Control device and operating method for a vehicle's regenerative braking system

Abstract

The present invention relates to a control device (16) for a regenerative braking system of a vehicle, and when it is possible to cause at least part of a required vehicle deceleration by means of at least one electric motor, a sub-step of determining a target differential pressure between a first wheel brake cylinder (10) of the braking system and a second wheel brake cylinder (12) of the braking system, a sub-step of controlling at least one wheel inlet valve (22) upstream of the second wheel brake cylinder (12) of the braking system by means of a current signal (52) output to the at least one wheel inlet valve (22) taking into account the determined target differential pressure, and a sub-step of determining a target current intensity of the current signal (52) taking into account the determined target differential pressure by selecting the target current intensity or an output value of the target current intensity of the current signal (52) from a value range including at least three current intensity values, and relates to an operating method for a regenerative braking system of a vehicle by executing differential pressure control within wheel brake cylinders (10, 12) of the braking system.

Description

Technical Field

[0001] The present invention relates to a control device for a regenerative braking system of a vehicle and a regenerative braking system of a vehicle. Further, the present invention relates to an operation method of a regenerative braking system of a vehicle.

Background Art

[0002] FIGS. 1a and 1b show coordinate systems for explaining a conventional method of operating a regenerative braking system of a vehicle known to the applicant as prior art inside. The abscissa of the coordinate systems of FIGS. 1a and 1b is the time axis t, respectively.

[0003] In the first braking process shown by the coordinate system of FIG. 1a, the driver of the vehicle requests a vehicle deceleration a not equal to zero by operating the brake operation element of the braking system from time t0. Therefore, in the conventional method, from time t0, the operating state Φ of the electric motor of the braking system operable in the regeneration mode Φ r is switched from the non-active mode Φ0 to the regeneration mode Φ r During the period between time t0 and t1, the non-zero vehicle deceleration a requested by the driver can be generated by the electric motor operating in the regeneration mode Φ r Therefore, during the period between time t0 and t1, the first target brake pressure p to be adjusted in the first wheel brake cylinder of the braking system assigned to the first axle of the vehicle 1target and the second target brake pressure p to be adjusted in the second wheel brake cylinder of the braking system assigned to the second axle of the vehicle 2targetis equal to zero. In order to avoid an increase in brake pressure within each one of the first wheel brake cylinders and each one of the second wheel brake cylinders for each brake circuit between times t0 and t1, a second wheel outlet valve disposed downstream of the second wheel brake cylinder is switched to an open state between times t0 and t1, which is not shown in the coordinate system of FIG. 1a. However, based on the coordinate system of FIG. 1a, it can be recognized that simultaneously with the switching of the first wheel inlet valve disposed upstream of the first wheel brake cylinder to an open state, the second wheel inlet valve disposed upstream of the second wheel brake cylinder is also switched to an open state between times t0 and t1. For this purpose, the current intensity I of the current signal output to the second wheel inlet valve that is open when de-energized is plotted in the coordinate system of FIG. 1a. Accordingly, between times t0 and t1, the first actual brake pressure p1 present within the first wheel brake cylinder and the second actual brake pressure p2 present within the second wheel brake cylinder are (substantially) equal to zero.

[0004] From time t1, the vehicle deceleration a required by the driver cannot be generated solely by the electric motor operating in the regeneration mode Φ r However, the required vehicle deceleration a can be generated between times t1 and t2 by the electric motor operating in the regeneration mode Φ r and the first wheel brake cylinder assigned to the first axle of the vehicle. Accordingly, between times t1 and t2, the first target brake pressure p 1target to be adjusted within the first wheel brake cylinder is determined to not be equal to zero, whereas the second target brake pressure p 2targetThe pressure remains equal to zero between times t1 and t2. Furthermore, the first wheel outlet valve located retrograde in the first wheel brake cylinder is held closed from time t1, while the second wheel outlet valve located retrograde in the second wheel brake cylinder remains open between times t1 and t2. The first target brake pressure p is determined by differential pressure control performed by the second wheel inlet valve of the second wheel brake cylinder during the time interval T0, which sets the first actual brake pressure p1 present in the first wheel brake cylinder. 1target Attempting to adjust according to this, conventional methods control the differential pressure during the time interval T0 by alternating between overflow (Ueberstromung) and underflow (Unterstromung) of the second wheel inlet valve. Additionally, brake fluid can also be pumped into the brake system from at least one low-pressure reservoir located behind the first and second wheel outlet valves by a non-zero pump rotation speed n of at least one pump in the brake system. However, as indicated by arrow 2, between times t1 and t2, a "waveform" pressure rise often occurs within the first wheel brake cylinder.

