Method and control unit for controlling a gear shift in an automated transmission

Abstract

Method for controlling a gearshift operation in an automated transmission with a gearshift system, wherein the switching system comprises pressure cylinders (10, 11, 12), switching valves (23) connected between the pressure cylinders (10, 11, 12) and a pressure control chamber (16), a reservoir (24) and main switching valves (27) connected between the reservoir (24) and the pressure control chamber (16), wherein, depending on the switching position of the switching valves (23), pressure chambers (33, 34) of the pressure cylinders (10, 11, 12) are supplied with pressure medium from the pressure control chamber (16), wherein, depending on the switching position of the main switching valves (27), the pressure control chamber (16) is supplied with pressure medium from the storage tank (24), wherein, when a gear shift is carried out in the transmission, the shift valves (23) of a pressure cylinder (10, 11, 12) involved in the gear shift are actuated in order to displace a piston (13, 14, 15) of the respective pressure cylinder (10, 11, 12) involved in the gear shift, characterized by the following steps: with or immediately after a request to execute a switching operation, at least one main switching valve (27) is opened, whereby an actual pressure within the pressure control chamber (16) is increased such that the actual pressure within the pressure control chamber (16) is greater than a target pressure required to execute the switching operation, after the actual pressure in the pressure chamber (16) has been increased, a pressure chamber acting in the direction of displacement of the respective piston (13, 14, 15) and a pressure chamber acting opposite to the direction of displacement of the respective piston (13, 14, 15) of the respective pressure cylinder (10, 11, 12) involved in the circuit execution are filled with a quantity of pressure medium, During the filling of the pressure chambers (33, 34) of the pressure cylinder (10, 11, 12) involved in the circuit execution with pressure medium, the actual pressure in the pressure control chamber (16) is regulated to the target pressure via a pressure regulator (35), namely already when the actual pressure in the pressure control chamber (16) is still greater than the target pressure, wherein immediately after the increase in the actual pressure in the pressure control chamber (16) the pressure regulator (35), which serves to regulate the actual pressure in the pressure control chamber (16) to the target pressure, is activated.

Description

[0001] The invention relates to a method for controlling a gearshift operation in an automated transmission with a gearshift system, according to the preamble of claim 1.

[0002] DE 102011 088 832 A1 discloses the basic structure of a shifting system for a motor vehicle transmission. The automatic or automated shifting system known from this prior art has pressure cylinders, referred to as pressure-actuated shift cylinders. At least one valve interacts with each pressure cylinder; these valves are referred to as shift valves. Depending on the switching position of the shift valves, pressure chambers of the pressure cylinders are supplied with pressure fluid. The chambers of the pressure cylinders are supplied with pressure fluid from a transmission reservoir, also referred to as the pressure control chamber, and the pressure in the pressure control chamber is regulated.The pressure control chamber can be supplied with pressure medium from a storage tank, whereby so-called main switching valves are connected between the storage tank and the pressure control chamber, which are controlled to regulate the pressure in the pressure control chamber depending on the pressure in the pressure control chamber.

[0003] In order to carry out a shifting operation from an actual gear of the transmission to a target gear of the transmission in a transmission with such a shifting system, the shift valves of the pressure cylinders involved in the shifting operation are controlled in order to move a piston of the respective pressure cylinder involved in the shifting operation from an actual position to a target position.

[0004] DE 10 2018 220 161 A1 discloses a method for controlling a gearshift in an automated transmission. In order to transfer the piston of the pressure cylinder involved in executing a gearshift from an actual position to a target position, a target speed of the respective piston is determined and compared with an actual speed. Depending on the difference between the target speed and the actual speed of the piston, a control frequency for the respective valve of the respective pressure cylinder is determined in order to control the respective valve depending on this control frequency.

[0005] The piston of a pressure cylinder involved in a shifting operation typically actuates a shifting element, namely a positive-locking shifting element, via a shift fork. If the shifting element to be actuated is a shifting element with a synchronization device, the shift fork actuates a sliding sleeve, which, along its displacement path, strikes the synchronization device of the synchronized shifting element. To protect the synchronization device and thus the synchronized shifting element from excessively high mechanical loads and thus from damage, the impact speed of the sliding sleeve on the synchronization device must be limited.

