Vehicle braking system with hydraulic reducer and disengagement clutch

Abstract

The present invention relates to a braking device for a vehicle having a hydraulic reducer (6) and a disengagement clutch (7) for coupling and disengaging the reducer (6) from the vehicle's powertrain (1, 2, 3) via force flow. A pump (9) is provided herein, which is designed to drain the working fluid of the reducer (6) from the working chamber of the reducer (6) when the disengagement clutch (7) is disengaged.

Description

Technical Field

[0001] This invention relates to a braking device for a vehicle, comprising a hydraulic reducer and a disengagement clutch for coupling and disconnecting the reducer from the vehicle's powertrain. The invention also relates to a method for operating such a braking device. A controller for such a braking device is also proposed. Background Technology

[0002] Vehicle braking systems with speed reducers are known and particularly common in heavy-duty vehicles. One advantage of speed reducers compared to conventional service brakes (such as disc brakes or drum brakes) is their virtually wear-free operation. Therefore, speed reducers are primarily used to alleviate the burden on easily worn service brakes during prolonged braking processes.

[0003] It is also known to design a reducer that can selectively couple and disconnect with the force flow of the vehicle's powertrain by means of a disengagement clutch. Publication SE 201050160 A1 is cited as an example only. Its advantage is that the operating losses of the powertrain are particularly small when the reducer is disconnected by means of the disengagement clutch. In this way, the drag loss of the reducer outside of its braking operation is minimized.

[0004] To switch this reducer to braking operation or prepare it for braking, the disengagement clutch must be engaged. The working fluid contained in the reducer's working chamber makes clutch engagement difficult. Even with the clutch sides of the clutch engaged when the disengagement clutch is closed, the residual amount of working fluid in the working chamber will produce a certain braking effect in the reducer. This necessitates an increased switching force to close the clutch. Consequently, even greater forces appear within the clutch, potentially damaging it. The clutch synchronizer, in particular, is susceptible to damage; for example, the synchronizer lining may burn out.

[0005] A method for controlling a hydraulic reducer in a motor vehicle that can be mechanically disengaged by a disengaging clutch is known from DE 10 2011 120 621 A1. The reducer has a rotor with blades mounted circumferentially and a stator with blades mounted thereon, or the reducer has a rotor with blades mounted circumferentially and a reverse rotor with blades mounted circumferentially in the opposite direction. They together form a working chamber, which is filled with a working medium during braking operation and emptied during non-braking operation. During braking operation, the rotor is driven by a power transmission system with the disengaging clutch engaged. During the transition from braking to non-braking operation, the working chamber is emptied and the disengaging clutch is disengaged. The transition from braking to non-braking operation is initiated by a reducer disengagement request from a driver assistance system or by an input device actuated by the vehicle driver. Here, after confirming the existence of a reducer disengagement request, the disengaging clutch is kept engaged for a predetermined time period. Here, the working medium in the reducer's working chamber is emptied by continuing to drive the rotor and by interrupting the supply of the working medium to the working chamber.

[0006] A drive unit having an engine, a transmission, and a hydraulic reducer is known from DE 102 42 736 A1. The reducer includes a rotor impeller and a stator impeller. The reducer is arranged in the vehicle's cooling circuit, and the working medium of the reducer is the vehicle's cooling medium. The reducer includes means for discharging residual liquid against external pressure established by the cooling system. These means are designed as cylinders connected to the cooling circuit and the reducer, and these cylinders draw residual liquid from the reducer. Summary of the Invention

[0007] The purpose of this invention is to improve upon existing technologies.

[0008] This objective is achieved by the measures given separately in the independent claims. Preferred embodiments can be derived from the dependent claims.

[0009] Therefore, a braking device for a vehicle is proposed, which includes a hydraulic reducer and a disengagement clutch. The disengagement clutch is used to couple and disconnect the force flow of the reducer from the vehicle's powertrain. A pump is used here, which is designed to extract the working fluid of the reducer from its working chamber even when the disengagement clutch is disengaged. In particular, the pump can operate independently of the switching state of the disengagement clutch, that is, it can operate both when the disengagement clutch is disengaged and when it is engaged.

