Method for operating a transmission device

Abstract

Method for operating a transmission device (1) of a 9-speed transmission, which can be transferred into different operating states via the actuation of shifting elements (A to F), wherein at least one of the shifting elements (A, F) is designed as a positive-locking shifting element, which is subjected to actuating pressure (p_sys) to represent a defined operating state of the transmission device (1) and is thereby transferred from a closed to an open operating state or from the open to the closed operating state, wherein a value of a pressure signal (p_sens) corresponding to the actuating pressure (p_sys) can be determined via a sensor device (22) upstream of a throttle device (21) which is connected to a transmission region (18) having substantially ambient pressure, and wherein when a threshold value (pS1) of the pressure signal (p_sens) is exceeded, currently in the region of the positive-locking shifting element (A,F) a change in operating state and, when the pressure signal (p_sens) falls below a further threshold value (pS2), the achievement of the requested operating state is determined, characterized in that, in the unactuated operating state of the positive switching element (A, F), the pressure in the transmission area (18) is determined via the sensor device (22), and, when a request for a change in operating state is present in the area of the positive switching element (A, F), the threshold value (pS1) and the further threshold value (pS2) are each determined from the sum of the pressure determined in the transmission area (18) before the request for the change in operating state was present and a pressure offset value.

Description

[0001] The invention relates to a method for operating a transmission device according to the type defined in the preamble of patent claim 1.

[0002] A method for operating a transmission device, in particular a nine-speed transmission, is known from the subsequently published DE 10 2013 202 707 A1 and the subsequently published DE 10 2013 202 708 A1 by the applicant. In each case, a value of a pressure signal corresponding to an actuation pressure of a positive shifting element of the transmission device can be determined via a sensor device upstream of a throttle device connected to a transmission region that is essentially at ambient pressure. If a threshold value of the pressure signal is exceeded, a change in operating state is detected in the region of the positive shifting element, and if the pressure signal falls below a further threshold value, the achievement of the requested operating state is determined.

[0003] The sensor device is designed as a so-called absolute pressure sensor, via which the absolute value of the pressure signal can be determined, which is obtained as a measured value from the sum of the respective ambient pressure and the relative pressure level resulting from the actuation pressure applied to the positive switching element. The relative pressure level is almost constant during a change in operating state of the positive switching element, while the ambient pressure varies depending on the weather and the altitude currently being traveled by a vehicle equipped with the transmission device. For this reason, the start of the operating state change in the area of the positive switching element, determined via the threshold value, and the respective specific time at which the positive switching element reaches the required operating state vary.Depending on this, the functions of a transmission device may therefore be initiated too late or too early, which may, however, have a detrimental effect on driving comfort during unfavourable operating conditions.

[0004] The present invention is therefore based on the object of providing a method for operating a transmission device, in particular a nine-speed transmission, which can be carried out with little control and regulation effort and with which a high level of driving comfort can be achieved.

[0005] According to the invention, this object is achieved by a method having the features of patent claim 1.

[0006] In the method according to the invention for operating a transmission device, in particular a nine-speed transmission, which can be transferred into different operating states via the actuation of shifting elements, wherein at least one of the shifting elements is designed as a positive shifting element which is subjected to actuating pressure to represent a defined operating state of the transmission device and is thereby transferred from a closed to an open operating state or from the open to the closed operating state, wherein a value of a pressure signal corresponding to the actuating pressure can be determined via a sensor device upstream of a throttle device which is connected to a transmission area having substantially ambient pressure,If a threshold value of the pressure signal is exceeded, a change in the operating state is detected in the area of the positive switching element, and if a further threshold value of the pressure signal is undershot, the required operating state is reached.

[0007] According to the invention, in the non-actuated operating state of the positive switching element, the pressure in the transmission area is determined via the sensor device and, when there is a request for a change of operating state in the area of the positive switching element, the threshold value and the further threshold value are each determined from the sum of the pressure determined in the transmission area before the request for the change of operating state was present and a pressure offset value in each case.

