Method and control device for functional testing of a pressure supply system of a gearbox

Abstract

Method for functional testing of a pressure supply system of a transmission (5), namely an electrically operated auxiliary pump (8) of the pressure supply system, which in addition to the auxiliary pump (8) comprises a main pump (7) operable via a transmission shaft of the transmission (5), wherein, if a pressure undersupply is detected in a current driving cycle with a gear engaged in the transmission (5) outside of a shift, the auxiliary pump (8) is functionally tested. First, it is checked whether the auxiliary pump (8) is active at the time the pressure undersupply is detected and / or was active within a defined time period before the time the pressure undersupply is detected. where, if it is determined that this is the case, it is then checked whether a fault has already occurred in the current driving cycle for at least one of the switching elements (13) of the transmission which are closed in the selected gear, If this is not the case, the pressure undersupply is provisionally assessed as a fault of the auxiliary pump (8), the auxiliary pump (8) is provisionally shut down and only the main pump (7) is used for further pressure supply, whereas, if this is the case, the pressure undersupply is not provisionally assessed as a fault of the auxiliary pump (8) and the auxiliary pump (8) is not provisionally shut down.

Description

[0001] The invention relates to a method and a control device for functional testing of a pressure supply system of a transmission.

[0002] DE 10 2011 075 224 A1 discloses a drive train of a hybrid vehicle with a hybrid drive comprising an internal combustion engine and an electric motor. The hybrid vehicle further comprises a transmission connected between the hybrid drive and an output. A pressure supply system for the transmission comprises a main pump and an auxiliary pump, wherein the main pump is driven mechanically by a transmission shaft of the transmission and the auxiliary pump is driven electrically by an electric motor. This prior art also discloses a method for operating such a drive train, with the aid of which the auxiliary pump of the pressure supply system can be checked for proper or improper functioning, i.e., whether or not there is a fault with the auxiliary pump.To this end, it is proposed that when the auxiliary pump ensures the transmission pressure supply when the electric motor of the drive unit is stationary or operating at low speed, a transmission ratio is determined from the transmission speeds and compared with a gear ratio specification of a gear specification. If the transmission ratio determined from the transmission speeds and the gear ratio specification of the gear specification do not match, a fault is concluded. After a defined number of faults in the provision of the transmission pressure supply via the main pump, the speed of the electric motor of the drive unit is increased, and the transmission ratio determined from the transmission speeds is further compared with the gear ratio specification of the gear specification.If it is determined that the gear ratio determined from the transmission speeds and the gear ratio specified by the gear specification match, it is concluded that there is a malfunction in the auxiliary pump. However, if it is determined that the gear ratio determined from the transmission speeds and the gear ratio specified by the gear specification still do not match, it is concluded that there is no malfunction in the auxiliary pump.

[0003] Although the method known from DE 10 2011 075 224 A1 can be used to check whether a fault in the transmission pressure supply can be attributed to the auxiliary pump or not, the method known from the prior art has the disadvantage that the same is carried out even if the fault in the transmission pressure supply is not caused by the auxiliary pump. This then delays treatment of the actual cause of the fault. Furthermore, the method known from the prior art cannot be completed if, for example, the driver changes the transmission state by disengaging the gear during the test sequence. Furthermore, the methods known from the prior art interrupt or abandon the standard sequence for checking plausible speed ratios in the transmission.

[0004] DE 11 2009 003 559 T5 discloses that when a malfunction occurs in an electric hydraulic pump, the hydraulic fluid from the electric hydraulic pump is not supplied to a high-pressure section, and the hydraulic fluid is supplied to the high-pressure section by a mechanical hydraulic pump, which usually supplies the hydraulic fluid to a low-pressure section. In this case, the hydraulic pressure generated by the mechanical hydraulic pump is increased by increasing the output from the machine driving the mechanical hydraulic pump.

