Method for controlling a hydrodynamic machine, and hydrodynamic machine

Abstract

The invention relates to a method for controlling a hydrodynamic machine, which has a bladed primary wheel (1) and a bladed secondary wheel (2), which together form a working chamber (3) that can be filled with working medium from a working medium supply in a working medium supply container (5) in order to transfer drive power hydrodynamically from the primary wheel to the secondary wheel by the forming of a work medium circuit in the working chamber; wherein a control pressure is applied to the working medium supply for a specified period of time and a pressure increase in the working medium supply container is thereby generated in order to force the working medium out of the working medium supply into the working chamber. The method according to the invention is characterized in that the application of the control pressure is ended after the specified period of time has elapsed, a pressure drop in the working medium supply container (5) is at least indirectly detected, and a fill level of the working medium supply in the working medium supply container and / or a degree of filling of the working chamber with working medium is determined according to the detected pressure drop.

Description

[0001] Method for controlling a hydrodynamic machine and hydrodynamic machine

[0002] The present invention relates to a method for controlling a hydrodynamic machine, in particular a hydrodynamic retarder, and to such a hydrodynamic machine, in particular a hydrodynamic retarder.

[0003] In hydrodynamic machines, the fill level of the working chamber with working fluid can be adjusted by various methods. According to one method, a shut-off valve is provided in the inlet to the working chamber and a control valve in the outlet from the working chamber. The shut-off valve can interrupt the supply of working fluid to the working chamber. The control valve allows the flow cross-section in the working fluid outlet to be varied such that a greater or lesser pressure drop in the working fluid outlet is achieved, thereby controlling the amount and pressure of working fluid in the working chamber. According to a second method, as per the present invention, a working fluid reservoir is provided, which is pressurized with a predetermined, variable control pressure to displace more or less working fluid from the reservoir into the working chamber.

[0004] In both methods, as well as in the present invention, the working medium can also serve as a lubricant for the hydrodynamic machine, for example for lubricating the bearings.

[0005] If, in hydrodynamic machines of the type described above, controlled according to the second method, the working fluid supply decreases during operation due to unavoidable leaks, the working fluid level in the reservoir may become too low. Such a low level can also result from incorrect filling during commissioning or maintenance of the hydrodynamic machine. During operation, this low level can lead to an undesirable increase in working fluid discharge and, furthermore, to insufficient lubrication of the hydrodynamic machine.

[0006] To solve this problem, DE 10 2019 100 485 A1 proposes to at least indirectly detect the pressure increase in the working medium reservoir when the control pressure is applied to the reservoir and to determine the fill level of the working medium reservoir based on this detected pressure increase. For example, the pressure in the working medium reservoir is at least indirectly detected for a predetermined time period after the control pressure is applied or a change in the control pressure is made and compared with a predetermined limit value. A low fill level is inferred if the detected pressure is below the predetermined limit value or a range encompassing the limit value.

[0007] A disadvantage of the described method is the lack of knowledge regarding the supply pressure in the vehicle, which is fed to a control unit for the hydrodynamic machine and which the control unit may throttle as the control pressure applied to the working fluid reservoir in the reservoir. In practice, it has been found that the supply pressure, in particular, has a significant influence on the pressure rise in the working fluid reservoir, meaning that the method described in DE 10 2019 100 485 A1 is subject to considerable uncertainties. Often, only significant underfilling can be detected. Overfilling detection is also not possible with the described method.

[0008] The present invention is based on the objective of improving the method for controlling a hydrodynamic machine, as well as the hydrodynamic machine itself, in such a way that an insufficient fill level of the working medium in the working medium reservoir and / or an insufficient fill level of the working chamber of the hydrodynamic machine with working medium is detected more reliably, regardless of variations in the supply pressure from which the control pressure is generated. In particular, overfilling of the working medium reservoir and / or the working chamber of the hydrodynamic machine should also be detected.

[0009] The problem according to the invention is solved by a method with the features of claim 1 and a hydrodynamic machine with the features of claim 9. The dependent claims describe advantageous and particularly expedient embodiments of the invention.

