Control device for a regenerative braking system of a vehicle, regenerative braking system for a vehicle and method for operating a regenerative braking system of a vehicle

Abstract

Control device (10) for a recuperative braking system of a vehicle with: a control device (12) which is designed to determine a first target value with respect to a brake fluid volume to be transferred between at least one brake circuit (16) of the brake system and a storage volume (30) of the brake system by means of at least one hydraulic component (28) of the brake system, taking into account a provided actual value (14) with respect to a generator braking torque currently exerted by at least one electric motor of the brake system, and to control the at least one hydraulic component (28) in such a way that the brake fluid volume corresponding to the determined first target value can be transferred between the at least one brake circuit (16) and the storage volume (30) by means of the at least one controlled hydraulic component (28); characterized in that the control device (12) is additionally designed to determine a second target value with regard to a force simulation chamber pressure to be set in a force simulation chamber (18) by means of the at least one hydraulic component and / or at least one further hydraulic component (50) of the brake system, taking into account the actual value and / or the first target value, and to control the respective at least one hydraulic component (50) in such a way that the force simulation chamber pressure in the force simulation chamber (18) can be set by means of the respective at least one hydraulic component (50) in accordance with the second target value, so that in addition to a force simulation chamber pressure which is to be set in at least one chamber (20,22) of a master brake cylinder (24) of the brake system, nor a simulation force caused by the force simulation chamber pressure in the force simulation chamber (18) can be exerted on a brake actuating element (26) of the brake system.

Description

[0001] The invention relates to a control device for a regenerative braking system of a vehicle. The invention also relates to a regenerative braking system for a vehicle. Furthermore, the invention relates to a method for operating a regenerative braking system of a vehicle. State of the art

[0002] DE 10 2010 001 941 A1 describes a method for operating a brake-boosted hydraulic braking system of a vehicle and a control device for a brake-boosted regenerative braking system of a vehicle. The operated braking system can be equipped with at least one plunger and / or at least one two-chamber cylinder, the first working chamber of which is hydraulically connected to a brake circuit of the braking system and the second working chamber of which is hydraulically connected to a brake fluid reservoir of the braking system. During operation of the braking system, the assist force of a brake booster of the braking system should be adaptable to at least one additional braking force exerted on at least one wheel of the vehicle, such as a generator braking force, in such a way that deceleration of the vehicle can be maintained despite fluctuations in the additional braking force.In addition, by shifting a brake medium volume between the at least one storage chamber of the at least one plunger / two-chamber cylinder and a volume of the brake system external to the storage chamber, a standard brake actuation feeling should be ensured despite the change in the assistance force of the brake booster.

[0003] Similar techniques are also disclosed in DE 10 2010 042 363 A1 and in DE 10 2012 220 770 A1.

[0004] The object of the present invention is to provide a possibility for volume blending for a recuperative braking system, which ensures standard braking of the vehicle equipped with the recuperative braking system despite the generator braking torque which generally varies over time. Disclosure of the invention

[0005] The invention relates to a control device for a recuperative braking system of a vehicle having the features of claim 1, a recuperative braking system for a vehicle having the features of claim 4 and a method for operating a recuperative braking system of a vehicle having the features of claim 11. Advantages of the invention

[0006] By shifting the brake fluid volume corresponding to the first target value between the at least one brake circuit and the storage volume, it is possible to adjust the brake pressure in at least one wheel brake cylinder connected to the at least one brake circuit such that, despite temporal variations in the currently applied generator braking torque, a target vehicle deceleration specified by the driver by actuating the brake actuating element can be reliably maintained. The present invention thus enables a process described as volume blending to be carried out. Despite the generally temporally varying generator braking torque, the advantageous volume blending ensures standardized braking of the vehicle equipped with the recuperative braking system.At the same time, the present invention provides the advantage that, by means of the force simulation chamber pressure adjustable according to the second target value, the simulation force exerted on the brake actuation element can be adjusted such that the driver has a standard brake actuation feel (pedal feel) despite the changed brake pressure. The present invention thus ensures a force blending in addition to the volume blending, whereby a standard (advantageous) characteristic curve of the brake actuation element, for example, a brake pedal, is still ensured.

[0007] The force blending achievable by the present invention can also be described as meaning that a change in the counterforce exerted on the brake actuation element caused by the changed brake pressure can be at least partially compensated by the additionally applied simulation force. Thus, the driver hardly notices the change in the counterforce over time during the actuation of the brake actuation element.

