Multi-stage manual transmission for a drive device of a motor vehicle
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-02-05
- Publication Date
- 2026-08-13
Smart Images
Figure EP2026052985_13082026_PF_FP_ABST
Abstract
Description
[0001] ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0002] Multi-stage transmission for a drive system of a motor vehicle
[0003] The present invention relates to a multi-stage transmission for a drive unit of a motor vehicle, a drive unit with such a multi-stage transmission, and a motor vehicle with a drive unit comprising such a multi-stage transmission.
[0004] A motor vehicle comprises a drive system that acts mechanically on at least one drive wheel of the motor vehicle to propel the vehicle. The drive can be provided by an internal combustion engine and / or an electric motor. Modern multi-stage transmissions, particularly those of planetary gear design, with eight or nine gears usually have five or more clutches. Regardless of the specific application, each individual clutch is typically controlled by its own hydraulic actuator, for example, a pressure regulating valve.
[0005] German patent DE 102017223015 A1 discloses a valve system for a hydraulic emergency driving gear function of a motor vehicle automatic transmission. The valve system comprises a position valve with a first piston valve and an electromagnetic pressure regulator with a falling characteristic curve. The first piston valve can be moved into a first position and a second position, with the first piston valve being pre-tensioned in the first position. When the first piston valve is in the second position, the electromagnetic pressure regulator is configured to connect a system pressure line of the motor vehicle automatic transmission to a first emergency driving gear clutch and a second emergency driving gear clutch of the motor vehicle automatic transmission, thereby actuating the first and second emergency driving gear clutches and engaging an emergency driving gear of the motor vehicle automatic transmission.
[0006] Typically, such transmissions also have a hydraulically actuated parking lock system, which can also be connected to individual clutches. The parking lock can be actuated in parallel with the clutches, i.e., ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0007] The parking lock can be designed to function simultaneously with the clutch actuation or alternatively in series with a clutch actuation.
[0008] When controlling the clutch pressure for a gear change, pressure levels must be specified very precisely. An engaging valve acts as a hydraulic power source to move a clutch piston, thereby generating frictional torque between the steel and friction linings. As soon as the friction linings begin transmitting torque, the pressure level of the engaging clutch is crucial for a smooth gear change. The pressure level of a disengaging clutch is only relevant during engine braking. It determines how long the torque is held by the disengaging clutch before the new gear engages.
[0009] An object of the present invention is to provide a simpler multi-stage transmission whose shift topology can be easily extended or modified, and in particular adapted to a different number of clutches. The present invention achieves this object by means of the subject matter of the independent claims. Dependent claims describe preferred embodiments.
[0010] According to a first aspect of the invention, a multi-stage transmission according to the invention for a drive unit of a motor vehicle comprises a first pressure valve arrangement and a second pressure valve arrangement, which are separately controllable and can be pressurized, and at least two clutches for controlling a power flow through the multi-stage transmission, wherein each clutch is associated with a holding valve, which can be selectively locked by an associated, separately controllable locking mechanism either in a filling position, in which a fluidic connection between the first pressure valve arrangement and the associated clutch is released, or in an emptying position, in which a fluidic connection between the associated clutch and the second pressure valve arrangement is released, and wherein each holding valve, when actuation of this holding valve is released by the locking mechanism,mit-ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06,
[0011] The control pressure of the first pressure valve arrangement can be switched from the emptying position to the filling position.
[0012] When the holding valve is actuated by a controlled pilot pressure, which may correspond to a system pressure, provided via the first pressure valve assembly, and thereby moved from the emptying position to the filling position, the associated coupling can be filled in a controlled manner and actuated accordingly by pressurization. Once the filling position is reached, the respective locking mechanism is actuated so that the associated holding valve is locked in the filling position.
[0013] When the holding valve is actuated by a controlled control pressure supplied via the second pressure valve assembly and moved from the filling position to the emptying position, the associated coupling can be emptied in a controlled manner. The respective locking mechanism is actuated after the emptying position is reached, locking the associated holding valve in the emptying position.
[0014] In this context, "locked" means that the respective holding valve cannot be moved to the other position without first reactivating the locking mechanism to unlock the respective holding valve.
[0015] The clutch holding valves are connected in parallel and fluidically linked to the first pressure valve assembly via a respective filling path. The respective clutch is filled via the filling path with an increasing pressure gradient. Each holding valve is also assigned a drain path, via which it is fluidically linked to the second pressure valve assembly. The respective clutch is emptied via the drain path with a decreasing pressure gradient. The drain path is connected to a control line, through which the respective holding valve can be pressurized to such an extent that it switches from the filling position to the draining position. Thus, the drain path also partially functions as a control line for controlling the position change of the ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0016] Holding valve, provided that the associated locking mechanism has previously released the holding valve.
[0017] With such a multi-stage transmission, a relatively large number of robust but cost-effective components can be used to achieve the desired functionality. To adjust the desired pressure levels and pressure profiles, especially during gear changes, only a few, in this case two, more complex and potentially more expensive pressure valve assemblies are used.
[0018] In principle, any number of clutches can be switched via the pressure valve assemblies, for example, to select a gear in a multi-stage transmission or to switch other hydraulic switching elements. The pressure valve assemblies are designed to actuate exactly two of the at least two clutches simultaneously. From any number of clutches, exactly two clutches can always be actuated via the two pressure valve assemblies.
[0019] The pressure valve assemblies and locking mechanisms can be controlled separately by a control unit. The control unit is designed to operate a pumping device for conveying fluid such that a system pressure is set in the fluid supply of the multi-stage transmission and supplied to the pressure valve assemblies. Oil, especially hydraulic oil, is particularly suitable as the pressure medium. Furthermore, the control unit is designed to actuate the locking mechanisms, depending on their configuration, for example, to energize them to release or lock / block the associated holding valve.
