Patent Application
20090012680
The invention concerns a method for optimizing the operating mode of a hydrodynamic component integrated in a drive train of a vehicle, in particular, for optimizing the transmissible torque or the available braking torque, in detail with the features from the preamble of claim 1; further, a method for optimizing the utilization of the available braking torque, in detail with the features from the preamble of claim 2.
In addition to hydraulic or mechanical systems, hydrodynamic retarders frequently find use as braking devices in vehicles. These are integrated at any site in the drive train either as an additional braking device or as the principal braking device. In the transmission of power from the driving machine to the wheels, the retarder can be arranged in front of the gearbox, in the gearbox or behind the gearbox. A specific characteristic diagram is assigned to the hydrodynamic retarder by the manufacturer, a diagram which was prepared, for example, in the final testing as a rigid actual characteristic diagram and a corresponding manipulated variable is assigned to each operating point in this characteristic diagram, as a function of what the driver wants, after a specific deceleration or generation of a specific braking power. As a rule, a control pressure functions as the manipulated variable. Depending on the selected working medium and the structure of the supply system for the working medium that results from it, as well as the triggering possibilities, the control pressure may correspond either to a static pressure that can be introduced on a resting level of working medium, a regulating pressure for the actuation of a valve device or else, in particular, in the design as a water pump retarder, may correspond to pressures for the control of the inlet and outlet cross sections or the differential pressures to and from the hydrodynamic retarder resulting therefrom. Depending on these pre-given set characteristic diagrams and the manipulated variables assigned to the individual operating points, as well as the wishes of the driver, a corresponding arrangement and triggering of the regulating device of the hydrodynamic retarder is provided. It has been shown, however, that during the operation of the vehicle, with the use of these rigid characteristic diagrams and the rigid assignment between the manipulated variables and the individual operating points assigned to them, the full braking power is frequently not exhausted; in particular, the hydrodynamic retarder does not produce the maximum braking power available to it in the corresponding operating points. In the individual case, this means longer braking paths and when used as the continuously operating brake due to the increased requirement for braking power over longer periods of time for achieving the desired result, a corresponding provision of cooling capacities, marginal conditions, which result from the incorporation, mounting, as well as other particular features during operation, cannot be taken into consideration also, due to the rigid advance setting of the characteristic diagrams.
The same type of problem applies analogously also for hydrodynamic couplings and hydrodynamic rpm/torque converters, in which the torque that can actually be transmitted in the case of structural units of the same type and the same marginal conditions can vary very greatly due to manufacturing tolerances. This leads frequently to the circumstance that the theoretically full transmissible torque is not actually available and thus either the hydrodynamic components are dimensioned correspondingly larger from the outset or else measures of a structural nature can be carried out subsequently for compensation.
Refer to the following documents for the written prior art:
The object of the invention is thus to develop a method for optimizing the utilization of the transmissible power that is theoretically available, in particular, the torque in a vehicle with a drive train, comprising a driving machine and a hydrodynamic component with a regulating device assigned to it in such a way that the full theoretically transmissible torque in an operating point of a set characteristic diagram is also utilized and transmitted as much as possible, and overdimensionings are thus avoided. In particular, in hydrodynamic retarders, the full braking power that is theoretically available with a retarder of a specific size with a pre-given filling will be utilized without additional structural measures.
The solution according to the invention is characterized by the features of claims 1 and 2. Advantageous configurations are presented in the subclaims.
