DE102012221944A1 - Apparatus for adjusting control pressure of hydrostatic drive for construction or agricultural machine, has unit for load measuring of hydrostatic drive and unit for adjusting control pressure based on detected load of drive - Google Patents

Abstract

The apparatus (100) has a unit for load measuring (110) of a hydrostatic drive (300) and a unit for adjusting (120) the control pressure based on a detected load of a drive. The adjusting unit is formed to adjust the control pressure in a speed area of the hydrostatic drive between 0 and a high rotational speed demand. The adjusting apparatus has a unit for detecting (130) rotational speed of the hydrostatic drive. Independent claims are included for the following: (1) a method for adjusting a control pressure of a hydrostatic drive; and (2) a computer program of executing the method.

Description

Embodiments of the present invention are concerned with an apparatus, a method and a computer program for adapting a control pressure of a hydrostatic drive, a hydrostatic drive and a construction machine with a hydrostatic drive.

Hydrostatic drives are already known from the field of conventional technology. In this case, a medium, such as hydraulic oil or hydraulic fluid, promoted by a pump, wherein one or more corresponding hydrostatic motors, which are also called hydraulic motors, are driven in the delivery circuit. For example, a hydrostatically driven vehicle may include a drive pump that is directly flanged to a drive motor, such as an internal combustion engine, such as a diesel engine, etc. In addition, the vehicle may have a hydraulic motor which is connected to two high-pressure hoses with the pump. If the control pressure of the pump is then increased while the drive motor is rotating and the pump is thereby swung out, the pump delivers oil into the transmission or the hydraulic motor and accelerates the vehicle. In this case, so-called swash plate machines can be used, which can be controlled or regulated via appropriate control pressures. With the change in the receiving volume of the hydraulic motor then the speed can be further varied. If a hydraulic motor is on the mechanical stop for maximum or minimum take-up volume, the vehicle speed can be regulated by the high pressure between the pump and the hydraulic motor. In principle, the vehicle speed can be regulated by the hydraulic motors via the delivery rate of the pump in the case of physically determined limits of the intake quantity.

In addition, it is known from the prior art that different components are used in such drives for driving speed control. For example, in construction and agricultural machinery, there may also be various modes of operation. An operating mode is normal driving, in which the driving speed is in a certain ratio to the drive speed. In another operating mode, such as a constant speed mode, however, the driving speed should be able to be set independently of the drive engine speed, such as diesel engine speed. In this mode, the drive motor speed remains constant, and depending on the output power of the driven pump and the drive motor corresponding performance is required. The constant speed operating mode of the drive motor can provide efficiency advantages. For example, then a desired driving speed via a controller or adaptive can be set. A disadvantage of this concept is that this only works in areas where a reliable output speed can be detected.

In addition, from the conventional field, the so-called boost function (of narrow "boost" for amplify) is known, which serves to shorten the downtime, for example when starting. In other words, by this function, the standstill time from the time when the driver steps on the accelerator pedal (= accelerator pedal) until the time when the wheel starts to rotate is shortened. In hydrostatically driven vehicles today, the boost function is solved so that depending on the difference between the desired engine speed (also called "desired engine speed") and the current engine speed (also called "engine speed"), a control pressure offset is applied to the pump becomes. The maximum sum control pressure, which can be composed of several components accordingly, is limited upwards. The engine information will vary according to, for example, the Norm SAE J1939 , either speed-dependent or sent after regular time periods, eg every 250 milliseconds (ms). This has the disadvantage that in the case of very dynamic adjustment processes, as occur, for example, with strong drive motors, and a transmission clock of 250 ms, this threshold, ie the maximum sum control pressure, is exceeded and the boost offset is then output too little or not at all.

The present invention is therefore based on the object to provide an improved concept for adjusting the control pressure of a hydrostatic drive.

The object is achieved according to the appended independent claims.

Embodiments are based on the core idea that the control pressure of a hydrostatic drive can be adjusted depending on a load of the hydrostatic drive. This can be done over all speed ranges, in embodiments, a specific speed range, such as a lower speed range, can be used for this adjustment. Embodiments are further based on the recognition that the output speed can be reduced by external loads, or this is desired, for example, is lowered by a driving potentiometer, and then it can come to turn off various control and control components. This is related to that A speed of the output in a low speed range can not be reliably determined, since here, for example, Hall sensors are used, which provide reliable values only from a certain frequency and thus speed. As a result, with respect to the output speed, a threshold can arise from which a controller switches on when the output speed increases, or switches off again when the output speed decreases. In this area, a corresponding hysteresis can be provided to avoid fast sequential switching operations. For example, below these thresholds, ie in the area in which the controller is switched off, in embodiments the control pressure can be adjusted load-dependent.

Exemplary embodiments therefore provide a device for adjusting a control pressure of a hydrostatic drive. The apparatus comprises means for load sensing the hydrostatic drive and means for adjusting the control pressure based on a detected load of the drive. The device for adjusting the control pressure can also be realized, for example, by means of a valve or a pump via which or the control pressure can be regulated. The device for load detection can be realized by sensors, for example, variables can be detected here, which can only be concluded by appropriate evaluation of the load. These may be, for example, pressure sensors, flow meters, flow sensors, etc. In embodiments, the device may be used in addition to a speed limitation function or a drive area code. For example, at low maximum output speed requirements and pump controller off, the reduction in traction on the hydrostatic drive can be compensated. Embodiments can thus provide the advantage that after falling below the Reglerausschaltschwelle or not reach the regulator threshold an adjustment of the control pressure can be load-dependent, and thus a standstill of the vehicle can be avoided under certain circumstances.