[0020] While the first pressure valve arrangement only allows for increasing pressure gradients, the second pressure valve arrangement only realizes decreasing pressure gradients. The increasing pressure gradient of the first pressure valve arrangement is achieved by providing a filling valve and an orifice located upstream of it in a filling path of the respective holding valve. The filling valve is located between the first pressure valve arrangement and the respective holding valve in the direction of flow during a filling process of the respective coupling. The filling valve functions as ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0021] A check valve prevents backflow of fluid or pressure medium via the filling path towards the first pressure valve assembly. The first pressure valve assembly is designed to fill the respective fluidically connected coupling with fluid in a controlled manner, provided that the pressure has been applied to the holding valve to effect the position change by releasing its adjustment from the initial or emptying position to the filling position. Thus, each holding valve, when actuated by the locking mechanism, can be switched from the emptying position to the filling position by means of the control pressure from the first pressure valve assembly.
[0022] The decreasing pressure gradient of the second pressure valve assembly is achieved by providing a drain valve in the discharge path of the respective holding valve. The drain valve is located, in the direction of flow with respect to a discharge operation of the respective coupling, between the holding valve and the second pressure valve assembly. The drain valve acts as a check valve, preventing backflow of the fluid or pressure medium via the discharge path towards the second pressure valve assembly. The second pressure valve assembly is designed to discharge fluid from a coupling connected to it in a controlled manner, provided that the holding valve has been pressurized beforehand by releasing its adjustment from the filling position to the initial position or the discharge position.Therefore, each holding valve, when actuation of this holding valve is enabled by the locking mechanism, can be switched from the filling position to the emptying position by means of the control pressure of the second pressure valve arrangement.
[0023] Preferably, each holding valve is pre-tensioned in the discharge position and has a transmission ratio such that, when actuation of this holding valve is released by the locking mechanism and a respective control pressure is applied via both the first pressure valve arrangement and the second pressure valve arrangement, this holding valve is switched to the discharge position. ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0024] Preferably, the second pressure valve arrangement includes a drain valve. The drain valve connects the second pressure valve arrangement to a sump. The drain valve can be understood as a pre-filling valve or vent line. The drain valve is designed to release the flow of the pressure medium that occurs when the respective holding valve is switched. Alternatively or additionally, the respective holding valve also includes a drain valve. Thus, a venting option can be integrated into the respective holding valve.
[0025] Since the second pressure valve arrangement is responsible for emptying in an overlapping configuration, the filling and emptying dynamics can be easily adjusted via the respective orifice, which acts as a filling throttle. Except during overrun cycles, emptying occurs at maximum dynamics and is limited only by the aforementioned drain valves. The orifices, like the drain valves, can be integrated directly into the respective holding valve. The second pressure valve arrangement ensures precisely controllable emptying behavior for each coupling.
[0026] "Overlap" refers to an opposing pressure profile of the two clutches involved in the gear change - that is, the pressure profile of the next clutch to engage or engage has a rising profile and the pressure profile of the clutch to disengage has a falling profile.
[0027] The multi-stage transmission has a number of locking mechanisms corresponding to the number of holding valves or clutches. In other words, each holding valve is associated with a locking mechanism. The respective locking mechanism is designed to lock or release the position change of the associated holding valve.
[0028] Preferably, the respective locking mechanism comprises a locking magnet that, to achieve the locking action, creates a positive connection with an actuating element of the associated holding valve. The locking magnet can be actuated, at least indirectly, by the aforementioned control device. The actuating element can be an axially displaceable component that can be moved between two positions as a result of pressurization of the filling or emptying path. ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0029] namely a first switching position or initial position corresponding to the emptying position of the associated holding valve and a second switching position corresponding to the filling position of the associated holding valve. To realize the respective switching position, the actuating element can have a positive locking element or a corresponding design which can be brought into positive locking with the locking magnet when the respective switching position is reached. When the locking magnet is actuated, in particular when energized, the locking magnet is disengaged from the positive locking with the actuating element. When the actuation, in particular the energizing, is discontinued, the locking magnet, which may be biased towards the actuating element, is moved to its initial position.The preload of the locking magnet ensures that it snaps into a positive engagement with the actuator of the associated valve as soon as the first or second switching position is reached. Alternatively, the locking mechanism can be designed such that the locking magnet must always be actively actuated, regardless of the direction of actuation, to move either towards the actuator or in the opposite direction.
[0030] Preferably, the multi-stage transmission has several gear stages, wherein one of the at least two clutches is configured to engage or disengage one of the gear stages from the power flow through the multi-stage transmission. In other words, a clutch, actuated or engaged via the first pressure valve arrangement, controls a power flow. In particular, this clutch creates a frictional connection between two components of the multi-stage transmission. The respective clutch is therefore a controllable friction clutch.
[0031] Preferably, one of the several transmission stages comprises a planetary gear set, wherein one of the at least two clutches is configured to introduce torque into the planetary gear set, to extract torque from the planetary gear set, or to lock an element of the planetary gear set relative to a housing. In other words, the respective clutch can create a torque-transmitting connection between two components of the multi-stage transmission or ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0032] To support a torque on a housing or to mount a component fixed to the housing. One possible design of an epicyclic gear unit is known as a planetary gear unit. A planetary gear unit is understood to be a gear unit that includes the components ring gear, carrier, and sun gear. The carrier serves to support the planets of the planetary gear unit.
