [Fig.l] shows the hydraulic diagram of a pump device 10 according to the invention. This pump device 10 comprises a main pump 18 and a feed pump 13 driven by a common motor shaft 19. The rotational speed (n) of the motor shaft 19 is measured with a rotational speed sensor 70 preferably installed in a fixed manner on the pump device 10.

[0045] The main pump 18 is an axial piston pump whose delivery flow rate can be adjusted continuously, preferably with a tilting cradle. The tilting cradle is movably coupled to the adjusting piston of a double-acting adjusting cylinder 20. The adjusting cylinder 20 has a first and a second adjusting chamber 21, 22 in which the respective pressure corresponds to the numerical values ​​p-DRE and p-3 / 2 in [Fig. 3]; these pressures act in opposite directions on the adjusting piston. The first adjusting chamber 21 is connected by a fluid connection directly to the pressure adjusting valve 30; this is preferably in the form of a pressure reducing valve, electrically controlled by a control electromagnet 31.The second adjustment chamber 22 is connected by a direct fluid connection to the 3 / 2-way slide valve 32, electrically controlled by a control electromagnet 33 and returned to a pre-stressed position by a return spring 34; in this position, the control input is open (open position). The pressure regulating valve 30 and / or the 3 / 2-way slide valve 32. are preferably controlled respectively by an electrical voltage whose working ratio is chosen to have on average an intensity whose numerical value corresponds to the value i-DRE or i-3 / 2. For this, preferably respectively a current regulation circuit with digital implementation is used which is at most preferably calculated by the control device 80 also applying the method of the invention.

[0046] The pressure control valve 30 here has a positive characteristic curve so that its currentless state corresponds to the lowest pressure in the control return 16, applied to the first control chamber 21. The 3 / 2-way spool 32 is open currentless so that for this currentless state, the high pressure will be applied to the control inlet 15 of the second control chamber 22. The present main pump 18 is regulated by passing through the zero delivery flow. Correspondingly, the currentless state, regulates a maximum delivery flow in amplitude as long as the motor shaft 19 rotates. The corresponding direction of rotation is designed so that the fan rotor 41 rotates correspondingly in the desired direction of the cooling air delivery.This behavior is desired in the majority of fan drive cases so that even if the electrical control fails, the cooling of the thermal engine will be sufficient.

[0047] The feed pump 13 is for example a vane pump. It draws the pressurized fluid from the reservoir 17 and delivers it on one side to the control inlet 15 and on the other side via the feed valve 23, to the closed hydraulic circuit. In [Fig.l], all the references to the reservoir 17 refer to the same reservoir. The pressurized fluid is preferably a liquid and very preferably hydraulic fluid. The outlet of the feed pump 13 is connected to a feed pressure limiting valve 14. The flow rate of the feed pump 13 is sufficiently high during most of the operating time of the pump device 10 so that the feed pressure limiting valve 14 is triggered and the pressure in the control inlet 15 is defined by the setting of the feed pressure limiting valve 14.The supply pressure limiting valve 14 is here fixedly adjusted by an electrically controlled supply pressure limiting valve (see [Fig. 5]).

[0048] The first and second working connections 11, 12 of the main pump 18 or of the pump device 10 are connected by a fluid connection, here in the sense of a closed hydraulic circuit, to a hydraulic motor 40. The hydraulic motor 40 directly drives a fan rotor 41 which cools the cooling circuit, for example the thermal engine of a relatively large vehicle, in particular of a mobile machine. The present invention is mainly intended for this application although it can also be used in other applications. The setpoint discharge pressure difference described below can be regulated for example by a main control circuit with which the rotational speed of the fan rotor 41 is regulated using it as a control variable. The method according to the invention is sufficient for the first and second pressure sensors 71, 72 and the rotational speed sensor 70 without necessarily requiring any other sensor. For example, a tilt angle sensor connected to the main pump 18 or another rotational speed sensor installed on the hydraulic motor 40 can be used as an option to improve the operating behavior of the overall system.

[0049] The first pressure sensor 71 measures a first actual pressure pA in the first working connection 11. The second pressure sensor 72 measures a second actual pressure pB in the second working connection 12.