[0006] The impact speed of the sliding sleeve on the synchronization device can be limited by filling a pressure chamber of the pressure cylinder involved in the switching operation that acts in the direction of displacement of the piston with pressure medium, as well as a pressure chamber that acts opposite to the direction of displacement of the piston. This is known as counter-ventilation. When the pressure chamber acting opposite to the direction of displacement is also filled with pressure medium, the switching pressure and thus the switching force of the respective switching element decreases. This can make the switching operation and the synchronization phase of the switching process take longer. Furthermore, a reduced switching pressure can lead to an accumulation of tooth-on-tooth positions on the switching element to be switched.

[0007] DE 10 2019 219 961 A1 discloses a method for controlling a gearshift operation in an automated transmission according to the preamble of claim 1.

[0008] DE 10 2006 040 476 A1 discloses a further method for controlling a gear shift in an automated transmission.

[0009] There is a need to perform gear shifts within a short period of time with sufficiently high shifting force while avoiding tooth-on-tooth positions, even when both the pressure chamber acting in the direction of displacement of the respective piston and the pressure chamber acting opposite to the direction of displacement of the respective piston are each filled with a certain amount of pressure medium during gear shifting. The invention is based on the object of creating a corresponding method and control device for regulating a gear shift in an automated transmission.

[0010] This object is achieved by a method according to claim 1. The method comprises the following steps: When or immediately after a request to execute a switching operation is received, at least one main switching valve is opened, preferably for a defined period of time, whereby an actual pressure within the pressure control chamber is increased such that the actual pressure within the pressure control chamber is greater than a target pressure required to execute the switching operation. After the actual pressure has been increased, a pressure chamber acting in the direction of displacement of the respective piston and a pressure chamber acting opposite to the direction of displacement of the respective piston of the respective pressure cylinder involved in the switching operation are filled with a quantity of pressure medium. While the pressure chambers of the pressure cylinder involved in the switching operation are filled with pressure medium, the actual pressure in the pressure control chamber is regulated to the target pressure via a pressure regulator.

[0011] With the method according to the invention, it is possible to carry out gear shifts within a short time with a sufficiently high gear shift force while avoiding tooth-on-tooth positions when, during gear shifting, both the pressure chamber acting in the displacement direction of the piston of the respective pressure cylinder involved in the gear shifting and the pressure chamber acting opposite to the displacement direction of the respective piston are filled with a quantity of pressure medium.

[0012] By opening the main switching valve, preferably for a defined period of time with or immediately after a request to execute a switching operation, the actual pressure in the pressure control chamber is increased such that the actual pressure in the pressure control chamber is greater than the target pressure required to execute the switching operation. This makes it possible to compensate for a pressure drop caused by filling the pressure chamber acting opposite to the direction of displacement of the respective piston and to provide a correspondingly high switching pressure and thus a correspondingly high switching force for executing the switching operation. This advantageous switching operation is supported by regulating the actual pressure in the pressure control chamber to the target pressure.

[0013] While the pressure chambers of the pressure cylinder involved in the switching operation are being filled, the actual pressure in the pressure control chamber is regulated to the target pressure via the pressure regulator even if the actual pressure in the pressure control chamber is greater than the target pressure. Immediately after the actual pressure in the pressure control chamber has increased, the pressure regulator, which serves to regulate the actual pressure in the pressure control chamber to the target pressure, is activated. By activating the pressure regulator even when the actual pressure is greater than the target pressure, the switching operation can be further improved. In particular, it is possible to prevent a switching element from getting stuck in a so-called back-roll and to provide a sufficiently high switching pressure or a sufficiently high switching force.

[0014] Preferably, a synchronized shifting element of the transmission is actuated via the respective piston of the respective pressure cylinder involved in executing the shifting operation. The invention is particularly used in shifting operations involving positive-locking shifting elements with synchronization devices.

[0015] The control device according to the invention is defined in claim 8.

[0016] 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 switching system of the transmission to illustrate the invention.