[0008] In an advantageous embodiment of the control device, the control device is designed to control a plunger with a first working chamber as the storage volume, a second working chamber and an adjustable piston arranged between the first working chamber and the second working chamber, the first working chamber of which is hydraulically connected to the at least one brake circuit and the second working chamber of which is hydraulically connected to the force simulation chamber, as the at least one hydraulic component in such a way that the brake fluid volume corresponding to the specified target size can be transferred between the at least one brake circuit and the first working chamber and a corresponding brake fluid volume can be pushed out of the second working chamber or sucked into the second working chamber.The volume of brake fluid supplied to or removed from the second working chamber can be used, at least in part, to adjust the desired force simulation chamber pressure in the force simulation chamber. The design of the control device for the plunger described here ensures a cost-effective and energy-saving design of the braking system, using which the advantageous volume blending can be implemented simultaneously with the advantageous force blending.

[0009] Preferably, the control device is additionally designed to control a pressure control valve, via which the second working chamber is hydraulically connected to a brake fluid reservoir, as the at least one further hydraulic component. The pressure control valve is a cost-effective component for setting the desired force simulation chamber pressure in the force simulation chamber.

[0010] The advantages described in the previous paragraphs can also be ensured by the recuperative braking system for a vehicle.

[0011] In an advantageous embodiment of the regenerative braking system, the plunger is designed to be self-locking. This eliminates the need to equip the braking system with shut-off valves to seal the plunger's working chambers fluid-tight. However, as an alternative to a self-locking plunger design, shut-off valves can also be used in the regenerative braking system.

[0012] In a further advantageous embodiment, the second working chamber is additionally hydraulically connected to a brake fluid reservoir via a pressure control valve. The pressure control valve ensures reliable adjustment of the simulation chamber pressure corresponding to the second target value.

[0013] Advantageously, a bypass line with a check valve that blocks flow in a direction from the second working chamber to the brake fluid reservoir runs parallel to the pressure control valve. Overpressurizing the check valve allows an additional volume of brake fluid to be drawn from the brake fluid reservoir into the simulation chamber.

[0014] An accumulator can also be hydraulically connected to the force simulation chamber. Locating the accumulator near the force simulation chamber generally facilitates setting the force simulation chamber pressure corresponding to the second target value.

[0015] In advantageous developments, the regenerative braking system comprises a vacuum brake booster and / or a hydraulic brake booster. The force blending effected by the plunger eliminates the need for an electromechanical brake booster, which is often used for force blending in the prior art. This allows the advantageous braking system to utilize more cost-effective brake boosters, which are also very popular due to their long-standing use in vehicles.

[0016] In a further advantageous embodiment, the regenerative braking system comprises one of the control devices described above. This also ensures the advantages already mentioned.

[0017] The advantages explained above can also be realized by implementing a corresponding method for operating a regenerative braking system of a vehicle. The method can be further developed in accordance with the embodiments described above. Short description of the drawings

[0018] Further features and advantages of the present invention are explained below with reference to the figures. They show: Fig. 1 schematic representations of embodiments of the control device and the cooperating recuperative braking system; and Fig. 2 a flowchart for explaining an embodiment of the method for operating a recuperative braking system of a vehicle. Embodiments of the invention

[0019] Fig. 1 shows schematic representations of embodiments of the control device and the cooperating recuperative braking system.

[0020] The Fig. The control device 10 schematically illustrated in Figure 1 can, for example, be integrated into a brake system control or a central vehicle control system. However, the control device 10 can also be installed as a separate component on a vehicle equipped with the regenerative braking system.

[0021] The control device 10 comprises a control device 12, which is designed to determine a first target value with respect to a brake fluid volume to be transferred between at least one brake circuit 16 of the brake system and a storage volume of the brake system by means of at least one hydraulic component of the brake system, taking into account a provided actual value 14 with respect to a generator braking torque currently exerted by at least one (not shown) electric motor of the brake system. The actual value 14 can, in particular, comprise a value of the at least one generator braking torque, a temporal change in the at least one generator braking torque, and / or a current operating level of the at least one electric motor.Other variables and data that (indirectly) indicate a current function of the at least one generator and / or a current value of the at least one generator braking torque can also be provided as the actual variable 14. The actual variable 14 can, for example, be provided to the control device 10 by a generator controller. Likewise, in a further development, the control device 10 can be designed to control the at least one electric motor. In this case, the actual variable 14 can be provided to the control device 12 by an internal unit of the control device 10.