[0010] In this way, even when the clutch is disengaged and the reducer is thus disconnected from the power flow in the vehicle's powertrain, the working chamber remains largely free of working fluid. Any residual working fluid can always be removed from the working chamber. In this disengaged state, the reducer is disconnected from the rest of the vehicle's powertrain. Therefore, braking is impossible. Dragging losses are minimized. In this state, any residual working fluid that may be present in the working chamber or any leakage of working fluid into the working chamber can be removed by means of a pump. The clutch can be actuated safely and simply. Clutch engagement is particularly simplified because the working chamber can be ensured to be emptied beforehand. The clutch actuator can be implemented more simply and easily. The clutch can also be implemented more simply because the switching force is smaller.

[0011] This invention is based on the understanding that commercially available hydraulic reducers have their own reducer pump for the working fluid, which is integrated into the reducer. If a disengagement clutch is provided in such a conventional reducer, the pump is located on the side of the reducer. When the clutch is disengaged, the reducer pump is therefore disconnected from the rest of the powertrain and cannot be driven. Consequently, the pump cannot remove any remaining or seeping working fluid from the working chamber. This working fluid issue is not a problem for reducers without a disengagement clutch, because here the reducer pump and reducer rotor are always driven and can deliver the working fluid out of the working chamber.

[0012] The solution proposed in DE 10 2011 120 621 A1 only ensures that the working chamber is emptied immediately after the clutch is disengaged. However, the working fluid that subsequently seeps into the working chamber due to leakage cannot be drained. This leakage is typically eliminated by additional seals in the reducer. With the proposed pump, the working chamber can now be kept free of working fluid whenever needed, regardless of the clutch disengagement status, eliminating the need for cumbersome seals in the reducer.

[0013] As explained at the beginning, a speed reducer is a braking device used to brake a vehicle that experiences almost no wear. Therefore, a speed reducer differs from a service brake, which operates due to friction between components and is therefore prone to wear. Service brakes are typically implemented as disc brakes or drum brakes.

[0014] The reducer is designed here as a hydraulic reducer. Therefore, the reducer, particularly in a manner known per se, has a bladed rotor and a stator or reverse rotor acting on the rotor. The rotor or reverse rotor also has blades. A working chamber of the reducer is formed between the rotor (on one hand) and the stator or reverse rotor (on the other hand). The working chamber is filled with working fluid, at least during braking operations of the reducer. During braking operations, the rotor moves relative to the stator or reverse rotor, thereby generating fluid flow in the working chamber. This flow of working fluid produces a braking effect on the rotor. The rotor can be coupled to the power transmission system via a disengagement clutch. Therefore, the reducer can produce a braking effect in the power transmission system when the clutch is engaged. This is not possible when the disengagement clutch is disengaged. Outside of braking operations, especially when the disengagement clutch is disengaged, the working fluid in the working chamber of the reducer is preferably emptied by a pump. After or during disengagement clutch engagement, the working chamber is at least partially filled with working fluid to prepare the reducer. Subsequently, the braking power of the reducer can be set, in particular, by setting the distance between the rotor and the stator (or between the rotor and the reverse rotor), and / or by setting the amount of working fluid in the working chamber.

[0015] The reducer particularly has at least one rotatably supported reducer shaft. The reducer rotor is preferably coupled to and can be driven by the reducer shaft. The reducer shaft can therefore also be referred to as the reducer rotor shaft, which has or carries the rotor. The reducer shaft can be selectively coupled and disconnected from the force flow of the vehicle's powertrain by means of a disengagement clutch.

[0016] The reducer can be arranged at any suitable location in the powertrain. It is particularly positioned on the input or output side of the transmission (especially a multi-speed transmission). However, the reducer can also be integrated into such a transmission, particularly by being located within its housing or housing portion (e.g., a housing cover). The mechanical branch from the powertrain to the reducer can be arranged at a suitable location in the powertrain. This branch is particularly formed by a spur gear transmission or a chain transmission, each specifically designed as a high-drive stage. A disengagement clutch can be arranged in the region of this branch or (functionally) between the branch and the reducer or the reducer's rotor. The disengagement clutch can also be arranged directly on the reducer's rotor, for example, on the reducer shaft.

[0017] The controller for the reducer can be independent of the transmission controller, or it can be integrated into the transmission controller. The controller can also be used to actuate and disengage the clutch. Therefore, the controller has the necessary means for this, such as input and output terminals, and a computing device, to implement the process. The controller for the reducer can be a component of the proposed braking device.