[0033] Preferably, a pressure sensor is arranged on the outlet side of the first pressure valve arrangement and / or on the outlet side of the second pressure valve arrangement. "Outlet side" here refers to the flow direction of the pressure medium corresponding to the pressure applied to the respective holding valve. In other words, the pressure sensor is arranged between the first pressure valve arrangement and the holding valves, or between the second pressure valve arrangement and the holding valves. Alternatively, a pressure sensor can be arranged in each line, i.e., in both the filling and emptying paths. The pressure applied to the respective pressure valve arrangement and present at the corresponding coupling can be measured via the optional pressure sensor.By measuring the clutch pressure using the pressure sensor, dynamic influences such as parameter disturbances, for example, due to air ingress which can lead to dead times during clutch pressure build-up, can be detected and compensated for in real time during filling. Steady-state deviations, for example, due to the temperature fluctuation of the pressure valve assemblies, can also be detected and compensated for. Simply by installing a single pressure sensor, all clutches can be diagnosed and adapted.
[0034] Since the couplings are supplied by the holding valves during ferry operation, the aforementioned pressure sensor enables online adaptation to non-load-bearing or unactuated couplings during ferry operation. This allows for coupling stiffness detection and touch-point adaptation. Furthermore, the characteristic curve(s) of one or more couplings can be modified during coupling filling. This can, for example, detect that a seal is no longer fully functional. If couplings are faulty, they can be isolated and no longer considered or controlled during vehicle operation. ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0035] Preferably, each holding valve is associated with a throttle valve. The throttle valve is designed to maintain a pressure level at the associated coupling once it is filled and has reached a predetermined control or system pressure. This allows the pressure application to this coupling by the first pressure valve arrangement to be terminated without the first coupling being able to change its switching state.
[0036] In one embodiment, one of the at least two clutches is designed as a parking lock actuation device. The parking lock actuation device can be part of a hydraulic parking lock system of the multi-speed transmission. The parking lock actuation device can include a cylinder that can be pressurized. In this case, the associated holding valve can be designed such that the pressure medium drains into a sump directly at the holding valve, allowing the cylinder to be emptied as quickly as possible when opened. The discharge path of the associated holding valve thus leads directly into a sump. The pressure medium then does not need to be routed first to a drain valve, for example, at the second pressure valve assembly. This makes a sudden opening of the cylinder possible.
[0037] Preferably, the multi-stage transmission includes a third pressure valve arrangement connected in parallel to the first and second pressure valve arrangements for engaging a further clutch. This allows for the simple integration of additional parallel hydraulic actuators into the transmission topology, for example, in the form of an all-wheel drive clutch. The additional clutch can be used and controlled independently and in parallel to the other clutches by appropriately controlling the third pressure valve arrangement.
[0038] Preferably, one, several, or all of the aforementioned pressure valve arrangements are designed as pilot-operated pressure valve arrangements, comprising a coupling valve and an electromagnetic pilot stage upstream of the coupling valve. The pressure valve arrangement not designed as a pilot-operated pressure valve arrangement can be designed as a direct-operated pressure valve. Accordingly, a, ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0039] Several or all pressure valve assemblies can be designed as direct-acting pressure valves. A combination of direct-acting and pilot-operated pressure valves is also conceivable. Direct-acting pressure valves react directly to pressure changes and control the valve opening using a spring or an electromagnet. This allows them to react quickly and precisely to pressure fluctuations, but they are usually only suitable for low flow rates. Pilot-operated pressure valves, on the other hand, use a smaller, direct-acting valve to regulate the pressure in the main chamber. Once the pilot pressure is reached, a main valve opens or closes, enabling higher flow rates. This type of valve control is more energy-efficient and better suited for higher pressures and flow rates, but usually reacts somewhat slower than direct-acting valves.
[0040] While such a multi-stage transmission is conceivable for transmissions with only two clutches, it is particularly well-suited for multi-stage transmissions with three or more clutches. One advantage is that any number of clutches can be controlled by exactly two pressure valves or pressure control valves. This multi-stage transmission can be less complex than other multi-stage transmissions, as it can utilize identical or very similar components. Each clutch is controlled by one of the two valves, i.e., filled or emptied.
[0041] Furthermore, the transmission topology can be easily expanded to include additional clutches or reduced to a smaller number of clutches. This allows for the implementation of a modular system, particularly if the components used are identical. A simple, modular, common-parts approach can thus be implemented for different transmission types.
[0042] The multi-stage transmission can be designed relatively cost-effectively, as only the pressure valve assemblies are more expensive, while the holding valves, throttle valves, drain valves, fill valves, empty valves, and orifices are simple and inexpensive components. In particular, the holding valves and locking mechanisms are simple switches that only need to be switched between end stops and, if necessary, detent. Data acquisition and adaptation effort: ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0043] The system is essentially limited to the two pressure valve arrangements. The reduced complexity of the system, in turn, increases the robustness of the multi-stage transmission, particularly against contamination, and ensures a lower probability of failure of parts and components.
[0044] For multi-stage transmissions, a shift mechanism assessment of the individual clutch filling profiles can be performed. This, together with a recorded history of previous fillings, allows for certain diagnostic conclusions to be drawn about the condition of the clutches and / or the actuating system. For example, if dead times occur during clutch pressure build-up at the first pressure valve assembly during several consecutive overlaps, air ingress due to insufficient oil level is likely. If a clutch experiences a gradual drop in a steady-state target pressure over its service life, this can indicate a faulty or damaged seal, which often results in increasing leakage. Since the same actuating system is used for all hydraulic consumers, namely the clutches, the system proposed here makes it easier to determine whether a valve fault or a fault in the hydraulic consumer is present.
[0045] Such a multi-stage transmission can also ensure continued, albeit limited, operation if, for example, the first pressure valve assembly fails or jams. An emergency gear stage can also be provided in principle with suitable spring placement on the holding valves.