Embodiments is therefore based on the finding that it would be desirable to be able to adjust the travel speed of such a vehicle steplessly and independently of the drive engine speed, such as a diesel engine speed. In addition, it would be advantageous if the driving speed was continuously adjustable and overshoot or a dependence on external loads could be hidden by appropriate adjustment. Using the example of a construction vehicle, this would mean that an empty vehicle could drive up a mountain just as a full vehicle or a bucket could be filled, even if only very small output speeds are desired. Embodiments of the present invention is further based on the finding that a driver always desires a reaction immediately when he actuates the accelerator pedal, or that dead times between an actuation of an accelerator pedal and the actual starting of the vehicle are unfavorable. In normal operation and at higher speeds, this function can be at least partially taken over by a controller. Since there are driving situations in which the controller is switched off and on, this can lead to jumps in the control pressure and a jerking of the vehicle. Exemplary embodiments may offer the advantage that this behavior can even be avoided, at least in some embodiments, in some embodiments.

In exemplary embodiments, the device for adaptation can be designed to adjust the control pressure in a speed range of the hydrostatic drive between 0 and an upper speed specification. To set the upper speed specification then a driving potentiometer can be provided. The driving potentiometer is, for example, a manually operable lever, switch or rotary wheel etc, ie a manually operable device. Accordingly, the upper speed specification in particular variable manually adjustable. In other words, a width of the available output rotational speed range is adjusted by means of the driving potentiometer on the basis of the upper rotational speed specification. In this case, a (conventional) driving condition can also be provided, by means of which the setpoint output speed of the hydrostatic drive is set within this output speed range. Corresponding to the set upper speed specification, the target output speed therefore changes with the same accelerator pedal position. For example, when the accelerator pedal is pressed halfway, half of the upper speed setpoint is present as the setpoint output speed. If the accelerator pedal is fully depressed, then exactly the upper speed setpoint is present as the setpoint output speed. Thus, a soulful slow driving (at low upper speed specification) and a dynamic high-speed driving (at high upper speed specification) can be realized, in each case the entire available accelerator pedal travel is available. In some embodiments, it can be provided that the load-dependent adaptation of the control pressure over the entire speed range takes place or only up to a certain speed limit. In some embodiments, this speed limit may coincide with the switching on and off of the controller, so that when the controller is switched off, a load-dependent adjustment of the control pressure can take place. In other words, in a hydrostatic drive, the amount or volume of the Hydraulic fluid, which is pumped under certain pressure into a hydraulic motor, the power delivered by the drive motor. Here, for example, radial piston machines or axial piston machines can be used. The control pressure of the pump, while the delivery volume of the pump, whereby here also radial piston machines or axial piston machines can be used. In some embodiments, the apparatus may further comprise means for detecting a rotational speed of the hydrostatic drive, wherein the means for adjusting the control pressure may be configured to further adjust the control pressure based on the rotational speed. In other words, the means for adjusting the control pressure can be designed to adjust the control pressure only load-dependent, if a certain speed limit of the output is exceeded. In other words, the means for adjusting the control pressure may be configured to adjust the control pressure below a speed limit of the hydrostatic drive.

In embodiments, the means for adjusting the control pressure may be further configured to adjust the control pressure based on a speed specification for the drive. In other words, in embodiments, a speed specification for the output of the hydrostatic drive can be specified, e.g. via an accelerator pedal and / or a driving potentiometer. The device for adaptation can then be designed to set a corresponding control pressure based on this specification in interaction with the instantaneous load. The device may therefore further comprise a pump, which is correspondingly coupled to the hydrostatic drive and the control pressure affects a delivery volume of the pump.

In embodiments, various methods for load detection can be used. In some embodiments, the load sensing device may be configured to derive information about the load from a pump failed amount of the pump and the hydrostatic drive. For example, the pump shortage amount can be calculated from the difference between a volume expected at a given control pressure, e.g. for the load-free case, and the actually conveyed or backflowing volume are determined. In other words, in the present case, the quantity of pumping fluid is understood to mean that quantity or volume difference which lies between a delivery rate of the pump for a specific control pressure in a defined load state and the actual delivery rate.

In such embodiments, volume meter or volume meter can accordingly be used. In other embodiments, the pump or the hydrostatic motor (= hydraulic motor) may be formed as a radial piston machine or axial piston machine and the means for load detection may further be designed to derive information about the load from a skew angle or tilt angle of the respective machine. As is known from the field of conventional technology, such hydraulic pumps can be present in various designs, for example as a radial piston machine or axial piston machine. In such machines, the delivery volume per revolution depends on a pivoting angle. For example, pivot angle sensors can be used here in order to close the load. In other embodiments, a speed of a drive motor driving the pump, such as engine speed, so diesel speed, etc., also be taken into account. In other words, with a constant speed and a given swivel angle in such a machine, the volume delivered under a given geometry only depends on the control pressure and the driving or high pressure. Neglecting slippage and any compressibility, it is possible to deduce the displacement directly from the swivel angle and the speed.

In further embodiments, the means for load detection may be configured to derive information about the load from a pressure difference. In such embodiments, for example, pressure sensors or high pressure sensors can be used. These can be located in several places and determine, for example, pressure conditions in an inlet to a hydrostatic motor or a hydrostatic drive, as well as in the return. From the pressure difference can then be closed to the corresponding load of the hydraulic motor. In other embodiments, a combination of the above methods may also be used to determine the load. Embodiments can therefore also be based on the knowledge that normally random load conditions of this drive are regulated by a controller. In order for the controller to work, a control difference must be provided to the controller. As already mentioned above, a range below a detection limit of a rotational speed sensor can be approached by driving speed reductions, so that it is not possible to detect a load without further information, which can be determined, for example, by sensors or other information means. In this case, the vehicle may stop or may not even start.