[0008] Thus, the determination of whether an operating state change is currently taking place in the area of the positive-locking switching element and whether the positive-locking switching element has reached the requested operating state change is carried out depending on the currently prevailing ambient pressure, and a vehicle equipped with a transmission device operated according to the invention can be operated in a simple manner with a high level of driving comfort. The determination of whether an operating state change is currently taking place in the area of the positive-locking switching element and when or whether the requested operating state change is reached is carried out by the procedure according to the invention in each case depending on the currently prevailing ambient pressure, whereby both the start of an operating state change and the achievement of the requested operating state can be determined more precisely than with previously used procedures.Depending on this, further operating sequences in the area of the transmission device and the vehicle can be carried out to the extent necessary to achieve a high level of driving comfort.

[0009] Furthermore, for example, undersupply operating states in the area of a hydraulic control unit of a transmission device can be avoided with little effort by the exact knowledge of an operating state change currently taking place in the area of the positive switching element, which is realized by means of a hydraulic fluid volume flow provided by the transmission control unit, if during such an operating phase of the transmission device, other hydraulic consumers are only supplied or acted upon with a hydraulic fluid volume flow that is adapted to it or preferably reduced.

[0010] If the pressure offset values provided for determining the threshold values differ from one another, for example, hydraulic delays or differing flow resistances in a line system of a hydraulic system of a transmission device that applies actuating pressure to the positive switching element can be easily taken into account.

[0011] If the pressure offset values provided for determining the threshold values correspond to each other, the method according to the invention can be carried out with little effort.

[0012] In an advantageous variant of the method according to the invention, the pressure in the transmission area is determined in the non-actuated operating state of the positive-locking shifting element after the expiration of a period of time that begins at the time at which the achievement of the requested operating state is determined. This achieves in a simple manner that the pressure in the area of the sensor device upstream of the throttle device is determined during a substantially constant operating state profile of a hydraulic system that applies actuating pressure to the positive-locking shifting element.The pressure in the transmission area determined by the sensor device is then essentially identical to the current ambient pressure of the transmission device, since the measurement result is not influenced by further control and regulation processes taking place in the transmission device area and depending on the hydraulic pressure supply.

[0013] In order to avoid undesired distortions of the measurement signal of the sensor device, the pressure in the transmission area is determined in the region of the sensor device in the non-actuated operating state of the positive switching element, preferably when an operating state of the transmission device exists in which the pressure in the transmission area is essentially unaffected by the representation of the current operating state of the transmission device.

[0014] If the pressure offset values are varied depending on at least one operating variable of the transmission device, the determination of whether an operating state change is currently taking place in the area of the positive switching element and whether the requested operating state has been reached in the area of the positive switching element can be carried out with little effort depending on the respective existing operating state.

[0015] In a further advantageous variant, the determination of whether a change in operating state takes place in the area of the positive switching element and whether the positive switching element has reached the requested operating state is carried out in a simple manner in a manner adapted to the respective existing operating state of a transmission device when the pressure offset values are changed as a function of the transmission temperature and / or a system pressure of a hydraulic actuation system of the transmission device.

[0016] In a further advantageous variant of the method according to the invention, the pressure offset values are multiplied by a factor less than one, particularly after restarting the transmission device when a request for a change in operating state in the area of the switching element is present, and are used to determine whether a change in operating state of the switching element is taking place and is complete. This ensures in a simple manner that air pockets present in the hydraulic system, for example, after a vehicle has been parked for extended periods, which cause deviations in the pressure signal dependent on the actuation pressure, do not cause erroneous determinations of the current operating state of a positive-locking switching element to be actuated.

[0017] If the factor, starting from a starting value less than one, is increased step by step by one value with each change in operating state of the positive switching element and / or other switching elements of the transmission device, it is possible in a simple manner to determine and monitor current operating state changes in the area of the positive switching element and the achievement of a requested operating state change with reduced pressure offset values until any air inclusions are pumped out or removed from a hydraulic actuation system of a transmission device assigned to the positive switching element.

[0018] In a further advantageous variant of the method according to the invention, the factor is increased to a value equal to one, whereby any impairments to the actuation of the positive switching element caused by air inclusions can be avoided and the monitoring of the positive switching element can be carried out again in the normal operating mode after defined, predeterminable actuation cycles of the positive switching element.

[0019] In order to be able to take into account events causing different amounts of air accumulation in the area of a hydraulic actuation system of a transmission device, such as after different lengths of downtime or after an oil change of a transmission, the number of operating state changes of the positive switching element and / or other switching elements of the transmission device can be varied starting from the starting value of the factor less than one until the value of the factor equal to one is reached.