[0046] According to a second aspect of the invention, a drive system for a motor vehicle comprises a drive unit and a multi-stage transmission according to the first aspect of the invention. The drive system can, in particular, comprise an electric drive axle or a hybrid drive axle. In addition to the electric motor, the electric drive axle includes the multi-stage transmission to provide torque for driving a drive wheel of the motor vehicle. An internal combustion engine can be provided as the drive motor, which also generates drive power and transmits it to the multi-stage transmission. The multi-stage transmission allows for the switching of gears by the individual gears. (ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06)
[0047] Tens of two, preferably three or more than three, clutches realize several gears or gear stages. In addition to the electric motor, an electric control device can also be included, which can be configured to control the locking mechanisms and the pressure valve arrangements of the multi-stage transmission according to the invention.
[0048] According to yet another aspect of the present invention, a motor vehicle comprises a drive unit as described herein. The motor vehicle can, in particular, be a motorcycle, a passenger car, a truck, or a bus. The drive unit can be part of a driven axle of the motor vehicle. The drive unit can therefore be assigned to a rear axle or a front axle of the motor vehicle.
[0049] The above definitions and descriptions of functions, technical effects, advantages and embodiments of the multi-stage transmission according to the first aspect of the invention also apply analogously to the drive device according to the second aspect of the invention and to the motor vehicle, and vice versa.
[0050] The invention will now be described in more detail with reference to the attached figures, in which:
[0051] Figure 1 shows a motor vehicle with a drive system according to the invention;
[0052] Figure 2 shows a highly schematic representation of a multi-stage transmission according to the invention for the drive unit of the motor vehicle according to Figure 1 in a first embodiment;
[0053] Figure 3 shows a highly schematic representation of the multi-stage transmission according to the invention as shown in Figure 2 after the filling of two clutches to realize a gear stage;
[0054] Figure 4 is a highly schematic representation of the multi-stage transmission according to the invention as shown in Figures 2 and 3 during the filling of several clutches to realize a gear stage; ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0055] Figure 5 shows a highly schematic representation of the multi-stage transmission according to the invention as shown in Figures 2 to 4 after the clutches have been filled;
[0056] Figure 6 shows a highly schematic representation of the multi-stage transmission according to the invention as shown in Figures 2 to 5 before or during a gear change;
[0057] Figure 7 shows a highly schematic representation of the multi-stage transmission according to the invention as shown in Figure 6 during gear changes;
[0058] Figure 8 shows a highly schematic representation of the multi-stage transmission according to a second embodiment;
[0059] Figure 9 shows a highly schematic representation of the multi-stage transmission according to the invention in a third embodiment;
[0060] represents, where identical or similar components are provided with the same reference numeral.
[0061] Figure 1 shows a drive unit 100 according to the invention in a motor vehicle 105. The drive unit 100 is configured to drive a drive wheel 110 of the motor vehicle 105. For this purpose, an electric machine 115 can be provided as a drive unit, which can be operated from an electrical energy storage device 125 by means of a power converter 120. While the power converter 120 can be included in the drive unit 100, the energy storage device 125 is usually part of the motor vehicle 105. A multi-stage transmission 130 is also provided to convert mechanical energy to the drive wheel 110. Optionally, the multi-stage transmission 130 is configured to be driven by a further drive machine 135 (not shown), for example, a reciprocating engine. Furthermore, a differential (not shown here) can be provided to transmit the drive power to both drive wheels 110 of the axle.The multi-stage transmission 130 has several gear stages, at least one of which comprises a planetary gear transmission 140.
[0062] Figure 2 shows a circuit topology of the multi-stage transmission 130 according to a first embodiment. Multi-stage transmission 130, ZF Friedrichshafen AG, File 305338, Friedrichshafen, 2025-02-06
[0063] The device features two parallel-controllable, pilot-operated pressure valve arrangements 200, 203, each comprising a coupling valve 206, 209 and an electromagnetic pilot stage 212, 215 upstream of the respective coupling valve 206, 209. The electromagnetic pilot stage 212, 215 controls a small pilot pressure via an electrical signal, which opens or closes the main pressure valve, i.e., the associated coupling valve 206, 209. In other words, the pressure level of the respective coupling valve 206, 209 is regulated via the associated electromagnetic pilot stages 212, 215.
[0064] The pressure valve assemblies 200 and 203 each allow two of the six clutches 221, 222, 223, 224, 225, and 226 shown here to be controlled simultaneously but separately for the control of power flow through the multi-stage transmission 130, i.e., opened or closed. In principle, the pressure valve assemblies 200 and 203 can also be designed as directly controlled valves. Alternatively, one pilot-operated and one direct-operated pressure valve can be used. From any number of clutches, exactly two can always be controlled via the two pressure valve assemblies 200 and 203. The first and second pressure valve assemblies 200 and 203 can be controlled separately by a control unit (not shown here) and can be pressurized with a system pressure pHD.
[0065] At least one of the clutches 221-226 is configured to engage or disengage one of the gear stages from the power flow through the multi-stage transmission 130. With respect to the planetary gear set 140, the clutches 221-226 are configured to introduce torque into the planetary gear set 140, to disengage torque from the planetary gear set 140, or to lock an element of the planetary gear set 140 relative to a housing (not shown here).
[0066] Each coupling 221-226 is assigned a holding valve 231, 232, 233, 234, 235, 236, which can each be actuated by an associated, separately controllable locking mechanism 241, 242, 243, 244, 245, 246. The locking mechanisms 241-246 are also controlled by the control unit (not shown here). ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0067] Each holding valve 231-236 can be selectively switched, depending on the control pressure provided or applied via the first and / or second pressure valve arrangement 200, 203, into a filling position, in which a fluidic connection between the first pressure valve arrangement 200 and the associated coupling 221-226 is enabled, or a draining position, in which a fluidic connection between the associated coupling 221-226 and the second pressure valve arrangement 203 is enabled. The locking mechanisms 241-246 can lock the associated holding valve 231-236 in its selected position.