In further embodiments, the means for adjusting the control pressure as Control be formed. This can for example adjust the control pressure based on a map. For example, further operating modes can be realized in embodiments such as speed limiter, manual controls such as driving potentiometers, etc. In this context, it can generally come to a decoupling of the output speed of the drive motor speed. The map can z. B. provide one or more input variables, of which at least one is load-dependent and deliver as an output variable influencing the control pressure size. In other words, in embodiments, simple controls can be provided which provide a simple relationship between a specific load and the control pressure, such as a linear or proportional relationship. In other exemplary embodiments, multi-dimensional maps may also be provided which provide an output variable based on a plurality of input variables, wherein the output variable has information about a control pressure to be set or adjusted.

In further embodiments, the means for adjusting the control pressure may also be designed as a regulator. In other words, the control pressure can then serve as a control variable, for example, to compensate for a difference between an actual output speed and a target output speed, which can be determined based on the respective load. In addition, embodiments provide a hydrostatic drive with a hydrostatic pump, a hydrostatic motor and a device as described above. Furthermore, embodiments can provide a construction or agricultural machine with such a hydrostatic drive.

Embodiments also provide a method for adjusting a control pressure of a hydrostatic drive. The method includes sensing a load of a hydrostatic drive and adjusting the control pressure based on the detected load of the drive.

Further, embodiments provide a computer program for performing any of the methods described above when the computer program is executed on a processor or in a programmable hardware component.

Some embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Show it

1 an embodiment of a device for adjusting a control pressure;

2 a principle equivalent circuit diagram of a hydrostatic drive;

3 a functional diagram of an axial piston machine in an embodiment;

4 a block diagram with an embodiment;

5 a flowchart of a method in an embodiment;

6 an overview of the interaction of an embodiment with other components in a system;

7 an overview of a hydraulic drive with an embodiment;

8th a diagram of an embodiment; and

9 a block diagram of a flowchart of an embodiment of a method for adjusting a control pressure.

In the following description of the attached figures showing embodiments, like reference numerals designate like or similar components. Further, summary reference numbers are used for components and objects that occur multiple times in one embodiment or in a drawing, but are described together in terms of one or more features. Components or objects which are described by the same or by the same reference numerals may be the same, but possibly also different, in terms of individual, several or all features, for example their dimensions, unless otherwise explicitly or implicitly stated in the description.

1 shows an embodiment of a device 100 for adjusting a control pressure of a hydrostatic drive and a device for adaptation 120 the control pressure based on a detected load of the drive. In the 1 Optional components are shown with dashed lines.

In the embodiment shown in the 1 is shown is the device for adaptation 120 further configured to make the adjustment of the control pressure in a speed range of the hydrostatic drive between 0 and an upper speed specification (= upper speed limit). Therefore, the device includes 100 in the 1 a device for detection 130 a speed at the output, so an output of the hydrostatic Drive, with the device for load detection 110 is configured to further detect the load based on the rotational speed. In further embodiments, the device for adaptation 120 the control pressure to further adjust the control pressure based on the rotational speed. In other words, the device is for customization 120 the control pressure is designed to adjust the control pressure below a speed limit of the hydrostatic drive. This speed limit, for example, at 5, 10, 20, 50, 100, etc. revolutions per minute (= rpm) are.

In the in the 1 the embodiment shown is the device for adaptation 120 the control pressure is further adapted to adjust the control pressure based on a speed specification for the drive. In the embodiment of 1 It is assumed that this speed specification of an accelerator pedal and optionally a driving potentiometer, which is designed for example as a manually operable lever, switch, wheel, etc., is specified. The accelerator pedal is, for example, a manually operated foot pedal or a hand throttle or lever. For example, the device 100 be implemented in a construction or agricultural machine, wherein an operator or the machine operator sets the upper speed specification via the driving potentiometer while he sets a target output speed between 0 and the set upper speed setting by the accelerator pedal. Accordingly, the upper speed specification is variably adjustable. As a result, a sensitive slow driving (low upper speed specification) and a dynamic high-speed driving (high upper speed specification) is possible. Alternatively, the upper speed default is fixed or not manually adjustable by the driver / operator of the machine.

Like in the 1 is shown, the device comprises 100 in the embodiment shown, a further pump 140 , which is coupled to the hydrostatic drive, wherein the control pressure is a delivery volume of the pump 140 affected. In other embodiments, the pump 140 also be arranged outside the device, as will be shown by the following embodiments. The hydraulic pump 140 is driven by a drive motor, not shown, such as an internal combustion engine, such as diesel engine, etc.

Like the embodiment of 1 shows, is the device for load detection 110 configured to provide information about the load from a pump shortage of the pump 140 and a hydraulic motor (in 1 not shown). As already mentioned above, in embodiments, the pump 140 and / or the hydraulic motor may be designed as an axial piston machine. The device for load detection 110 can then also be designed to provide information about the load from a swing angle of the pump 140 derive. In further embodiments, the means for load detection 110 be designed to derive information about the load from a pressure difference. This pressure difference can, for example, in an inlet and a drain of the pump 140 be determined.

2 shows a schematic diagram of a hydrostatic drive 300 , which is a drive motor 510 includes, which may be embodied as an internal combustion engine, such as a diesel engine, etc., for example. The drive motor 510 drives a pump 140 whose delivery volume is variable per revolution, ie q _Pu = var. The pump 140 is hydraulic with a hydraulic motor 150 coupled, whose displacement is constant per revolution, ie q _Hydro = const. The hydraulic motor 150 Alternatively, it can also be designed so that its absorption volume can be variably adjusted. Then, namely, an output speed of the hydraulic motor 150 even then be increased when the pump 140 reached their maximum funding volume. The pump 140 can for example be designed as a radial or axial piston machine, so that the delivery volume per revolution q _Pu depends on a pivot angle and thus of a control pressure, as well as the hydraulic motor 150 ,

3 shows above a schematic diagram of an axial piston machine, which in one embodiment as a pump 140 can be used. The axial piston machine has a drain 140a on, through which the pump 140 the hydraulic fluid with a first pressure p1 in the hydraulic motor (in 3 not shown) promotes and an inflow 140b through which the pump resumes the hydraulic fluid at a second pressure p2. In the process 140a or feed 140b are cylinders 140c and 140d provided, the corresponding piston 140e . 140f lead, in turn, on sliding shoes 140h and 140i on the swash plate 140g to run. The swivel angle of the swash plate 140g is in the 3 denoted by β and is influenced by the control pressure described above. The 3 also shows the two opposing forces Fx1 and Fx2 at the swashplate 140g attack and their swing angle β also influence. The influence should be based on the sketch in the 3 will be explained below. The 3 Below shows a construction vehicle that with a corresponding hydraulic drive 300 is equipped and moves uphill on the inclined plane as indicated by the arrow. The angle of the plane is denoted by α.