[0010] The hydrodynamic machine according to the invention is in particular designed as a hydrodynamic retarder.

[0011] The method according to the invention is used in a hydrodynamic machine which has a bladed primary wheel and a bladed secondary wheel which together form a working chamber which can be filled with working medium from a working medium supply in a working medium supply container in order to transfer drive power hydrodynamically from the primary wheel to the secondary wheel by forming a working medium circuit in the working chamber, wherein a control pressure is applied to the working medium supply for a predetermined period of time and thereby a pressure increase is generated in the working medium supply container in order to displace the working medium from the working medium supply into the working chamber.

[0012] The control pressure is generated, in particular, from the supply pressure of a compressed air source in a motor vehicle in which the method according to the invention is applied, wherein the supply pressure can vary. For example, the supply pressure is provided in a compressed air tank of the motor vehicle. In particular, a control device is provided, for example, a retarder control unit, which has a compressed air inlet with the supply pressure and a compressed air outlet at which the control pressure is applied. The control unit can have a control valve, for example, in the form of a proportional valve, which generates the control pressure from the supply pressure depending on its actuation by a control device that is also part of the control unit.

[0013] If the hydrodynamic machine is a hydrodynamic retarder, in particular only the bladed primary wheel rotates, while the bladed secondary wheel remains stationary in order to hydrodynamically decelerate the primary wheel. However, a retarder with a secondary wheel driven in the opposite direction to the primary wheel is also conceivable. In a hydrodynamic machine designed as a hydrodynamic clutch or hydrodynamic converter, as described in one embodiment of the present invention, the primary wheel hydrodynamically drives the secondary wheel, optionally with the interposition of at least one guide wheel or guide vane ring positioned in the working space.

[0014] According to the invention, after the specified time period, the application of the control pressure is terminated, a pressure drop in the working medium reservoir is at least indirectly detected, and depending on the detected pressure drop, a fill level of the working medium reservoir in the working medium reservoir and / or a degree of filling of the working space with working medium is determined.

[0015] Additionally, when applying the control pressure to the working medium reservoir during the specified time period, the pressure increase in the working medium reservoir can be at least indirectly detected, and the fill level of the working medium reservoir in the working medium reservoir and / or the degree of filling of the working space with working medium can also be determined depending on the detected pressure increase.

[0016] By taking into account the pressure increase and the pressure drop, the fill level of the working medium supply in the working medium reservoir and / or the degree of filling of the working space with working medium can be better determined even without knowledge of the current absolute magnitude of the control pressure applied to the working medium supply for the given time period.

[0017] Particularly preferred is at least one pressure, which can also be referred to as a pressure value, in the working medium reservoir during the pressure increase and / or the pressure drop, at least indirectly recorded, evaluated with an artificial neural network (ANN) and thereby the fill level of the working medium reservoir in the working medium reservoir and / or the degree of filling of the working space with working medium determined.

[0018] The artificial neural network can initially be trained in a learning phase at the beginning of the inventive method. For example, given a known fill level in the working medium reservoir and / or fill level of the working chamber, one or more predetermined control pressures are applied to the working medium reservoir for one or more predetermined time periods. After these periods have elapsed, the respective pressure in the working medium reservoir is at least indirectly detected and fed to the artificial neural network along with the corresponding fill level in the working medium reservoir and / or fill level of the working chamber. Thus, the artificial neural network can learn which fill level and / or fill level corresponds to which pressure rise and / or pressure drop profile when a specific control pressure is applied to the working medium reservoir for a specific time period.Based on this knowledge, the artificial neural network then determines the current fill level in the working medium reservoir and / or the current fill level of the working space of the hydrodynamic machine, especially the hydrodynamic retarder, depending on the detected pressure drop and, in particular, the detected pressure increase.

[0019] According to the invention, the process does not involve recording a single pressure value in the working medium reservoir and comparing it with a predetermined reference value or reference range. Instead, by using an artificial neural network, the absolute fill level of the working medium reservoir and / or the absolute degree of filling of the working chamber with working medium can be determined. The method according to the invention is therefore significantly more accurate than known methods and operates precisely even with a varying supply pressure in a compressed air source, for example, a compressed air tank from which the control pressure is generated, advantageously even without knowledge of the absolute magnitude of the current control pressure.