[0020] Both the features specified in the patent claims and the features specified in the following exemplary embodiments of the subject matter according to the invention are suitable, either individually or in any combination with one another, for further developing the subject matter according to the invention. The respective combinations of features do not represent any limitation with regard to the further development of the subject matter according to the invention, but are essentially merely exemplary in nature.

[0021] Further advantages and advantageous developments of the invention emerge from the patent claims and the exemplary embodiments described in principle with reference to the drawing.

[0022] It shows: Fig. 1 a wheel set diagram of a transmission device; Fig. 2 a tabular circuit logic of the Fig. 1 shown gear device; Fig. 3 a hydraulic diagram of a part of a hydraulic system of the transmission device according to Fig. 1; Fig. 4 shows a curve of a control current of an electro-hydraulic pressure regulator and of an actuating pressure of a positive switching element of the transmission device according to Fig. 1 corresponding pressure signal over time t and operating states of the positive switching element assigned to the electro-hydraulic pressure regulator corresponding to these two curves; Fig. 5 shows a curve of the pressure signal and a curve of a factored threshold value over time t after restarting a vehicle equipped with the transmission device, the curves occurring during the implementation of an advantageous variant of the method according to the invention.

[0023] Fig. Figure 1 shows a gear diagram of a transmission device 1 or a nine-speed transmission, which is generally known from DE 10 2008 000 429 A1. The transmission device 1 comprises a transmission input shaft 2 and a transmission output shaft 3, which, when mounted in a vehicle, is connected to an output of the vehicle. The transmission input shaft 2 is operatively connected to a drive motor 27 via a hydrodynamic torque converter 4 and a torque converter lock-up clutch 5 associated with the torque converter 4.

[0024] Furthermore, the transmission device 1 comprises four planetary gear sets P1 to P4, wherein the first and second planetary gear sets P1, P2, which are preferably designed as negative planetary gear sets, form a switchable primary gear set, while the third and fourth planetary gear sets P3 and P4 constitute the main gear set. In addition, the transmission device 1 comprises six shifting elements A to F, of which shifting elements C, D, and F are designed as brakes, and shifting elements A, B, and E are designed as clutches.

[0025] The switching elements A to F are connected according to the Fig. 2, a selective switching of nine forward gears D1 to D9 and one reverse gear R can be realized, wherein in order to establish a power flow in the transmission device 1, essentially three switching elements are to be led or held in a closed operating state at the same time.

[0026] The shifting elements A and F are designed here as positive-locking shifting elements without additional synchronization in order to reduce drag torques caused by open frictional shifting elements during operation of the transmission device 1, compared to transmission devices that are designed only with frictional shifting elements. Since positive-locking shifting elements can generally only be converted from an open operating state to a closed operating state within a very narrow differential speed range around the synchronous speed, the synchronization of a positive-locking shifting element to be engaged is achieved without additional structural modifications by correspondingly actuating the shifting elements involved in the shifting.This applies to both traction and overrun shifts, whereby the positive shift elements can be designed as claw clutches, which are designed with or without additional synchronization.

[0027] Fig. 3 shows a hydraulic diagram of part of a hydraulic actuation system 1A of the transmission device 1, via which, among other things, the two positive-locking switching elements A and F can each be subjected to actuation pressure and via which an operating state of two bidirectionally actuated hydraulic actuating devices 2A, 3A of the switching elements A, F, which are here designed as claw switching elements, can be determined. The actuating devices 2A, 3A can each be subjected to hydraulic pressure in the region of active surfaces 6, 7 and 8, 9 of a piston element 10, 11.

[0028] When a hydraulic pressure p_sys of a high-pressure region 34 is applied in the region of a first active surface 6 or 8 on the piston element 10 or 11, a force component acting in the direction of a first end position of the piston element 10 or 11 acts. If, however, the hydraulic pressure p_sys of the high-pressure region 34 is applied to the second active surface 7 or 9 of the piston element 10 or 11, a force component acting in the direction of a second end position of the piston element 10 or 11 acts on the piston element 10 or 11.