[0018] A disengaging clutch should be understood as a mechanical device by which the input and output ends of the device can be selectively mechanically coupled and disengaged. Here, in the coupled / closed state, force or torque transmission can be achieved between the input and output ends of the clutch, which is virtually impossible in the disengaged / disengaged state. The disengaging clutch is preferably implemented as a form-fit or friction-fit clutch, such as a claw clutch or a multi-plate clutch. The disengaging clutch is implemented such that it can selectively couple the reducer with the force flow of the powertrain (clutch engaged) and can disengage the reducer from the force flow of the powertrain (clutch disengaged). In this powertrain, the force flow is realized at least during the traction operation of the powertrain between the vehicle's drive motor for travel and the road surface. For this purpose, the drive motor drives the vehicle's drive wheels or tracks, which then drive-contact the road surface. By coupling the reducer to the force flow, the vehicle can therefore be braked by the reducer. By disengaging the reducer from the force flow, the vehicle can therefore not be braked by the reducer. The actuation of the disengaged clutch is particularly accomplished by means of its actuator. This actuator can be actuated by a controller.

[0019] The pump is preferably a rotary piston pump, such as, in particular, a rotary slide valve pump, a rotary piston pump, a swing slide valve pump, or a gear pump. Thus, the pump can be easily driven by a rotating shaft.

[0020] Besides the pump mentioned above, it is preferable not to install a separate reducer pump. Therefore, this pump is the only pump provided for filling and emptying the working chamber of the reducer with the working fluid. As a result, the reducer can have a simple construction.

[0021] The pump is preferably electrically driven. The pump therefore includes an electric motor that drives the pump and thus produces the pumping action. This eliminates the need for mechanical coupling between the pump and the power flow in the vehicle's powertrain. Therefore, the pump can be located in or at the gearbox, or at another suitable location on the vehicle. The pump can operate regardless of the clutch engagement / disengagement state. The electric motor is specifically designed to drive the pump. The pump and electric motor can thus form a pump-motor unit, which can be flexibly assembled, for example, into the gearbox housing or transmission housing.

[0022] Pumps can also be mechanically driven by the vehicle's powertrain. In this case, the pump is mechanically coupled to the force flow in the vehicle's powertrain, thereby driving the pump. Such pumps can be implemented very inexpensively.

[0023] The pump can be configured for (another) component of the powertrain. Thus, the pump is used not only to operate the reducer, especially to empty the working chamber when the clutch is disengaged, but also to operate the powertrain component. Therefore, the pump is particularly used to deliver working fluid to the powertrain component. Thus, the pump, which is necessary in the powertrain regardless, can also be used for the reducer. The working fluid is used specifically for both the reducer and the component. The powertrain component is, for example, the transmission or drive motor of a vehicle's powertrain. The connection between the pump and the component and the reducer can be made in such a way that the component or the reducer (or both simultaneously) can be selected as the pump's suction area by means of a switchable channel. The corresponding provisions can be applied to the pump's discharge area. Therefore, the working fluid can be flexibly used for the component and / or the reducer.

[0024] This component is, in particular, the transmission. This can be a multi-speed transmission. The transmission is designed to be arranged within the powertrain. Thus, in the completed state of the transmission installation, the flow of power in the powertrain is realized via the transmission. The transmission particularly has a lubricant circuit in which working fluid can be delivered by a pump as transmission lubricant. The working fluid of the reducer also serves as lubricant for the transmission. The pump can now be selectively or simultaneously used to deliver working fluid in both the transmission (especially in the lubricant circuit) and the reducer. Therefore, the pump can operate in a manner that delivers working fluid only in the transmission, and can also operate in a manner that delivers working fluid only in the reducer, for example, to remove working fluid from the working chamber. The pump can also preferably operate in such a manner that it delivers working fluid in both the transmission and the reducer simultaneously. Thus, when the clutch is disengaged, the transmission can be lubricated, and working fluid can be removed from the working chamber simultaneously. Here, the lubricant reservoir is particularly used as the pump's intake area for the transmission.