[0022] The control device 12 is also designed to control the at least one hydraulic component in such a way that the brake fluid volume corresponding to the specified target value can be transferred between the at least one brake circuit 16 and the storage volume by means of the at least one controlled hydraulic component. Furthermore, the control device 12 is additionally designed to define a second target value with respect to a force simulation chamber pressure to be set in a force simulation chamber 18 by means of the at least one hydraulic component and / or at least one further hydraulic component of the brake system, taking into account the actual value and / or the first target value.Subsequently, the control device 12 is designed to control the respective at least one hydraulic component such that the force simulation chamber pressure in the force simulation chamber 18 can be adjusted by means of the respective at least one hydraulic component in accordance with the second target value. In this way, it can be ensured that, in addition to a counterforce caused by the master cylinder pressure present in at least one chamber 20 and 22 of a master brake cylinder 24 of the brake system, a simulation force caused by the force simulation chamber pressure in the force simulation chamber 18 can also be exerted on a brake actuating element 26 of the brake system. The brake actuating element 26 can be a brake pedal, for example.

[0023] The control device 10 is thus designed to control the cooperating braking system such that, when the at least one electric motor is used as a generator, the braking pressure present in the at least one braking circuit 16 can be adjusted such that temporal fluctuations in the at least one generator braking torque can be at least partially compensated for by changing the at least one braking pressure in the at least one braking circuit 16. In particular, the at least one braking pressure in the at least one braking circuit 16 can be adjusted by means of the control device 10 such that a vehicle deceleration specified by a driver by actuating the brake actuating element 26 can be reliably maintained despite temporal fluctuations in the at least one generator braking torque.Since the control device 10 can react quickly to changes in the generator braking torque, even a sudden loss of the maximum generator braking torque that can be achieved by the at least one electric motor, for example due to a full charge of a vehicle battery and / or a vehicle speed below a minimum generator activation speed, often has (virtually) no effect on vehicle deceleration. The volume blending that can be performed by the control device 10 thus enables complete blending without the residual pressure remaining and without being limited to a jump-in range.

[0024] Furthermore, the control device 10 is designed to at least partially compensate for a changed counterforce of the master brake cylinder 24 on the brake actuating element 26 due to the displacement of the brake fluid volume corresponding to the first target value (between the at least one brake circuit 16 and the storage volume) using the newly generated simulation force. The force simulation chamber pressure can also be referred to as the support pressure, with which the changes in the counterforce can be at least partially compensated. Preferably, the counterforce and the simulation force add up to a total force that remains constant during the blending process. The at least one electric motor can thus be used as a generator without the driver perceiving the blending of the at least one generator braking torque (by means of the at least one newly determined brake pressure) when actuating the brake actuating element 26.

[0025] Operating the braking system by means of the control device 10 thus allows for volume blending and force blending to maintain the specified vehicle deceleration and a desired brake actuation feel (pedal feel) despite temporal fluctuations in the at least one generator braking torque. The use of the control device 10 thus increases the acceptance of the electric motor used to brake the vehicle, the use of which enables lower-emission and more energy-efficient driving of the vehicle equipped with it.

[0026] Not only a volume can be specified as the first target variable. Instead, the first target variable can also be at least one variable that specifies a function of the at least one hydraulic component and / or a state of the at least one hydraulic component. Accordingly, the second target variable can be specified as a target pressure, a desired function of the respective at least one hydraulic component, and / or a target state of the respective at least one hydraulic component.

[0027] In Fig. 1 also schematically shows the recuperative braking system interacting with the control device 10, comprising the master brake cylinder 24, the at least one brake circuit 16 connected to at least one chamber 20 of the master brake cylinder 24, the force simulation chamber 18 arranged internally or externally of the master brake cylinder, and a plunger 28 with a first working chamber 30 (as the storage volume), a second working chamber 32 and an adjustable piston 34 arranged between the first working chamber 30 and the second working chamber 32. The brake actuating element 26 is arranged on the force simulation chamber 18 and the master brake cylinder 24 in such a way that, in addition to the counterforce caused by the master brake cylinder pressure in the at least one chamber 20 and 22 of the master brake cylinder 24, a simulation force caused by the force simulation chamber pressure in the force simulation chamber 18 can also be exerted on the brake actuating element 26.This can be reliably achieved primarily by integrating the force simulation chamber 18 into the master brake cylinder 24, in particular on one side of the master brake cylinder 24 with an output rod 36 (output piston). The force simulation chamber 18 can, in particular, be arranged serially with the at least one chamber 20 and 22 of the master brake cylinder 24. However, the master brake cylinder 24 can also be designed as a multi-stage master brake cylinder. It is also noted that integrating the force simulation chamber 18 into the master brake cylinder 24 is not necessary.

