DE102019218528A1 - Method for determining a pneumatic conductance value of a switching valve, method for checking the plausibility of a pressure measurement signal and control device - Google Patents

Abstract

Method for determining a pneumatic conductivity value of a pneumatic switching valve (30) of a pneumatic switching system of the transmission, which controls in particular a starting clutch (29) of a transmission, with the following steps: Calculating a system pressure prevailing in a storage container (24) of the switching system on the basis of a predetermined pneumatic conductivity value of the pneumatic switching valve (30). Measuring a pressure prevailing in the pressure regulator space (16) and corresponding to the system pressure with the aid of the pressure sensor (28). Determining the pneumatic conductance of the pneumatic switching valve (30) by solving an optimization function that is dependent on the calculated system pressure and the measured pressure.

Description

The invention relates to a method for determining a pneumatic conductance value of a pneumatic switching valve of a pneumatic switching system of the transmission which, in particular, controls a starting clutch of a transmission. The invention also relates to a method for the plausibility check of a pressure measurement signal detected with the aid of a pressure sensor in a pressure actuator space of a pneumatic switching system of a transmission, as well as a control device.

From the DE 10 2011 088 832 A1 a pneumatic shift system of a transmission with pressure-medium-actuated shift cylinders is known. At least one switching valve interacts with each switching cylinder. A pressure regulator space of the switching system, from which the switching cylinders can be supplied with pressure medium depending on the switching position of the switching valves, can be supplied with pressure medium from a storage container. The pressure actuator space is also referred to as the transmission actuator space. Switching valves, which can be used to regulate the pressure in the pressure regulator space, are connected between the reservoir and the pressure regulator space of the gearshift system. These switching valves connected between the storage container and the pressure regulator space are also referred to as main shut-off valves.

The pressure prevailing in the pressure actuator space or transmission actuator space can be measured using a pressure sensor. In order to control and / or regulate the operation of a transmission precisely without the risk of damage to the shifting elements of the transmission, it is important that the pressure measurement signal provided by the pressure sensor is not incorrect. If the pressure measurement signal of the pressure sensor is faulty, it is possible that gearshifts in the transmission are carried out at too high a pressure, in which case shifting elements of the transmission can be damaged. If the pressure sensor is defective or if it supplies an imprecise pressure measurement signal, this can lead to damage to the gear unit.

On the DE 10 2015 215 293 A1 a method is known with the aid of which the system pressure prevailing in the reservoir of the pneumatic actuating system of a transmission can be determined, namely calculated. For this purpose, when the starting clutch of the transmission is closed, at least one pneumatic switching valve serving to activate the starting clutch is activated for a defined activation period in the opening direction of the starting clutch. The position of the actuating piston of a pneumatic actuating cylinder of the starting clutch is recorded by measurement. Depending on the length of the defined control period, depending on the position of the actuating piston before or at the beginning of the defined actuating period and depending on the position of the actuating piston after or at the end of the defined actuating period, the system pressure can be determined, namely calculated, based on a formula , into which a pneumatic conductance value of the pneumatic switching valve controlling the starting clutch flows. In order to be able to precisely calculate the system pressure according to this prior art, precise knowledge of the pneumatic conductance of the pneumatic switching valve is therefore important. Up to now it has not always been guaranteed that an exact pneumatic conductance of the pneumatic switching valve is available, so that the computational determination of the system pressure can then be incorrect.

There is a need to precisely determine the pneumatic conductance of a pneumatic switching valve of a pneumatic switching system of a transmission in order to be able to precisely calculate the system pressure of the pneumatic switching system. Furthermore, there is a need to simply and precisely check a plausibility check of a pressure measurement signal from the pressure sensor, which is recorded by measurement technology and measures the pressure in the pressure regulator space.

The invention is based on the object of a novel method for determining a pneumatic conductance value of a pneumatic switching valve of a pneumatic switching system of the transmission, which controls in particular a starting clutch of a transmission, a novel method for plausibility checking of a pressure sensor in a pressure regulator chamber of a pneumatic switching system of a transmission To create a pressure measurement signal and a control unit.

This object is achieved by a method for determining a pneumatic conductance value of a pneumatic switching valve of a pneumatic switching system of the transmission, which in particular controls a starting clutch of a transmission. The method comprises the following steps: Calculating a system pressure prevailing in a storage container of the switching system on the basis of a predetermined pneumatic conductance value of the pneumatic switching valve. Measurement of a pressure prevailing in the pressure regulator room, corresponding to the system pressure, with the aid of the pressure sensor. Determination of the pneumatic conductance of the pneumatic switching valve by solving an optimization function dependent on the calculated system pressure and the measured pressure. With this method according to the invention, a pneumatic conductance value of the pneumatic switching valve can be determined precisely by solving an optimization function that is derived from the calculated system pressure and from measured pressure is dependent. The system pressure of the pneumatic switching system can be precisely calculated on the basis of a pneumatic conductance value determined in this way.