[0025] Specifically, one or more valves are provided to allow setting the pump's operation. Therefore, a first valve position can be provided in which the pump is connected to the transmission and accordingly delivers working fluid into the transmission (especially in the lubricant circuit), while the pump is separated from the working chamber of the reducer. A second valve position can also be provided in which the pump is connected to the reducer and thus accordingly delivers working fluid into the reducer, while the pump is separated from the transmission (especially from the lubricant circuit). A third valve position can also be provided in which the pump is simultaneously connected to both the reducer and the transmission, and in this third valve position, the pump delivers working fluid into both. Thus, the pump can be used in a very flexible manner.

[0026] The release clutch is preferably designed as a form-fit type. Force transmission in the closed state is then achieved through the form fit within the clutch, for example, via pawls or teeth. The release clutch preferably has a synchronizer. This synchronizer is used to synchronize the rotational speeds between the two separable clutch sides (i.e., the input and output ends of the aforementioned release clutch) before the clutch is finally engaged. In this way, the rotational speeds of these clutch sides are initially equal to each other. The synchronizer can be designed in a type of construction known per se, for example, as one or more synchronizer rings. The synchronizer is particularly designed as a pin-type synchronizer. The pin-type synchronizer prevents the final engagement of the release clutch before the rotational speeds on the clutch sides are sufficiently equal. The synchronizer simplifies the coupling of force flow between the reducer and the powertrain. As mentioned above, such a synchronizer is susceptible to the amount of residual or leaking working fluid in the working chamber. Therefore, the proposed measures can be used particularly advantageously here.

[0027] Preferably, a controller is provided. This controller can then be specifically designed to determine an unacceptably high working fluid level in the working chamber when the disengagement clutch is disengaged. Therefore, the controller identifies when there is excessive working fluid in the working chamber when the disengagement clutch is disengaged. Here, "excessive" working fluid may mean that the working chamber contains or exceeds a certain amount of residual or leaked working fluid. Furthermore, the controller can then be specifically designed to actuate a pump such that if the determining device determines an unacceptably high working fluid level in the working chamber when the disengagement clutch is disengaged, the pump removes working fluid from the working chamber. This ensures that the working chamber is always emptied sufficiently to allow the disengagement clutch to close at any time. When using one or more of the aforementioned valves, the controller is preferably also designed to influence the desired valve position.

[0028] A level sensor can be installed in the working chamber to determine the unacceptably high working fluid level within the chamber. The controller can then have a switch for turning the pump on and off. Subsequently, whenever the level sensor confirms an unacceptably high working fluid level in the working chamber when the clutch is disengaged, the pump is turned on by actuating the switch. Here, the pump draws working fluid from the working chamber.

[0029] When using an electrically driven pump, the controller can be designed to actuate the pump to determine an unacceptably high working fluid level in the working chamber. Thus, for example, the pump is additionally activated when the clutch is disengaged to determine the filling level in the working chamber. The controller is then also designed to determine the unacceptably high working fluid level in the working chamber based on the current consumption of the pump during this actuation. In other words, the electric pump is operated selectively, its current consumption is determined, and the unacceptably high working fluid level is inferred from the current consumption. This eliminates the need for an additional level sensor.

[0030] This process is based on the principle that the power consumption of an electric pump depends on the filling level of the working chamber. Therefore, power consumption is minimal when the working chamber is emptied, as the pump runs dry; and it reaches its maximum when the working chamber is fully filled, as the pressure rises sharply. Because the voltage by which the pump operates (especially the vehicle's on-board voltage) is relatively constant in most cases, power consumption depends primarily on current consumption. Therefore, the filling level can be deduced simply and accurately based on the current consumption. Depending on the type of construction of the electric motor used to drive the pump, the current consumption can be determined, for example, in the form of the phase current or excitation current. The determination of current consumption in electric motors is known in itself and therefore requires no further interpretation. The relationship between the current filling level and the determined current consumption can be stored in the controller as a characteristic curve, formula, table, or graph. An unacceptably high working fluid level can exist when the working chamber is not emptied and therefore the pump's current consumption increases compared to the emptied state.