[0029] Regions 12, 13, 14, 15, or piston chambers, which can be acted upon by the hydraulic pressure p_sys of the high-pressure region 34 and are assigned to the active surfaces 6, 7, 8, 9 of the piston elements 10, 11, are connected to one another via a throttle device 16, 17, when the piston elements 10, 11 are in positions between their end positions. In addition, one of the regions 12, 13, 14, or 15 can be coupled to the high-pressure region 34 for adjusting a piston element 10 or 11, and the other region 13, 12, 15, or 14 can be coupled to a transmission region 18, or a low-pressure region, which is essentially at ambient pressure. For this purpose, two valve devices 19, 20 are provided, in the areas of which the piston chambers 12, 13 and 14, 15 can each be coupled either to the high-pressure area 34 or to the low-pressure area 18.

[0030] Upstream of the low-pressure region 18 and downstream of the valve devices 19, 20, a further throttle device 21 is provided, and again upstream of the further throttle device 21 and downstream of the valve devices 19 and 20, a pressure measuring device 22 is provided. The valve devices 19 and 20, which are designed as 4 / 2-way valves in the present case, can each be subjected to a control pressure p_VS23, p_VS24 supplied from the high-pressure region 34 via an electro-hydraulic actuator 23 or 24, which is designed as a solenoid valve, against a spring device 25 or 26, respectively, in order to apply the hydraulic pressure p_sys of the high-pressure region 34 to the actuating devices 2A, 3A as required in the region of the piston chambers 12 and 13 or in the region of the piston chambers 14 and 15, or to connect them to the low-pressure region 18.

[0031] Because a single pressure measuring device 22 is provided to monitor the position of the two piston elements 10 and 11, orifices 35, 36 are provided between the valve devices 19 and 20 and a pressure relief valve 33, which exclude any mutual influence of the actuating pistons 10 and 11 in the event of actuation.

[0032] The pressure measuring device 22, which comprises a simple pressure sensor or pressure switch, can be used to detect the end positions of the piston elements 10, 11 or the corresponding operating states of the positive switching elements A and F. In addition, the position sensing is ideally provided in the area of the hydraulic control system, with all end positions of the piston elements 10 and 11 being detectable by means of a single absolute pressure sensor in the manner described in more detail below.

[0033] Between the two end positions of the piston elements 10 and 11, the piston chambers 12 and 13, or 14 and 15, are connected to each other via the throttle devices 16 and 17, depending on their position. The throttle devices 16 and 17, or the connections between the piston chambers 12 and 13, or 14 and 15 in the area of the throttle devices 16 and 17, are released by the piston elements 10 and 11 whenever the piston elements 10 and 11 are not in their end positions.

[0034] In this case, a hydraulic fluid volume flow is guided via the throttle devices 16 and 17 in positions of the piston elements 10 and 11 between their end positions, starting from the piston chamber 12 or 13 or 14 or 15, which is connected to the high-pressure region 34 via the valve device 19 or 20, in the direction of the piston chamber 13 or 12 or 15 or 14, which is coupled to the low-pressure region 18, which in the present case is the transmission sump of the transmission device.

[0035] In the area of the further throttle device 21, which represents a dust orifice, a dynamic pressure p_sens builds up depending on the throttle cross section of the further throttle device 21 and depending on the leakage flow flowing from the piston chamber 12 or 13 or 14 or 15 in the direction of the low-pressure area 18, which is determined by measurement in the area of the pressure measuring device 22.

[0036] A response pressure p_DBV of the pressure relief valve 33, which is arranged downstream of the valve devices 19 and 20 and upstream of the further throttle device 21, lies above a predefined pressure threshold of the pressure measuring device 22, above which a malfunction in the area of the actuating device 2A or 3A is determined via the pressure measuring device 22. Due to the arrangement of the pressure relief valve 33 upstream of the further throttle device 21, the pressure downstream of the valve devices 19 and 20 and upstream of the further throttle device 21 rises during actuation of the piston element 10 or 11 to at least the response pressure p_DBV of the pressure relief valve 33. After the end position of the piston element 10 or 11 is reached, the leakage volume flow in the area of the throttle device 16 or17 is interrupted by the piston element 10 or 11 in the manner described above, whereby the hydraulic pressure p_sens upstream of the further throttle device 21 can no longer reach the pressure level of the response pressure p_DBV of the pressure relief valve 33. This results from the fact that the hydraulic system upstream of the valve devices 19 and 20 is vented via the further throttle device 21 in the direction of the low-pressure region 18.