[0005] From time t2, regenerative mode Φ r The electric motor operating at and the first wheel brake cylinder assigned to the first axle of the vehicle become insufficient to produce the required vehicle deceleration a which is not equal to zero. Therefore, from time t2, a second target brake pressure p should be adjusted in the second wheel brake cylinder. 2targetThe second wheel outlet valve, located retrograde to the second wheel brake cylinder, is held closed from time t2 (similar to the first wheel outlet valve located retrograde to the first wheel brake cylinder). The differential pressure control performed by the second wheel inlet valve determines the first target brake pressure p1 present in the first wheel brake cylinder. 1target Accordingly, and the second actual brake pressure p2 present in the second wheel brake cylinder is set to the second target brake pressure p 2target Further adjustments are attempted accordingly. In the conventional method, this is continued by switching between overflow and underflow of the second wheel inlet valve. Arrow 4 indicates that the resulting increase in pressure in the second wheel brake cylinder may unfortunately cause a rapid decrease in pressure in the first wheel brake cylinder.

[0006] In the second braking process shown by the coordinate system in Figure 1b, the driver requests a vehicle deceleration a that is not equal to zero by operating the brake control elements from time t0, but this vehicle deceleration is still in regenerative mode Φ between times t0 and t1. r This can be produced by an electric motor operating at . However, compared to the first braking process described above, in the second braking process the driver requires much faster braking of the vehicle. In the second braking process as well, the non-zero vehicle deceleration a required by the driver is generated between times t0 and t1 by the regenerative mode Φ r With only the electric motor operating and the first wheel brake cylinder of the first axle, and from time t2, regenerative mode Φ r This can be accomplished by an electric motor operating on a first wheel brake cylinder and a second wheel brake cylinder on the second axle. The first target brake pressure p to be adjusted within the first wheel brake cylinder 1target and the second target brake pressure p which should be adjusted within the second wheel brake cylinder2target This is determined accordingly. In order to adjust the first actual brake pressure p1 present in the first wheel brake cylinder and the second actual brake pressure p2 present in the second wheel brake cylinder, differential pressure control is performed during the time interval T0 by a second wheel outlet valve newly positioned in front of the second wheel brake cylinder, by exchanging between the overflow and underflow of the second wheel inlet valve in the conventional manner. Arrow 6 indicates the first target brake pressure p to be adjusted in the first wheel brake cylinder based on the requirement for faster braking of the vehicle. 1target This demonstrates that a significant difference can arise between the initial brake pressure p1 actually increased within the first wheel brake cylinder and the initial brake pressure p1, which may be perceived by the driver as an unpleasant "soft" braking element. [Overview of the Initiative]

[0007] The present invention provides a control device for a vehicle regenerative braking system having the features of claim 1, a vehicle regenerative braking system having the features of claim 6, and a method for operating a vehicle regenerative braking system having the features of claim 7.

[0008] The present invention provides the possibility of operating a vehicle's regenerative braking system in such a way that the driver of the vehicle does not (substantially) perceive the harmonic process (Verblendvorgaenge) performed while operating the brake operating elements of the brake system. For example, switching between braking the vehicle by at least one electric motor operating in regenerative mode and braking the vehicle by at least one electric motor and a first wheel brake cylinder of a brake system assigned to the vehicle's first axle does not result in any undesirable "waveform" pressure rise within the first wheel brake cylinder. Similarly, switching between braking the vehicle by at least one electric motor, the first wheel brake cylinder, and a second wheel brake cylinder of a brake system assigned to the vehicle's second axle does not (usually) result in a pressure drop within the first wheel brake cylinder or a significant deviation of the first actual brake pressure present within the first wheel brake cylinder from a first target brake pressure desirable for the first wheel brake cylinder. Thus, the possibility of operating a vehicle's regenerative braking system provided by the present invention provides the driver of the vehicle with improved driving and braking comfort. Therefore, the present invention contributes to encouraging drivers to purchase vehicles equipped with a regenerative braking system, and the operation of such vehicles is linked to reduced energy consumption and, in some cases, a reduction in harmful emissions.