[0031] To determine whether an unacceptably high working fluid level exists in the working chamber, the braking device (especially the aforementioned controller) is preferably designed to temporarily operate the pump when the clutch is disengaged. This operation can be performed at regular or random time intervals. If an increase in current consumption is confirmed at this point, it is clear that working fluid has leaked into the working chamber or that the working chamber was not adequately emptied beforehand. The pump then (continues) to operate until an unacceptably high level no longer exists. In particular, the pump continues to operate until the pump's current consumption reaches the level of an empty working chamber. In this case, a turn-on current can be provided to initiate pump operation. This also allows working fluid to be drained from the working chamber. A (lower) turn-off current can be provided to shut down the pump. Alternatively or additionally, the pump can operate for a pre-set maximum time period. Thus, if the reducer has an unacceptably large leakage due to a malfunction, undesirable continuous operation of the pump can be prevented.

[0032] In particular, after the disengagement clutch is disengaged, the pump operates in such a way that it draws working fluid from the working chamber, preferably down to a level below the permissible high level of working fluid in the working chamber. Compared to the prior art described above, the disengagement clutch therefore does not need to be held for a longer period than required for the braking operation of the reducer. Therefore, the disengagement clutch can be disengaged immediately after the braking request of the reducer ends. The remaining amount of working fluid in the working chamber of the reducer can then be drawn out by means of the pump. This process (disengagement clutch disengagement, and then drawing working fluid from the working chamber by means of the pump) is implemented, in particular, by a controller, and the controller is designed accordingly.

[0033] In some cases, the pump may fail to expel working fluid from the working chamber when the disengagement clutch is disengaged. This is especially likely if the pump and / or its associated control mechanism and / or associated electrical contact mechanism malfunctions. This results in the gearbox's working chamber not being completely emptied, or working fluid leaking into and remaining there. As explained at the outset, engaging the disengagement clutch then becomes difficult and / or there is a risk of damage to the disengagement clutch.

[0034] For situations where the working fluid cannot be extracted from the working chamber using a pump, a method utilizing a braking device is proposed, by which the disengagement clutch can be safely closed. A shaft on the power transmission side of the reducer is provided. This shaft is therefore coupled with the force flow of the power transmission. A disengagement clutch is provided between the reducer and this shaft. Therefore, the reducer can be disconnected from the shaft by disengaging the disengagement clutch. When the disengagement clutch is closed, the force flow between the reducer and the power transmission is realized through this shaft. Within the scope of this method:

[0035] Step (A): The shaft on the powertrain side comes to a standstill when the clutch is disengaged. Here, at least a residual amount of working fluid remains in the working chamber. The reducer rotor also stands still in this state because the clutch is disengaged and therefore the rotor is disconnected from the powertrain. This stopping of the shaft on the powertrain side occurs particularly when the vehicle is stopped. Alternatively, it can be proposed that step (A) be performed when the vehicle stops for other reasons, such as traffic conditions. For this purpose, the vehicle speed is monitored, and step (A) is triggered when the vehicle is stationary.

[0036] Step (B): Then, engage the disengage clutch, i.e., engage the disengage clutch while the shaft on the powertrain side is stationary. Therefore, the reducer rotor is rotatably coupled to the vehicle's powertrain via the disengage clutch and the shaft on the powertrain side. Since both clutch sides (input and output) of this disengage clutch are stationary, this can be done safely and without increasing the switching force.

[0037] Step (C): Subsequently, when the disengaged clutch is engaged, the powertrain drives the shaft on the powertrain side to rotate, and thereby also drives the rotor of the reducer to rotate. Here, the rotor transports the working fluid located in the working chamber out of the working chamber. This is especially useful for starting the vehicle and / or continuing to move forward. Preferably, the vehicle's drive motor, for example, by the controller for the reducer, additionally requests the driving force required to discharge the working fluid from the working chamber. This prevents the drive motor from stopping. In this way, the working fluid in the working chamber is emptied by the transport effect of the rotor driven by the powertrain.

[0038] The procedure is requested to be executed, especially when an unacceptably high working fluid level is detected in the working chamber and the pump is found to be inoperable (e.g., due to pump malfunction).

[0039] This process is preferably executed automatically by the reducer's controller. Accordingly, a controller for an actuating braking device is also proposed, wherein the controller is specifically designed to execute the proposed method. Therefore, the controller particularly has a data memory and corresponding devices, such as input and output terminals, as well as a computing device.

