Method for ascertaining behavior of a valve installed in a vehicle, and vehicle

Abstract

A method for ascertaining a control-caused behavior of a valve installed in a vehicle for adjusting a flow of a medium. Operating a pump, which has an electric motor and at least one pump element for conveying the medium, so that the medium is conveyed by the pump in that the pump element is driven by means of the electric motor. Controlling the valve by an electronic computing device of the vehicle. The control of the valve is varied by the electronic computing device. While the medium is conveyed by the pump, and while the control of the valve is varied: sensing at least one parameter characterizing the operation of the pump. Determining the behavior of the valve as a function of the sensed parameter.

Claims

1. A method for ascertaining a control-caused behavior of a valve installed in a vehicle for adjusting a flow of a medium, comprising: operating a pump, which has an electric motor and at least one pump element for conveying the medium, wherein the medium is conveyed by the pump and the pump element is driven by the electric motor; controlling a position of the valve by an electronic computing device of the vehicle, wherein the valve is varied by the electronic computing device between a first end position in which the medium exclusively flows to a first coupling, a second end position in which the medium exclusively flows to a second coupling, and a third position centered between the first end position and the second end position in which the medium bypasses the first coupling and the second coupling; sensing at least one parameter during the operation of the pump while the medium is conveyed and while the valve is varied; and determining the position of the valve as a function of the sensed parameter.

2. The method according to claim 1, wherein the parameter comprises a power consumption of the electric motor.

3. The method according to claim 2, wherein, during the operation of the pump, the electric motor is operated at a constant rotational speed.

4. The method according to claim 1, wherein the parameter comprises a rotational speed of the electric motor.

5. The method according to claim 4, wherein, during the operation of the pump, the electric motor is operated with a constant electrical current.

6. The method according to claim 1, wherein a characteristic curve of the valve is determined.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawing shows in:

(2) FIG. 1 a diagram for illustrating a first embodiment of a method for ascertaining control-caused behavior of a valve installed in a vehicle;

(3) FIG. 2 another diagram for illustrating a second embodiment of the method;

(4) FIG. 3 a schematic illustration of a hydraulic system for a vehicle, with at least one hydraulic circuit in which a valve is arranged;

(5) FIG. 4 a schematic illustration of the valve; and

(6) FIG. 5 a characteristic curve of the valve.

(7) In the figures, identical or functionally identical elements are furnished with the same reference numbers.

DETAILED DESCRIPTION

(8) FIG. 1 shows a diagram 10 for illustrating a first embodiment of a method for ascertaining control-caused behavior of a valve 12, which is installed in a vehicle and is schematically illustrated in FIG. 3, for adjusting a flow of a medium in the form of a fluid.

(9) The valve 12 is utilized, for example, in a hydraulic system of the vehicle illustrated schematically in FIG. 3. The hydraulic system has at least one hydraulic circuit through which the medium can flow, with the medium being an oil. The hydraulic system further comprises at least one pump 16, which is arranged in the hydraulic circuit 18, for conveying the oil. From a sump 13, the oil is conveyed by means of the pump 16 through the hydraulic circuit 18 and thereby conveyed to the valve 12. In this case, the pump 16 comprises at least one pump element 20 and an electric motor 22, by means of which the pump element 20 can be driven or is driven. Through driving of the pump element 20, the oil is conveyed by means of the pump element 20 through the hydraulic circuit.

(10) In order to drive the pump element 20 by means of the electric motor 22, the electric motor 22 is supplied with electrical current, so that the electric motor 22 has a current consumption or a power consumption.

(11) The valve 12 is constructed as a shiftable or adjustable valve and comprises at least one valve element 24, which, for example, is arranged at least in part in at least one line of the hydraulic circuit 18. The valve element 24 can be shifted, that is, moved, for example, between at least two positions.

(12) It can be recognized from FIG. 4 that, in the present case, the valve 12 is constructed as a 4/3-way valve and, in this case, has three shift positions and four connections P, T, K1, and K2. The three shift positions are understood to mean that the valve element 24 can be moved into three different positions. For movement of the valve element 24, the valve 12 comprises an actuator 26, which, for example, can be operated as an electric actuator and accordingly is electrically operable. For example, what is involved in the case of the actuator 26 is an electromagnet or an electric motor. For movement of the valve element 24, the actuator 26 is supplied with electrical current, with this electrical current with which the actuator 26 or the valve 12 is supplied also being referred to as the valve current.

(13) Also arranged in the hydraulic circuit 18 are two couplings 14 and 15 of the vehicle. Moreover, the hydraulic circuit 18 has a line 19, via which the oil can bypass the couplings 14 and 15. This is understood to mean that the oil flowing through the line 19 bypasses the couplings 14 and 15 and accordingly does not flow to or through the couplings 14 and 15. The oil is used, for example, to cool the respective couplings 14 and 15, which are designed, for example, as friction couplings of the vehicle.