[0009] In one advantageous embodiment of the control device, the electronics in differential pressure control mode are designed and / or programmed to determine a target current intensity or output value of the target current intensity of a current signal according to a specified continuous function having a range of values ​​including at least three current intensity values, depending on a determined target differential pressure. This enables "glatte" control of at least one (second) wheel inlet valve preceded by a second wheel brake cylinder, as described herein by the embodiment of the control device.

[0010] Preferably, the electronic equipment is designed and / or programmed to determine an offset value for the target current intensity of the current signal, taking into account the deviation of each of the at least one first actual brake pressures in the first wheel brake cylinders measured or estimated during a specified comparison time interval from a first target brake pressure to be adjusted simultaneously in each first wheel brake cylinder, even after the start of the differential pressure control mode, and to determine the target current intensity of the current signal as the sum of the output value of the target current intensity and the offset value. The offset value thus determined, or the resulting target current intensity, can favorably compensate for component tolerances and / or degradation phenomena of each regenerative braking system.

[0011] In an advantageous development, the electronic equipment may, after the start of the differential pressure control mode, additionally, be designed and / or programmed to determine a period during which the first actual brake pressure in at least one measured or estimated first wheel brake cylinder differs from a first target brake pressure to be simultaneously adjusted in each first wheel brake cylinder by at least one specified minimum pressure deviation, and if the determined period exceeds a specified time threshold, to determine the target current intensity of the current signal so that at least one wheel inlet valve is switched to a closed state for a period of time specified or determined by the current signal output thereto. In this way, the occurrence of a "soft" brake operating element / brake pedal, which often occurs in the prior art, can be avoided by the embodiments of the control device described herein.

[0012] In another advantageous development, the electronics may be designed and / or programmed to determine a target differential pressure at the beginning of the differential pressure control mode as the difference between a first target brake pressure to be adjusted in a designated or determined first wheel brake cylinder and a second target brake pressure to be adjusted in a designated or determined second wheel brake cylinder; however, if the measured or estimated first actual brake pressure in the first wheel brake cylinder is simultaneously smaller than the first target brake pressure to be adjusted in the first wheel brake cylinder by at least one specified limit deviation, the electronics may be designed and / or programmed to determine the target differential pressure for a specified or determined transition time as the difference between the measured or estimated first actual brake pressure in the first wheel brake cylinder and a second target brake pressure to be adjusted in the second wheel brake cylinder. Therefore, the advanced form of the control device described herein is advantageous in that it can respond to a significant deviation of the first actual brake pressure from the first target brake pressure, thereby preventing the occurrence of the same / corresponding deviation of the second actual brake pressure in the second wheel brake cylinder from the second target brake pressure to be adjusted in the second wheel brake cylinder.

[0013] The advantages described above are also guaranteed in a vehicle regenerative braking system comprising such a control device, a first wheel brake cylinder assigned to the first axle of the vehicle, a second wheel brake cylinder assigned to the second axle of the vehicle, and at least one wheel inlet valve positioned in front of the second wheel brake cylinder.

[0014] Furthermore, implementing the corresponding operating method of the vehicle's regenerative braking system also provides the aforementioned advantages. It should be explicitly stated that the operating method of the vehicle's regenerative braking system can also be developed using the control device embodiments described above. [Brief explanation of the drawing]

[0015] [Figure 1a] This figure shows a coordinate system used to explain conventional methods for operating a vehicle's regenerative braking system. [Figure 1b] This figure shows a coordinate system used to explain conventional methods for operating a vehicle's regenerative braking system. [Figure 2] This is a schematic diagram of a vehicle's regenerative braking system to illustrate the operating principle of an embodiment of a control device that works in cooperation with the vehicle's regenerative braking system. [Figure 3a] This figure shows a coordinate system for illustrating one embodiment of the operation method of a vehicle's regenerative braking system. [Figure 3b] This figure shows a coordinate system for illustrating one embodiment of the operation method of a vehicle's regenerative braking system. [Modes for carrying out the invention]

[0016] The following describes in detail, with reference to the figures, other features and advantages of the present invention.