[0017] Fig. Figure 1 shows a highly schematic block diagram of a pneumatic shift system of an automated transmission of a motor vehicle designed as a group transmission. Fig. 1 pressure cylinder 10, 11, and 12, namely a pressure cylinder 11 for a so-called main group of the range-change transmission, a pressure cylinder 10 for a so-called front-mounted group of the range-change transmission, and a pressure cylinder 12 for a so-called rear-mounted group of the range-change transmission. The front-mounted group is also referred to as a splitter group, and the rear-mounted group is also referred to as a range-change group.

[0018] Each pressure cylinder 10, 11, 12 has a piston 13, 14, or 15, which can be moved within the respective pressure cylinder 10, 11, 12 to perform shifts in the respective group of the group transmission. The piston 13, 14, 15 divides a cylinder chamber of the pressure cylinder 10, 11, 12 into two pressure chambers 33, 34. In each displacement direction of a piston 13, 14, 15, one of the pressure chambers 33, 34 of the respective pressure cylinder 10, 11, 12 acts in the displacement direction, and the other of the pressure chambers 33, 34 of the respective pressure cylinder 10, 11, 12 acts against the displacement direction.

[0019] The respective pressure cylinder 10, 11, 12 can be supplied with compressed air from a pressure control chamber 16 of the switching system, with compressed air lines 17, 18 or 19, 20 or 21, 22 leading from the pressure control chamber 16 in the direction of the respective pressure cylinder 10, 11, 12. In the illustrated embodiment, two compressed air lines 17, 18 or 19, 20 or 21, 22 lead to each pressure cylinder 10, 11, 12 in order to supply the pressure chambers 33, 34 of the respective pressure cylinder 10, 11, 12 with compressed air.

[0020] A switching valve 23 is integrated into each of the compressed air lines 17 to 22. Depending on the switching position of the switching valves 23, the pressure chambers 33, 34 of the pressure cylinders 10, 11, 12 can be supplied with pressure medium from the pressure control chamber 16.

[0021] The pressure chamber 16 can be supplied with compressed air from a reservoir 24, also referred to as a pressure vessel. Compressed air lines 25, 26 lead from the reservoir 24 toward the pressure chamber 16 to convey compressed air from the reservoir 24 into the pressure chamber 16, depending on the position of main control valves 27 integrated into these compressed air lines 25, 26.

[0022] A pressure sensor 28 is installed in the pressure control chamber 16, with which the pressure in the pressure control chamber 16 can be measured. The pressure sensor 28 provides its pressure measurement signal 30 to a control unit 29. The control unit 29 compares the actual pressure in the pressure control chamber 16, measured by the pressure sensor 28, with a desired target pressure in order to control the main switching valves 27 with a respective control signal 31 depending on a deviation between the actual pressure and the target pressure. The control unit 29 can also control the switching valves 23 via additional control signals 32. For the sake of clarity, Fig. 1 the corresponding control signals 31, 32 are not shown for each of the valves 23, 27.

[0023] Pistons 13, 14, 15 of the respective pressure cylinders 10, 11, 12 serve to actuate a shift fork, which ultimately serves to actuate a shifting element of the transmission. At least in the case of the front-mounted group or splitter group of the group transmission, this is a transmission group with a synchronized shifting element, which has a synchronizing device, typically in the form of a synchronizer ring. In this case, piston 13 serves to actuate a sliding sleeve, which encounters the synchronizing device along its adjustment path.

[0024] The invention is now about carrying out switching operations in a component-friendly manner within a short time with sufficient switching pressure and thus sufficient switching force while avoiding tooth-on-tooth positions.

[0025] According to the invention, upon or immediately after a request to execute a switching operation, at least one of the main switching valves 27 is initially opened, preferably for a defined period of time. This increases the actual pressure within the pressure control chamber 16, specifically such that the actual pressure within the pressure control chamber 16 is greater than a target pressure required to execute the switching operation.

[0026] The increase in the actual pressure in the pressure control chamber 16 with or immediately after the request to execute the switching operation can occur, in particular, in conjunction with a system pressure measurement. For this purpose, at least one main switching valve 27 is opened for a defined period of time.