Assuming that α> 0 follows so that the pressure p1 increases or the force Fx2 increases. If then simultaneously the pivot angle β constant should remain, the control pressure pX, which is proportional to the force Fx1, must rise.

For example, is for α = 0 = pX pX _{feed forward.} In other words, in the load-free case, the control pressure results from a value which is predetermined by a precontrol. Then pX increases for α> 0 = pX pX _feedforward + pX _load, that a load-dependent component. In an alternative representation, the displacement of the hydraulic motor 150 are considered per revolution, which is then composed of a portion of the pilot control and a load-dependent component, for example by a controller. In this respect, it should be noted that between the intake and delivery of pump 140 and engine 150 There are equivalent relationships.

Under consideration of 2 Furthermore, it holds that for a constant delivery volume q _Pu = const per revolution at the pump 140 , ie for constant swivel angle, the output speed of the hydraulic motor 150 n _AB = f (q _hydro , n _diesel ) a function of the displacement q _hydro per revolution of the hydraulic motor 150 and the speed of the drive motor 510 is. Looked at the other way around, the displacement volume q _hydro per revolution of the hydraulic motor can be considered 150 as a function of the output speed and the speed of the drive motor 510 q _hydro = f (n _AB , n _diesel ). Take the displacement of the hydraulic motor 150 as constant, q _Hydro = const, then the output speed is given as a function of the delivery volume q _Pu per revolution of the pump 140 and the speed of the drive motor 510 , n _AB = f (q _pu , n _diesel ). The output speed can also be represented as n _AB = Q _Pu / (q _Hydro · i _n ), where Q _{Pu is} the delivery volume of the pump 140 with respect to time, and i _{n represents} a gear ratio to a (Hall) sensor sensing the output speed n _AB .

4 shows a further block diagram of an embodiment of a device 100 , which is implemented as an electronic control unit (ECU). The 4 also shows a drive motor 510 that a pump 140 drives. The pump 140 is hydraulic with a hydraulic motor 150 coupled, which provides an output speed n _AB . In the hydraulic circuit between the pump 140 and the hydraulic motor 150 is the flow rate Q _flow from the pump 140 promoted. The ECU 100 gives the pump 140 a control pressure prevailing in the 4 denoted by I _pump . In this case, the speed of the drive motor 510 n _Mot , which is set for example based on a corresponding default. The ECU 100 can also be the output speed n _AB and the displacement per revolution q _{hydro of} the hydraulic motor 150 consider.

In the following, the pump shortfall dQ is defined based on the difference between the expected delivery rate of the pump _delivery Q 140 , which adjusts in the load-free case for a given control pressure, and the actual delivery Q _{delivery rate} , with the intake quantity Q _receiving the hydraulic motor 150 matches. For example, dQ = Q _conveyor - Q _consumption = q · _Pu n _Mot - q · n _{Hydro Hydro,} with n = i _n x n _{Hydro AB.}

In addition, a detection threshold x (also referred to below as the second threshold) is given, from which the output rotational speed can be reliably determined, for example, by means of a Hall sensor. Below this threshold, ie for n _AB <x, the control pressure pX is obtained in the present exemplary embodiment pX = pX feed _forward + pX _load , where the load-dependent part of the adjustment device 120 is provided is designated pX _load and the pilot control component with pX _{feed forward.} Above the threshold, ie for n _AB ≥ x, the control pressure pX results pX = pX _{pilot control} + pX _controller , in which case the proportion pX _{controller is} specified by a controller based on the output rpm n _AB .

The procedure in this embodiment is in the 5 shown in a flow chart. The output speed n _AB is in the 5 from the outside (eg accelerator pedal, driving potentiometer, etc.) specified. Then, a determination is made as to whether the output speed is below the threshold (n _AB <x) and whether the pump shortage dQ is above a threshold dQ _load (dQ> dQ _load ) that is in the 5 with the block 400 is shown. The background of the second condition is that a minimum deviation of the pumping quantity is ensured in order to avoid intervention, ie control or regulation activities, with small deviations. If both conditions are met, the adjustment of the control pressure takes place according to pX = pX feed _forward + pX _{load, n} in the block 402 (left branch in the 5 ), whereby the adaptation of the load-dependent component pX _{load, n} takes place here incrementally on a discrete-time plane, ie pX _{load, n} = pX _{load, n-1} + i _dP see block 404 where n represents the time index and i _dP the pressure increments. If the two conditions are not met, the control pressure is adjusted according to the block 406 . pX = pX _{pilot control} + pX _controller (right branch in the 5 ).

It should be noted here that the controller component pX _controller below the threshold (n _AB <x) can also be zero. As the 5 further shows the control pressure in both cases up through appropriate limiters 408 . 410 limited to a maximum pX _max .