According to the invention, the scattering of values caused by tolerances or other marginal conditions that occur during the operation of the hydrodynamic component, in particular, the coupling, converter, or the hydrodynamic retarder in a drive train, in particular the drive train of a vehicle in which the actual characteristic curve or actual characteristic diagram describing the transmission behavior, which is achievable by means of a hydrodynamic component, is minimized in this way and thus the actual values are adapted to the set characteristic curve or set characteristic diagrams describing the theoretically possible transmission behavior such that the actual values that are adjusted lie at least in a pre-defined tolerance range of the set characteristic curve or of the set characteristic diagram of the variables describing the operating mode at least indirectly, and preferably correspond directly to these, by adjusting the manipulated variable, in particular, adapting it. A hydrodynamic retarder thus involves the actual characteristic curve or actual characteristic diagram describing this and obtainable with this in a braking process, this curve or diagram characterizing the operating mode of the hydrodynamic retarder at least indirectly. In this way, the actual characteristic curve is adapted to the set characteristic curves or a set characteristic diagram that can be theoretically obtained with the retarder of a specific type, by adapting the manipulated variable such that the actual values that are adjusted lie at least in the tolerance range of the set characteristic curve or of the set characteristic diagram of the variables describing the operating mode of the hydrodynamic retarder at least indirectly, and preferably correspond directly to these, The actual characteristic curve or the actual characteristic diagram contains the variables characterizing at least indirectly the operating mode of the hydrodynamic component—hydrodynamic coupling, converter or hydrodynamic retarder. This is solved by the fact that in general a theoretical set characteristic curve or a set characteristic diagram for a hydrodynamic component of a specific type is filed in a memory storage unit, wherein a set manipulated variable is assigned to each operating point of the set characteristic curve or the set characteristic diagram for adjusting it. Depending on an advance setting according to a torque to be transmitted, a power or a variable describing this at least indirectly or an advance setting after producing a specific braking torque, a desired deceleration or another variable characterizing the braking process, for example, a braking path, etc., the regulating device is actuated with the set manipulated variable that is pre-given for adjusting the desired operating point. This preferably applies to the entire transmission or braking process, i.e., for example, to the braking process for the building up of the braking torque over the time period of the braking process or the change in the rpm of the element to be braked. For this purpose, the variables characterizing these variables at least indirectly are determined and compared with the corresponding variables of the respective operating point of the set characteristic curve or of the set characteristic diagram. If there is a deviation, the manipulated variable for the adjustment for influencing at least indirectly the actual values of the parameters characterizing the individual operating points is changed for the respective operating point. The modified set manipulated variable is stored as a new set manipulated variable for the respective operating point, in the case of a desired repeated adjusting of the respective operating point this value being used as the set manipulated variable for actuating the regulating device for influencing the transmission behavior, in particular the torque and in retarders, the braking torque.
The solution according to the invention is used both in driving operation as well as in the final testing of the vehicle on a test stand, in particular a roller-type test stand. For the retarder, the latter is then braked against the engine.
The solution according to the invention makes it possible, even with larger structural parts and installation tolerances as well as different marginal conditions with the same requirements to transmit essentially at all times the same torque or to provide the same braking power. This is accomplished very simply by the corresponding calibration of the characteristic diagram, in particular, the characteristic diagram of the manipulated variables. An improvement of the matching between the control variables and the initial values is achieved in this way. The new set manipulated variables are then filed in an at least writable and readable memory for the individual operating points of a corresponding characteristic diagram or a characteristic curve. In the simplest case, this filing is provided in a memory storage unit for properties, which is assigned to the hydrodynamic component, in particular, the hydrodynamic coupling, converter or hydrodynamic retarder, whereby the latter can be disposed preferably on the housing of the hydrodynamic component or at a short spatial distance from it. The property storage device itself can store, in addition to the storage of characteristic curves, but preferably of characteristic diagrams, in particular, the characteristic diagram of manipulated variables and the set characteristic diagram for the operating mode of the retarder, still other variables describing the operating mode and/or the functioning of the hydrodynamic retarder. For this purpose, corresponding inputs are assigned to this, which are coupled with corresponding recording devices. Preferably, at least one communications interface is provided, which makes possible the read-in of data into the property storage unit as well as its read-out. The property storage unit can be connected with a data communications network or a control device for this purpose. In this way, the set characteristic diagram or the set manipulated variables, when used in vehicles, are usually read out when the control device is first put into operation and then processed and adapted in this device. After adapting the characteristic curves or characteristic diagrams for the manipulated variables, a corresponding communication can also be made in turn to the property storage unit, so that, in particular, when the control device is changed, the set manipulated variable characteristic curve already adapted to the hydrodynamic retarder for obtaining the optimal characteristic curve is also made available to the new control. This means, taken in detail, that the corresponding actuating control curve always remains for the hydrodynamic component. However, this is not absolutely necessary. It is also conceivable to file the set characteristic curves for the individual characteristic curves as well as the set characteristic curves and the set characteristic diagrams for the manipulated variables in a control device and to process them as needed. The control device can thus be formed from a central control device, which is assigned to a multiple number of components of the drive train, or else is a separate control device assigned to the hydrodynamic component or to the unit containing this component. The latter may in turn be disposed on the housing of the unit or that of the hydrodynamic component or can even be disposed in this component. This control device then serves also for processing additional set and actual values during operation. In particular, in addition to the processing of the recorded actual values, the variables characterizing the operating mode of the hydrodynamic component at least indirectly are also recorded and processed in the control device.