[0037] If the piston element 10 does not reach the desired end position, the leakage volume flow through the throttle device 16 remains high and leads to a pressure increase in the area of the dust orifice 21 until the pressure relief valve 33 responds and limits the pressure p_sens in the system. The pressure p_sens in the tank line, which has the additional throttle device 21, rises to a level that exceeds the predefined pressure threshold in the area of the pressure measuring device 22, and the electronic transmission control unit receives a signal corresponding to an incorrect piston position.

[0038] In Fig. Figure 4 shows a curve of an actuating current i23 or i24 of the electrohydraulic actuator 23 or 24 and a curve of the pressure p_sens over time t. Additionally, the actuating device 2A or 3A is shown in various operating states, which correspond to the curve of the actuating current i23, i24 and the curve of the pressure signal p_sens that can be determined in the area of the pressure measuring device.

[0039] Up to a time T1, the course of the actuating current i23 or i24 of the electrohydraulic actuator 23 or 24 has a substantially constant course, at which time the actuating device 2A or 3A is in a first operating state, at which time the piston element 10 or 11 is held in its first end position by the applied actuating pressure, in which the throttle device 16 or 17 is closed. Due to the closed operating state of the throttle device 16 or 17, no pressure is guided by the actuating device 2A or 3A via the switching element 19 or 20 in the direction of the further throttle device 21 and thus the low-pressure region 18 and the pressure measuring device 22. This means that in the region of the pressure measuring device 22, essentially the pressure prevailing in the low-pressure region, which essentially corresponds to the ambient pressure of the transmission device 1, is determined.At time T1, a request for a change of operating state is issued in the area of switching element A or F in order to transfer the positive-locking switching element A or F from an open operating state to a closed operating state or from a closed operating state to an open operating state. This depends on whether the open operating state or the closed operating state of the positive-locking switching element A or F corresponds to the operating state of the actuating device 2A or 3A represented before time T1.

[0040] The following description is based on the assumption that the first end position of the piston element 10 or 11 present before time T1 corresponds to a closed operating state of the positive switching element A or F and that the request for a change in operating state of the positive switching element A or F present at time T1 results in a request to open the positive switching element A or F.

[0041] The request to open the positive switching element A or F at time T1 results in the actuating current i23 or i24 of the electro-hydraulic actuator 23 or 24 being suddenly reduced to zero, which causes the valve device 19 or 20 to change into a corresponding switching position, in which the piston chamber 12 or 14 of the actuating device 2A or 3A is subjected to the high pressure or system pressure p_sys. This results in the piston element 10 or 11 being moved from a first end position into the intermediate position shown after time T1 between its first end position and its second end position, in which the throttle device 16 or 17 is open. Hydraulic fluid volume then flows via the throttle device 16 or 17 from the piston chamber 12 in the direction of the piston chamber 13 orfrom the piston chamber 14 in the direction of the piston chamber 15, which leads to a pressure increase downstream of the valve device 19 or 20 and upstream of the further throttle device 21. This pressure increase is determined from a time T2, which follows the time T1. The pressure increase corresponds to the jump in the pressure p_sens at the time T2. The events taking place at the times T1 and T2 are spaced from one another because the sudden drop in the actuating current i23 or i24, due to hydraulic delays in the area of the hydraulic actuating system 1A, only results in a change in the pressure p_sens determined in the area of the pressure measuring device 22 at a later time.

[0042] At a time T3, the piston element 10 or 11 has essentially reached its second end position due to the applied system pressure p_sys, which is shown above the curves i23, i24, and p_sens after the time T3. Upon reaching the second end position of the piston element 10 or 11, the throttle device 16 or 17 is blocked again by the piston element 10 or 11. There is then no exchange of hydraulic fluid between the piston chambers 12 and 13, or 14 and 15, until the system pressure p_sys is again applied in the area of the piston chamber 13 or 15 and the throttle device 16 or 17 is released again by the piston element 10 or 11.

[0043] At time T3, the pressure p_sens initially drops abruptly to an intermediate value and remains essentially at this level until time T4. This results from the fact that the pressure upstream of the further throttle device 21 only decreases with increasing time t and, at time T4, again abruptly returns to the level at time T1.

[0044] In order to check whether the change in operating state requested at time T1 in the area of the positive switching element A or F has actually begun and whether the requested operating state has also been achieved to the requested extent at time T3, the pressure p_sens determined in the area of the pressure measuring device 22 is continuously monitored when a request for a change in operating state is present.