[0040] Optionally, a computer program product is proposed. This computer program product has instructions that, when executed by a computing unit, cause the computing unit to perform the proposed method. Therefore, the computing unit controls or regulates the operation of the braking system according to the proposed method. The computing unit may be, for example, a computer or a microcontroller, or may include such a computer or microcontroller. The computing unit may, for example, be part of the proposed controller. The computer program product may, for example, be an electronic data storage device on which the instructions are stored electronically. The computer program product is particularly implemented for use specifically in the mentioned controller. Attached Figure Description

[0041] The following is illustrated with reference to the attached diagram. Figure 1 The present invention is described in detail below, and other preferred embodiments of the invention can be derived from the accompanying drawings. Figure 1 The powertrain of a vehicle (especially a motor vehicle, especially a truck or bus) is shown schematically and from a top view. Detailed Implementation

[0042] The powertrain includes a drive motor 1 for propelling the vehicle, and a transmission 2 for converting the torque of the drive motor 1. Here, the transmission is particularly a multi-stage transmission. The transmission can be, for example, an automated shift transmission or a torque converter automatic transmission. A drive axle 3 of the powertrain is located on the driven side of the transmission 2. This drive axle is coupled to drive wheels 4. Therefore, driving force (and thus the corresponding driving torque and corresponding driving power) can be mechanically transmitted from the drive motor 1 to the drive wheels 4 by means of the powertrain. The drive wheels 4 are supported on the road surface. Therefore, during vehicle traction, the vehicle can be driven by the drive motor 1.

[0043] The vehicle's service brake, in the form of a disc brake or drum brake, is arranged in the area of ​​the drive wheel 4. The service brake 5 is specifically used for short-term braking. The service brake 5 is subject to friction due to its structural design.

[0044] A hydraulic reducer 6 is also provided in the vehicle as a continuous brake. The reducer 6 and the service brake 5 can each be part of a common braking device. However, the reducer 6 can also be implemented as a separate braking device. The reducer 6 as a braking device can also be a component of the transmission 2.

[0045] The reducer 6 includes: a rotor 6A with blades arranged on it; and a stator 6B fixed to the housing, also with blades arranged on it. Instead of the stator 6B fixed to the housing, a reverse rotor may be provided, which always rotates in the opposite direction to the rotor 6A when the rotor 6A rotates. However, this does not change the operation of the reducer 6 as described below.

[0046] A working chamber for the reducer 6 is created between the rotor 6A and the stator 6B. This working chamber can be filled with a working fluid. When the working chamber is fully filled with the working fluid and relative rotation occurs between the rotor 6A and the stator 6B, the reducer 6 generates a braking torque on its reducer shaft 6C, which is coupled to the rotor 6A. This braking torque can depend on the degree of filling of the working chamber with the working fluid, and it can also depend on the distance between the rotor 6A and the stator 6B. In the reducer 6, either or both of these factors can be designed to be settable.

[0047] The reducer 6 is, for example, located in the output end region of the transmission 2 and can be coupled to the powertrain there. Alternatively, the reducer can be coupled to the powertrain at other suitable locations. A disengagement clutch 7 is provided between the powertrain and the reducer 6. The clutch 7 can be selectively disengaged and engaged. According to an embodiment of the clutch 7, the clutch can also be set to an intermediate state, allowing only partial disengagement and engagement. Therefore, the reducer 6 can selectively mechanically couple and disengage with the force flow of the powertrain via the clutch 7. When the reducer 6 is coupled (clutch 7 is engaged), the reducer 6 can apply braking force to the vehicle. When the reducer 6 is disengaged (clutch 7 is disengaged), the reducer 6 is mechanically separated from the force flow of the powertrain. Thus, the reducer cannot apply braking force to the vehicle.

[0048] The clutch 7 preferably operates in a form-fit manner. The clutch 7 preferably has a mechanical synchronizer, such as one or more synchronizer rings.

[0049] The reducer 6 does not achieve any significant braking effect in the coupled state. This is only the case when the fill level of the reducer 6 is set additionally for braking operations and / or when the distance between the rotor 6A and the stator 6B is set for braking operations. However, the reducer 6 always produces a certain drag loss in the coupled state. This drag loss can be minimized to a large extent by disengaging the release clutch 7.

[0050] A controller 8 is provided for actuating the clutch 7 and the reducer 6. The controller 8 is also used to set the braking action of the reducer 6, particularly by setting the fill level of the reducer 6 and / or the distance between the rotor 6A and the stator 6B. Information and commands can be transmitted to the controller 8. The controller 8 processes the received information and commands by means of logic circuitry and outputs the corresponding commands to the clutch 7 and / or the reducer 6.