6 illustrates an overview of the interaction of an embodiment with other components in a drive system in a corresponding machine. 6 shows a first component 600 which may correspond, for example, to a computing unit of a vehicle manufacturer. This includes a device for detecting the engine speed 602 a drive motor, such as an internal combustion engine, (eg Hall sensor, CAN bus, etc.) and means for detecting a maximum output speed 604 (= upper speed specification), eg by means of the driving potentiometer. Both facilities 602 . 604 deliver their values to a device for processing the interfaces 606 (eg bus controller), allowing communication with the device 100 is possible. The device 100 includes a device for load detection 110 a hydrostatic drive 300 and a fitting device 120 the control pressure based on a detected load of the drive 300 , The drive 300 is in the 6 shown separately and includes means for detecting the swallow volume 302 the hydraulic motor (eg volume or volume flow sensors) and means for detecting the speed 304 the hydraulic motor (actual speed), eg by means of Hall sensor. rotation speed 304 and swallowing volume 302 become the device 100 , in particular the algorithm for load detection 110 provided. In the considered embodiment, the device comprises 100 furthermore a feedforward control 160 which supplies the pre-control values already described above.

The corresponding values for the control pressure are then sent to a pump 140 passed, with a control pressure device 170 the predetermined values to a total control pressure pX summarizes. A swivel angle device 180 , which may be realized by a swash plate, then sets based on the control pressure, the swivel angle and thus a corresponding delivery volume.

In the present embodiment, the means for adaptation 120 the control pressure is designed as a controller. This determines to adjust the control pressure from a characteristic an output, via the on the pump 140 the control pressure is adjustable. The pump 140 then delivers a corresponding delivery volume. The map has several input variables, wherein the pump failure amount is the load-dependent variable and the speed specification and the speed represent further input variables.

The 7 illustrates the general structure of a hydrostatic drive 300 on the basis of a diagram that should further clarify the interaction of the individual components. The term "MB" in the 7 stands for hydraulic motor B, ie a second hydraulic motor in addition to a hydraulic motor A. This already shows that one or more consumers, such as hydraulic motors, can occur in such a system. The hydrostatic drive 300 includes a hydrostatic pump 140 and a hydrostatic motor (hydraulic motor) 150 , and can be attached to a device 100 according to the description of 1 be coupled. The device 100 can be implemented as a control unit (ECU). For example, an engine control unit (EECU of "engine" ECU), a vehicle control unit (VECU of the "vehicle" ECU) or a transmission control unit (TECU of the "transmission" ECU) come into question.

The 7 shows on the left side of the specification of a target value for the speed of an output, which is designated n_Ab_Soll. Overall, the shows 7 that both the pump 140 as well as the hydraulic motor 150 are integrated into a control loop. A difference pictures 500 Therefore, first determines a control difference, which results from the setpoint for the speed of the output and the actual speed of the output, wherein the actual speed is also denoted by n_Ab. This control difference is a speed controller 502 supplied, which is then to specify a desired control pressure for the subsequent pump, this control pressure is designated pX_Soll. In addition, it should be mentioned that the entire cruise control via the pump in the embodiment shown here only up to a first threshold, such as 380rpm (ie 380 Revolutions per minute, from tight. "Revolutions per minute"), 380pm being understood as a preferred but not limiting example of the first threshold. As the 7 shows, there is a limit for speeds> 380rpm. In addition, no regulation takes place below a second threshold, for example 50 rpm. Thus, the specification of the control pressure for the pump 140 through the throttle 502 only in a range between the first and the second threshold, in the example between 50rpm and 380rpm. In the present embodiment, the throttle is 502 preferably designed as a PID controller, ie as a proportional-integral-derivative controller. However, other suitable regulators, such as an I or PI controller may be used. The pump 140 includes another regulator 504 who the Pump pressure pX for the actual pump 506 based on the target control pressure regulates.

At the pump 506 Therefore, the predetermined control pressure pX is detected, and the default of the speed controller 502 through the subtraction element 508 deducted. This results in the control deviation for the pump controller 504 who tries to correct this and is preferably also designed as a PID controller. Other suitable regulators, such as an I or PI controller, may also be used here. The pump regulator 504 Now supplies a manipulated variable, which is designated by pX-controller. In the present embodiment, it is further assumed that the pump 140 from a drive motor 510 is driven. The drive motor 510 specifies a nominal speed, which is designated n_Mot, ie it drives the pump at this speed 140 at. The drive motor 510 however, does not itself form part of the hydraulic motor 150 or the pump 140 (see. 2 and 4 ). This rated speed of the drive motor 510 forms an input variable of a characteristic field 512 , which receives as a further input variable a maximum setpoint for the speed of the output (= upper speed specification), which is also designated N_Ab_Soll_max. This upper speed specification N_Ab_Soll_max is set manually in particular by means of the driving potentiometer by the driver or operator. The map 512 thus acts as a pilot control and provides an additive contribution to the output value of the pump controller 504 , The two values are in the summation element 514 added and then provided to the pump as input pX. The pump 506 then sets the control pressure, which was specified as input pX, in a delivery volume Vg PU, which is promoted per pump revolution. The multiplication element 516 indicates that this volume per revolution multiplied by the speed of the drive motor 510 then the volume flow Q results, the flow rate of the pump 140 equivalent.

As the 7 further shows, includes the hydraulic motor 150 several components, which are shown in the diagram. Among other things, the engine points 150 the hydraulic component 518 on (= hydraulic part of the engine 150 ), the volume flow Q of the pump 140 is supplied. This volume flow Q then results in a speed of the hydraulic component 518 , with corresponding mechanical ratios in the mechanical part 520 of the motor 150 can take their influence. It can be at the output of the hydraulic component 518 the actual recording volume, also denoted by q_ist, is detected. As the 7 shows, this is returned and a sip volume controller 522 supplied, which is preferably also designed as a PID controller. Other suitable regulators, such as an I or PI controller, may also be used here. The intake volume is the motor controller 522 not fed directly, but it is initially in difference images 524 the difference to the output of the speed controller 502 formed in the present embodiment for target output speeds greater 380rpm (= first threshold), here sets a target intake volume. Background of this difference 524 is that from a certain target speed, the first threshold, here exemplarily> 380rpm, the speed of the output no longer depends on the delivery volume of the pump, since its maximum is then reached, and therefore the speed adjusted by the displacement of the hydraulic motor in the transmission becomes. Accordingly, the engine has 150 or its hydraulic component 518 here via a variably adjustable absorption volume.