[0045] A curve of a pressure signal or the sensor pressure p_sens occurring during a change of operating state of the positive switching element A or F depending on the respective actuating pressure p_sys in the area of the pressure measuring device 22 is shown in Fig. 5 shows, in addition to further curves of various operating variables of the transmission device 1 over time t. At time T1, at which the request for a change of operating state in the area of the positive switching element A or F is issued, the curve of the actuating current i23 or i24 of the electrohydraulic actuator 23 or 24 decreases in the Fig. 4, the sensor pressure p_sens abruptly drops from an upper value to a lower value. This causes the sensor pressure p_sens to rise with a large gradient at time T2. At time T5, the sensor pressure p_sens corresponding to the actuation pressure p_sys exceeds a threshold value pS1 of the sensor pressure p_sens.

[0046] When the threshold value pS1 of the sensor pressure p_sens is exceeded in the area of the positive switching element A or F, the beginning of the requested operating state change is detected, which results in an actuating movement of the piston element 10 or 11, whereby the actuating movement X10 or X11 of the piston element 10 or 11 is also in Fig. 5 over time t. The curve of the actuating movement X10 or X11 of the piston element 10 or 11 represents merely an exemplary curve, in which the piston element 10 or 11 remains in a defined axial position between times T6 and T7 despite the applied actuating pressure p_sys. This can be caused, for example, by an insufficient actuating pressure p_sys or excessive frictional forces between the piston element 10 or 11 and a cylindrical housing of the actuating device 2A or 3A.

[0047] At time T7, the piston element 10 or 11 is increasingly displaced toward the second position by an amount corresponding to the course of the travel X10 or X11, respectively, which the piston element 10 or 11 reaches to the previously described extent at time T3. The sensor pressure p_sens drops again with a large gradient due to the throttle device 16 or 17 then being blocked. At a time T8, the sensor pressure p_sens falls below a further threshold value pS2 of the sensor pressure p_sens, whereby the achievement of the requested operating state in the area of the positive switching element A or F is then determined.

[0048] Since the pressure measuring device 22 is designed as a cost-effective absolute pressure sensor, the sensor pressure p_sens determined in the area of the pressure measuring device 22 is the sum of the ambient pressure or the pressure present in the low-pressure region 18 and the relative pressure level resulting from the actuation pressure p_sys in the area of the actuating device 2A or 3A. For this reason, the threshold values pS1 and pS2 are each determined based on the currently existing pressure in the low-pressure region 18 or the ambient pressure of the transmission device 1 and a pressure offset value, which are essentially constant for comparable operating states of the transmission device, i.e., at the same transmission temperatures and the same system pressures p_sys.

[0049] This procedure results in the determination of whether a request for a change in operating state in the area of the positive-locking switching element A or F has already begun and whether the positive-locking switching element A or F has reached the requested operating state, at comparable transmission temperatures and comparable actuation pressures p_sys by varying pressure values in the low-pressure region 18 or at varying ambient pressures of the transmission device 1 at different times T5 and T8. This means that while a vehicle is traveling at sea level, the start of an operating state change in the area of the positive-locking switching element A or F is determined at a later time using the last-described procedure than is the case when a vehicle is traveling in high mountains, for example at an altitude of 3000 m.At the same time, weather-related fluctuations in atmospheric pressure also lead to deviations in determining the start of an operating state change and in determining whether the requested operating state has been reached, which is undesirable.

[0050] Deviations in the ambient pressure of the transmission device 3 can produce inaccurate monitoring results, particularly in conjunction with component tolerances. In addition, due to the more precise monitoring of the ambient pressure of the transmission device 3, the threshold values pS1 and pS2 can be more precisely adapted to the current operating state of the transmission device 1, and the transmission device 1 can be operated with greater spontaneity, since shorter safety intervals are required to detect the respective beginning of an operating state change and the achievement of the required operating state.

[0051] For this reason, the pressure in the low-pressure region 18 is measured continuously or after predefined time intervals in the non-actuated operating state of the positive switching element A or F and is used to determine the threshold values pS1 and pS2. This easily prevents influences resulting from altitude- or weather-related deviations in the pressure in the low-pressure region 18 or the ambient pressure of the transmission device 1.