[0027] With or immediately after the request to execute the switching operation, the actual pressure in the pressure control chamber 16 is also measured, specifically with the aid of the pressure sensor 28, which is formed as a result of the opening of at least one main switching valve 27 in the pressure control chamber 16.

[0028] After the actual pressure in the pressure control chamber 16 has been increased, both the pressure chamber of the respective pressure medium cylinder 10, 11, 12 involved in the switching operation, which pressure chamber acts in the direction of displacement of the respective piston 13, 14, 15, and the pressure chamber of the respective pressure medium cylinder 10, 11, 12 involved in the switching operation, which pressure chamber acts counter to the direction of displacement of the respective piston 13, 14, 15, are filled with a quantity of pressure medium, namely the pressure chamber acting in the direction of displacement of the respective piston 13, 14, 15 with a first quantity of pressure medium and the pressure chamber acting counter to the direction of displacement of the respective piston 13, 14, 15 with a second quantity of pressure medium, wherein the first quantity of pressure medium is greater than the second quantity of pressure medium.

[0029] The two pressure chambers 33, 34 of the respective pressure cylinders 10, 11, 12 involved in the circuit execution can be filled with the pressure medium quantity in such a way that the filling of the pressure chamber acting opposite to the direction of displacement of the respective piston 13, 14, 15 with the second pressure medium quantity and the filling of the pressure chamber acting in the direction of displacement of the respective piston 13, 14, 15 with the first pressure medium quantity occur at an overlapping time. Alternatively, it is also possible to first fill the pressure chamber 10, 11, 12 acting opposite to the direction of displacement of the respective piston 13, 14, 15 with the second pressure medium quantity and then fill the pressure chamber acting in the direction of displacement of the respective piston with the first pressure medium quantity.

[0030] During the filling of the pressure chambers 33, 34 of the pressure cylinders 10, 11, 12 involved in the circuit execution with the pressure medium, the actual pressure in the pressure control chamber 16 is already regulated to the target pressure via a pressure regulator 35 of the control unit 29 when the actual pressure in the pressure control chamber 16 is greater than the target pressure. In this context, immediately after the actual pressure in the pressure control chamber 16 increases, the actual pressure is measured via the pressure sensor 28, and the pressure regulator 35 of the control unit 29 is activated.

[0031] To execute a shift, the actual pressure in the pressure control chamber 16 is first increased to an actual pressure that is greater than the target pressure required to execute the shift. Subsequently, both pressure chambers 33, 34 of the respective pressure cylinder 10, 11, 12 involved in the shift are filled, namely both the pressure chamber acting in the direction of displacement and the pressure chamber acting opposite to the direction of displacement. The pressure drop that occurs when the pressure chamber acting opposite to the direction of displacement is filled can be compensated for by increasing the actual pressure in the pressure control chamber 16 before the shift is executed. This ensures that a sufficiently high switching pressure and a sufficiently high switching force can be provided so that the execution of the shift and also a synchronization phase of the shift are not prolonged.

[0032] Pressure regulator 35 is activated as soon as the actual pressure is still greater than the target pressure. This early activation of pressure regulator 35 and regulation of the actual pressure to the target pressure ensures that switching is performed at the desired switching pressure, even when the pressure chamber acting opposite to the displacement direction of the respective piston 13, 14, 15 is filled. Switching pressure drops and the jamming of a switching element in a so-called back-rolling motion can be avoided.

[0033] The invention is preferably used when performing a shift on a synchronized, positive-locking shift element of the transmission. In particular, this can prevent an excessive impact speed of a sliding sleeve on a synchronization device of the shift element. Furthermore, tooth-on-tooth positions on a shift element of the transmission to be shifted can be avoided.