[0005] Based on this, the invention is based on the object of creating a method for functional testing of a pressure supply system of a transmission and a control device for carrying out the method, with the aid of which the electrically operated auxiliary pump of the pressure supply system can be checked for proper or improper function within a short time, integrated into a check of plausible speed ratios.

[0006] This object is achieved by a method according to patent claim 1. According to the invention, if a pressure deficiency is detected in a current driving cycle with a gear engaged in the transmission outside of a gearshift, in order to test the function of the auxiliary pump, it is first checked whether the auxiliary pump is active at the time at which the pressure deficiency is detected and / or was active within a defined period of time before the pressure deficiency is detected.If it is determined that this is the case, a check is then carried out to determine whether a fault has already occurred in the current driving cycle for at least one of the gearshift elements of the transmission that are closed in the engaged gear. If this is not the case, the pressure deficiency is provisionally assessed as a fault in the additional pump, the additional pump is provisionally blocked, and only the main pump is used to supply further pressure. If this is the case, the pressure deficiency is not provisionally assessed as a fault in the additional pump, and the additional pump is not provisionally blocked.

[0007] The method according to the invention can be used to easily, reliably, and quickly determine whether a pressure deficiency in the transmission is attributable to the auxiliary pump. The method can be integrated into the standard procedure for checking plausible speed ratios and for handling any implausible speed ratios detected in the transmission, without affecting the process for checking the plausibility of the speed ratios and, if necessary, correcting implausible speed ratios. The entire test procedure can be integrated into existing safety concepts, thereby ensuring that the functional test can be performed within the permissible timeframe.

[0008] According to a further development, if the pressure deficiency is provisionally assessed as a malfunction of the additional pump, the additional pump is provisionally blocked and only the main pump is used to supply further pressure, and if a renewed pressure deficiency is subsequently detected outside of a gearshift, a check is carried out to determine whether at least one of the shift elements of the transmission is closed in the gear now currently engaged, which was also closed in the gear in which the additional pump was provisionally blocked after a pressure deficiency was detected, in which case this is the case, the pressure deficiency is no longer provisionally assessed as a malfunction of the additional pump and the additional pump is released, whereas if this is not the case, the pressure deficiency is still provisionally assessed as a malfunction of the additional pump and the additional pump is still provisionally blocked.This allows the functional testing of the auxiliary pump of the pressure supply system to be further improved.

[0009] If the pressure deficiency is provisionally assessed as a malfunction of the auxiliary pump, the auxiliary pump is temporarily disabled, and only the main pump is used to continue supplying pressure. If no further pressure deficiency is subsequently detected outside of a shift, a check is performed to determine whether the currently engaged gear corresponds to the gear in which the auxiliary pump was temporarily disabled after a pressure deficiency was detected. If this is the case, the pressure deficiency is definitively assessed as a malfunction of the auxiliary pump, and the auxiliary pump continues to be disabled. This also allows the functional testing of the auxiliary pump in the pressure supply system to be further improved.

[0010] Preferably, outside of a gearshift, a pressure deficiency is detected by comparing a target gear ratio of the currently engaged gear with an actual gear ratio of the currently engaged gear determined from measured and / or calculated engine speeds. If the actual gear ratio deviates from the target gear ratio by more than a defined limit, a pressure deficiency is detected. This allows for a simple and reliable conclusion about a pressure deficiency in the transmission.

[0011] The control device according to the invention is defined in claim 5.

[0012] Preferred developments emerge from the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail, without being limited thereto, with reference to the drawings. Herein: Fig. 1 a diagram of a powertrain; Fig. 2 a signal flow diagram to illustrate the method according to the invention.

[0013] The invention relates to a method for functional testing of a pressure supply system of a transmission and a control device for functional testing of a pressure supply system of a transmission. The invention is described below with reference to Fig. 1 and Fig. 2 described in detail, where Fig. 1 shows a schematic view of a drive train of a motor vehicle designed as a hybrid vehicle.