The method according to the invention for the plausibility check of a pressure measurement signal detected with the aid of a pressure sensor in a pressure regulator chamber of a pneumatic shift system of a transmission is defined in claim 5 and comprises the following steps: Calculating a system pressure in the storage container on the basis of the pneumatic conductance of the shift valve determined by the optimization function. Measurement of a pressure prevailing in the pressure regulator room, corresponding to the system pressure, with the aid of the pressure sensor. Determination of a discrepancy between the calculated system pressure and the measured pressure, in which case, if the discrepancy is greater than a limit value, an implausible pressure measurement signal from the pressure sensor is deduced, and in which case, if the discrepancy is less than the limit value, a plausible one Pressure measurement signal of the pressure sensor is closed. With this method, a pressure measurement signal from a pressure sensor can be checked for plausibility in a simple and precise manner, using the pneumatic conductance of the switching valve determined with the optimization function.

The control device according to the invention is defined in claim 8.

• 1 ein Schema eines Getriebes und eines Schaltsystems des Getriebes zur Verdeutlichung der Erfindung.

Preferred developments emerge from the subclaims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being restricted thereto. It shows:

• 1 a diagram of a transmission and a switching system of the transmission to illustrate the invention.

1 shows a highly schematic block diagram of a pneumatic shifting system of a transmission of a motor vehicle designed as a group transmission.

So shows 1 Hydraulic cylinder 10 , 11 and 12th , namely a fluid cylinder 11 for a so-called main group of the group transmission, a pressure cylinder 10 for a so-called upstream group of the group transmission and a pressure cylinder 12th for a so-called downstream group of the group transmission. The upstream group is also referred to as a splitter and the downstream group is also referred to as the area group.

Each pressure cylinder 10 , 11 , 12th has a piston 13th , 14th or. 15th , the one in the respective pressure cylinder 10 , 11 , 12th is displaceable in order to carry out shifts in the respective group of the group transmission. The respective pressure cylinder 10 , 11 , 12th can be based on a pressure regulator room 16 of the switching system of the transmission are supplied with compressed air, for this purpose from the pressure regulator space 16 Compressed air lines 17th , 18th or. 19th , 20th or. 21 , 22nd in the direction of the respective pressure cylinder 10 , 11 , 12th to lead. The pressure regulator room 16 is also referred to as the gearbox actuator room.

In the embodiment shown, lead starting from the pressure regulator space 16 to each pressure cylinder 10 , 11 , 12th two compressed air lines each 17th , 18th or. 19th , 20th or. 21 , 22nd to pressure chambers of the respective pressure medium cylinder 10 , 11 , 12th to be supplied with compressed air. In each of the compressed air lines 17th to 22nd is one valve each 23 integrated.

The pressure regulator room 16 can starting from a storage container 24 , which is also referred to as a pressure vessel, can be supplied with compressed air. From the storage container 24 lead compressed air lines 25th , 26th in the direction of the pressure regulator room 16 to depending on the position of valves 27 that are in these compressed air lines 25th , 26th are integrated, compressed air starting from the storage tank 24 in the pressure regulator room 16 to promote. This between the storage container 24 and the pressure regulator room 16 switched valves 27 are also referred to as main shut-off valves. In the storage container 24 there is a system pressure of the pneumatic switching system.

In the pressure regulator room 16 is a pressure sensor 28 built in, with the help of which the pressure in the pressure regulator area 16 can be recorded by measurement. One using the pressure sensor 28 metrologically actual pressure in the pressure regulator area 16 can be compared with a desired setpoint pressure in order to control the valves depending on a deviation between the actual pressure and the setpoint pressure 27 for regulating the pressure in the pressure regulator room 16 head for.

1 furthermore shows a starting clutch in a highly schematic manner 29 of the transmission via a pneumatic switching valve 30th can be controlled.

For the mathematical determination of the system pressure in the storage tank 24 is when the valves are closed 27 and with the starting clutch closed 29 the switching valve 30th the starting clutch 29 which controls the starting clutch 29 serves, for a defined control period in the opening direction of the starting clutch 29 controlled, in this case the position of an actuating piston, not shown, via the switching valve 30th with compressed air supplied and also not shown actuating cylinder of the starting clutch 29 is recorded by measurement. The valves 27 remain closed.