[0028] In the embodiment of the Fig. 1, a force generated by the force simulation chamber pressure is supported against the housing of the master brake cylinder 24 and acts on the output rod (output piston) 36. While an annular region 35 of the output rod 36 defines the force simulation chamber 18, a frontal region of the output rod 36 protrudes through an opening in a partition 37 between the force simulation chamber 18 and an adjacent rod piston chamber 22, so that the output rod 36 can contact the rod piston 38. In this way, a force exerted on the output rod 36 can also be transmitted via the rod piston 38 to the floating piston 40. Preferably, the force simulation chamber 18 can sniff volume from a brake fluid reservoir 42, at least when the output rod 36 is in its unactuated position.The at least one chamber 20 and 22 of the master brake cylinder 24 can also be hydraulically connected to the brake fluid reservoir 42 via at least one sniffer bore. The brake fluid reservoir 42 can also have separate chambers for the force simulation chamber 18 and the at least one chamber 20 and 22 of the master brake cylinder 24 in order to separate the respective hydraulic circuits from each other.

[0029] The first working chamber 30 of the plunger 28 is hydraulically connected to at least one brake circuit 16. This is merely an example of the brake circuit 16 connected to the floating piston chamber 20 of the master brake cylinder 24. As an alternative or in addition, the first working chamber 30 can also be connected, for example, to a brake circuit 44 connected to the rod piston chamber 22.

[0030] The second working chamber 32 of the plunger 28 is hydraulically connected to the force simulation chamber 18 via a line 45. The control device 12 is designed to control the plunger 28 as the at least one hydraulic component by means of a plunger control signal 46 such that the brake fluid volume corresponding to the specified first target value can be transferred between the at least one brake circuit 16 and the first working chamber 30 as the storage volume. In particular, the transfer of the brake fluid volume between the at least one brake circuit 16 and the first working chamber 30 can be achieved by adjusting the piston 34 by means of a motor 48 of the plunger 28. The first target value can thus also include a target position of the piston 34, a target displacement of the piston, a target energization duration of the motor 48, and / or a target energization intensity of the motor 48.Suction of the brake fluid volume from the at least one brake circuit 16 into the first working chamber 30 causes a corresponding brake fluid volume to be forced out of the second working chamber 32. By reducing the pressure in the at least one brake circuit 16, a simultaneous pressure increase in the force simulation chamber 18 can thus be easily achieved. Accordingly, pushing the brake fluid volume out of the first working chamber 30 into the at least one brake circuit 16 leads to the corresponding brake fluid volume being sucked into the second working chamber 32. Thus, a pressure increase in the at least one brake circuit 16 can easily trigger a pressure decrease in the force simulation chamber 18.

[0031] The plunger 28 is a cost-effective component for simultaneously causing a pressure change in the at least one brake circuit 16 and a further pressure change in the at least one force simulation chamber 18. The use of the plunger 28 thus enables a cost-effective design of the brake system with full volume blending capability. Furthermore, the plunger 28 can be used without requiring extensive modifications to the brake system. However, it should be noted that equipping the brake system with the plunger 28 represents only one possibility for implementing a brake system that can be operated with the advantageous control device 10.

[0032] In the Fig. In the braking system schematically illustrated in Figure 1, the second working chamber 32 of the plunger 28 is hydraulically connected to the brake fluid reservoir 42 via a pressure control valve 50 inserted into a line 49. (The lines 45 and 49 connected to the second working chamber 32 can be described as a force simulation circuit.) The pressure control valve 50 can be a switching valve or a continuously adjustable / continuously controllable valve. The control device 12 is additionally designed to control the pressure control valve 50 as the at least one further hydraulic component by means of a pressure control valve control signal 52. In this way, the force simulation chamber pressure present in the force simulation chamber 18 can be adjusted with high accuracy and in a simple manner using the pressure control valve 50. The pressure control valve 50 also represents a cost-effective option for precisely regulating the force simulation chamber pressure.As a second target variable, a target state of the pressure control valve 50, a target opening duration of the pressure control valve 50, a target energization duration of the pressure control valve 50 and / or a target energization intensity of the pressure control valve 50 can also be defined.