[0020] The inventive method using an artificial neural network thus represents, in particular, a virtual sensor of the fill level and / or the degree of filling.

[0021] In the inventive method, it is also possible to issue a warning message, in particular an acoustic and / or a visual warning message, if an insufficient fill level of the working medium supply in the working medium reservoir and / or a sufficient fill level of the working chamber is detected. Additionally or alternatively, it is possible to block future activation of the hydrodynamic machine until a sufficient fill level and / or fill level is restored or detected.

[0022] A pressure value or pressure profile, used to determine the pressure rise and / or drop, can be detected by a pressure sensor located in the working fluid reservoir. In principle, however, such a pressure sensor can also be located elsewhere, for example, in a working fluid connection line that leads both into the working fluid reservoir and, at least indirectly, into the working chamber. Generally, it is also possible to indirectly detect the pressure rise and / or drop in the working fluid reservoir by measuring other parameters and determining the pressure rise / drop from these other parameters. Preferably, a vehicle operator is informed by a corresponding display when the hydrodynamic machine is no longer available. This can be done, for example, via a vehicle display.

[0023] According to one embodiment of the invention, it is also possible, unlike previously described, to detect the pressure drop and, in particular, the pressure increase based on (at least) a single or discrete pressure value. For example, the pressure in the working fluid reservoir is detected, at least indirectly, for a predetermined time period after the start and / or end of the application of the control pressure or the start and / or end of the application of a modified control pressure, and compared with a predetermined limit value. The fill level is then determined from this comparison. In particular, a low fill level can be inferred if the detected pressure is below the predetermined limit value or a limit range encompassing the limit value.

[0024] Advantageously, no additional sensors beyond those already present are required to carry out the method according to the invention. For example, the hydrodynamic machine can be activated by filling the working chamber with working fluid via a switch-on command from a vehicle operator or a control device, and deactivated by emptying the working chamber via a corresponding switch-off command. The control pressure is applied to the working fluid reservoir after the switch-on command is detected to achieve a predetermined fill level of the working chamber. To determine the fill level of the working fluid reservoir in the reservoir, a predetermined control pressure can also be applied to the working fluid reservoir in a deactivated state, i.e., without the detection of a switch-on command or when no switch-on command is present, in order to determine the fill level.With one and the same pressure sensor or with several identical pressure sensors, the pressure in the reservoir can then be detected in the activated state of the hydrodynamic machine and used to control or regulate the filling level of the working chamber, and at the same time, when determining the fill level of the working medium reservoir in the deactivated state of the hydrodynamic machine, the pressure in the reservoir can be detected.

[0025] In particular, the working medium reservoir is free of a float for detecting the fill level of the working medium reservoir.

[0026] According to one embodiment of the invention without the use of an artificial neural network, a predetermined fill level of the working medium reservoir is used to determine the limit value.

[0027] The working fluid reservoir is set, and a predetermined control pressure is applied to it for the specified time period. Later, after the specified time period has elapsed, if a pressure drop has occurred in the working fluid reservoir, the pressure is at least indirectly measured and set as a limit value. This constitutes a calibration.

[0028] According to one embodiment of the invention, a reference pressure profile is specified over a period of time after the elapsed period of time, i.e. during the pressure drop, and a pressure profile in the working medium reservoir is at least indirectly recorded during the pressure drop and compared with the reference pressure profile to determine the fill level.

[0029] A hydrodynamic machine according to the invention has a control device which is configured to carry out a method according to the invention, such that after applying the control pressure to the working medium supply, a pressure drop and, in particular, a pressure increase in the working medium supply container can be detected at least indirectly, and depending on the detected pressure increase, a fill level of the working medium supply in the working medium supply container or a filling degree of the working chamber of the hydrodynamic retarder can be determined.

[0030] The invention will below be described by way of example using an embodiment and the figures.