(14) The vehicle is, for example, a motor vehicle, which comprises a drive motor, such as, for example, an internal combustion engine. The drive motor comprises, for example, a driven shaft, by way of which the drive motor can supply torques for driving the motor vehicle. At least one of the couplings 14 and 15 can be shifted, for example, between a closed or engaged state and an opened or disengaged state. In the closed state, the driven shaft is coupled via the respective coupling 14 or 15, for example, to another shaft of the vehicle, so that torques can be transmitted between the driven shaft and the other shaft. In the opened state, the other shaft, for example, is decoupled from the driven shaft, so that no torques can be transmitted between the driven shaft and the other shaft via the coupling 14 or 15.

(15) In this case, the vehicle comprises the hydraulic system and accordingly the hydraulic circuit 18, the pump 16, the pump element 20, the electric motor 22, the valve 12, the valve element 24, and the actuator 26, as well as the couplings 14 and 15, so that the hydraulic system is installed as a component of the completely manufactured vehicle and accordingly is installed in the vehicle. The vehicle further comprises an electronic computing device 28, which is also referred to as a control unit. The control unit can control the valve 12 and, in particular, the actuator 26. In particular, the control unit (electronic computing device 28) can electrically control the actuator 26 in that, for example, electrical signals are transmitted from the electronic computing device 28 to the actuator 26 and received by the actuator 26. Through the control of the valve 12 brought about by means of the electronic computing device 28, the valve current is adjusted, for example. Through varying the control of the valve 12, for example, the valve current is varied, as a result of which the valve element 24, for example, can be moved into different positions, that is, into the different shift positions in order to thereby adjust, for example, different flows or volume flows of the oil.

(16) This means that the control of the valve 12 results in a movement or a position of the valve element 24. In this case, it is desirable to know precisely the respective position of the valve element 24 resulting from the respective, corresponding control of the valve 12 in order to adjust precisely the flow of the oil. The respective movement or position of the valve element 24 resulting from the respective control of the valve 12 is referred to as the control-caused behavior of the valve 12, because the valve 12 and, in particular, the valve element 24 behave or move corresponding to the control.

(17) Depending on the position of the valve 12 and, in particular, of the valve element 24, and, accordingly, depending on the control of the valve 12 and, in particular, of the actuator 26, the oil coming from the pump 16 via the coupling 14 and/or via the coupling 15 and/or via the line 19 is returned to a sump 13 accommodated in a tank, for example. In other words, the valve 12 is utilized in order to adjust, for example, a first amount of oil flowing to the coupling 14, a second amount of oil flowing to the coupling 15, and a third amount of oil flowing through the line 19.

(18) Here, FIG. 5 shows a characteristic curve of the valve 12, with this characteristic curve applying nominally for the valve 12. Plotted on the abscissa 54 is the valve current in the unit milliamperes (mA) and plotted on the ordinate 56 is the volume flow of the oil, in particular through the valve 12. Qmax is the maximum volume flow of the oil. At 0, no oil flows. In FIG. 5, a curve 58 depicts the volume flow of the oil to the coupling 14. Furthermore, a curve 60 depicts the volume flow of the oil to the coupling 15 and a curve 62 depicts the volume flow of the oil to or through the line 19.

(19) A first of the positions of the valve element 24, for example, is a first end position, while a second of the positions is a second end position of the valve element 24. The third position is, for example, a centered position of the valve element 24 lying between the end positions and, in particular, exactly in the middle between the end positions, with the centered position also being referred to as the center position.

(20) At nominally 750 milliamperes, the valve 12 or the valve element 24 occupies its center position. In this case, this center position is the position of the valve 12 or of the valve element 24 in which the oil or the volume flow thereof is carried exclusively via the line 19not, however, via the couplings 14 and 15to the sump 13, so that neither the coupling 14 nor the coupling 15 is exposed to or supplied with oil.

(21) The valve element 24 occupies the first position at nominally 0 milliampere. At nominally 1500 milliamperes, the valve element 24 occupies the second end position. Accordingly, the first end position is a position for exclusive exposure of the first coupling 14, while the second position is a position for exclusive exposure of the second coupling 15.

(22) FIG. 1 depicts a first embodiment of a method, by means of which the behavior of the valve 12 caused by control of the valve 12 can be ascertained especially precisely and simply and cost-effectively. In a first step of the method, the pump 16 is operated, so that, by means of the pump 16, the oil is conveyed in that the pump element 20 is driven by means of the electric motor 22. In a second step of the method, the valve 12 is controlled by means of the electronic computing device 28, with the control of the valve 12 being varied by means of the electronic computing device 28. In a third step of the method, at least one parameter characterizing the operation of the pump 16 is sensed, with the fluid (oil) being conveyed by means of the pump 16 to and, in particular, through the valve 12 and being varied during the control of the valve 12.