[0033] Preferably, a bypass line 54 with a check valve 56 that blocks flow in a direction from the second working chamber 32 to the brake fluid reservoir 42 runs parallel to the pressure control valve 50. Thus, brake fluid can be drawn from the brake fluid reservoir 42 into the force simulation chamber 18 via the bypass line 54 without creating a vacuum in the second working chamber 32. The line 49 formed with the pressure control valve 50 can be described as an actively blocking return line.

[0034] Optionally, an accumulator 58 is hydraulically connected to the force simulation chamber 18 or the second working chamber 32. The accumulator pressure held in the accumulator 58 assists the start-up of the motor 48, particularly at the beginning of a return flow to the braking system.

[0035] In the braking system of the Fig. 1, the plunger 28 exhibits improved return flow dynamics due to the accumulator 58. The accumulator 58 can be described as a medium-pressure accumulator. In conjunction with the control valve 50, the accumulator 58 compensates for the reduced brake pressure caused by the volume absorption into the first accumulator chamber 30 in the brake circuit 16 by a pressure change in the force simulation chamber 18.

[0036] The Fig. The braking system schematically illustrated in Figure 1 also has shut-off valves 60, wherein the first working chamber 30 is hydraulically connected to the at least one brake circuit 16 via a first shut-off valve 60, and the second working chamber 32 is hydraulically connected to the force simulation chamber 18 and the pressure control valve 50 via a second shut-off valve 60. By using the shut-off valves 60, a highly efficient gear system can be used for the plunger 28. The volume consumption of a plunger 28 with a high gear system efficiency can be drastically reduced by means of the at least one shut-off valve 60. Due to the high efficiency of the plunger 28, its drive can be downsized or its pressure delivery capacity can be improved. As an alternative to equipping the braking system with the shut-off valves 60, the plunger 28 can also be designed to be self-locking.

[0037] The braking system of the Fig. 1 also includes a vacuum brake booster 62. In a further preferred embodiment, the braking system includes a hydraulic brake booster. Equipping the braking system with a vacuum brake booster or a hydraulic brake booster is advantageous because such brake booster types are comparatively inexpensive. (For example, very inexpensive electric vacuum pumps can be used in the vacuum brake booster 62.) Furthermore, these brake booster types eliminate the difficulties associated with an electromechanical brake booster in the case of ABS recirculation. Furthermore, both brake booster types have been on the market for a long time and are therefore well accepted by drivers. The use of an electromechanical brake booster, which is comparatively expensive and also new, is not necessary with the braking system described here.While conventionally the electromechanical brake booster is often used for force blending due to the good controllability of its booster force, this function can be carried out by means of the advantageous control device 10.

[0038] Optionally, a sensor, such as a rod travel sensor and / or a pedal travel sensor, can also be integrated into the master brake cylinder 24. A sensor signal provided by this, such as in particular a travel sensor signal, can additionally be used for the blending algorithm.

[0039] The control device 10, the plunger 28, the pressure control valve 50, the accumulator 58, and / or the shut-off valves 60 can be designed as a single component, which can be described as a smart actuator 64. This facilitates assembly of the components 28, 50, 58, and / or 60 on a vehicle. As an alternative to using a smart actuator 64, the components 28, 50, 58, and / or 60 can also be designed separately. As a further development, the smart actuator 64 can also have at least one pressure sensor 66, by means of which a sensor signal 68 can be output to a brake system controller 70.

[0040] The brake system control 70, by means of which at least one further hydraulic component 72 of the brake system (e.g., components of an ESP-Hev) can be controlled to set a desired brake pressure in the wheel brake cylinders 74 (as schematically represented by arrow 76), can be integrated into the control device 10 in an advantageous further development. Alternatively, however, a control device 10 designed separately from the brake system control 70 can also be used in the brake system.