[0017] Figure 2 shows a schematic diagram of a vehicle's regenerative braking system to illustrate the operating principle of an embodiment of a control device that works in cooperation with the vehicle's regenerative braking system.

[0018] The regenerative braking system schematically shown in Figure 2 has a first wheel brake cylinder 10 and a second wheel brake cylinder 12. The first wheel brake cylinder 10 is assigned to the first axle of the vehicle equipped with the braking system, and the second wheel brake cylinder 12 is assigned to the second axle of the vehicle. This can be understood as the first wheel brake cylinder 10 being mounted on the first axle of the vehicle, and the second wheel brake cylinder 12 being mounted on the second axle. In the braking system of Figure 2, an X-shaped brake circuit configuration is implemented simply as an example, with each of the first wheel brake cylinders 10 and each of the second wheel brake cylinders 12 being coupled to one of two brake circuits 14a and 14b. The first axle may be, for example, the front axle, while the second axle is the rear axle. However, alternatively, the first axle may be the rear axle and the second axle may be the front axle.

[0019] The brake system, which works in cooperation with the control device 16, also includes at least one first wheel inlet valve 18 positioned in front of the first wheel brake cylinder 10, at least one first wheel outlet valve 20 positioned behind the first wheel brake cylinder 10, at least one second wheel inlet valve 22 positioned in front of the second wheel brake cylinder 12, and at least one second wheel outlet valve 24 positioned behind the second wheel brake cylinder 12. For example, each of the first wheel brake cylinders 10 may be coupled with one first wheel inlet valve 18 and one first wheel outlet valve 20, and each of the second wheel brake cylinders 12 may be coupled with one second wheel inlet valve and one second wheel outlet valve. Preferably, the brake circuits 14a and 14b are coupled to a master brake cylinder 26, which may be preceded by a brake operating element 28, such as a brake pedal 28. The brake booster 30 and / or brake fluid reservoir 32 can also be selectively hydraulically coupled to the master brake cylinder 26.

[0020] Optionally, each brake circuit 14a and 14b may be retrofitted with one storage chamber 34, in particular a low-pressure storage chamber 34, to at least one first wheel outlet valve 20 and / or a second wheel outlet valve 24. It may also be advantageous if the brake circuits 14a and 14b have at least one pump 36, which can be operated in particular by a common pump motor 38 of the brake system. As other optional components, the brake circuits 14a and 14b of the brake system in Figure 2 further have one switching valve 40 and one high-pressure switching valve 42 each.

[0021] However, it should be noted that the configuration of the brake system shown in Figure 2 should be interpreted as merely illustrative. Instead, any regenerative braking system having at least components 10, 12, and 18-24 in the hydraulic system can be used in conjunction with the control device 16 described below. Furthermore, the usability of the control device 16 or the regenerative braking system working with it is not limited to a specific vehicle type of vehicle / automobile equipped with the brake system.

[0022] The control device 16 has electronic equipment 16a designed and / or programmed to query or confirm whether the required vehicle deceleration can be produced in part by the brake system or by at least one electric motor (not shown) operating in the vehicle's regenerative mode. The at least one electric motor may be, for example, the vehicle's electric drive motor. The required vehicle deceleration can be understood as, for example, the vehicle deceleration requested by the vehicle's driver through the operation of a brake operating element 28. In particular, at least one brake operating element sensor 44 that outputs a sensor signal 46 corresponding to the operation of the brake operating element 28 may be incorporated into the brake system, for example, a rod displacement sensor and / or a differential displacement sensor. Alternatively or additionally, the required vehicle deceleration may also be requested by a corresponding brake request signal from the vehicle's (not shown) automatic speed control device.