Depending on the position of the actuating piston before or at the beginning of the defined control period, depending on the position of the actuating piston after or at the end of the defined actuation period and depending on the length of the defined control period, the system pressure in the reservoir 24 be determined.

wobei p₁ der Systemdruck ist, wobei t_ON die Länge der definierten Ansteuerzeitdauer ist, wobei s₃ die Position des Stellkobens vor oder zu Beginn der definierten Ansteuerzeitdauer und p₃ der entsprechenden Stelldruck ist, wobei s₄ die Position des Stellkobens nach oder zu Ende der definierten Ansteuerzeitdauer und p₄ der entsprechenden Stelldruck ist, wobei I_MAX ein maximaler Stellweg des Stellkobens ist, wobei A die Fläche des Stellkobens ist, wobei V₀ ein Füllvolumen des Stellzylinders vor oder zu Beginn der definierten Ansteuerzeitdauer ist, wobei C ein pneumatischer Leitwert des Schaltventil 30 ist, wobei p die Luftdichte ist, wobei T die Lufttemperatur ist, und wobei Rs die speizische Gaskonstante von Luft ist. Die definierte Ansteuerzeitdauer für die Ansteuerung des Schaltventils 30 wird zur Ermittlung des Systemdrucks derart bemessen, dass das Schaltventil 30 der Anfahrkupplung 29 über die gesamte definierte Ansteuerzeitdauer bei unterkritischen Druckverhältnissen betrieben wird.For this purpose, a corresponding actuating pressure of the respective actuating cylinder is determined for the position of the actuating piston before or at the beginning of the defined actuation period and for the position of the actuating piston after or at the end of the defined actuation period, depending on a so-called force characteristic of the actuating piston or the actuating cylinder. Before or at the beginning of the defined control period, the actuating piston of the actuating cylinder assumes a position s _{3 , pressure p 3} then prevailing in the actuating cylinder 9, preferably ambient pressure or atmospheric pressure. After or at the end of the defined control period, the actuating piston of the actuating cylinder assumes a position s ₄ , to which a pressure p ₄ belongs. For the two positions s ₃ and s _{4 of} the actuating piston of the actuating cylinder before or after or at the beginning or at the end of the defined control period, the corresponding actuating pressures p ₃ and p _{4 are} determined depending on the respective force characteristic. The system pressure can then be calculated depending on the above positions s ₃ , s _{4 of} the control piston, depending on the set pressures p ₃ and p ₄ determined using the force characteristic, and depending on the length of the defined control period, preferably using the following formula: $$p_1=\frac{p_{\mathrm{4th}}\ast \left(\left(l_{\mathrm{M.}\mathrm{A.}X}-s\mathrm{4th}\right)\ast \mathrm{A.}+V_0\right)-p_{\mathrm{3rd}}\ast \left(\left(l_{\mathrm{M.}\mathrm{A.}X}-s_{\mathrm{3rd}}\right)\ast \mathrm{A.}+V_0\right)}{{\mathrm{R.}}_{\mathrm{S.}}\ast T\ast \mathrm{C.}\ast \rho \ast t_{ON}}$$

where p _{1 is} the system pressure, where t _{ON is} the length of the defined control period, where s _{3 is} the position of the actuating piston before or at the beginning of the defined actuating period and p _{3 is} the corresponding actuating pressure, where s _{4 is} the position of the actuating piston after or at the end the defined control time and p _{4 is} the corresponding control pressure, where I _{MAX is} a maximum travel of the control piston, where A is the area of the control piston, where V _{0 is} a filling volume of the control cylinder before or at the start of the defined control time, where C is a pneumatic conductance of the switching valve 30th where p is the air density, where T is the air temperature, and where Rs is the specific gas constant of air. The defined activation time for the activation of the switching valve 30th is dimensioned to determine the system pressure in such a way that the switching valve 30th the starting clutch 29 is operated over the entire defined control period under subcritical pressure conditions.

More details on how to calculate the storage tank 24 system pressure are off DE 10 2015 215 293 A1 known.

When calculating the above in the storage container 24 The prevailing system pressure is the exact knowledge of the pneumatic conductance C of the switching valve 30th significant. According to a first aspect of the present invention, a method is proposed for the pneumatic conductance of the starting clutch 29 controlling pneumatic control valve 30th to determine exactly, so also an exact calculation of the in the storage container 24 to enable the prevailing system pressure.