[0031] They show:

[0032] Figure 1 shows a hydrodynamic machine according to the invention;

[0033] Figure 2 shows the comparison of a recorded pressure value or pressure curve with a limit value or reference pressure curve in order to determine the fill level;

[0034] Figure 3 shows an exemplary representation of an artificial neural network that can be used according to the method according to the invention.

[0035] Figure 1 schematically shows a hydrodynamic machine in the form of a hydrodynamic retarder 10. This machine has a bladed primary wheel 1 driven by a drive shaft 7 and a bladed secondary wheel 2, which is axially opposite the primary wheel 1 and is designed here as a stator. By rotating the primary wheel 1, a working fluid circuit 8 is generated in a working chamber 3 formed by the primary wheel 1 and the secondary wheel 2. Torque or drive power is transmitted from the primary wheel 1 to the secondary wheel 2 by means of this circuit, thereby braking the primary wheel 1 and thus the drive shaft 7. Such a hydrodynamic retarder 10 is, for example, a component of a motor vehicle drivetrain.The hydrodynamic machine in general, here the hydrodynamic retarder 10, has an external working fluid circuit 9 with a working fluid reservoir 5 that holds a working fluid supply 4. The exemplary external working fluid circuit 9 shown also includes a cooler 11. Further components, not shown here, could be provided.

[0036] To pump more or less working medium from the working medium reservoir 5 or the working medium reservoir 4 into the working chamber 3, a predetermined control pressure is applied to the working medium level of the working medium reservoir 4 in the working medium reservoir 5. A control valve, in this case a proportional valve 12, is provided to generate the control pressure. This valve is positioned in a control air line 13 between a compressed air source 14 and the air space in the working medium reservoir 5. The proportional valve 12 is actuated by a control device 15, allowing it to set the desired control pressure according to the required braking torque.The proportional valve 12 and the control device 15 can be part of an electropneumatic control unit, in particular a retarder control unit, which is designed in particular as an independent, compact unit for controlling the hydrodynamic machine, in particular the hydrodynamic retarder 10.

[0037] The hydrodynamic retarder 10 is activated when, after receiving an activation command from a driver or a vehicle control unit (transmission control unit of a vehicle transmission, not shown here, of a motor vehicle powertrain of which the retarder 10 is a part), the control unit 15 actuates the proportional valve 12, thereby filling the working chamber 3 of the hydrodynamic retarder 10, which was largely empty in the deactivated state, with working fluid from the working fluid reservoir 4. When the retarder 10 is deactivated, the working chamber 3 is emptied again and the working fluid is pumped back into the working fluid reservoir 4. The control unit 15 can be part of the aforementioned vehicle control unit, transmission control unit, or the separate retarder control unit.

[0038] To regulate the control pressure, a pressure sensor 6 is provided in the air space of the working medium reservoir 5, which detects the pressure in the working medium reservoir 5. The detected pressure is processed, for example, in the control device 15.

[0039] The fill level of the working fluid reservoir 4 in the working fluid reservoir 5 can vary. For example, the fill level decreases if working fluid is lost through leaks in the hydrodynamic retarder 10 during operation. This can result in a lower fill level in the working fluid reservoir 5, as indicated by the dashed line representing the working fluid level. However, to ensure proper function and lubrication of the hydrodynamic retarder 10, a minimum fill level in the working fluid reservoir 5 must be maintained. Furthermore, an undesirably low or high fill level of the working fluid in the working fluid reservoir 5 can lead to an incorrect fill level of the working chamber 3 with working fluid.

[0040] To determine the current fill level of the working medium supply 4 in the working medium reservoir 5 and / or the degree of filling of the working chamber 3 with working medium, preferably with the hydrodynamic retarder 10 deactivated (generally with the hydrodynamic machine deactivated), a predetermined control pressure is introduced into the working medium reservoir 5 by means of the proportional valve 12 in cooperation with the compressed air source 14 and the pressure sensor 6 is used to detect the actual pressure that is established after a pressure drop, after the control pressure has been maintained for a predetermined period of time in order to first cause a pressure build-up in the working medium reservoir 5.According to the invention, the fill level of the working medium supply 4 in the working medium supply container 5 and / or the degree of filling of the working chamber 3 with working medium is determined from this measured pressure or a pressure profile determined by a plurality of successively measured pressures (or pressure values).