[0041] In Fig. 1, the brake circuits 16 and 44 are shown only schematically. It is expressly pointed out that a multitude of differently designed brake circuits 16 and 44 can be used together with the control device 10 in the braking system. In particular, the plunger 28 can be used with conventional brake circuits 16 and 44 without significant modifications to the brake circuits 16 and 44. Changes can be made on the software and communication side so that a setpoint value can be generated for a preferred position of the piston 34 depending on the generator recuperation potential and / or driving stability information. The braking system can optionally be designed for an X-brake circuit division and / or for a II-brake circuit division (parallel brake circuit division). The equipment of the braking system with the Fig. The components shown in Figure 1 do not cause any additional loads compared to a pump mechanism.

[0042] The functionality of the braking system controlled by control device 10 will be explained once again below. It should be noted that the corresponding functional sequences can be executed even to blend a high generator braking torque of up to 0.3 g or more. These processes are executed in particular when the generator braking torque exceeds the level of the jump-in braking torque (or jumper braking torque of the respective brake booster 62), for example, from 0.1 g. Typically, in this operating state, the driver is forcefully connected to the master brake cylinder 24 during braking without blending.

[0043] In such a situation, to blend a temporally increasing generator braking torque, a pressure reduction can be carried out in at least one brake circuit 16. For the pressure reduction, the first working chamber 30 of the plunger 28 absorbs a volume of brake fluid in a pressure-controlled and / or volume-controlled manner. The movement of the piston 34 causes a pressure increase in the second working chamber 32 of the plunger 28. As a result, a volume of brake fluid is displaced into the accumulator 58. The accumulator 58 is preferably designed such that more pressure is always generated at the accumulator 58 than is reduced in the braking system for blending. Subsequently / simultaneously, the pressure in the force simulation chamber 18 can be adjusted via the pressure control valve 50 such that the total force comprising the counterforce and the simulation force remains constant.

[0044] As long as the generator braking torque remains unchanged, the pressure present in at least one brake circuit 16 can be kept constant. This can be ensured, for example, by closing the pressure control valve 50 and / or the shut-off valves 60. The pressure in the accumulator 58 thus also remains constant. The piston 34 in the plunger 28 is not moved. The motor 48 of the plunger 28 can be de-energized.

[0045] As soon as the generator braking torque decreases over time, the brake pressure present in the at least one brake circuit 16 can be increased. To achieve such a pressure buildup, the plunger 28 feeds an additional volume of brake fluid from the first working chamber 30 back into the at least one brake circuit 16 in a pressure-controlled and / or volume-controlled manner. In the process, the movement of the piston 34 of the plunger 28 reduces the pressure in the second working chamber 32. The accumulator pressure in the accumulator 58 also decreases accordingly. This causes a decrease in the force simulation chamber pressure and thus a decrease in the simulation force, which at least partially compensates for the increase in the counterforce. To prevent a vacuum in the force simulation circuit, brake fluid can be drawn from the brake fluid reservoir 42 via the bypass line 54.

[0046] To shut down the system implemented by the plunger 28, the shut-off valves 60, which are designed as normally-off valves, can remain de-energized. Thus, the piston 34 of the plunger 28 is not moved even at high master cylinder pressures in the master cylinder 24. Therefore, even at high master cylinder pressures, there is no unwanted volume intake into the plunger 28. Due to the double-sided filling of the plunger 28, the shut-off valves 60 do not need to be monitored. This can also be described as ensuring mechanical redundancy due to the dual presence of the shut-off valves 60. In this case, the accumulator 58 is depressurized. The pressure control valve 50 can be open when de-energized.

[0047] If the driver engages the braking system in this state, a volume of brake fluid is shifted from the force simulation chamber 18 past the accumulator 58 into the brake fluid reservoir 42. Thus, the force simulation circuit offers no additional resistance when the brake actuation element 26 is actuated.

[0048] The braking system also provides a beneficial backup. If the braking system is equipped with a vacuum brake booster 62, the driver can apply additional braking force several times in the event of an on-board power system failure, depending on the volume of the vacuum brake booster 62 and the initial pressure.

[0049] For ABS braking, part or all of the volume of the first working chamber 30 can be pumped back from the plunger 28 into the at least one brake circuit 16. High pressures can arise due to the start-up of a return pump and the closing of at least one inlet valve. Preferably, the shut-off valves 60 are closed after the return has taken place. Likewise, the pressure control valve 50 can be opened in such a situation to release any residual pressure still present in the accumulator 58. Furthermore, the vacuum brake booster 62 can divert part of the master cylinder pressure in the master cylinder 24 to the driver's foot if the activation point of the vacuum brake booster 62 is exceeded.