The 7 shows that the flow rate Q of the pump 140 along with the output speed set point and engine status, another map 526 is fed, that a further additive contribution to the output of the swallow volume controller 522 supplies. The engine status can be several hydraulic motors 150 or consumers of the overall system. The desk 528 shows that the flow rate or the speed of the drive motor 510 can be taken into account, with both sizes input variables for the map 526 can form. In the summation element 530 then the output value of the intake volume control 522 and the map 526 added, and then with the flow Q of the pump 140 merged. In this respect, the displacement volume control results for the hydraulic input of the hydraulic component 518 of the motor 150 ,

In addition, it is assumed below that the corresponding in 7 shown arrangement in a vehicle, such as a construction or agricultural machine is integrated. In order to move a vehicle, a minimum torque, which is dependent on the vehicle characteristics and the vehicle condition, must be generated. In a fully hydrostatic drive, as in the 7 is also shown, the output torque is proportional to the driving high pressure in the system. High pressure can be generated, for example, by reducing an oil-filled volume, ie by compression, or by a volume control, Vol (t0)> Vol (t1) (i), dV / dt (on)> dV / dt (off) (ii).

For example, according to equation (ii), the high pressure can be set via a volume control, to which the pump becomes 140 , which provides the delivery volume, from the drive motor 510 driven. The delivery volume is via the control pressure in the adjusting chamber for the swinging out of the variable displacement pump 506 set. The value to be set (X, pX), ie the control pressure, on the unit to be adjusted, ie in the pump 140 , usually always results from a controlled share and a rule share. In the following equations the parameter X is generally used which can stand for pressure (pX) or also for volume flows (Q). X = X_vorsteuerung + X_regulator (iii).

The value of the controller 502 can be variable and results from the different driving conditions, such as whether the vehicle is driving straight uphill, downhill, loaded, unloaded, etc. So that the throttle 502 can output a value, a control difference is first set, which is in the present case from the example desired by the driver target speed n _AB, and the actual speed n _AB results. Since, for physical reasons, the rotational speed sensors, for example Hall sensors or Hall sensors, do not guarantee reliable detection in low-frequency magnetic fields, the regulators usually become smaller in low rotational speed ranges, ie at rotational speeds less than the second threshold, for example in rotational speed ranges of n <50 rpm 502 . 504 disabled. The result then is the adjustment value (pX) as follows: X = X_vorsteuerung // with X_regulator = 0 (iv).

Since the high pressure at constant power from the difference between flow rate (Q) and intake, P = dp (Q _out - Q _Ein ) compare also equation (ii), and the flow rate (Q) is a function of delivery volume Vg PU and drive speed n _Mot is, can an intelligent pilot for the control pressure pX, which is the regulator 502 in a speed range low speeds, ie below the second threshold, for example, <50rpm, replaced and relieved in a speed range of higher speeds, a great advantage. This can lead to an improvement in driveability and ride comfort in the constant engine speed case, that is, in the case where the driving drive motor 510 should have a constant speed. The intelligent feedforward control in the exemplary embodiment then results below the control threshold, ie below the second threshold, as follows: X = X_precontrol + X_precontrol_load (v).

In equation (v), the first addend represents the feedforward that is from the map 512 is adjusted in order to be able to drive on a plane in the no-load state. This means that if you were driving on the level, the control percentage (with the controller switched on) would be close to 0, and only the ride properties would have to be compensated. This precontrol can, for example, from a three-dimensional map 512 come, which takes into account the dependence of the input speed and the driver's request. In the 7 this is as a map 512 shown. The precontrol component can always be jumped if it does not exceed the permissible maximum limit for the control pressure (pX_max). This can also save the dead time when starting from 0, cf. above described boost function. In addition, embodiments can provide the advantage that depending on the pedal position not too much pilot pressure is output and thus there is an undesirably strong starting pressure or overshoot of the output speed.

The second summand is the load-dependent pre-control component pX_Vorsteuerung_Last, that of the device 100 according to the embodiment is supplied. This becomes with the controller off 502 activated and determined by an additional size, which gives information about the current load in the drive train. In the exemplary embodiment, this is the pump failure amount, which is a function of the driving high pressure. As the pressure increases, the shortfall becomes greater. In exemplary embodiments, it can further be ensured that the load-dependent pre-tax component is not switched on abruptly, since otherwise unwanted vehicle reactions can occur in the event of abrupt changes in the load signal. In other words, therefore, a limitation of the rise gradient for the load-dependent pre-tax component can be made or adjustable. In order for the transitions from the load-dependent precontrol, compare equation (v), to cruise control, see equation (iii), to work, a configurable threshold speed for load detection may be implemented. In embodiments, here an overlap between activated controller 502 . 504 and load detection are set. In embodiments, hysteresis may be provided to avoid instabilities or vibrations near the limit speed, ie the second threshold. In other words, allow the controller 502 near a lower limit speed does not begin to oscillate, a hysteresis can be provided at the regulator on or off threshold, ie the second threshold. In other words, the second threshold then has two different threshold values: one for activating the controller 502 . 504 and one for disabling the controller 502 . 504 ,

The 8th shows a further diagram of an embodiment. The 8th shows a hydrostatic drive 300 who is here from one Pump and a corresponding gear composed, preferably with the components 2 . 4 or 7 (Pump 140 , Engine 150 Etc.). Input variable for this hydrostatic drive 300 is a control pressure by the limiting member 531 is kept within the limits p_X_unlim (lower control pressure limit) until p_X_max (upper control pressure limit). Input quantity of the limiting element 531 is a control pressure, which is composed of different components depending on the output speed. As the 8th shows this component based on the equations (iii) to (v) always by the output of the pilot control 512 , p_X_vorvorsteuerung influenced. In the addition element 528 is added to this component depending on the output speed, another component. This further component is replaced by a switch 534 selected. This may be, for example, a software switch (date, flag, etc.) or other device for selecting at least two operating modes. It does not have to be a switch in the mechanical sense.