[0050] It should however be noted that the two supply valves 23 compensate for leaks by supplying the pressurized fluid from the supply pump 13 to the closed hydraulic circuit. It is possible to envisage a pump device 10 equipped with a flushing valve to take, beyond the leaks mentioned above, in a targeted manner, pressurized fluid from the closed hydraulic circuit to avoid overheating of its pressurized fluid. This risk is low in the case of this fan drive.

[0051] The pump device 10 comprises a control device 80 which preferably has a programmable digital computer, in particular a microprocessor and / or an FPGA circuit. The input of the control device 80 is connected to the first and second pressure sensors 71; 72 and to the rotation speed sensor 70 so that the control device 80 receives the first and second actual pressure pA; pB and the actual rotation speed (n) for calculating the first and second adjustment current i-DRE; i_3 / 2. At the output, the actuating electromagnets 31, 33 of the pressure adjustment valve 30 and the 3 / 2-way distributor 32 are connected to the control device 80.

[0052] Furthermore, it is worth noting the first and second throttle members 83, 84 which are respectively located between the first or second control chamber 21, 22 and the associated control valve 30, 32. With the first and second control members 83, 84, the speed with which the discharge flow can be reliably restricted upwards is adjusted to protect the hydraulic motor 40 and the fan 41 against damage.

[0053] [Fig. 2] shows a part of a control diagram implemented by the method of the invention. The part of the control diagram of [Fig. 2] can be applied in multiple variants without departing from the scope of the invention. It is possible for example, using only the pilot control with the path planning filter 50 and the inverse model 51 of the axial piston machine. Similarly, one can consider using only the regulator 52. In each case, the overall system works; [Fig. 2] shows the most complete variant with the best operating characteristics.

[0054] For the pump device, a setpoint discharge pressure difference dp-cons is predefined from the outside; this difference is that of the first and second measured sensor pressures, i.e. the first and second actual pressures pA; pB set to the setpoint discharge pressure difference dp-cons.

[0055] This adjustment is made as quickly as possible, first of all by a pilot control based on the inverse model 51 of the pump device. The description of document DE 10 2019 210 003 A1 gives mathematical formulas which model the behavior of the axial piston machine. Document DE 10 2021 200 693 A1 describes a method with which the mathematical model of the axial piston machine is experimentally determined. All these models have in common that they provide usable results by inversion only if the timing diagram of the discharge pressure difference used at the inlet can be effectively adjusted on a real axial piston machine.

[0056] The setpoint discharge pressure difference dp-cons can, however, have abrupt variations which are not those of the actual discharge pressure difference because the latter can only vary continuously. This is why the setpoint discharge pressure difference dp-cons is first applied to a path planning filter 50 before applying it to the inverse model 51 of the pump device. In the simplest case, the path planning filter 50 is a low-pass filter whose cut-off frequency is set fixedly. This makes it possible to simply eliminate the abrupt variations mentioned above.However, the path planning filter 50 described in document DE 10 2019 210 003 Al makes it possible to make the best use of the available power of the pump device to achieve, within the framework of the pilot control, a particularly rapid approach to the setpoint discharge pressure difference dp-cons.

[0057] In addition to the modified setpoint discharge pressure difference, the measured values ​​of the sensors, namely the actual rotational speed (n) of the motor shaft and the first and second actual pressures pA, pB, are also applied to the inverse model 51 of the pump device to calculate the model 51. The result then provided by the inverse model 51 of the axial piston machine is the setpoint adjustment pressure difference dpX-cons, which must be adjusted in theory to bring the actual discharge pressure difference and the difference as close as possible as quickly as possible. setpoint discharge pressure dp-cons. This theoretical value may not correspond perfectly to real conditions. This is why a 50 regulation is combined (superimposed) on the pilot control.

[0058] The control variable of the regulator 52 is preferably another setpoint control pressure difference additively combined 54 with the pilot control to obtain the value dpX-cons. It is also possible to envisage applying the control variable of the regulator 52 to a suitable point of the inverse model 51 of the pump device to improve the control behavior.