[0050] Fig. 2 shows a flowchart for explaining an embodiment of the method for operating a recuperative braking system of a vehicle.

[0051] The method described below can be implemented, for example, using the braking system explained above. However, the feasibility of this method is not limited to the use of such a braking system or to the use of the control device described above.

[0052] In a method step S1, a first target value is determined regarding a brake fluid volume to be transferred between at least one brake circuit of the brake system and a storage volume by means of at least one hydraulic component of the brake system. The first target value is determined taking into account an actual value regarding a generator braking torque currently exerted by at least one electric motor of the brake system. Examples of the actual value have already been given above.

[0053] In a further method step S2, the at least one hydraulic component is controlled such that the brake fluid volume corresponding to the specified first target value is transferred between the at least one brake circuit and the storage volume. Method steps S1 and S2 thus realize the advantages of volume blending described above.

[0054] The method also includes a method step S3 with the setting of a second target value regarding a force simulation chamber pressure to be set in a force simulation chamber by means of the at least one hydraulic component and / or at least one further hydraulic component of the brake system, taking into account the actual value and / or the first target value. Method step S3 can be executed before, during, or after method step S1. The numbering of method steps S1 and S3 does not specify a chronological order for their execution.

[0055] In a further method step S4, the at least one hydraulic component and / or the at least one further hydraulic component of the brake system (as the respective at least one hydraulic component) are controlled such that the force simulation chamber pressure in the force simulation chamber is set according to the second target value. In this way, it can be ensured that, in addition to a counterforce caused by a master cylinder pressure present in at least one chamber of a master brake cylinder of the brake system, a simulation force caused by the force simulation chamber pressure in the force simulation chamber is also exerted on a brake actuating element of the brake system. The advantageous force blending can thus also be carried out using the method described here.

[0056] In a preferred embodiment of the method, a plunger with a first working chamber as the storage volume, a second working chamber, and an adjustable piston arranged between the first working chamber and the second working chamber, the first working chamber of which is hydraulically connected to the at least one brake circuit and the second working chamber of which is hydraulically connected to the force simulation chamber, is controlled as the at least one hydraulic component. This occurs in such a way that the brake fluid volume corresponding to the specified first target value is transferred between the at least one brake circuit and the first working chamber, and a corresponding brake fluid volume is forced out of the second working chamber or sucked into the second working chamber. Thus, the cost-effective and advantageous plunger can also be used to carry out the method.

[0057] By implementing this method, volume blending and force blending can also be performed without the use of an electromechanical brake booster. Furthermore, the method described here can also be further developed according to the above explanations.