[0023] When the sensor signal 46 from the brake operation element sensor 44 and / or the brake request signal from the automatic speed control device are provided to the electronic device 16a, the electronic device 16a can be designed / programmed to control / activate the regenerative mode of at least one electric motor. In this case, the electronic device 16a (automatically) determines whether the requested vehicle deceleration can be achieved by only at least one electric motor operating in regenerative mode when controlling at least one electric motor. Alternatively, the control of at least one electric motor can be performed by a motor control device, in which case the motor control device controls / activates the regenerative mode of at least one electric motor, taking into account at least one sensor signal 46 from at least one brake operation element sensor 44 and / or the brake request signal from the automatic speed control device. In this case, the electronic device 16a recognizes that the requested vehicle deceleration cannot be achieved by only at least one electric motor operating in regenerative mode by querying / reading the information signal output to the electronic device 16a by the motor control device.

[0024] In some cases, i.e., when the required vehicle deceleration can be partially generated by at least one electric motor operating in regenerative mode, the electronics 16a is in its differential pressure control mode. In differential pressure mode, the electronics 16a is designed and / or programmed to determine the target differential pressure between the first wheel brake cylinder 10 and the second wheel brake cylinder 12. The target differential pressure that can be determined by the electronics 16a in differential pressure control mode is defined as the difference between a first target brake pressure or actual brake pressure and a second target brake pressure. The first target brake pressure can be understood as the pressure to be adjusted within the first wheel brake cylinder 10, which may be specified to or determined by the electronics 16a. A first actual brake pressure that can be used to specify the target differential pressure instead of the first target brake pressure is the first actual brake pressure in the first wheel brake cylinder 10 as measured or estimated. For example, a pressure sensor 48 coupled to one of the brake circuits 14a and 14b can output a pressure sensor signal 50 corresponding to a first actual brake pressure to the electronic device 16a. The second target brake pressure is the pressure to be adjusted in the second wheel brake cylinder 12, which may also be specified to or determined by the electronic device 16a. For example, an information signal output to the electronic device 16a by the motor control device may include the first target brake pressure and / or the second target brake pressure. The advantages of the electronic device 16a determining the first target brake pressure and / or the second target brake pressure will be discussed further later.

[0025] The electronic device 16a in differential pressure control mode is further designed and / or programmed to output a current signal 52 to at least one second wheel inlet valve 22, taking into account the determined target differential pressure, so that at least one second wheel inlet valve 22 is controllable by the output current signal 52. Additionally, the electronic device 16a in differential pressure control mode is designed and / or programmed to determine the target current intensity of the current signal 52, taking into account the determined target differential pressure. To this end, the electronic device 16a in differential pressure control mode selects the target current intensity of the current signal 52 or the output value of the target current intensity from a range of values ​​including at least three current intensity values, taking into account the determined target differential pressure. The electronic device 16a in differential pressure control mode then outputs a current signal 52 to at least one second wheel inlet valve 22 having a (actual) current intensity corresponding to the determined target current intensity.

[0026] Based on the advantageous design / programming of the electronic equipment 16a described in the preceding paragraph, the control unit 16, or the regenerative braking system working in cooperation with it, provides the advantages described with reference to the following diagrams. The electronic equipment 16a of the control unit 16 can be designed / programmed to perform the process / method steps described below. Therefore, please refer to the following description for other advantageous characteristics of the control unit 16 or the regenerative braking system working in cooperation with it.

[0027] Figures 3a and 3b show a coordinate system illustrating one embodiment of how a vehicle's regenerative braking system operates. In the coordinate systems of Figures 3a and 3b, the horizontal coordinate is the time axis t.

[0028] The method described below is performed merely illustratively with the regenerative braking system described above. However, it should be noted that the feasibility of the method is not limited to such brake system types. Rather, it should be noted that the method can be performed with (almost) all brake system types having at least a first wheel brake cylinder 10 assigned to the first axle of the vehicle, a second wheel brake cylinder 12 assigned to the second axle of the vehicle, at least one first wheel inlet valve 18 positioned in front of the first wheel brake cylinder 10, at least one first wheel outlet valve 20 positioned behind the first wheel brake cylinder 10, at least one second wheel inlet valve 22 positioned in front of the second wheel brake cylinder 12, and at least one second wheel outlet valve 24 positioned behind the second wheel brake cylinder 12. Similarly, the feasibility of the method is not limited to any particular vehicle / automobile type of vehicle / automobile equipped with each brake system.