(23) Furthermore, in a fourth step of the method, the behavior of the valve 12 is ascertained as a function of the sensed parameter. In the first embodiment, it is provided that the parameter comprises at least the power consumption of the electric motor 22. Plotted in the diagram 10 are curves 30 and 32, which depict the power consumption of the electric motor 22 over time. This power consumption of the electric motor 22 is also referred to as the motor current. It can be seen from FIG. 1 that the curves have respective minima 34 and 36. Further plotted in the diagram 10 are curves or lines 38 and 40, which each depict the valve current and accordingly the control, that is, the varying control.

(24) In the scope of varying the control, the valve 12 and, in particular, the actuator 26, are controlled by means of a rising ramp, depicted by the line 38, and/or by means of a falling ramp, depicted by the line 40, of the valve current. Furthermore, in the first embodiment, it is provided that, during the operation of the pump 16, the electric motor 22 is operated at a constant rotational speed. In this case, it is provided, in particular, that the electric motor 22 is operated in a defined temperature window of the oil at a defined and constant rotational speed. If the valve current is then adjusted in the form of a rising ramp (line 38) and/or of a falling ramp (line 40), the position of the valve element 24 changes and, accordingly, a through-flow resistance for the oil flowing through the valve 12 is created by the valve 12 and, in particular, by the valve element 24, so that the through-flow resistance is changed, in particular as a function of the valve current.

(25) This leads, in turn, to a change in the power consumption of the electric motor 22, which can be seen on the basis of the curves 30 and 32. The curve 30 indicates, for example, the motor current for rising valve current (curve 40), while the curve 32 indicates, for example, the motor current for falling valve current (curve 38). For example, in the respective region of the end positions, also referred to as the limit positions, and of the center position of the valve element 24, the through-flow resistance is smallest, so that, in these regions, the lowest power consumption of the electric motor 22 is adjusted. Accordingly, this lowest power consumption occurs at the positions of the minima 34 and 36 and is indicated in FIG. 1 by the vertical lines 39.

(26) The power consumption of the electric motor 22, that is, the respective curve 30 or 32 and, in particular, the respective minima 34 or 36, and accordingly the center position, can be identified by a minimum value analysis of the respective curve 30 or 32. Accordingly, the associated valve current represents the center position of the valve element 24. In other words, the valve current belonging to the respective minimum 34 or 36 results in the center position of the valve element 24. If, for example, the method is carried out repeatedly with a rising and falling ramp of the valve current, then any hysteresis of the center position and the scatter thereof are determined and are stored in a memory device, such as, for example, an EEPROM of the control unit (electronic computing device 28), which is designed, for example, as a gearbox control unit. The method can be carried out both directly after manufacture of the vehicle in its new condition and also during repair of the vehicle, so that it is not necessary to resort to separate test devices.

(27) FIG. 2 shows a diagram 42, by means of which a second embodiment of the method is illustrated. In the second embodiment, the parameter comprises a rotational speed of the electric motor, with the electric motor being operated with a constant electrical current during operation of the pump 16. Plotted in the diagram is a curve or line 64, which depicts the motor current, on the basis of which it can be seen that the motor current is constant, at least substantially.

(28) Further plotted in the diagram 42 is a curve 44, which depicts the rotational speed of the electric motor 22 over time. Moreover, plotted in the diagram 42 is a curve or line 46, which depicts the valve current and accordingly the varying control of the valve 12. In the second embodiment, the electric motor 22 is operated, for example, in a defined temperature window of the oil at its maximum rotational speed, with this maximum speed being limited, on the one hand, by the maximum allowed motor current and, on the other hand, by the through-flow resistance for the oil.

(29) If the electric motor 22 is then operated with the maximum allowed motor current and the valve current is varied, in particular in the form of a rising or falling ramp, the through-flow resistance changes as a function of the valve current and this leads, in turn, to a change in the rotational speed of the electric motor 22. This change in the rotational speed of the electric motor 22 can be determined on the basis of the curve 44. In the present example, the through-flow resistance for the oil brought about by the valve 12 is lowest in the region of the center position of the valve 12 and, in particular, of the valve element 24, as a result of which it is possible to adjust the highest rotational speeds there. This is indicated in FIG. 2 by vertical lines 48, whichlike the vertical lines 39 in FIG. 1limit or indicate the hysteresis of the center position of the valve element 24.

(30) The curve 44 has, for example, a maximum 50 for a falling valve current and a maximum 52 for a rising valve current, with the lines 48 passing through the maxima 50 and 52. Accordingly, the respective maximum 50 or 52 is an excessive rotational speed in the region of the center position, with this excessive speed being identified by a maximum value analysis of the curve 44. The associated valve current represents the center position of the valve 12 and, in particular, of the valve element 24. If the method is carried out repeatedly with a rising and falling ramp of the valve current, then any hysteresis of the center position and the scatter thereof can be determined and stored in the memory device of the electronic computing device 28. The second embodiment of the method can also be carried out during a repair.