[0041] In addition, at least one pressure, i.e., a single pressure value, or preferably the pressure profile that develops during the specified time period of applying the control pressure to the working medium reservoir 4, can be detected by the pressure sensor 6, i.e., preferably a plurality of successive pressures (or pressure values) in the working medium reservoir 5 during the pressure increase, and can be used to determine the fill level of the working medium reservoir 4 in the working medium reservoir 5 and / or the degree of filling of the working chamber 3 with working medium.

[0042] Preferably, the measured pressures or pressure values ​​during pressure build-up and pressure drop are fed into an artificial neural network 16, as exemplified in Figure 3. The artificial neural network functions in particular as a virtual level sensor and was trained during a learning phase. During the learning phase, test bench and vehicle measurements can be used where the fill level in the working fluid reservoir and / or the fill level of the working chamber 3 of the hydrodynamic retarder 10 is known. This is specifically a so-called "supervised learning" process.For example, if the fill level in the working medium reservoir 5 and / or the fill level of the working chamber 3 of the hydrodynamic retard 10 is known, several predetermined control pressures are applied to the working medium reservoir 4 for one or more predetermined time intervals. After these intervals have elapsed, the respective pressure in the working medium reservoir 4 is at least indirectly recorded and fed to the artificial neural network 16, along with the corresponding fill level in the working medium reservoir 4 and / or fill level of the working chamber 3. From this, the artificial neural network 16 can learn which fill level and / or fill level corresponds to which pressure rise and / or pressure drop profile when a specific control pressure is applied to the working medium reservoir 4 for a predetermined time interval.During operation of the motor vehicle with the hydrodynamic retarder 10 (or generally with the hydrodynamic machine), the artificial neural network 16 can then reliably determine the current fill level in the working medium reservoir 5 and / or the current fill level of the working chamber 3 of the hydrodynamic retarder 10, depending on the detected pressure increase and pressure drop.

[0043] As already described in DE 10 2019 100 485 A1, the pressure rise and fall profiles differ at various fill levels in the working fluid reservoir 5, which is pressure-tight sealed against the environment, because the air volume is compressible. Therefore, the pressure rise and fall can be used to determine the current fill level of the working fluid reservoir 4 in the working fluid reservoir 5 and the degree of filling of the working chamber 3 of the hydrodynamic retarder 10 with working fluid.

[0044] Figure 2 shows a diagram illustrating the control pressure py generated or provided by the proportional valve 12 over time for a method according to the invention. At time a, the proportional valve 12 opens (see Figure 1) and pressurizes the working medium reservoir 5 with the control pressure py. At time b, the proportional valve 12 closes again, so that the control pressure py drops back to zero. The time interval between the two times a and b is referred to as the predetermined time interval At.

[0045] The pressure or pressure profile in the working fluid reservoir 5, as measured by the pressure sensor 6, is denoted by pist. At a relatively high fill level, a relatively high measured pressure pist is observed after the time interval At, and a relatively high measured pressure profile pist is observed over the time interval At. At a relatively low fill level, a correspondingly lower measured pressure or pressure profile p'ist is observed, which is shown here as a dashed line. Accordingly, the pressure rise and fall are steeper at a relatively high fill level than at a relatively low fill level. By evaluating the different pressure profiles, the artificial neural network 16, as shown in Figure 3, can determine the absolute value of the current fill level in the working fluid reservoir 5 and / or the absolute value of the fill level of the working chamber 3 with working fluid.A comparison with a reference curve is not necessary.