[0014] The Fig. The drive train of a hybrid vehicle shown in Figure 1 comprises a drive unit 1 with an internal combustion engine 2 and an electric machine 3. A transmission 5 is connected between the drive unit 1 and an output 4, wherein the transmission 5 converts torques and speeds and thus provides the tractive power of the drive unit 1 to the output 4. In the exemplary embodiment shown, a separating clutch 6 is connected between the internal combustion engine 2 and the electric machine 3, wherein when the separating clutch 6 is open, the internal combustion engine 2 is decoupled from the output 4 and can be shut down.

[0015] The transmission 5 comprises several switching elements 13, wherein Fig. 1, only one such shifting element 13 is engaged. In each gear of the transmission 5, a first number of shifting elements 13 are open, and a second number of shifting elements 13 are closed. The shifting elements 13 of the transmission 5 can be frictionally engaged shifting elements or positively engaged shifting elements. Preferably, the transmission 5 comprises a plurality of frictionally engaged shifting elements 13 and, if appropriate, at least one positively engaged shifting element 13.

[0016] A pressure supply system is used to supply pressure to the gearbox 5, with the pressure supply system in Fig. 1 a main pump 7 is shown. The main pump 7 is in Fig. 1 is coupled to the transmission input shaft of the transmission 5 and can therefore be mechanically driven from the transmission input shaft of the transmission 5.

[0017] In addition, the pressure supply system of the transmission 5 includes an electrically driven auxiliary pump 8, which can be driven by an electric motor 9. Energy for operating the electric motor 9 of the auxiliary pump 8 is provided by an electrical energy storage device 10, which can be charged by the electric machine 3 of the drive unit 1 when the electric machine 3 of the drive unit 1 is operating as a generator.

[0018] Fig. 1 further shows an engine control device 11 and a transmission control device 12, wherein the engine control device 11 serves to control and / or regulate the operation of the drive unit 1 and the transmission control device 12 serves to control and / or regulate the operation of the transmission 5. For this purpose, the engine control device 11 exchanges, according to the Fig. 1 shown double arrows on the one hand with the combustion engine 2 and on the other hand with the electric machine 3 and the transmission control device 12 with the transmission 5 data. Fig. 1 shows that the engine control device 11 further controls and / or regulates the operation of the electrical energy storage device 10, and the transmission control device 12 controls and / or regulates the operation of the electric motor 9 of the auxiliary pump 8. Furthermore, the engine control device 11 and the transmission control device 12 exchange data required for the operation of the assemblies controlled by them.

[0019] The present invention now relates to a method by means of which the pressure supply system of the transmission 5, namely the electrically operated auxiliary pump 8 thereof, can be subjected to a functional test, simply and reliably within a short time, without the need to interrupt established processes for checking the plausibility of speed ratios in the transmission or even processes for eliminating implausible speed ratios in the transmission.

[0020] The method according to the invention for functional testing of the electrically operated auxiliary pump 8 of the supply system of the transmission 5 is described below with reference to the signal flow diagram of Fig. 2, whereby block 14 of the Fig. 2 symbolizes the start of the method according to the invention.

[0021] First, according to a block 15 for testing the function of the auxiliary pump 8, a check is carried out to determine whether, in a current driving cycle of the hybrid vehicle, a pressure deficiency exists in the transmission 5 when a gear is engaged in the transmission outside of a gearshift or outside of a gear change. A pressure deficiency in the transmission 5 can be determined, in particular, by the transmission control device 12 by comparing a target gear ratio of the gear currently engaged in the transmission 5 with an actual gear ratio of the currently engaged gear determined from measured and / or calculated speeds. If the actual gear ratio deviates from the target gear ratio by more than a defined limit value, a pressure deficiency for the transmission 5 is determined.