[0051] A pump 9 is provided for supplying the working fluid to the reducer 6. With the aid of the pump 9, the working fluid can be not only removed from the working chamber but also supplied to it. Therefore, the pump 9 can be used to empty the working fluid from the working chamber when the reducer 6 is not needed, and can also be used to fill the working chamber with working fluid for operation of the reducer 6 during braking. The braking action of the reducer 6 can then be set by changing the filling degree, i.e., changing the amount of working fluid present in the working chamber, with the aid of the pump 9. The pump 9 is preferably also used to transport the working fluid through a heat exchanger. In this way, the heat generated and absorbed by the working fluid during the operation of the reducer 6 and / or the transmission 2 can be dissipated.

[0052] The working fluid in the working chamber makes it difficult or even prevents the clutch 7 from closing. Especially when a synchronizer is used in the clutch 7, there is a risk of synchronizer overload if there is still residual fluid in the working chamber when the clutch 7 is closed. Therefore, the pump 9 is designed to remove working fluid from the working chamber even when the clutch 7 is disengaged. In particular, the pump 9 can operate independently of the switching state of the clutch 7.

[0053] Therefore, pump 9 can be an electric pump. Thus, the pump is driven by an electric motor specifically designed for pump 9. Pump 9 can also be mechanically driven. In this case, pump 9 is integrated into the power transmission system in such a way that the pump can be driven by the power transmission system even when clutch 7 is disengaged.

[0054] exist Figure 1 In this configuration, pump 9 is also used in transmission 2. Transmission 2 has a lubricant circuit with a lubricant reservoir. This lubricates the structural components of transmission 2 (e.g., bearings, gears, and / or shifting elements). The working fluid of reduction gear 6 serves as the lubricant. Pump 9 can be integrated into transmission 2. Therefore, this pump can be a transmission lubricant pump. In particular, no separate pump is provided for transmission 2 and reduction gear 6. Figure 1 In the diagram, the flow direction of the working fluid in the channels of the transmission 2 and the reducer 6 is indicated by arrows.

[0055] A first valve 10 is provided. Therefore, it is possible to select whether pump 9 draws working fluid from the working chamber of reducer 6, from the lubricant reservoir of transmission 2, or from both. The lubricant reservoir of transmission 2 and / or the working chamber of reducer 6 can thus be selected as the suction area of ​​pump 9 via valve 10.

[0056] A second valve 11 is also provided. Therefore, it is possible to select whether pump 9 delivers working fluid to the lubricant circuit of transmission 2, to the working chamber of reduction gear 6, or both. The lubricant circuit of transmission 2 and / or the working chamber of reduction gear 6 can thus be selected as the discharge area of ​​pump 9 via valve 11.

[0057] Valves 10 and 11 are actuated by controller 8. The corresponding valve positions can thus be set by controller 8, and pump 9 can be operated accordingly. In this way, controller 8 can empty the working chamber of reducer 6 even when clutch 7 is disengaged. Therefore, it can be proposed that when there is a request to engage clutch 7, controller 8 first empties the working chamber by operating pump 9 and / or valves 10 and 11. However, this takes a certain amount of time, during which clutch 7 cannot be engaged. Therefore, alternatively or additionally, it can be proposed that controller 8 empties the working chamber by operating pump 9 and / or valves 10 and 11 when clutch 7 is disengaged and independently of the request to engage clutch 7. For this purpose, pump 9 and / or valves 10 and 11 are temporarily operated, especially when clutch 7 is disengaged, so that the working chamber of reducer 6 is emptied. This can be done periodically or irregularly. Even when clutch 7 is disengaged, it can be determined whether there is an unacceptably high working fluid level in the working chamber. If so, pump 9 and / or valves 10 and 11 are operated to empty the working chamber of reducer 6.

[0058] It can be proposed that the controller 8 identifies an unacceptably high working fluid level in the working chamber based on the current consumption of the electrically driven pump 9. Here, the pump 9 operates temporarily when the clutch 7 is disengaged to deliver the working fluid out of the working chamber. This can be done periodically or irregularly. Here, the current consumption of the pump 9 is determined. If the current consumption increases unacceptably compared to the current consumption when the working chamber is emptied, an unacceptably high working fluid level is considered to exist. The pump 9 and / or valves 10, 11 are then (further) operated to guide the working fluid out of the working chamber. When the current consumption reaches an acceptable level and / or when a preset time period has elapsed, the pump 9 can be stopped and / or valves 10, 11 can be switched. The working chamber is then considered to have been sufficiently emptied. In this way, an additional level sensor for the working chamber can be eliminated.