In a first switch position of the switch 534 (shown upper position) forms the corresponding offset of the precontrol (load-dependent precontrol component pX_Vorsteuerung_Last) as described in equation (v) the other component. In a second switch position of the switch 534 (lower position) forms the corresponding control component (pX_regulator) as described in equation (iii) the other component.

As the 8th shows, the switch takes 534 the first switch position shown only if the following conditions are met:
First, there must be a load on the drive 300 concern or this load exceed a certain limit (= load detection). This recognition is preferably carried out by means of the algorithm for load detection according to 6 ,
Second, a setpoint for the speed n_Ab_Soll of the output, ie output, of the drive 300 below the above-mentioned second threshold, eg <50 rpm. This detection occurs in step 538 ,
Third, the upper speed specification (N_Ab_Soll_max) must be below a third threshold. This detection occurs in step 536 ,

The third threshold may be the same as the second threshold or different thereto, It may also be provided if necessary, other conditions and / or waived one or two of the above conditions.

If the conditions are met (here: load detected / load threshold exceeded, and target output speed n_Ab_Soll below second threshold, and upper speed specification N_Ab_Soll_max below third threshold), the switch is activated 534 on the upper branch. Otherwise the switch will switch 534 on the lower branch.

In the 8th Further, various signals are designated by the numbers 1 to 5 in rectangular boxes. In order to use the method below a detection threshold of the output speed sensor, so the second threshold, ie in that area in which the controller 502 . 504 are turned off, the pumping amount is used as an indicator of a pending load in the present embodiment. In other embodiments, of course, other information carriers can be used. As the number 1 in the load detection in the 8th shows, thereby the load can be detected and so the control pressure and the power consumption of a traction drive 300 be increased control technology. This is done by the additional offset for the precontrol, which is indicated at the number 2. As the 8th also shows, this takes place load-dependent, if the output speed n_ab is below the second and third threshold, see paragraphs 1, 4 and 5. Then drives the vehicle or exceeds the speed, ie the second threshold, for example, formed by the detection hurdle of the output speed sensor , then the controller can be deactivated and the controller ( 7 : Regulator 502 . 504 ) takes over this task, what in the 8th at the number 3 is displayed. This procedure can also be used when driving uphill. Another advantage is in working mode. By the method, a very low output speed request on the accelerator pedal and the driving potentiometer (speed limiter, speed limiter) in the labor input to the full efficiency of the drive 300 to lead.

Embodiments can thus offer the advantage that even at minimum rotational speeds which are below the detection limit of a sensor, the maximum possible tensile force, for example in the form of a torque, can be made available. Embodiments may also provide the advantage that the functions described above can be integrated into many or even each hydrostatically powered vehicle. For example, an output speed preselection (setpoint speed n_Ab_Soll) via an accelerator pedal, possibly in conjunction with a driving potentiometer, be realized, regardless of the rotational speed of a drive motor, such as a diesel engine speed. In this respect, embodiments can provide a pilot control for hydraulic motors that completes or complements a driving potentiometer. In embodiments, therefore, for example, depending on the state of a pump and the speed of the simultaneously operated Hydraulic motors are introduced a pilot control to keep the control components as low as possible and to avoid overlaps of the pump and motor controller. The load can be compensated in embodiments of a controller, since the engine receiving volume change only when faster moving vehicle, ie when rotating output.

In other embodiments, alternatively, a speed limit functionality by means of the driving potentiometer (Speedlimiterfunktionalität) can also be solved by adaptive controller in a range in which the speed detection is reliably possible. In such embodiments, then the traction adaptation and boosting can be suppressed. Embodiments may therefore provide mechanisms that mitigate or eliminate interactions of multiple active controllers, or suppress or mitigate unwanted driveability that may arise from, for example, continuous manual turning or adjustment to the drive potentiometer. Exemplary embodiments can provide the advantage that the adaptive controller can be implemented and implemented in a cost-effective manner.

9 shows a block diagram of a flowchart of an embodiment of a method for adjusting a control pressure of a hydrostatic drive 300 , The method comprises a step of detecting 210 a load of the hydrostatic drive 300 , The method further includes a step of adjusting 220 the control pressure based on the detected load of the drive 300 ,

Embodiments further include a computer program for performing one of the methods described above when the computer program is executed on a processor or a programmable hardware component.

The features disclosed in the preceding description, in the following claims and in the attached figures can be important and implemented individually as well as in any combination for the realization of an embodiment in its various embodiments.

Although some aspects have been described in the context of a device, it will be understood that these aspects also constitute a description of the corresponding method, so that a block or a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device.

Depending on particular implementation requirements, embodiments of the invention may be implemented in hardware or in software. The implementation may be performed using a digital storage medium, such as a floppy disk, a DVD, a Blu-Ray Disc, a CD, a ROM, a PROM, an EPROM, an EEPROM or FLASH memory, a hard disk, or other magnetic disk or optical memory are stored on the electronically readable control signals, which can cooperate with a programmable hardware component or cooperate such that the respective method is performed.

A programmable hardware component may be integrated by a processor, a central processing unit (CPU), a graphics processing unit (GPU), a computer, a computer system, an application-specific integrated circuit (ASIC) Circuit (IC = Integrated Circuit), a system on chip (SOC), a programmable logic element, a micro-controller or a field programmable gate array with a microprocessor (FPGA = Field Programmable Gate Array) may be formed.

The digital storage medium may therefore be machine or computer readable. Thus, some embodiments include a data carrier having electronically readable control signals capable of interacting with a programmable computer system or programmable hardware component such that one of the methods described herein is performed. One embodiment is thus a data carrier (or a digital storage medium or a computer readable medium) on which the program is recorded for performing any of the methods described herein.