[0029] In the first braking process schematically shown in Figure 3a, from time t0, a non-zero vehicle deceleration a of the vehicle equipped with the regenerative braking system described above is required. This non-zero vehicle deceleration a can be requested, for example, by the driver of the vehicle operating the brake operating element 28 of the braking system, or by the vehicle's automatic speed control device. As soon as a non-zero vehicle deceleration a is requested, the method described herein applies the requested vehicle deceleration a to the regenerative mode Φ r It is confirmed whether the braking system / vehicle can be partially generated by at least one electric motor operating at time t0. Additionally, from time t0, the operating state Φ of at least one electric motor changes from inactive mode Φ0 to regenerative mode Φ0. r It can be switched to.

[0030] In the first braking process described here, the required vehicle deceleration a is very small between times t0 and t1, so this vehicle deceleration is regenerative mode Φ rThis can be achieved by at least one electric motor operating on it. Therefore, in order to produce the highest possible regenerative efficiency during the first braking process, a first target brake pressure p should be adjusted within the first wheel brake cylinder 10 between times t0 and t1. 1target and a second target brake pressure p which should be adjusted within the second wheel brake cylinder 12 2targetThe pressure is (almost) zero or less than or equal to the response pressure of each wheel brake cylinder 10 or 12. Furthermore, between times t0 and t1, at least one first wheel inlet valve 18 positioned in front of the first wheel brake cylinder 10, at least one first wheel outlet valve 20 positioned behind the first wheel brake cylinder 10, at least one second wheel inlet valve 22 positioned in front of the second wheel brake cylinder 12, and at least one second wheel outlet valve 24 positioned behind the second wheel brake cylinder 12 are (substantially) prevented from increasing the brake pressure in the first wheel brake cylinder 10 and the second wheel brake cylinder 12, and thus the first brake pressure p1 (possibly) present in the first wheel brake cylinder 10 and the second brake pressure p2 (possibly) present in the second wheel brake cylinder 12 are controlled to be less than or equal to the response pressure of each wheel brake cylinder 10 or 12. For this purpose, at least one first wheel outlet valve 20 located behind the first wheel brake cylinder 10 and at least one second wheel outlet valve 24 located behind the second wheel brake cylinder 12 can be switched to an open state between times t0 and t1, although this is not shown in the coordinate system of Figure 3a. At least one first wheel inlet valve 18 located in front of the first wheel brake cylinder 10 can also be switched to an open state between times t0 and t1. As can be seen from the coordinate system of Figure 3a, at least one second wheel inlet valve 22 located in front of the second wheel brake cylinder 12 is controlled to an open state by a current signal 52 between times t0 and t1, and because at least one second wheel inlet valve 22 is designed as a valve that is (usually) open when not energized, the current intensity I of the current signal 52 is equal to zero between times t0 and t1.

[0031] In the first braking process shown in Figure 3a, the required vehicle deceleration a becomes very high from time t1, and the vehicle deceleration a is regenerated in mode Φ.r It can only be partially generated by at least one electric motor operating at [a certain time interval]. Therefore, the following time interval T Δp During this process, differential pressure control (Δp control), as described below, is performed in the first wheel brake cylinder 10 and the second wheel brake cylinder 12 of the brake system.

[0032] Time interval T Δp In the first substep of differential pressure control performed therein, the target differential pressure Δp between the first wheel brake cylinder 10 and the second wheel brake cylinder 12 is set. target The target differential pressure Δp is determined. target To determine the first target brake pressure p which should be adjusted within the first wheel brake cylinder 10 1target and a second target brake pressure p which should be adjusted within the second wheel brake cylinder 12 2target The target brake pressure p in the wheel brake cylinders 10 and 12 of the brake system. 1target and p 2target If the following is strictly followed, the required vehicle deceleration a will be in regenerative mode Φ r The system can be continuously determined to be generated with a high probability by at least one electric motor operating in a certain manner, a first brake pressure p1 present in the first wheel brake cylinder 10, and a second brake pressure p2 present in the second wheel brake cylinder 12.