[0052] In order not to falsify the determination of the pressure in the low-pressure area 18 by actuating the switching element A or F, which essentially represents a calibration of the control system assigned to the hydraulic actuation system, the determination of the pressure in the low-pressure area 18 or the ambient pressure of the transmission device 1 is interrupted when there is a request for a change of operating state in the area of the positive switching element A or F. This is Fig. 5 is graphically represented by a status line W jumping from the value 1 to the value 0 at time T1. As long as the status line W is at the value 0, the pressure in the low-pressure region 18 last determined before time T1 or the last determined value of the ambient pressure of the transmission device 1 is used to determine the threshold values pS1 and pS2. The pressure of the low-pressure region 18 measured and filtered in the area of the pressure measuring device 22 is held or frozen when a request for a change of operating state in the area of the positive-locking switching element A or F is present with the start of a corresponding electrical control of the positive-locking switching element A or F and is used for the procedure described above.

[0053] The determination of the pressure in the low-pressure region 18 via the pressure measuring device 22 is only restarted when the movement of the positive-locking switching element A or F or the change in operating state of the positive-locking switching element A or F is completed and it is in a safe end position. In order to be able to carry out the pressure determination in the area of the pressure measuring device 22 to the desired extent, the status line W is only returned to the value 1 at a time T9, and the determination of the pressure in the low-pressure region 18 via the pressure measuring device 22 is only resumed at a time T9, at which the hydraulic actuation system 1A is in a required operating state or a rest state.For this purpose, a defined delay time is waited for after time T3, which extends until time T9, in order to ensure that the actual pressure value in the low-pressure region 18 is determined via the pressure measuring device 22.

[0054] Since in the present case the determination of the pressure in the low-pressure region 18 is omitted upon electrical actuation of the positive switching element A or F, it is also possible in a simple manner to monitor an influence that impairs the determination of the pressure in the low-pressure region 18, for example an actuation of further switching elements of the transmission device 1 that are to be filled or emptied or a changing system pressure p_sys, via corresponding electrical control signals and to interrupt a determination of the pressure in the low-pressure region 18 if necessary.

[0055] Since longer periods of inactivity of a vehicle, during which hydraulic pressure is interrupted in the transmission device 1, cause air to accumulate in the area of the hydraulic actuation system 1A, the sensor pressure p_sens does not reach the usual value in the area of the positive switching element A or F during a change of operating state as long as the air accumulations have not been pumped out of the hydraulic actuation system 1A. For this reason, the pressure offset values used to determine the threshold values pS1 and pS2 are used in the following for Fig. 6 in order to be able to determine the beginning of a requested operating state change and the achievement of the requested operating state even in the presence of air accumulation. The factorization is carried out depending on a defined number of consecutive actuations of the positive switching element A or F in the current driving cycle.

[0056] In Fig. 6 shows a real curve of the sensor pressure p_sens over time t after restarting a vehicle equipped with the transmission device 1 with the associated renewed hydraulic supply of the hydraulic actuation system 1A, which curve occurs during several successive actuations of the positive switching element A or F. The curve of the sensor pressure p_sens in Fig.6 the unfiltered raw signal of the sensor pressure p_sens determined via the pressure measuring device 22. In addition, a curve of the threshold values pS1 and pS2, which are equally predefined depending on the present application, is shown over time t, wherein the threshold values pS1 and pS2 are multiplied by a factor less than 1 and thus factored upon first actuation at a time T=45 s.

[0057] The factorization of the threshold values pS1 and pS2 is provided for because air accumulations trapped in the hydraulic actuation system 1A mean that the sensor pressure p_sens does not reach the usual value when the positive switching element A or F is actuated until the air has been pumped out of the hydraulic actuation system 1A. Since it is known that several consecutive actuations of the positive switching element A or F or also of the further switching elements B, C, D, E increasingly pump such air accumulations out of the hydraulic actuation system 1A, the threshold values pS1 and pS2 are multiplied by a higher factor with each actuation of the switching element A or F or also of the further switching elements B to E, wherein the threshold values pS1 and pS2 in the present case are after the sixth actuation of the switching element A or F.F is multiplied by a factor equal to one and used to determine whether a change in operating state of the switching element A or F is taking place and is completed.