In general, embodiments of the present invention may be implemented as a program, firmware, computer program, or computer program product having program code or data, the program code or data operative to perform one of the methods when the program resides on a processor or a processor programmable hardware component expires. The program code or the data can also be stored, for example, on a machine-readable carrier or data carrier. The program code or the data can be used inter alia as source code, Machine code or bytecode and as other intermediate code.

Another embodiment is further a data stream, a signal sequence, or a sequence of signals that represents the program for performing any of the methods described herein. The data stream, the signal sequence or the sequence of signals can be configured, for example, to be transferred via a data communication connection, for example via the Internet or another network. Embodiments are also data representing signal sequences that are suitable for transmission over a network or a data communication connection, the data representing the program.

A program according to an exemplary embodiment may implement one of the methods during its execution, for example by reading out or writing into these memory locations one or more data, whereby switching operations or other operations in transistor structures, in amplifier structures or in other electrical, optical, magnetic or other processes caused by another working principle working components. Accordingly, by reading a memory location, data, values, sensor values or other information can be detected, determined or measured by a program. A program can therefore acquire, determine or measure quantities, values, measured variables and other information by reading from one or more storage locations, as well as effect, initiate or execute an action by writing to one or more storage locations and control other devices, machines and components ,

The embodiments described above are merely illustrative of the principles of the present invention. It will be understood that modifications and variations of the arrangements and details described herein will be apparent to others of ordinary skill in the art. Therefore, it is intended that the invention be limited only by the scope of the appended claims and not by the specific details presented in the description and explanation of the embodiments herein.

LIST OF REFERENCE NUMBERS

100

contraption

110

Device for load detection

120

Device for adaptation

130

Device for detecting a speed

140

pump

140a

procedure

140b

Intake

140c

cylinder

140d

cylinder

140e

piston

140f

piston

140g

swash plate

150

hydraulic motor

210

To capture

220

To adjust

300

drive

302

Device for detecting the swallow volume

304

Device for detecting the speed

400

Query n _AB <x and dQ> dQ _load

402

pX = pX feed _forward + pX _{load, n}

404

pX _{load, n} = pX _{load, n-1} + i _dP

406

pX = pX _{pilot control} + pX _controller

408

Limitation to pX _Max

410

Limitation to pX _Max

500

addition element

502

Speed controller PID

504

Pump controller PID

506

pump

508

difference images

510

drive motor

512

map

514

addition element

516

multiplication element

518

Hydraulic part motor

520

Mechanical part of engine

522

Motor controller / displacement controller PID

524

difference images

526

map

528

switch

530

addition element

531

limiter

532

addition element

534

switch

536

step

538

step

600

Component of a vehicle manufacturer

602

Device for detecting the engine speed

604

Device for detecting a maximum output speed

606

Device for processing the interfaces

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Standard SAE J1939 [0004]

Claims (15)

Contraption ( 100 ) for adjusting a control pressure of a hydrostatic drive ( 300 ), with a device for load detection ( 110 ) of the hydrostatic drive ( 300 ) and an adjustment facility ( 120 ) of the control pressure based on a detected load of the drive ( 300 ). Contraption ( 100 ) according to claim 1, wherein the means for adaptation ( 120 ) is adapted to adjust the control pressure in a speed range of the hydrostatic drive ( 300 ) between 0 and an upper speed specification. Contraption ( 100 ) according to claim 1, comprising means for detecting ( 130 ) a speed of the hydrostatic drive ( 300 ), the adjustment facility ( 120 ) of the control pressure is adapted to further adjust the control pressure based on the rotational speed. Contraption ( 100 ) according to claim 3, wherein the means for adaptation ( 120 ) of the control pressure is adapted to the control pressure below a speed limit of the hydrostatic drive ( 300 ). Contraption ( 100 ) according to one of the preceding claims, in which the device for adaptation ( 120 ) of the control pressure is further adapted to the control pressure based on a speed specification for the drive ( 300 ). Contraption ( 100 ) according to one of the preceding claims, further comprising a pump ( 140 ) connected to the hydrostatic drive ( 300 ) and wherein the control pressure is a delivery volume of the pump ( 140 ). Contraption ( 100 ) according to claim 6, wherein the means for load detection ( 110 ) is adapted to receive information about the load from a pump shortage of the pump ( 140 ) and the hydrostatic drive ( 300 ) or the pump ( 140 ) or the hydrostatic drive ( 300 ) is designed as axial or radial piston machine and the device for load detection ( 110 ) is designed to derive information about the load from a pivot angle of the axial or radial piston machine. Contraption ( 100 ) according to claim 6, wherein the means for load detection ( 110 ) is designed to derive information about the load from a pressure difference. Contraption ( 100 ) according to one of the preceding claims, wherein the means for adaptation ( 120 ) of the control pressure is designed as a controller. Contraption ( 100 ) according to claim 9, wherein the means for adaptation ( 120 ) of the control pressure is adapted to adapt the control pressure based on a characteristic map, wherein the characteristic field has one or more input variables, of which at least one is load-dependent, and provides as output a variable influencing the control pressure. Contraption ( 100 ) according to one of claims 1 to 8, wherein the means for adjusting the control pressure is designed as a regulator. Hydrostatic drive ( 300 ) with a hydrostatic pump ( 140 ), a hydrostatic motor ( 150 ) and a device ( 100 ) according to one of the preceding claims. Construction or agricultural machine with a hydrostatic drive ( 300 ) according to claim 10. Method for adjusting a control pressure of a hydrostatic drive ( 300 ), with capture ( 210 ) a load of the hydrostatic drive ( 300 ); and customizing ( 220 ) of the control pressure based on the detected load of the drive ( 300 ).  Computer program for performing the method according to claim 14, when the computer program is executed on a processor or a programmable hardware component.

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