[0068] The locking mechanism 241-246 comprises a locking magnet 248, which can be brought into positive engagement with an actuating element 250 of the associated holding valve 231-236 to lock the associated holding valve 231-236. When the locking mechanism 241-246 is actuated, the respective locking magnet 248 is disengaged from the positive engagement to unlock the associated holding valve 231-236, thus enabling actuation of the holding valve 231-236 between the filling and emptying positions, and vice versa. Once the desired position of the respective holding valve 231-236 is reached, actuation of the associated locking mechanism 241-246 or the corresponding locking magnet 248 can be terminated, allowing a new positive engagement to be established.Alternatively, the locking magnet 248 can be actuated again to be returned to the position for realizing the positive locking.
[0069] When the locking magnet 248 is actuated, for example by energizing it, a magnetic field is generated which causes the locking magnet 248 to move from a first position, in which the locking magnet 248 is positively engaged with the actuating element 250, to a second position in which there is no positive engagement between the actuating element 250 and the locking magnet 248, so that movement of the associated holding valve 231-236 between the filling position and the emptying position, or vice versa, is permitted. When the actuation of the locking magnet 248 is terminated, for example when the energizing process is stopped, the locking magnet 248, in particular ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0070] by means of a spring preload or the like, back to the first position, in order to create a positive locking connection again in the respective set position of the holding valve. Alternatively, the actuation of the locking magnet 248 can be actively modified such that the locking magnet 248 moves from the second position to the first position.
[0071] All holding valves 231-236 are coupled in parallel to both the first and second pressure valve arrangements 200, 203, whereby in the emptying position of the respective holding valve 231-236 no filling or pressurization of the respective coupling 221-226 is possible. Conversely, in the filling position of the respective holding valve 231-236 no emptying of the respective coupling 221-226 is possible.
[0072] However, the holding valves can be acted upon by both the first and the second pressure valve arrangement 200, 203 with a predetermined control pressure in order to perform a change of position of the respective holding valve 231 - 236 when the associated locking mechanism 241 - 246 has released the holding valve 231 - 236.
[0073] Each holding valve 231-236, when actuated by the associated locking mechanism 241-246, can be switched from the emptying position to the filling position by means of the control pressure of the first pressure valve assembly 200. The first pressure valve assembly 200 is configured to fill the respective fluidically connected coupling 221-226 with fluid in a controlled manner, provided that the associated holding valve 231-236 has previously been moved into the filling position. Only an increasing pressure gradient for filling and pressurizing the couplings 221-226 is implemented via the first pressure valve assembly 200.
[0074] Conversely, each holding valve 231-236, when actuation of this holding valve 231-236 is enabled by the associated locking mechanism 241-246, can be switched from the filling position to the emptying position by means of the control pressure of the second pressure valve arrangement 203. The second pressure valve arrangement 203 is configured to control the respective fluidically connected coupling 221-226. (ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06)
[0075] to drain, i.e. to let a fluid drain out, provided that the associated holding valve 231 - 236 has previously been put into the drain position.
[0076] In this case, a pressure sensor 252 is arranged on the output side of the first pressure valve assembly 200, i.e., between the first pressure valve assembly 200 and the parallel-connected holding valves 231-236. The pressure sensor 252 can be used to measure the set fluid pressure at the first coupling valve 206. It is also conceivable that a further or alternative pressure sensor 252 is arranged between the second pressure valve assembly 203 and the parallel-connected holding valves 231-236.The pressure sensor 252 between the first pressure valve arrangement 200 and the parallel-connected holding valves 231 - 236 is arranged in a filling path 254 of the respective holding valve 231 - 236, whereas the alternative or supplementary pressure sensor 252 between the second pressure valve arrangement 203 and the parallel-connected holding valves 231 - 236 is arranged in a draining path 256, in particular a control line 260 of the respective holding valve 231 - 236 connected to the draining path 256.
[0077] The second pressure valve arrangement 203 has a drain valve 258 designed as a pre-filling valve on the second coupling valve 209. This drain valve serves to release any oil flow that occurs when the respective holding valve 231-236 is switched to the drain position, thereby draining the coupling 221-226. Alternatively or additionally, such a venting option can also be integrated directly in or on the respective holding valve 231-236.
[0078] An input signal fed into the system via the first pressure valve arrangement 200 is provided to all holding valves 231-236 via the filling path 254. If the respective locking mechanism 241-246 has previously released the corresponding holding valve 231-236, this signal causes the holding valve 231-236 to be actuated from its initial position (i.e., the emptying position) to the filling position, thus initiating or completing the filling of the respective coupling 221-226 with the pressure medium, in this case, for example, hydraulic oil. ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0079] An input signal introduced into the system via the second pressure valve arrangement 203 is provided via a control line that is directly connected to the drain path 256 of the respective holding valve 231-236, and causes, if the respective locking mechanism 241-246 has previously released the associated holding valve 231-236, this holding valve 231-236 to be actuated from the filling position back to the initial position, i.e. the drain position, so that a draining of the respective coupling 221-226 begins or takes place, whereby the pressure medium can drain via the drain valve 258 on the second coupling valve 209 into a sump 262.
[0080] To drive the drive wheels 110 of the motor vehicle 105, or to drive the motor vehicle 105 in a gear, three of the six clutches 221-226 must be engaged simultaneously. To change gear, one of the three load-bearing clutches 221-226 must be opened and another clutch 221-226, or a different clutch 221-226, must be engaged. Therefore, only two clutches need to be actuated for a gear change: one opened and one closed, while the two other load-bearing clutches remain at their system pressure level and the non-load-bearing clutches remain open.