The actual values, which are determined for each braking process, at least of one value characterizing the braking process, at least indirectly and preferably continuously, usually involve the braking torque or a variable describing it at least indirectly, whereby these variables are preferably determined by the change in the rpm of the element to be braked. Therefore, each time depending on the desired braking power, the braking torque can either be adjusted in steps or else continually adjusted. In the first-named case, the characteristic diagram is comprised of at least one characteristic curve, preferably a plurality of individual characteristic curves assigned to the individual braking steps, while in the other case, each operating point between a pre-given maximum and minimum curve for the course of the braking torque can be triggered via an rpm of the element to be braked, preferably the rpm of the rotor impeller, whereby a corresponding set manipulated variable is also assigned to each individual operating point in the characteristic diagram, and this will bring about the adjusting of this operating point. The individual braking torque is thus a function of the manipulated variable, in particular, the control pressure. This pressure determines the filling of the retarder.
This applies analogously also to hydrodynamic components in the form of couplings and converters. The variables characterizing the transmission behavior are thus recorded or determined over the entire time period of transmission, preferably continuously or in time intervals. The variables characterizing the transmission behavior involve, for example, the transmissible torque, the conversion or at least one variable describing these variables at least indirectly.
According to a further development of the invention, a specific tolerance range is always given in advance for the set characteristic diagram or a set characteristic curve, wherein the limiting values describing these diagrams or curves can either be defined in advance or else are established. The tolerance band, i.e., the deviation upward and/or downward at an operating point, thus preferably amounts to a maximum of 20% of the braking torque, when taking the braking torque as an example.
According to a particularly advantageous further development, a prognostic or forward-looking adaptation is optionally also offered. This means that the correction or adaptation of the operating points is additionally stored. For this purpose, for example, the adaptations provided with respect to the determined or obtained operating points are also stored. Trends for future adaptations can thus be derived from the different correction values and adaptations. Thus, for example, at a specific rpm n and temperature of the working medium, a specific regulating pressure was present as a manipulated variable in order to achieve a specific torque. Due to aging, in particular, cavitation of the circuit parts, increasing leakages in the circuit and thus a circuit pressure that is difficult to maintain, an adaptation of the regulating pressure is continually necessary over time. If the operating point is triggered after a longer period of time, the control pressure that is now to be used can be quasi-predicted based on a stored algorithm. This forward-looking adaptation is particularly meaningful for operating points that are seldom actuated. That is, a specific operating point should be adapted based on its history, in particular the change over time as well as the history of other operating points, primarily adjacent ones, in particular their changing behavior over time.
The actual variables are adapted to the set variable by determining a deviation of the actual variables that characterize the operating mode, preferably for a retarder in the case of an actual variables characterizing the braking torque in an operating point, from the theoretically adjustable braking torque in this operating point by the change in the manipulated variable, whereby this change can either be functional or else can be carried out by means of a correction value. This change is carried out in the next run though this operating point or else in each nth passage though the same desired operating point when a deviation occurs. This applies analogously also to the other possible hydrodynamic components—coupling, converter. Here, the variables characterizing the operating mode involve, for example, the torque.