[0046] Reference symbol list

[0047] 1 Primary gear

[0048] 2 Secondary gear

[0049] 3 workroom

[0050] 4. Work media supply

[0051] 5 working medium storage containers

[0052] 6 Pressure sensor

[0053] 7 Drive shaft

[0054] 8 Working fluid circuit

[0055] 9 external working fluid circuit

[0056] 10 hydrodynamic retarders

[0057] 11 coolers

[0058] 12 Proportional valve

[0059] 13 Control air line

[0060] 14 Compressed air source

[0061] 15 Control device

[0062] 16 artificial neural network

[0063] At time span a, b point in time pist, p'ist recorded pressure / pressure profile

Claims

Patent claims 1. Method for controlling a hydrodynamic machine comprising a bladed primary wheel (1) and a bladed secondary wheel (2), which together form a working chamber (3) that can be filled with working medium from a working medium reservoir (4) in a working medium reservoir (5) in order to transfer drive power hydrodynamically from the primary wheel (1) to the secondary wheel (2) by forming a working medium circuit (8) in the working chamber (3); wherein a control pressure (py) is applied to the working medium reservoir (4) for a predetermined time interval (At) and thereby generates a pressure increase in the working medium reservoir (5) in order to displace the working medium from the working medium reservoir (4) into the working chamber (3);characterized in that, after the specified time period (At) has elapsed, the application of the control pressure (py) is terminated, a pressure drop in the working medium reservoir (5) is at least indirectly detected, and, depending on the detected pressure drop, a fill level of the working medium reservoir (4) in the working medium reservoir (5) and / or a degree of filling of the working chamber (3) with working medium is determined.

2. Method according to claim 1, characterized in that, in addition, when the control pressure (py) is applied to the working medium reservoir (4) during the specified time period (At), the pressure increase in the working medium reservoir container (5) is at least indirectly detected and the fill level of the working medium reservoir (4) in the working medium reservoir container (5) and / or the degree of filling of the working chamber (3) with working medium is also determined as a function of the detected pressure increase.

3. Method according to claim 1 or 2, characterized in that at least one pressure (pist) in the working medium reservoir (5) is at least indirectly detected during the pressure increase and / or pressure drop and evaluated with an artificial neural network (16) and thereby the fill level of the working medium reservoir (4) in the working medium reservoir (5) and / or the fill level of the The workspace (3) is determined using the work medium.

4. Method according to one of claims 1 to 3, characterized in that the hydrodynamic machine can be activated by means of a switch-on command from a vehicle driver or a control device by filling the working chamber (3) with working medium and can be deactivated by means of a corresponding switch-off command by emptying the working chamber (3), wherein the control pressure (py) is applied to the working medium reservoir (4) after detection of the switch-on command in order to effect a predetermined filling level of the working chamber (3) with working medium, and in order to determine the fill level and / or the filling level, a predetermined control pressure (py) is additionally applied to the working medium reservoir (4) in a deactivated state without detection of a switch-on command of the hydrodynamic machine.

5. Method according to one of claims 2 to 4, characterized in that a pressure sensor (6) is provided in the working medium reservoir (5) which detects the pressure (pist) in the working medium reservoir (5).

6. Method according to claims 4 and 5, characterized in that the pressure (pist) in the hydrodynamic machine is also measured by the pressure sensor (6) in the activated state. The working medium reservoir (5) is recorded and used to control the fill level of the working space (3). 18 7. Method according to one of claims 1 to 6, characterized in that the artificial neural network (16) is first trained in a learning phase by applying one or more predetermined control pressures (py) to the working medium reservoir (4) for one or more predetermined time intervals (At) when the fill level in the working medium reservoir (5) and / or the fill level of the working chamber (3) is known, after which the respective pressure (pist) in the working medium reservoir (5) is at least indirectly detected and supplied to the artificial neural network (16) together with the associated fill level in the working medium reservoir (5) and / or fill level of the working chamber (3).

8. Method according to one of claims 1 to 7, characterized in that the hydrodynamic machine is operated as a hydrodynamic retarder (10).

9. Hydrodynamic machine with a bladed primary wheel (1 ) and a bladed secondary wheel (2) which together form a working chamber (3) that can be filled with a working medium in order to transfer drive power hydrodynamically from the primary wheel (1 ) to the secondary wheel (2) by means of a working medium circuit (8) in the working chamber (3), and with a working medium reservoir (4) in a working medium reservoir (5) which can be pressurized with a control pressure (py) in order to displace more or less working medium from the working medium reservoir (4) into the working chamber (3) to set a predetermined fill level; characterized in that a control device (15) is provided which is configured to carry out a method according to one of claims 1 to 8.

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