[0081] The pressure level at the first pressure valve assembly 200 serves exclusively for filling the couplings 221-226. A filling valve 264 located in the filling path 254 of the respective holding valve 231-236, with an orifice 266 positioned upstream, ensures that only an increasing pressure gradient is possible for filling the respective coupling 221-226 via the first pressure valve assembly 200. The second pressure valve assembly 203 serves for emptying the respective coupling 221-226. An emptying valve 268 located in the emptying path 256 of the respective holding valve 231-236 ensures that only a decreasing pressure gradient is possible for emptying the respective coupling 221-226 via the second pressure valve assembly 203.The term “falling pressure gradient” refers here to the emptying of the couplings 221 - 226, and not to the property of the second pressure valve arrangement 203, which holds the holding valves 231 - 236 with a ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06.
[0082] to be able to apply control pressure in order to switch it from the filling position to the emptying position.
[0083] The filling path 254, the emptying path 256, the control line 260, the filling valve 264, the orifice 266, and the emptying valve 268 are only shown here with reference symbols in the area of the first holding valve 231 as examples. For the sake of clarity, reference symbols are omitted for the other holding valves 232–236.
[0084] In this context, a gear is considered engaged when three of the six clutches 221-226 are filled and pressurized. In this case, clutches 221-226 are each considered "closed." A first gear, which can be used, for example, for starting off, is achieved, for instance, by a closed second, fourth, and fifth clutch 222, 224, 225. Initially, for example, the second and fifth clutches 222, 225 are filled simultaneously, as shown in Figure 3. Since there is no torque transmission or power flow from one drive side of the multi-stage transmission 130 to one output side of the multi-stage transmission 130 when only two clutches are closed, the filling of the second and fifth clutches 222, 225 can occur in parallel, and no torque transfer, i.e., no overlap of two pressure curves, needs to be considered during the filling process.Although only the first pressure valve arrangement 200 is used to fill the couplings, in special cases more than one coupling can be filled simultaneously.
[0085] To fill the respective clutches 222, 225, the respective locking magnet 248 is first actuated so that it is no longer positively engaged with the associated actuating element 250. Subsequently, the first pressure valve assembly 200 is brought to a predetermined pressure level, which merely corresponds to the system pressure level as an example, in order to push the second and fifth holding valves 232, 235 from the emptying position, here the left end stop, to the filling position, here the right end stop. In principle, the circuit topology according to this embodiment also allows for preconditioning of the multi-stage transmission 130 during the last shutdown process, for example by switching off the hydraulic system. (ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06)
[0086] Hydraulic supply only occurs when the locking magnets 248 of the second and fifth holding valves 232, 235 are engaged in the position shown in Figure 3. During a subsequent engine start, these two holding valves 232, 235 would then not need to be moved to the new (right) end position, i.e., the filling position. Instead, the parallel filling of the second and fifth clutches 222, 225 could occur immediately during the engine start, as soon as the first pressure valve arrangement 200 has reached a target pressure value for the pressure level in the two clutches 222, 225. Preconditioning for a subsequent start phase, particularly for initial starts of the drive unit 100, is easily implemented with such a circuit topology and the strategy described herein. This can represent an improvement in the dynamics of the vehicle 105's starting process.
[0087] Figure 3 shows the situation after switching of the second holding valve 232 and the fifth holding valve 235, with the holding magnets of these two holding valves 232, 235 being in the filling position of the respective holding valve 232, 235. The other holding valves 231, 233, 234 and 236 are each in the emptying position.
[0088] Subsequently, the second and fifth couplings 222, 225 can be filled with the pressure medium via throttle valves 270 and via the first pressure valve arrangement 200, which simultaneously provides a volume flow via the orifices 266 belonging to the second and fifth holding valves 233, 235, and thus brought to a defined pressure level as hydraulic capacities.
[0089] Subsequently, the locking magnets 248 of the second and fifth holding valves 233 and 235 are re-engaged, so that the holding valves 233 and 235 remain in the filling position. They continue to be supplied with the system pressure pHD via the associated throttle valves 270. The throttle valves 270 are able to compensate for any leaks in the lines between the holding valves 232 and 235, for example, due to leaking seals. The other holding valves 231, 233, 234, 236 also receive a force on their control surface from the pressure setting of the first pressure valve arrangement 200, which is intended to adjust the holding valves 231, 233, 234, 236 into the filling position, however, ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0090] The locking magnets 248 of these holding valves 231, 233, 234, 236 cause a corresponding change in position, whereby their pressure level – see dashed lines of the drain path 256 and the control line 260 – is determined by the second pressure valve arrangement 203. When the second pressure valve arrangement 203 is deactivated, the pressure level at the non-load-bearing couplings is determined by the drain valve 258. The drain valve 258 prevents the couplings 221–226 from running freely when the motor vehicle 105 is stationary.
[0091] To establish a power flow through the planetary gear set 140 and to start moving in first gear, the fourth clutch 224, which here functions as the starting clutch, must also be filled after the second and fifth clutches 222 and 225 have been filled and engaged. Due to the commencement of torque transmission from one drive side to one output side of the planetary gear set 140, a predefined filling sequence, i.e., a pressure specification for the fourth clutch 224, must be followed. For this purpose, the associated locking magnet 248 is actuated, so that it is released from the positive engagement with the corresponding actuating element 250 of the associated holding valve 234. Using the control pressure of the first pressure valve assembly 200, the associated holding valve 234 is then pressed to the right end stop, i.e., from the emptying position to the filling position.Figure 4 shows in this context the time of pressurization of the fourth holding valve 234, before movement of the holding valve 234 was released by the associated locking mechanism 244.