[0058] The number of operating state changes of the positive switching element A or F or of the further switching elements B to E can be varied starting from the starting value of the factor less than one until the value of the factor equal to 1 is reached, if the hydraulic actuation system 1A is essentially free of air accumulations after a smaller number of multiple consecutive actuations of a switching element or only after a larger number of actuations of one of the switching elements. Reference symbol 1 gear device 1A hydraulic actuation system 2 transmission input shaft 2A adjusting device 3 Gearbox output shaft 3A adjusting device 4 hydrodynamic torque converter 5 torque converter lock-up clutch 6 Effective area 7 Effective area 8 Effective area 9 Effective area 10 Piston element 11 Piston element 12 Piston chamber 13 Piston chamber 14 Piston chamber 15 Piston chamber 16 Throttle device 17 Throttle device 18 Gearbox area, low pressure area 19 Valve device 20 Valve device 21 additional throttle device, dust cover 22 Pressure measuring device 23 electrohydraulic actuator 24 electrohydraulic actuator 25 Spring device 26 Spring device 27 drive machine 33 Pressure relief valve 34 High pressure area 35 aperture 36 aperture D1 to D9 gear ratio for forward travel A to F switching element i23, i24 Control current of the electrohydraulic actuator p_VS control pressure p_sens dynamic pressure, sensor pressure p_sys hydraulic pressure of the high pressure area P1 to P4 planetary gear set R gear ratio for reversing t time T1 to T9 discrete time W status line

Claims

[1] Method for operating a transmission device (1) of a 9-speed transmission, which can be transferred into different operating states via the actuation of shifting elements (A to F), wherein at least one of the shifting elements (A, F) is designed as a positive-locking shifting element, which is subjected to actuating pressure (p_sys) to represent a defined operating state of the transmission device (1) and is transferred from a closed to an open operating state or from the open to the closed operating state, wherein a value of a pressure signal (p_sens) corresponding to the actuating pressure (p_sys) can be determined via a sensor device (22) upstream of a throttle device (21) which is connected to a transmission region (18) having substantially ambient pressure, and wherein when a threshold value (pS1) of the pressure signal (p_sens) is exceeded, currently in the region of the positive-locking shifting element (A,F) a change in operating state and when a further threshold value (pS2) of the pressure signal (p_sens) is undershot, the achievement of the requested operating state is determined, , characterized by that in the unactuated operating state of the positive switching element (A, F) the pressure in the transmission area (18) is determined via the sensor device (22) and when there is a request for a change of operating state in the area of the positive switching element (A, F) the threshold value (pS1) and the further threshold value (pS2) are each determined from the sum of the pressure determined in the transmission area (18) before the request for the change of operating state was made and in each case a pressure offset value. [2] Method according to claim 1, characterized by that the pressure offset values used to determine the threshold values (pS1, pS2) differ from each other. [3] Method according to claim 1, characterized bythat the pressure offset values used to determine the threshold values (pS1, pS2) correspond to each other. [4] Method according to one of claims 1 to 3, characterized by that the pressure in the transmission area (18) in the non-actuated operating state of the positive switching element (A, F) is determined in the area of the sensor device (22) after the expiry of a period of time started at the time (T8) at which the achievement of the requested operating state is determined. [5] Method according to one of claims 1 to 4, characterized by that the pressure in the transmission area (18) in the unactuated operating state of the positive switching element (A, F) is determined in the area of the sensor device (22) when an operating state of the transmission device (1) is present, in which the determination of the pressure in the transmission area (18) is essentially unaffected by the representation of the current operating state of the transmission device (1). [6] Method according to one of claims 1 to 5, characterized by that the pressure offset values are varied depending on at least one operating variable of the transmission device (1). [7] Method according to claim 6, characterized by that the pressure offset values are changed depending on the transmission temperature and / or a system pressure (p_sys) of a hydraulic actuation system (1A) of the transmission device (1). [8] Method according to one of claims 1 to 7, characterized by that the pressure offset values are multiplied by a factor less than one after restarting the transmission device (1) when there is a request for a change of operating state in the area of the switching element (A to F) and are used to determine whether a change of operating state of the switching element (A to F) is taking place and is completed. [9] Method according to claim 8, characterized bythat the factor, starting from a starting value less than one, is gradually increased by one value with each change in the operating state of a switching element (A to F). [10] Method according to claim 9, characterized by that the factor is increased to a value equal to one. [11] Method according to claim 9 or 10, characterized by that the number of operating state changes of a switching element (A to F) can be varied starting from the starting value of the factor less than one until the value of the factor equal to one is reached.

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