[0059] On the input side of the controller 52, the actual discharge pressure difference is first calculated as the difference 53 between the first and second actual pressure pA, pB. The control deviation is the difference 53 between the setpoint discharge pressure difference dpX-cons and the actual discharge pressure difference. The control deviation is applied to the controller 52, which is preferably a continuous linear controller, in particular a PID controller. The controller 52 applies a cycle-based calculation method discretely in time, preferably within the input.

[0060] [Fig. 3] shows another part of the control diagram of [Fig. 2]. The interface between Figures 2, 3 is the setpoint adjustment pressure difference dpX-cons which is also the primary input quantity of the process according to the invention.

[0061] According to the invention, in particular control valves are used, namely a pressure control valve and a 3 / 2-way slide valve. This choice has considerable advantages in the context of driving a fan, since different variants of conventional fans can be produced with the same components. In particular, the side of the control cylinder to which the pressure control valve is associated can be freely selected, and the 3 / 2-way slide valve is then installed on the other side. This advantage comes at the cost of a significant disadvantage avoided by the present invention. In particular, the control behavior of the control valves for a setpoint control pressure difference dpX-cons must be equal to zero, which corresponds to a significant discontinuity of the two control valves. The control valves cannot be used with a purely hydraulic, conventional control device, even if they are actuated hydraulically.Therefore, within the framework of the invention, a method is applied which is preferably implemented by a programmable digital computer which has a microprocessor.

[0062] The discontinuity mentioned above is taken into account by distinguishing three cases, namely: a zero case 60, a positive case 61 and a negative case 62. In the zero case 60, the difference in setpoint adjustment pressure dpX-cons is practically zero, which also includes cases in which, due to adjustment inaccuracies, it is not not sure whether the actual, actually set pressure difference is positive or negative.

[0063] In the positive case 61, the setpoint adjustment pressure difference dpX-cons is positive and there is no zero case 60. In the positive case 61, the second adjustment chamber is connected by the 3 / 2-way slide valve to the control return so that in the second adjustment chamber, the pressure is practically zero. In the case of the pressure adjustment valve of [Fig.l], with an increasing characteristic curve, the current i-DRE increases practically proportionally to the setpoint adjustment pressure difference dpX-cons. The corresponding relationship is shown in [Fig.4].

[0064] In the negative case 62, the setpoint adjustment pressure difference dpX-cons is negative but there is no zero case. The second adjustment chamber is then connected to the control input by the 3 / 2-way slide valve so that a high pressure prevails in the second adjustment chamber; this pressure is at the same time defined as the maximum pressure to which the pressure adjustment valve is set. In the case of the pressure adjustment valve of [Fig.l], with a positive characteristic curve, the current i-DRE decreases in a manner practically inversely proportional to the amplitude of the desired setpoint adjustment pressure difference dpX-cons.

[0065] In the zero case 61, two zero adjustment positions can be available for the adjustment valves (30, 32 [Fig.l]). Thus, the two adjustment chambers are connected to the control input or the two adjustment chambers (21, 22, [Fig.l]) are connected to the control return. In both cases of zero adjustment, zero pressure is applied to the adjustment piston. Theoretically, the pressure adjustment valve should not be set to an intermediate value. But in practice this is unavoidable, in particular for the transition from the positive case 61 to the negative case 62 or vice versa (zero crossing). This problem is remedied by a corresponding switching, only if this is actually necessary and then it is carried out in a particularly rapid manner.

[0066] For this purpose, the four possible cases for the first and second adjustment pressure p-DRE are preferably calculated continuously and almost simultaneously; p-3 / 2, i.e. in the case of zero adjustments as a constant and only for a distinction of cases 63, the one of the four cases which will be used to control the adjustment valves (30, 32 of [Fig.l]) is fixed.

[0067] This distinction of case 63 is simple if we are incontestably in the positive case or in the negative case 61, 62. The situation is more delicate if there is a crossing through zero. For this we can consider adjusting the difference in setpoint adjustment pressure dpX-cons, abruptly by passing through zero. This sub-case results in a simple distinction of cases, between the positive case and the negative case 61, 62, to have the result desired; the discontinuity necessarily caused by the adjustment system is not disturbed by the discontinuous adjustment of the setpoint adjustment pressure difference dpX-cons.