[0092] The second and fifth couplings 222, 225 are pressurized to system pressure via their associated throttle valves 270, with the associated check valves or filling valves 264 remaining closed and thus not consuming any flow from the first pressure valve assembly 200. The fourth coupling 224 is supplied with a flow rate dependent on the system pressure. This flow rate is very low via the associated throttle valve 270, while the first pressure valve assembly 200 simultaneously provides the crucial and controllable flow rate for filling and pressure level adjustment. This pressure level can optionally be measured via the associated pressure sensor 252. ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0093] Once a slip phase of the fourth clutch 224 is completed, the fourth clutch 224 has reached the system pressure level, so that the fourth holding valve 234 can be locked in the holding position or in the filling position at the right end stop by means of the associated locking magnet 248. Subsequently, the pressure at the first pressure valve assembly 200 can be released and starting can take place in first gear, see Figure 5. The system pressure level in the holding valves 232, 234 and 235 or the clutches 222, 224 and 225 is maintained by the associated throttle valves 270.
[0094] To shift from the first gear to a different gear, one of the supporting clutches 222, 224, or 225 must be opened and another clutch 221, 223, or 226 must be closed. In other words, during a gear change, a new clutch must generally be engaged, i.e., brought into the power flow, and one of the supporting clutches already engaged must be opened, i.e., removed from the power flow. For this embodiment, it is assumed that the fourth, fifth, and sixth clutches 224, 225, and 226 must be closed to implement a second gear. Therefore, the second clutch 222 must be opened and the sixth clutch 226 closed.
[0095] For this purpose, the pressure at the first pressure valve assembly 200 or the first coupling valve 206 is first increased, and the locking magnet 248 on the sixth holding valve 236 is actuated to release an actuating movement of the sixth holding valve 236, see Figure 6. The pressure of the first pressure valve assembly 200 actuates the sixth holding valve 236 from the emptying position to the filling position, whereby the sixth locking mechanism 246 then holds or locks the sixth holding valve 236 in the filling position. In the filling position of the sixth holding valve 236, the filling of the sixth coupling 226 begins. At the same time, the pressure at the second pressure valve assembly 203 is increased and set to a predetermined control pressure. Furthermore, the second locking mechanism 242 unlocks the second holding valve 232, so that the second holding valve 232 is actuated from the filling position to the emptying position.ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06.
[0096] The holding valves 231-236 are pre-tensioned in the discharge position and have a transmission ratio such that, when the respective coupling 221-226 is pressurized to maximum pressure via the first pressure valve arrangement 200, the holding valves 231-236 can be returned to their initial position or discharge position via the second pressure valve arrangement 203 when the respective coupling 223 is pressurized to maximum pressure. Therefore, even in the event of a fault, for example, if the first coupling valve 206 is stuck in the open position to provide control or system pressure and thus provides maximum pressure, it is still possible to discharge the couplings 221-226 via the second pressure valve arrangement 203.
[0097] Switching the second holding valve 232 from the filling position to the emptying position, with the associated emptying of the second coupling 222 via the second pressure valve arrangement 203, and the simultaneous filling of the sixth coupling 226 via the sixth holding valve 236 and the first pressure valve arrangement 200, results in opposing pressure profiles at the second and sixth couplings 222, 226 and at the second and sixth holding valves 232, 236, respectively, which can be understood as an overlap. The emptying valve 268 allows only decreasing pressure profiles at the second coupling 222 during emptying. Simultaneously, after filling the sixth coupling 226, pressure builds up at the sixth coupling 226, see Figure 7.
[0098] The process can be continued and carried out for the other gear stages as desired.
[0099] High dynamic performance can be achieved with a multi-stage transmission like the 130. The faster the shifting process, the lower the probability of a malfunction occurring during shifting. The driving software generally attempts to avoid shifting in such malfunction situations. However, this high dynamic performance requires precise system knowledge and consideration of all relevant boundary conditions. The 130 multi-stage transmission is particularly advantageous when three or more clutches are to be shifted. ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06
[0100] Figures 8 and 9 are intended to illustrate that the switching topology of the multi-stage gearbox 130 can be easily adapted, in particular modified or extended.
[0101] Figure 8 illustrates that further hydraulically actuated components that can be operated in parallel can be easily integrated into the circuit topology, such as, for example, an all-wheel drive clutch, which can generally be used independently and in parallel to the shift clutches, i.e., the pressure valve arrangements 200, 203. In this embodiment, the multi-stage transmission 130 includes a third pressure valve arrangement 800, connected in parallel to the first and second pressure valve arrangements 200, 203, for switching a further clutch 805, namely the all-wheel drive clutch. The third pressure valve arrangement 800 is designed here as a directly controlled pressure valve arrangement.
[0102] Figure 9 illustrates that the circuit can also be used to control other hydraulic components, such as a parking lock system. The first coupling 221 is configured here as an alternative to actuating a hydraulic parking lock system. The first holding valve 231 of the first coupling 221 is slightly modified. Specifically, this holding valve 231 is directly connected to a reservoir line 900 to allow direct drainage of the first coupling 221 into a sump 905 when the holding valve 231-236 is switched accordingly. The reservoir line 900 functions as the drain path 256 of the first coupling 221. The supply line of the first holding valve 231, which is fluidically connected to the second pressure valve arrangement 203, is therefore to be understood here merely as a control line 260, which is connected to the drain paths 256 of the other holding valves 232-236.The sequential connection of the pressure valve arrangements 200, 203 via the holding valves 231 - 236 also fulfills all requirements for single redundancy; the circuit is therefore, in principle, capable of remote start. ZF Friedrichshafen AG File 305338.