[0059] Alternatively, a level sensor can be present to determine the working fluid level in the working chamber at an unacceptably high level. The controller 8 can then use the level sensor to identify whether an unacceptably high level exists. If so, the pump 9 and / or valves 10, 11 operate as explained above, causing the working fluid to be directed out of the working chamber.

[0060] List of reference numerals

[0061] 1. Drive motor

[0062] 2. Transmission

[0063] 3 drive axles

[0064] 4 drive wheels

[0065] 5. Service brakes

[0066] 6. Hydraulic reducer

[0067] 6A Rotor

[0068] 6B stator

[0069] 6C reducer shaft

[0070] 7. Disengage the clutch

[0071] 8 controllers

[0072] 9. Pumps, reducer pumps, transmission pumps

[0073] 10 valves

[0074] 11 valves

Claims

1. A braking device for a vehicle, the braking device having a hydraulic reducer (6) and a disengagement clutch (7), the disengagement clutch being used to couple and disconnect the reducer (6) from the powertrain of the vehicle. characterized in that A pump (9) is designed to draw working fluid from the working chamber of the reducer (6) when the disengagement clutch (7) is disengaged, wherein the pump (9) is operable independently of the switching state of the disengagement clutch, both when the disengagement clutch is disengaged and when the disengagement clutch is engaged, wherein the braking device has a transmission (2), wherein the pump (9) is selectively or simultaneously used to deliver working fluid in the transmission (2) and in the reducer (6), wherein the transmission has a lubricant circuit in which the working fluid can be delivered by the pump as a transmission lubricant.

2. The braking device according to claim 1, wherein the pump (9) is an electrically driven pump (9).

3. The braking device according to claim 1, wherein the pump (9) is a mechanically driven pump (9) configured to be driven by the force flow of the power transmission system.

4. The braking device according to any one of claims 1 to 3, wherein the release clutch (7) has a synchronizer.

5. The braking device according to claim 1, comprising a controller (8), the controller being designed to: When the disengaged clutch (7) is disengaged, the working fluid level in the working chamber of the reducer (6) is determined to be at an unacceptably high level; and When the unacceptably high working fluid level is determined, the pump (9) is actuated so that the pump (9) discharges the working fluid from the working chamber.

6. The braking device according to claim 5, wherein the pump (9) is an electrically driven pump (9), and wherein the controller (8) is designed to: - Actuate the electrically driven pump (9) to determine the unacceptably high working fluid level in the working chamber, and - Based on the current consumption of the pump (9) during the actuation of the pump (9), it is determined that there is an unacceptably high working fluid level in the working chamber of the reducer (6).

7. The braking device according to any one of claims 1 to 3, wherein the braking device is configured to periodically or irregularly actuate the pump (9) when the disengagement clutch (7) is disengaged.

8. The braking device according to any one of claims 1 to 3, wherein the controller (8) of the braking device is configured to periodically or irregularly actuate the pump (9) when the disengagement clutch (7) is disengaged.

9. A method for operating a braking device according to any one of claims 1 to 8, wherein the vehicle is capable of being driven by a drive motor (1) and wherein a shaft (3) is provided on the power transmission side. The separation clutch (7) is provided between the reducer (6) and the shaft (3) on the power transmission system side. In cases where the working fluid cannot be extracted from the working chamber by means of the pump (9) when the disengaged clutch (7) is disengaged: - When the disengagement clutch (7) is disengaged, the shaft (3) is brought to a stationary state, and - Close the disengagement clutch (7) so that the rotor (6A) of the reducer (6) is rotatably coupled to the powertrain of the vehicle via the disengagement clutch (7) and the shaft (3), and - Drive the shaft (3) to rotate, and thereby drive the rotor (6A) to rotate, so that the rotor (6A) delivers the working fluid located in the working chamber of the reducer (6) out of the working chamber.

10. A controller (8) for actuating a braking device, wherein the controller (8) is designed to perform the method according to claim 9.

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