To the pneumatic conductance of the pneumatic switching valve 30th to be determined first is the one in the storage container 24 The prevailing system pressure based on a predetermined pneumatic conductance of the pneumatic switching valve 30th calculated. As described above, this takes place with the valves closed 27 via the control of the starting clutch 29 via the switching valve using the relationships and formula described above.

The following is the one in the pressure regulator room 16 prevailing pressure using the pressure sensor 28 measured, namely with the valves open 27 , with the valves open 27 the pressure in the pressure regulator area 16 the system pressure in the storage tank 24 corresponds to.

The following is the pneumatic conductance of the pneumatic switching valve 30th by solving one of the calculated system pressure in the storage tank 24 and the measured pressure in the pressure regulator room 16 dependent optimization function.

wobei

J

die Optimierungsfunktion ist,

Ck

der zu bestimmende pneumatische Leitwert des Schaltventils (30) ist,

p1,k

der berechnete Systemdruck im Vorratsbehälter 24 ist,

p2,k

der gemessene Druck im Druckstellerraum 16 ist,

k

ein Abtastzeitpunkt ist,

n

eine Gesamtdauer der Messung ist.

The following optimization function is preferably solved: $$J=\underset{{\mathrm{C.}}_k}{{\displaystyle \text{min}}}{\displaystyle \sum _{k=0}^n{\left(p_{\mathrm{1,}k}-{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="DE102019218528A1\_0005.png"\; state="\{\{state\}\}">p</figure-callout>}}_{\mathrm{2,}k}\right)}^2}$$

in which

J

the optimization function is

Ck

the pneumatic conductance of the switching valve to be determined ( 30th ) is

p1, k

the calculated system pressure in the storage tank 24 is

p2, k

the measured pressure in the pressure regulator room 16 is

k

is a sampling time,

n

is a total duration of the measurement.

This optimization function is preferably solved on a test stand, depending on different ambient temperatures and different pressure conditions, the more temperature-dependent and pressure-dependent the pneumatic conductance of the switching valve 30th to be determined by solving the optimization function and to store the corresponding values in a control unit. However, the determination of these guide values offline on a test bench is not mandatory; rather, the determination of the guide values can also take place online in the control device when a vehicle having the transmission is operated in the field.

With access to the pneumatic conductance determined according to the invention for the switching valve 30th the system pressure in the storage tank 24 can always be calculated exactly.

If there is a measured pressure in the pressure regulator area 16 using the pressure sensor 28 with the valves open 27 is measured, a deviation between the measured pressure and the calculated system pressure can then be determined in order to either refer to a plausible pressure measurement signal from the pressure sensor on the basis of this deviation 28 or to an implausible pressure measurement signal from the pressure sensor 28 close.

According to a second aspect of the invention, a method for the plausibility check of a with the aid of a pressure sensor is provided 28 in a pressure plate room 16 of a pneumatic switching system of a transmission is proposed with the following steps:

Calculate one in the reservoir 24 The system pressure prevailing in the pneumatic switching system is based on a pneumatic conductance value of a switching valve determined by the optimization function 30th .

The pneumatic conductance of the switching valve determined by the optimization function is determined in the sense of the method according to the first aspect of the invention as described above.

Measure one in the pressure regulator room 16 prevailing pressure corresponding to the system pressure with the help of the pressure sensor 28 .

Determine a discrepancy between the calculated system pressure and the measured pressure. If the deviation is greater than a limit value, an implausible pressure measurement signal from the pressure sensor is triggered 28 closed. If the deviation is smaller than the limit value, a plausible pressure measurement signal from the pressure sensor is activated 28 closed.

The invention further relates to a control unit of a transmission which is set up to carry out the method or methods described above on the control side. The control device comprises means for carrying out the method according to the invention, namely hardware-based means and software-based means. The hardware-side means include data interfaces in order to exchange data on the control side with the assemblies involved in the execution of the method according to the invention, for example with the pressure sensor 28 . Furthermore, the control device comprises, as hardware-side means, a processor for data processing and a memory for data storage. The software-based means include program modules for carrying out the method according to the invention.