According to an advantageous further development, additional dependences are also recorded in conjunction. Thus, for example, it is considered that the transmissible torque in the case of hydrodynamic couplings and converters and the braking torque in the case of hydrodynamic retarders are strongly dependent on the temperature. Therefore, the temperature is preferably also recorded in conjunction and there results at least a three-dimensional characteristic diagram, wherein the torque is plotted as a function of the manipulated variable in the form of the regulating pressure and the temperature. Also conceivable is the consideration of other dependences, so that the characteristic diagram for the variables characterizing the operating mode at least indirectly is always multidimensional.
When a correction value k is used, this may involve a fixed pre-given correction value, which is applied to the manipulated variable, or else a correction value that can be calculated or determined, wherein functional relationships can thus be considered. In the simplest case, the correction value is a fixed quantity, which, when there is a deviation relative to the currently used set value for adjusting the actual variables to be adjusted, is added or subtracted. According to a particularly advantageous configuration, a finely stepped scanning is possible in order to keep the correction value variable, by calculating it as a function of values determined between two sequential identical operating points with multiple runs through the same operating point. Thus, the manipulated variable Yset is determined, for example, from the product of the manipulated variable established in the last adjustment of the operating point and the quotient from the currently determined torque, for retarders, in particular, the actual braking moment and the determined actual braking moment for the adjustment of this operating point or for previous such adjustments. Then, if the operating parameters that can be obtained with the new value for the set variable, in particular, the corresponding actual values for the braking torque, still lie in the tolerance range of the set characteristic values, the determined set manipulated variable is set and stored as the new set manipulated variable for this operating point. In this way, any change in the set value can be stored.
The solution according to the invention will be explained in the following on the basis of figures. Therein, the following are shown in detail:
a-3c thus illustrate the theoretical pre-given set characteristic diagram for a hydrodynamic retarder based on rpm/torque diagrams, the actual characteristic diagram determined during the operation run with deviations and the characteristic diagram for the hydrodynamic retarder that is corrected with the method according to the invention.
the correction of the manipulated variable pYset2 results for the specific rpm n2 and the torque Mset2 for rpm n2. Therefore, the set value for the manipulated variable pYset2 is newly determined, by determining it from the product of pYactual2 at rpm n2 and the quotient from the current actual torque Mactual2 at rpm n2 and the last measurement Mactual2-(1) for rpm n2. Then, if the necessary accuracy is achieved, this new set value can be read in as a fixed pre-given set value for the specific operating point n.
a to 3c, which are based on different characteristic curves, illustrate the application and the effect of the method according to the invention. Here, the set characteristic diagram for the hydrodynamic retarder, which is the basis for the final testing, is reproduced in
In comparison to this,
The corrected manipulated variables pYset for the individual operating points n are newly read in, at least into a writable and readable memory. This memory can be attached to the hydrodynamic component 1, in particular, to the hydrodynamic retarder, for example, accommodated in the housing. It is also conceivable to read in the corrected set characteristic diagram pYset resulting from a plurality of these individual set values for manipulated variables into the control device 8 assigned to the hydrodynamic component 1, in particular, to the hydrodynamic retarder.
The embodiments presented in
The solution according to the invention is not limited to the possibility of the change in the manipulated variable pYset that is described here. It is conceivable, as has already been stated, to employ a change in steps by a specific pre-defined or pre-given correction value. This correction value can be calculated or else it can be freely established. This is particularly also associated with the interval in which such corrections will result. The correction can be provided by sequential runs through the specific operating point or else only by every ith adjustment of the operating point n.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 048 120.2 | Oct 2004 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP05/10178 | 9/21/2005 | WO | 00 | 1/23/2008 |