[0068] If the zero crossing is carried out by a continuous adjustment of the setpoint adjustment pressure difference dpX-cons, with the derivative of the setpoint adjustment pressure difference as a function of time, the zero crossing is theoretically expected. A short time before the theoretical zero crossing, a respective zero adjustment is carried out which does not require an abrupt adjustment of the control valves. During the zero case 60, the setpoint adjustment pressure difference dpX-cons is continued to be observed. If the zero case 60 is unilaterally left in a zero crossing, the other zero adjustment is carried out abruptly.

[0069] The inverse model 64 of the pressure control valve determines the first adjustment current i-DRE required to adjust the desired pressure. This can be done with the static model of [Fig.4] which is simply a valve characteristic curve. Alternatively, a dynamic model can be used which takes into account how quickly the pressure control valve reacts to changes in the first adjustment current i-DRE. Because of the particularly rapid adjustment desired for the zero case 60, it is advantageous to have a dynamic inverse model 64.

[0070] With the inverse model 65 of the 3 / 2-way spool, the second setting current i-3 / 2 required to set the desired pressure is determined. The basic switching characteristic here only allows a principle to be distinguished in two cases. In the first case, i-3 / 2 is equal to zero. In the other case, i-3 / 2 is as large as possible without risking overheating of the corresponding actuating electromagnet (33 [Fig.l]). During the switching period, a second setting current i-3 / 2 can be set, which is larger than in the subsequent period in which the 3 / 2-way spool is to maintain its setting. This results in rapid switching on the one hand and, on the other, minimized current consumption and risk of overheating.

[0071] [Fig. 4] shows a diagram representing the inverse model of the pressure control valve. This is a static model in the form of a valve characteristic curve. The horizontal axis represents the (average) current in the actuating magnet and the vertical axis represents the pressure at the outlet of the pressure control valve. The pressure control valve is preferably designed to have at least a monotonic characteristic curve. This ensures the possibility of a unambiguous inversion of the model. For a predefined first control pressure p-DRE, it is then sufficient to set only the first control current i-DRE.

[0072] The present characteristic curve is practically linear. In the context of preferential numerical calculation, the present approximation quality is sufficient in itself- even because the residual non-linearity is compensated by the inverse model without risk of technical drawback.

[0073] [Fig. 5] shows a diagram corresponding to the hydraulic diagram of [Fig. 1] of a pump device 10' according to a second embodiment of the invention. This second embodiment is identical to the first embodiment according to Figures 1 to 3 except for the differences described below for which reference will also be made to the explanations given in relation to Figures 1 to 3.

[0074] In the second embodiment, the pressure control valve 30 is associated with the second control chamber 22 and the 3 / 2-way valve 32 is associated with the first control chamber 21. Furthermore, a pressure control valve 30 with a decreasing characteristic curve is used. This associates, in the currentless state, the pressure in the control inlet 15 with the second control chamber 22. To achieve the desired, fail-safe behavior, the 3 / 2-way valve 31 is designed so that in the currentless state, the first control chamber 21 is connected to the control return 16. In the currentless state, the first and second embodiments behave in the same way for the direction of flow between the first and second working connections 11; 12 because in both cases the highest pressure is that of the second control chamber 22.

[0075] If in the currentless state it is desired to reverse the direction of passage between the first and second working connections 11, 12, it is necessary to exchange the two valves 30, 32 both in [Fig.l] and in [Fig.5] and adapt the adjustment to the control device 80. For this purpose, use is made of the fact that the transfer direction of the pump device can be reversed by simply adjusting the delivery flow rate.

[0076] In the second embodiment, the supply pressure limiting valve 14 is electrically adjusted with a pre-control valve 85. The pre-control valve 85 is here an electrically controlled pressure reducing valve and its outlet pressure is applied to the side opposite the spring of the supply pressure limiting valve 14. Thus the trigger pressure of the supply pressure limiting valve 14 decreases when the pressure at the outlet of the pre-control valve 85 increases. The pre-control valve 85 is connected at the output to the control device 80 and the third adjustment current i-alim or the associated supply pressure are taken into account for the control of the pressure regulating valve 30 and the 3 / 2-way distributors 32.