List of reference symbols

10

Hydraulic cylinder

11

Hydraulic cylinder

12th

Hydraulic cylinder

13th

piston

14th

piston

15th

piston

16

Pressure regulator room

17th

Pressure medium line

18th

Pressure medium line

19th

Pressure medium line

20th

Pressure medium line

21

Pressure medium line

22nd

Pressure medium line

23

Valve

24

Storage container

25th

Pressure medium line

26th

Pressure medium line

27

Valve

28

Pressure sensor

29

coupling

30th

Switching valve

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• DE 102011088832 A1 [0002]
• DE 102015215293 A1 [0004, 0021]

Claims (8)

Method for determining a pneumatic conductance value of a pneumatic switching valve (30) of a pneumatic switching system of the transmission, which controls in particular a starting clutch (29) of a transmission, with the following steps: Calculating a system pressure prevailing in a storage container (24) of the switching system on the basis of a predetermined pneumatic conductance value of the pneumatic switching valve (30), Measuring a pressure prevailing in the pressure regulator space (16) and corresponding to the system pressure with the aid of the pressure sensor (28), Determining the pneumatic conductance of the pneumatic switching valve (30) by solving an optimization function that is dependent on the calculated system pressure and the measured pressure. Procedure according to Claim 1 , characterized in that the following optimization function is solved: $$J=\underset{{\mathrm{C.}}_k}{{\displaystyle \text{min}}}{\displaystyle \sum _{k=0}^n{\left(p_{\mathrm{1,}k}-p_{\mathrm{2,}k}\right)}^2}$$

where J is the optimization function, C _{k is} the pneumatic conductance of the switching valve (30) to be determined, p _{1, k is} the calculated system pressure in the reservoir (24), p _{2, k is} the measured pressure in the pressure regulator chamber (16), k a Is the sampling time, n is a total duration of the measurement. Procedure according to Claim 1 or 2 , characterized in that the pneumatic conductance is determined as a function of the temperature. Method according to one of the Claims 1 to 3rd , characterized in that the pneumatic conductance is determined as a function of the pressure. Method for the plausibility check of a pressure measurement signal detected with the aid of a pressure sensor (28) in a pressure actuator space (16) of a pneumatic switching system of a transmission, with the following steps: Calculating a system pressure prevailing in a storage container (24) of the pneumatic switching system on the basis of a pneumatic conductance value of a switching valve (30) determined via an optimization function, Measuring a pressure prevailing in the pressure regulator space (16) and corresponding to the system pressure with the aid of the pressure sensor (28), Determination of a deviation between the calculated system pressure and the measured pressure, where, if the deviation is greater than a limit value, an implausible pressure measurement signal from the pressure sensor (28) is inferred, if the deviation is smaller than the limit value, a plausible pressure measurement signal of the pressure sensor (28) is inferred. Procedure according to Claim 5 , characterized in that the pneumatic conductance of the switching valve (30) determined by the optimization function in the sense of the method according to one of the Claims 1 to 4th is determined. Method according to one of the Claims 1 to 6th , characterized in that in order to determine the calculated system pressure when the starting clutch (29) is closed, the switching valve (30) used to control the starting clutch (29) is controlled for a defined control period in the opening direction of the starting clutch (29), with the position of an actuating piston of a pneumatic actuating cylinder of the starting clutch (29) is measured, and depending on the length of the defined actuation period, depending on the position of the actuating piston before or at the beginning of the defined actuation period and depending on the position of the actuating piston after or at the end of the defined actuation period, the system pressure the following formula is still calculated: $$p_1=\frac{p_{\mathrm{4th}}\ast \left(\left(l_{\mathrm{M.}\mathrm{A.}X}-s\mathrm{4th}\right)\ast \mathrm{A.}+V_0\right)-p_{\mathrm{3rd}}\ast \left(\left(l_{\mathrm{M.}\mathrm{A.}X}-s_{\mathrm{3rd}}\right)\ast \mathrm{A.}+V_0\right)}{{\mathrm{R.}}_{\mathrm{S.}}\ast T\ast \mathrm{C.}\ast \rho \ast t_{ON}}$$

where p _{1 is} the calculated system pressure, t _{ON is} the length of the defined control period, s _{3 is} the position of the actuating piston before or at the beginning of _{the actuating period, p 3 is} the actuating pressure before or at the beginning of the actuating period, s _{4 is} the position of the actuating piston after or at the end of the actuation period, p _{4 is} the control pressure after or at the end of the actuation period, I _{MAX is} a maximum travel of the actuating piston, A is the area of the actuating piston, V _{0 is} a filling volume of the actuating cylinder before or at the beginning of the actuation period, C is the pneumatic one The conductance of the switching valve is, where p is the air density, T is the air temperature, Rs is the specific gas constant of air. Control unit of a transmission, characterized in that the same is set up the method according to one of the Claims 1 to 7th to be carried out on the control side.

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