[0034] The invention further relates to the control unit 29, which is configured to automatically execute the method described above on the control side. Thus, the control unit 29, via the control signals 31, controls at least one main switching valve 27, preferably for a defined period of time, upon or immediately after a request to execute a gearshift in the transmission is received, such that the actual pressure within the pressure control chamber 16 is increased, specifically such that the actual pressure within the pressure control chamber 16 is greater than the target pressure required to execute the gearshift.Subsequently, the control unit 29 uses the control signals 32 to control the switching valves 23 of the pressure cylinder involved in the switching operation, in such a way that both a pressure chamber of the respective pressure cylinder 10, 11, 12 acting in the direction of displacement of the respective piston 13, 14, 15 and a pressure chamber of the respective pressure cylinder 10, 11, 12 acting opposite to the direction of displacement are filled with pressure medium. While the pressure chambers 33, 34 are being filled with the pressure medium, the pressure regulator 35 of the control unit 29 regulates the actual pressure in the pressure control chamber 16 to the target pressure, namely via the control signals 31 by controlling the main switching valves 27, even when the actual pressure is still greater than the target pressure.

[0035] The control unit 29 is preferably an electrical or electronic transmission control unit, which has both hardware and software means for implementing the method according to the invention. The hardware means include data interfaces for exchanging data with the assemblies involved in executing the method according to the invention, for example, with the pressure sensor 28, the switching valves 23, and the main switching valves 27. The hardware means also include a processor for data processing and a memory for data storage. The software means include program modules implemented in the control unit 29 for implementing the method according to the invention. Reference symbol 10 pressure cylinders 11 pressure cylinders 12 pressure cylinders 13 pistons 14 pistons 15 pistons 16 Pressure setting room 17 Pressure medium line 18 Pressure medium line 19 Pressure medium line 20 Pressure medium line 21 Pressure medium line 22 Pressure medium line 23 Switching valve 24 storage containers 25 Pressure medium line 26 Pressure medium line 27 Valve 28 Pressure sensor 29 Control unit 30 measurement signal 31 Control signal 32 control signal 33 pressure chamber 34 pressure chamber 35 pressure regulators