[0022] If it is determined in block 15 that there is a pressure deficiency for transmission 5, the system branches from block 15 to block 16. Block 16 then checks whether the auxiliary pump 8 of the pressure supply system is or was active at the time the pressure deficiency is detected and / or within a defined period of time prior to the time the pressure deficiency is detected. If this is the case, the system branches from block 16 to block 17.

[0023] In block 17, a check is then carried out to determine whether a fault has already occurred in the current driving cycle for at least one of the shift elements 13 of the transmission 5 that is closed in the currently engaged gear in which the pressure deficiency was detected. Such faults in the shift elements can be detected by the transmission control unit 12 in a manner known from practice and stored there.

[0024] If it is determined in block 17 that no fault previously existed for any of the shift elements of transmission 5 that are closed in the currently engaged gear, the system branches from block 17 to block 18. In block 18, the detected pressure deficiency is then provisionally evaluated as a fault in auxiliary pump 8, auxiliary pump 8 is temporarily blocked for subsequent operation, and only main pump 7 is subsequently used for further pressure supply. After this, the system branches back from block 18 to block 15.

[0025] Likewise, starting from block 17, the system branches directly back to block 15, bypassing block 18, if block 17 determines that a fault has already occurred in the current driving cycle for at least one of the shift elements of transmission 5 that are closed in the currently engaged gear. In this case, the pressure deficiency is not provisionally evaluated as a fault of auxiliary pump 8, and auxiliary pump 8 is not blocked.

[0026] In block 18, not only is the detected pressure undersupply provisionally assessed as a fault of the additional pump 8 and the additional pump 8 is subsequently provisionally blocked, but in block 18 the gear of the transmission is also stored in the transmission control device 12 for which the pressure undersupply was detected and provisionally assessed as a fault of the additional pump 8.

[0027] In particular, if in block 18 the pressure undersupply was provisionally assessed as a fault of the additional pump 8, the additional pump 8 was provisionally blocked and only the main pump 7 is used for further pressure supply, a further check is subsequently carried out in block 15 as to whether a renewed pressure undersupply for the transmission 5 is detected in the current driving cycle outside of a gearshift or outside of a gear change.

[0028] If this is the case, the program branches from block 15 to block 16, where it is again checked in block 16 whether the auxiliary pump 8 is active or was active for a defined period of time before the pressure insufficient supply was detected. Since, as already explained, an insufficient pressure supply has already been provisionally assessed as a fault in the auxiliary pump 8 and the auxiliary pump 8 has been provisionally blocked, it is determined in block 16 that this is not the case or that the auxiliary pump 8 is or was inactive, and the program branches from block 16 to block 19, where it is checked in block 19 whether the auxiliary pump 8 is provisionally blocked. If this is not the case, the program branches back from block 19 to block 15.

[0029] If, however, it is determined in block 19 that the additional pump 8 is suspected or temporarily blocked, the process branches from block 19 to block 20, whereby in block 20 it is checked whether in the gear currently engaged for which the renewed pressure shortage was determined, at least one of the switching elements 13 is closed, which was also closed in the gear in which the additional pump was temporarily blocked after the pressure shortage was determined.

[0030] If it is determined in block 20 that this is not the case, the system branches back from block 20 to block 15 and the auxiliary pump 8 remains temporarily blocked. If, on the other hand, it is determined in block 20 that the current gear for which the renewed pressure deficiency is detected involves a switching element that was also closed in the gear for which the pressure deficiency was detected and the auxiliary pump was temporarily blocked, the system branches from block 20 to block 21, whereby in block 21 the detected pressure deficiency is no longer evaluated as a fault in the auxiliary pump 8, and the temporary blocking of the auxiliary pump 8 is lifted and the auxiliary pump 8 is therefore released for operation again. Starting from block 21, the system branches back to block 15.

[0031] If it is determined in block 15 that there is no pressure deficiency in transmission 5 when a gear is engaged outside of a shift, the system branches from block 15 to block 22. In block 22, as in block 19, it is checked whether the auxiliary pump 8 is temporarily blocked.