[0077] [Fig. 6] is a sectional view of the pressure regulating valve 30 and the associated first or second receiving bore 81, 82. The pressure regulating valve 30 is a pressure reducing valve described in the technical notice “reducing valve” cited above. This valve is used in the context of the present invention but other types of valve can also be used. The data sheet of this valve shows that the first and second receiving holes 84, 82 have appropriate dimensions. For these receiving holes there is also a 3 / 2-way distributor.

[0078] The pressure reducing valve 30 comprises an actuating magnet 31 which electrically adjusts, by applying a magnetic force, the control spool 86 of the pressure adjusting valve 30. The valve segment 87 of the pressure adjusting valve 30 is fixed in the associated first or second receiving bore 81; 82 by being screwed at 88.

[0079] The first or second throttle member 83, 84 are preferably separate inserts which are fixedly installed, in particular screwed into the bottom of the first or second receiving bore 81, 82.

[0080] NOMENCLATURE OF MAIN ELEMENTS

[0081] 10 Pump device (first embodiment)

[0082] 10' Pump device (second embodiment)

[0083] 11 First working connection

[0084] 12 Second working connection

[0085] 13 Feed pump

[0086] 14 Supply pressure limiting valve

[0087] 15 Command Input

[0088] 16 Return of order

[0089] 17 Tank

[0090] 18 Main pump

[0091] 19 Motor shaft

[0092] 20 Adjustment cylinder

[0093] 21 First adjustment chamber

[0094] 22 Second adjustment chamber

[0095] 23 Feed valve

[0096] 30 Pressure adjustment valve

[0097] 31 Pressure adjustment valve control electromagnet

[0098] 32 3 / 2-way distributor

[0099] 33 3 / 2-way distributor actuating electromagnet

[0100] 34 Return spring

[0101] 35 First position

[0102] 36 Second position

[0103] 40 Hydraulic motor

[0104] 41 Fan rotor

[0105] 50 Path planning filter

[0106] 51 Inverse model of the axial piston machine

[0107] 52 Regulator

[0108] 53 Actual value / setpoint value comparison

[0109] 54 Superposition of pilot control and regulation

[0110] 55 Determination of the difference in the actual discharge pressure [YES] 60 Zero cases