Claims

[1] Method for controlling a gearshift operation in an automated transmission with a gearshift system, wherein the switching system comprises pressure cylinders (10, 11, 12), switching valves (23) connected between the pressure cylinders (10, 11, 12) and a pressure control chamber (16), a reservoir (24) and main switching valves (27) connected between the reservoir (24) and the pressure control chamber (16), wherein, depending on the switching position of the switching valves (23), pressure chambers (33, 34) of the pressure cylinders (10, 11, 12) are supplied with pressure medium from the pressure control chamber (16), wherein, depending on the switching position of the main switching valves (27), the pressure control chamber (16) is supplied with pressure medium from the storage tank (24), wherein, when a gear shift is carried out in the transmission, the shift valves (23) of a pressure cylinder (10, 11, 12) involved in the gear shift are actuated in order to displace a piston (13, 14, 15) of the respective pressure cylinder (10, 11, 12) involved in the gear shift, characterized by following steps: with or immediately after a request to execute a switching operation, at least one main switching valve (27) is opened, whereby an actual pressure within the pressure control chamber (16) is increased such that the actual pressure within the pressure control chamber (16) is greater than a target pressure required to execute the switching operation, after the actual pressure in the pressure chamber (16) has been increased, a pressure chamber acting in the direction of displacement of the respective piston (13, 14, 15) and a pressure chamber acting opposite to the direction of displacement of the respective piston (13, 14, 15) of the respective pressure cylinder (10, 11, 12) involved in the circuit execution are filled with a quantity of pressure medium, During the filling of the pressure chambers (33, 34) of the pressure cylinder (10, 11, 12) involved in the circuit execution with pressure medium, the actual pressure in the pressure control chamber (16) is regulated to the target pressure via a pressure regulator (35), namely already when the actual pressure in the pressure control chamber (16) is still greater than the target pressure, wherein immediately after the increase in the actual pressure in the pressure control chamber (16) the pressure regulator (35), which serves to regulate the actual pressure in the pressure control chamber (16) to the target pressure, is activated. [2] Method according to claim 1, characterized bythat with or immediately after the request to carry out the switching process, the at least one main switching valve (27) is opened for a defined period of time, and a measurement of the actual pressure which is formed in the pressure control chamber (16) is carried out via a pressure sensor (28) which interacts with the pressure control chamber (16). [3] Method according to claim 1 or 2, characterized by that after the increase of the actual pressure in the pressure control chamber (16), the pressure chamber acting in the direction of displacement of the respective piston (13, 14, 15) of the respective pressure medium cylinder (10, 11, 12) involved in the circuit execution is filled with a first amount of pressure medium and the pressure chamber acting opposite to the direction of displacement of the respective piston (13, 14, 15) is filled with a second amount of pressure medium. [4] Method according to claim 3, characterized bythat first the pressure chamber acting opposite to the direction of displacement of the respective piston (13, 14, 15) is filled with the second amount of pressure medium and then the pressure chamber acting in the direction of displacement of the respective piston (13, 14, 15) is filled with the first amount of pressure medium. [5] Method according to claim 3, characterized by that the filling of the pressure chamber acting opposite to the direction of displacement of the respective piston (13, 14, 15) with the second amount of pressure medium and the filling of the pressure chamber acting in the direction of displacement of the respective piston (13, 14, 15) with the first amount of pressure medium is carried out in a timely manner. [6] Method according to one of claims 1 to 5, characterized bythat the pressure chamber of the respective pressure cylinder (10, 11, 12) acting in the direction of displacement of the respective piston (13, 14, 15) is filled with a larger quantity of pressure medium than the pressure chamber of the respective pressure cylinder (10, 11, 12) acting opposite to the direction of displacement of the respective piston (13, 14, 15). [7] Method according to one of claims 1 to 6, characterized by that a synchronized shifting element of the transmission is actuated via the respective piston (13, 14, 15) of the respective pressure cylinder (10, 11, 12) involved in the execution of the shifting operation. [8] Control unit (29) for controlling a gearshift operation in an automated transmission with a gearshift system, wherein the switching system comprises pressure cylinders (10, 11, 12) and switching valves (23) connected between the pressure cylinders (10, 11, 12) and a pressure control chamber (16), wherein, depending on the switching position of the switching valves (23), pressure chambers (33, 34) of the pressure cylinders (10, 11, 12) are supplied with pressure medium from the pressure control chamber (16), wherein the switching system further comprises a reservoir (24) and main switching valves (27) connected between the reservoir (24) and the pressure control chamber (16), wherein, depending on the switching position of the main switching valves (27), the pressure control chamber (16) is supplied with pressure medium from the reservoir (24), wherein, when a gear shift is carried out in the transmission, the control unit (29) controls the switching valves (23) of a pressure cylinder (10, 11, 12) involved in the gear shift in order to displace a piston (13, 14, 15) of the respective pressure cylinder (10, 11, 12) involved in the gear shift, characterized by , that the control unit (29) controls at least one main switching valve (27) with or immediately after a request to execute a switching operation in such a way that an actual pressure within the pressure control chamber (16) is increased in such a way that the actual pressure within the pressure control chamber (16) is greater than a target pressure required to execute the switching operation, the control unit (29), after increasing the actual pressure in the pressure control chamber (16), controls switching valves (23) of the pressure cylinder (10, 11, 12) involved in the switching operation in such a way that a pressure chamber acting in the direction of displacement of the respective piston (13, 14, 15) and a pressure chamber acting opposite to the direction of displacement of the respective piston (13, 14, 15) of the respective pressure cylinder (10, 11, 12) involved in the switching operation are filled with a quantity of pressure medium, the control unit (29) regulates the actual pressure in the pressure control chamber (16) to the target pressure via a pressure regulator (35) during the filling of the pressure chambers (33, 34) of the pressure medium cylinder (10, 11, 12) involved in the circuit execution with pressure medium, namely already when the actual pressure in the pressure control chamber (16) is still greater than the target pressure, wherein the control unit (29) is set up to activate the pressure regulator (35), which serves to regulate the actual pressure in the pressure control chamber (16) to the target pressure, immediately after the increase in the actual pressure in the pressure control chamber (16). [9] Control device according to claim 8, characterized by that it is arranged to carry out the method according to one of claims 1 to 7 automatically.

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