[0032] If this is not the case, the system branches back from block 22 to block 15. If, however, it is determined in block 22 that the auxiliary pump 8 is temporarily blocked, the system branches from block 22 to block 23, where it is checked in block 23 whether the currently engaged gear corresponds to the gear that was engaged in transmission 5, for which the auxiliary pump 8 was temporarily blocked after the pressure deficiency was determined.

[0033] If this is the case, the system branches from block 23 to block 24, where in block 24 the pressure deficiency is not only provisionally but definitively assessed as a fault in auxiliary pump 8, and auxiliary pump 8 remains blocked for further operation. If, however, it is determined in block 23 that the gear in which no pressure deficiency is detected does not correspond to the gear for which a pressure deficiency was provisionally assessed as a fault in auxiliary pump 8 in block 18, the system branches back from block 23 to block 15, auxiliary pump 8 then continues to be provisionally assessed as faulty, and auxiliary pump 8 remains provisionally blocked.

[0034] The method according to the invention is carried out by the transmission control device 12, which is designed as an electronic transmission control device and has means for carrying out the method. These means include data interfaces for exchanging data with the components involved in carrying out the method according to the invention. Furthermore, these means of the transmission control device 12 include a processor for data processing and a memory for data storage. The data interfaces, the processor, and the memory are hardware-side means of the transmission control device 12. The software-side means of the transmission control device 12 for carrying out the method according to the invention are program modules that are stored in the memory and executed by the processor.

[0035] The invention is used in transmissions 5 with frictional shifting elements 13 and possibly at least one positive shifting element 13. Reference symbol 1 drive unit 2 combustion engine 3 electric machine 4 downforce 5 gearboxes 6 Separating clutch 7 Main pump 8 Additional pump 9 Electric motor 10 energy storage 11 Engine control device 12 Gearbox control device 13 Switching element 14 blocks 15 blocks 16 blocks 17 Blocks 18 blocks 19 Block 20 blocks 21 Block 22 blocks 23 Block 24 blocks