[0103] Friedrichshafen 2025-02-06
[0104] Reference mark
[0105] 100 drive unit
[0106] 105 motor vehicles
[0107] 110 drive wheel
[0108] 115 electric machine
[0109] 120 power converters
[0110] 125 energy storage units
[0111] 130 multi-stage gearbox
[0112] 135 Drive machine
[0113] 140 Um impeller gearbox
[0114] 200 First pressure valve arrangement
[0115] 203 Second pressure valve arrangement
[0116] 206 First clutch valve
[0117] 209 Second clutch valve
[0118] 212 First input control stage
[0119] 215 Second input stage
[0120] 221 First clutch
[0121] 222 Second clutch
[0122] 223 Third clutch
[0123] 224 Fourth clutch
[0124] 225 Fifth clutch
[0125] 226 Sixth clutch
[0126] 231 First holding valve
[0127] 232 Second holding valve
[0128] 233 Third holding valve
[0129] 234 Fourth holding valve
[0130] 235 Fifth holding valve
[0131] 236 Sixth holding valve
[0132] 241 First locking mechanism 242 Second locking mechanism 243 Third locking mechanism ZF Friedrichshafen AG File 305338
[0133] Friedrichshafen 2025-02-06
[0134] 244 Fourth locking mechanism 245 Fifth locking mechanism 246 Sixth locking mechanism 248 Locking magnet
[0135] 250 locking element
[0136] 252 Pressure sensor
[0137] 254 Filling path
[0138] 256 Drainage path
[0139] 258 Drain valve
[0140] 260 control line
[0141] 262 Swamp
[0142] 264 Filling valve
[0143] 266 aperture
[0144] 268 Drain valve
[0145] 270 Throttle valve
[0146] 800 Third pressure valve arrangement
[0147] 805 Clutch
[0148] 900 tank line
[0149] 905 Swamp
[0150] pHD system pressure
Claims
ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06 Patent claims 1. Multi-stage transmission (130) for a drive unit (100) of a motor vehicle (105), comprising - a first pressure valve arrangement (200) and a second pressure valve arrangement (203), which can be controlled separately and pressurized with a system pressure; and - at least two clutches (221 - 226) for controlling a power flow through the multi-stage transmission (130); wherein each coupling (221 - 226) is associated with a holding valve (231 - 236), which can be selectively locked by an associated, separately controllable locking mechanism (241 - 246) either in a filling position, in which a fluidic connection between the first pressure valve arrangement (200) and the associated coupling (221 - 226) is released, or in an emptying position, in which a fluidic connection between the associated coupling (221 - 226) and the second pressure valve arrangement (203) is released, and wherein each holding valve (231 - 236), when actuation of this holding valve (231 - 236) is released by the locking mechanism (241 - 246), can be switched from the emptying position to the filling position by means of control pressure of the first pressure valve arrangement (200).
2. Multi-stage transmission (130) according to claim 1, wherein each holding valve (231 - 236), when actuation of this holding valve (231 - 236) is released by the locking mechanism (241 - 246), can be switched from the filling position to the emptying position by means of control pressure of the second pressure valve arrangement (203).
3. Multi-stage transmission (130) according to claim 1, wherein each holding valve (231 - 236) is biased into the discharge position and has a transmission ratio such that, when actuation of this holding valve (231 - 236) is released by the locking mechanism (241 - 246) and a respective control pressure is applied both via the first pressure valve arrangement (200) and via the ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06 When the second pressure valve arrangement (203) is applied, this holding valve (231 - 236) is switched to the empty position.
4. Multi-stage transmission (130) according to one of the preceding claims, wherein the first pressure valve arrangement (200) is configured to fill the respective fluidically connected clutch (221 - 226) with fluid in a controlled manner, and wherein the second pressure valve arrangement (203) is configured to release fluid from a fluidically connected clutch (221 - 226) in a controlled manner.
5. Multi-stage transmission (130) according to one of the preceding claims, wherein several transmission stages are provided, and wherein one of the at least two clutches (221 - 226) is configured to switch one of the transmission stages into a power flow through the multi-stage transmission (130) or to exclude it from the power flow.
6. Multi-stage transmission (130) according to claim 5, wherein one of the several transmission stages comprises a planetary gear transmission (140), and wherein one of the at least two clutches (221 - 226) is configured to introduce torque into the planetary gear transmission (140), to expel torque from the planetary gear transmission (140) or to fix an element of the planetary gear transmission (140) relative to a housing.
7. Multi-stage transmission (130) according to one of the preceding claims, wherein the locking mechanism (241-246) comprises a locking magnet (248) which generates a positive locking with an actuating element (250) of the associated holding valve (231-236) to realize the locking.
8. Multi-stage transmission (130) according to one of the preceding claims, wherein a pressure sensor (236) is arranged on the output side of the first pressure valve arrangement (200) and / or on the output side of the second pressure valve arrangement (203). ZF Friedrichshafen AG File 305338 Friedrichshafen 2025-02-06 9. Multi-stage transmission (130) according to claim 8, wherein each holding valve (231 - 236) is further assigned a throttle valve (270).
10. Multi-stage transmission (130) according to one of the preceding claims, wherein a filling valve (264) and an orifice (266) arranged upstream of it are provided in a filling path (254) of the respective holding valve (231 - 236).
11. Multi-stage transmission (130) according to one of the preceding claims, wherein a drain valve (268) is provided in a drain path (256) of the respective holding valve (231 - 236).
12. Multi-stage transmission (130) according to one of the preceding claims, further comprising a third pressure valve arrangement (700) connected in parallel to the first and second pressure valve arrangements (200, 203) for switching a further clutch (705).
13. Multi-stage transmission (130) according to one of the preceding claims, wherein at least one of the pressure valve arrangements (200, 203, 700) is designed as a pilot-operated pressure valve arrangement, comprising a clutch valve (206, 209) and an electromagnetic pilot stage (212, 215) upstream of the clutch valve (206, 209).
14. Multi-stage transmission (130) according to one of the preceding claims, wherein at least one of the pressure valve arrangements (200, 203, 700) is designed as a directly controlled pressure valve.
15. Drive unit (100) for a motor vehicle (105), comprising a drive unit and a multi-stage transmission (130) according to one of the preceding claims.