Claims

[1] Control device (10) for a recuperative braking system of a vehicle comprising: a control device (12) which is designed to determine a first target value with respect to a brake fluid volume to be transferred between at least one brake circuit (16) of the brake system and a storage volume (30) of the brake system by means of at least one hydraulic component (28) of the brake system, taking into account a provided actual value (14) with respect to a generator braking torque currently exerted by at least one electric motor of the brake system, and to control the at least one hydraulic component (28) in such a way that the brake fluid volume corresponding to the determined first target value can be transferred between the at least one brake circuit (16) and the storage volume (30) by means of the at least one controlled hydraulic component (28); characterized by , that the control device (12) is additionally designed to determine a second target value with regard to a force simulation chamber pressure to be set in a force simulation chamber (18) by means of the at least one hydraulic component and / or at least one further hydraulic component (50) of the brake system, taking into account the actual value and / or the first target value, and to control the respective at least one hydraulic component (50) in such a way that the force simulation chamber pressure in the force simulation chamber (18) can be set by means of the respective at least one hydraulic component (50) in accordance with the second target value, so that in addition to a force simulation chamber pressure which is to be set in at least one chamber (20,22) of a master brake cylinder (24) of the brake system, nor a simulation force caused by the force simulation chamber pressure in the force simulation chamber (18) can be exerted on a brake actuating element (26) of the brake system. [2] Control device (10) according to claim 1, wherein the control device (12) is designed to control a plunger (28) with a first working chamber (30) as the storage volume (30), a second working chamber (32) and an adjustable piston (34) arranged between the first working chamber (30) and the second working chamber (32), the first working chamber (30) of which is hydraulically connected to the at least one brake circuit (16) and the second working chamber (32) of which is hydraulically connected to the force simulation chamber (18), as the at least one hydraulic component (28) in such a way that the brake fluid volume corresponding to the specified first target value can be transferred between the at least one brake circuit (16) and the first working chamber (30) and a corresponding brake fluid volume can be pushed out of the second working chamber (32) or sucked into the second working chamber (32). [3] Control device (10) according to claim 2, wherein the control device (12) is additionally designed to control a pressure control valve (50), via which the second working chamber (32) is hydraulically connected to a brake fluid reservoir (42), as the at least one further hydraulic component (50). [4] Regenerative braking system for a vehicle for cooperating with the control device (10) according to claim 2 or 3, comprising: a master brake cylinder (24); at least one brake circuit (16) connected to at least one chamber (20, 22) of the master brake cylinder (24); a force simulation chamber (18) arranged internally or externally of the master brake cylinder (24), on which a brake actuating element (26) can be arranged or is arranged such that, in addition to a counterforce caused by a master brake cylinder pressure present in the at least one chamber (20, 22) of the master brake cylinder (24), a simulation force caused by a force simulation chamber pressure in the force simulation chamber can also be exerted on the brake actuating element (26); and a plunger (28) with a first working chamber (30), a second working chamber (32) and an adjustable piston (34) arranged between the first working chamber (30) and the second working chamber (32), the first working chamber (30) of which is hydraulically connected to the at least one brake circuit (16) and the second working chamber (32) of which is hydraulically connected to the force simulation chamber (18). [5] Recuperative braking system according to claim 4, wherein the plunger (28) is self-locking. [6] Recuperative braking system according to claim 4 or 5, wherein the second working chamber (32) is additionally hydraulically connected to a brake fluid reservoir (42) via a pressure control valve (50). [7] Recuperative braking system according to claim 6, wherein a bypass line (54) with a check valve (56) blocking in a direction from the second working chamber (32) to the brake fluid reservoir (42) runs parallel to the pressure control valve (50). [8] Recuperative braking system according to one of claims 4 to 7, wherein an accumulator (58) is hydraulically connected to the force simulation chamber (18). [9] Recuperative braking system according to one of claims 4 to 8, wherein the recuperative braking system comprises a vacuum brake booster (62) and / or a hydraulic brake booster. [10] Recuperative braking system according to one of claims 4 to 9, wherein the recuperative braking system comprises a control device (10) according to claim 2 or 3. [11] Method for operating a recuperative braking system of a vehicle, comprising the steps: Determining a first target value with respect to a brake fluid volume to be transferred between at least one brake circuit (16) of the brake system and a storage volume (30) by means of at least one hydraulic component (28) of the brake system, taking into account an actual value (14) with respect to a generator braking torque (S1) currently exerted by means of at least one electric motor of the brake system; and Controlling the at least one hydraulic component (28) in such a way that the brake fluid volume corresponding to the specified first target value is transferred between the at least one brake circuit (16) and the storage volume (30) (S2); characterized bythe step: Determining a second target value with respect to a force simulation chamber pressure to be set in a force simulation chamber (18) by means of the at least one hydraulic component and / or at least one further hydraulic component (50) of the brake system, taking into account the actual value and / or the first target value (S3); and Controlling the respective at least one hydraulic component (50) in such a way that the force simulation chamber pressure in the force simulation chamber (18) is set in accordance with the second target value such that, in addition to a counterforce caused by a master brake cylinder pressure present in at least one chamber (20, 22) of a master brake cylinder (24) of the brake system, a simulation force caused by the force simulation chamber pressure in the force simulation chamber (18) is also exerted on a brake actuating element (26) of the brake system (S4). [12] Method according to claim 11, wherein a plunger (28) with a first working chamber (30) as the storage volume (30), a second working chamber (32) and an adjustable piston arranged between the first working chamber (30) and the second working chamber (32), the first working chamber (30) of which is hydraulically connected to the at least one brake circuit (16) and the second working chamber (32) of which is hydraulically connected to the force simulation chamber (18), is controlled as the at least one hydraulic component (28) in such a way that the brake fluid volume corresponding to the specified first target value is transferred between the at least one brake circuit (16) and the first working chamber (30) and a corresponding brake fluid volume is pressed out of the second working chamber (32) or sucked into the second working chamber (32).

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