[0112] 61 Positive case

[0113] 62 Negative case

[0114] 63 Distinction of cases

[0115] 64 Reverse model of the pressure adjustment valve

[0116] 65 Reverse model of the 3 / 2-way distributor

[0117] 70 Rotation speed sensor

[0118] 71 First pressure sensor

[0119] 72 Second pressure sensor

[0120] 80 Control device

[0121] 81 First receiving drilling

[0122] 82 Second receiving hole

[0123] 83 First strangulation

[0124] 84 Second strangulation

[0125] 85 Pilot valve of the supply pressure limiting valve

[0126] 86 Pressure adjustment valve control drawer

[0127] 87 Valve segment

[0128] 88 Screwing

[0129] dpX-cons Setpoint adjustment pressure difference

[0130] dp-cons Discharge pressure difference

[0131] i-DRE First adjustment current

[0132] i_3 / 2 Second adjustment current

[0133] i_alim Third adjustment current

[0134] p_A First actual pressure

[0135] p_B Second actual pressure

[0136] n Actual rotation speed

[0137] p_DRE First adjustment pressure

[0138] p_3 / 2 Second adjustment pressure

Claims

1. Claims Pump device (10; 10') with a first and a second working connection (11; 12) to which a closed hydraulic circuit (40) is connected by a fluid connection, - the pump device (10; 10') having a drive shaft (19), * a complete rotation of the drive shaft (19) ensuring the transfer of a delivery volume of pressurized fluid between the first and the other working connection (11; 12), * the delivery volume being continuously adjustable by a double-acting adjustment cylinder (20) having a first and a second adjustment chamber (21; 22), * the first and the second adjustment chamber (21; 22) being associated respectively with a first and a second receiving bore (81; 82) connected respectively by a permanent fluid connection to the first and the second adjustment chamber (21; 22), * the first and second receiving holes (81, 82) being identical, being made respectively for the fixing of an integrated valve, * a first pressure sensor (71) being provided to measure a first actual pressure (pA) at the first working connection (H), * a second pressure sensor (72) being provided for measuring a second actual pressure (pB) at the second working connection (12), * a control device (80) being connected to the first and second pressure sensors (71, 72), pump device characterized in that a pressure adjustment valve (30) in the form of an integrated valve is installed in the first or second receiving bore (81, 82), * the other bore among the second or the first receiving bore (82, 81) receiving a 3 / 2-way slide valve (32) in the form of an integrated valve, * the pressure adjustment valve (30) and the 3 / 2-way distributor (32) each being electrically controlled, connected respectively to the control device (80), * the control device (80) predefines a discharge pressure setpoint difference (dp-cons), * the control device (80) controls the pressure adjustment valve (30) and the 3 / 2-way valve (32) to adjust the discharge flow rate so that the difference between the first and second actual pressure (pA; pB) approaches the discharge pressure setpoint difference (dp-cons).

2. Pump device (10; 10') according to claim 1, wherein in the control device (80) the first and second receiving bores (81; 82) which receive the pressure regulating valve (30) or the 3 / 2-way valve (32) is adjusted, * the control device (80) being designed so that this adjustment is taken into account for the control of the pressure regulating valve (30) and for the control of the 3 / 2-way valve (32).

3. Pump device (10; 10') according to one of the preceding claims, comprising: a rotational speed sensor (70) which measures the actual rotational speed (n) of the drive shaft (19), * the control device (80) being designed such that the pressure control valve control (30) and the control of the 3 / 2-way valve (32) exclusively take into account the actual rotational speed (n) and the first and second actual pressure (pA; pB) as actual values ​​measured in current operation.

4. Pump device (10; 10') according to one of the preceding claims, wherein the control device (80) implements a pre-control (51) to which a regulation (52) is imposed.

5. Pump device (10; 10') according to one of the preceding claims, wherein the control device (80) sets an increasing or decreasing characteristic curve of the pressure adjustment valve (30) actually used, * the control device (80) is designed to take this into account in controlling the pressure adjustment valve (30).

6. Pump device (10; 10') according to one of the preceding claims, in which the 3 / 2-way valve (32) is pre-tensioned by a return spring (34) in a first position (35), and it can be switched into a second position (36) by an associated actuating magnet (33), * the first or second control chamber (21, 22) concerned is connected by the switching of the 3 / 2-way valve (32) by a fluid connection optionally to a control inlet (15) or to a control return (16), * in the control device (80) it can be set whether the 3 / 2-way valve (32) actually used, established in the first position (35) a fluid connection between the associated control chamber, namely the first or second control chamber (21;22) and the control input (16) or the control feedback (15), * the control device (80) being designed to take this setting into account for the control of the 3 / 2-way distributor (32).;

7. Pump device (10) according to one of the preceding claims, wherein - the pressure regulating valve (30) has an increasing characteristic curve, and - the 3 / 2-way distributor (32) makes a connection with a control input (15) in its first position (35).

8. Pump device (10') according to one of claims 1 to 6, wherein - the pressure adjustment valve (30) has a decreasing characteristic curve, and the 3 / 2-way distributor (32) makes a connection with a control return (16) in the first position (35).

9. Pump device (10; 10') according to one of the preceding claims, comprising: a feed pump (13) in driving connection with the motor shaft (19), * this pump is connected at the outlet to the control inlet (15) by a fluid connection, * a supply pressure limiting valve (14) regulates the pressure at the control inlet (15), * the control device (80) takes into account the adjustment of the supply limiting valve (14) for controlling the pressure adjustment valve (30) and for controlling the 3 / 2-way distributor (32).

10. Pump device (10; 10') according to one of the preceding claims, wherein the first and / or the second adjustment chamber (21; 22) are permanently connected by a fluid connection with a first or a second throttle member (83, 84) respectively to the associated first or second receiving bore (81, 82).

11. Pump device (10; 10') according to one of the preceding claims, in which the delivery flow rate is continuously adjusted so that the direction of flow between the first and second working connections (11; 12) can be reversed solely by controlling the adjustment cylinder (20) for the same direction of rotation of the drive shaft (19).

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