Claims

[1] Method for functional testing of a pressure supply system of a transmission (5), namely an electrically operated auxiliary pump (8) of the pressure supply system, which in addition to the auxiliary pump (8) comprises a main pump (7) operable via a transmission shaft of the transmission (5), wherein, if in a current driving cycle with a gear engaged in the transmission (5) outside of a gearshift, a pressure undersupply is detected, for functional testing of the auxiliary pump (8) first, it is checked whether the additional pump (8) is active at the time at which the pressure shortage is detected and / or was active within a defined period of time before the pressure shortage is detected, if it is determined that this is the case, it is then checked whether a fault has already occurred in the current driving cycle for at least one of the switching elements (13) of the transmission which are closed in the engaged gear, If this is not the case, the pressure shortage is provisionally assessed as a fault of the auxiliary pump (8), the auxiliary pump (8) is provisionally blocked and only the main pump (7) is used for further pressure supply, whereas if this is the case, the pressure deficiency is not provisionally assessed as a fault of the auxiliary pump (8) and the auxiliary pump (8) is not provisionally blocked. [2] Method according to claim 1, characterized bythat if the pressure shortage is provisionally assessed as a fault in the auxiliary pump, the auxiliary pump is provisionally blocked and only the main pump is used for further pressure supply, and if a renewed pressure shortage is subsequently detected outside of a gearshift, it is checked whether at least one of the shift elements of the transmission is closed in the gear currently engaged, which was also closed in the gear in which the auxiliary pump was provisionally blocked after a pressure shortage was detected, If this is the case, the pressure deficiency is no longer provisionally assessed as a fault of the auxiliary pump and the auxiliary pump is released, whereas if this is not the case, the pressure deficiency will continue to be provisionally assessed as a fault of the auxiliary pump and the auxiliary pump will continue to be provisionally blocked. [3] Method according to claim 1 or 2, characterized bythat if the pressure shortage is provisionally assessed as a fault in the auxiliary pump, the auxiliary pump is provisionally blocked and only the main pump is used to supply further pressure, and subsequently no further pressure shortage is detected outside of a gearshift, a check is carried out to determine whether the currently engaged gear corresponds to the gear in which the auxiliary pump was provisionally blocked after a pressure shortage was detected, in which case this is the case, the pressure shortage is finally assessed as a fault in the auxiliary pump and the auxiliary pump continues to be blocked. [4] Method according to one of claims 1 to 3, characterized bythat outside of a gearshift, a pressure deficiency is determined by comparing a target gear ratio of the currently engaged gear with an actual gear ratio of the currently engaged gear determined from measured and / or calculated speeds, whereby if the actual gear ratio deviates from the target gear ratio by more than a defined limit value, a pressure deficiency is determined. [5] Control device for functional testing of a pressure supply system of a transmission (5), namely an electrically operated auxiliary pump (8) of the pressure supply system, which in addition to the auxiliary pump (8) comprises a main pump operable via a transmission shaft of the transmission (5), wherein, if the control device detects an undersupply of pressure to the transmission (5) in a current driving cycle with a gear engaged in the transmission (5) outside of a gearshift, for functional testing of the auxiliary pump (8) of the pressure supply system of the transmission (5) first checks whether the auxiliary pump is active at the time the pressure deficiency is detected and / or was active within a defined period of time before the pressure deficiency is detected, wherein, if the control device determines that this is the case, the control device then checks whether a fault has already occurred in the current driving cycle for at least one of the switching elements (13) of the transmission (5) which are closed in the engaged gear, If this is not the case, the control device provisionally evaluates the pressure shortage as a fault in the additional pump (8), temporarily blocks the additional pump (8) and uses exclusively the main pump (7) for further pressure supply, whereas if this is the case, the control device does not provisionally evaluate the pressure shortage as a fault of the additional pump (8) and does not provisionally block the additional pump (8). [6] Control device according to claim 5, characterized bythat when the control device provisionally assesses the pressure shortage as a fault in the additional pump (8), the additional pump (8) provisionally blocks the additional pump (8) and uses exclusively the main pump (7) for further pressure supply, and subsequently the control device detects a renewed pressure shortage of the transmission (5) outside of a gearshift, checks whether in the now currently engaged gear at least one of the shift elements (13) of the transmission (5) is closed, which was also closed in the gear in which the additional pump (8) was provisionally blocked after detecting a pressure shortage, if this is the case, the control device no longer provisionally evaluates the pressure deficiency as a fault of the additional pump (8) and releases the additional pump (8), whereas if this is not the case, the control device continues to provisionally evaluate the pressure shortage as a fault of the additional pump (8) and continues to provisionally block the additional pump (8). [7] Control device according to claim 5 or 6, characterized by that if the control device provisionally assesses the pressure deficiency as a fault in the additional pump (8), the additional pump (8) provisionally blocks the additional pump (8) and uses only the main pump (7) for further pressure supply, and the control device subsequently does not detect a renewed pressure deficiency outside of a shift, checks whether the currently engaged gear corresponds to the gear in which the additional pump (8) was provisionally blocked after a pressure deficiency was detected, in which case this is the case, the control device definitively assesses the pressure deficiency as a fault in the additional pump (8) and continues to block the additional pump [8] Control device according to one of claims 5 to 7, characterized by that the control device detects a pressure deficiency outside of a gearshift by comparing a target gear ratio of the currently engaged gear with an actual gear ratio of the currently engaged gear determined from measured and / or calculated speeds, wherein a pressure deficiency is detected if the actual gear ratio deviates from the target gear ratio by more than a defined limit value. [9] Control device according to one of claims 5 to 8, characterized by that the control device is designed as an electronic transmission control device (12).

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