[0033] Preferably, during differential pressure control, when the vehicle deceleration a is in regenerative mode Φ r A motor brake torque applied to the vehicle by at least one electric motor operating in the same location, and a first target brake pressure p that can be generated / is produced by the first wheel brake cylinder 10. 1target If this is achievable within the first wheel brake cylinder 10 (by the corresponding first brake pressure p1 present within the first wheel brake cylinder 10), then a second target brake pressure p should be adjusted within the second wheel brake cylinder 12. 2targetThis is determined to be equal to zero. The required vehicle deceleration a is the regenerative mode Φ r If it can be generated (with a high probability) by only at least one electric motor operating in the first wheel brake cylinder 10, then braking of the vehicle's second axle by the second wheel brake cylinder 12 can be omitted. Otherwise, i.e., regenerative mode Φ r If the motor brake torque generated by at least one electric motor operating in the first wheel brake cylinder 10 is no longer sufficient to produce the required vehicle deceleration a, then the first target brake pressure p 1target and the second target brake pressure p 2target Both can be determined to be not equal to zero, and the second target brake pressure p 2target Typically, the first target brake pressure p 1target The following is specified. In particular, in this case, the second target brake pressure p 2target The required vehicle deceleration a, the motor brake torque of at least one electric motor, and the first target brake pressure p 1target This can be taken into consideration when making a decision.

[0034] Next, the first target brake pressure p 1target Alternatively, the first actual brake pressure p1 and the second target brake pressure p 2target The difference between the two is the target differential pressure Δp target It is identified as such. Therefore, the target differential pressure Δp target It is defined by the following equation (Equation 1) or equation (Equation 2). (Formula 1) Δp target =p 1target -p 2target (Formula 1) Δp target =p1-p 2target The first actual brake pressure p1 can be understood as the (most likely) dominant measured or estimated pressure value within the first wheel brake cylinder 10.

[0035] In the next substep, the target current intensity of the current signal 52 output to at least one second wheel inlet valve 22 is determined. The determination of the target current intensity of the current signal 52 is based on the previously determined target differential pressure Δp target This is done taking that into consideration. For that purpose, the target differential pressure Δp is determined. target Taking this into consideration, the target current intensity or the output value of the target current intensity of the current signal 52 is selected from a value range that includes at least three current intensity values. This is the determined target differential pressure Δp target This can also be described as "smooth Δp control" through continuous control of the target current intensity of the current signal 52 using the current signal 52.

[0036] In the next substep, at least one second wheel inlet valve 22 is controlled by a current signal 52 output to at least one second wheel inlet valve 22, and the (actual) current intensity I of the output current signal 52 (substantially) corresponds to a determined target current intensity. Thus, the control of at least one second wheel inlet valve 22 is performed in the differential pressure control described herein, with a time interval T Δp The target differential pressure Δp determined during the process target This is done with consideration to the above. In this way, a "smooth" control / switching of at least one second wheel inlet valve 22 is obtained, as shown by arrow 60 in the coordinate system of Figure 3a. The "continuous" pressure increase in the first wheel brake cylinder 10, marked by arrow 62 in the coordinate system of Figure 3a, does not result in the "waveform" pressure rise as in the prior art described above. Arrow 64 in the coordinate system of Figure 3a further indicates the first target brake pressure p that should be adjusted in the first wheel brake cylinder 10 at the same time. 1target This shows that only a relatively small deviation occurs in the first actual brake pressure p1 within the first wheel brake cylinder 10.

[0037] In particular, the target current intensity or the output value of the target current intensity of the current signal 52 is determined by the target differential pressure Δp targetIt is determined according to a specified continuous function having a value range containing at least three current intensity values. This can be easily done. In particular, the continuous function has a value range containing at least four current intensity values. The value range of the continuous function can, in particular, contain more than four current intensity values. Determined target differential pressure Δp target The value of the continuous function obtained depending on the target differential pressure Δp target It can also be proportional to the target current intensity of the current signal 52 or the output value of the target current intensity, determined by the target differential pressure Δp. target Depending on the configuration, it can be specified according to a given stair function having at least three staircases, preferably at least four staircases, and especially more than four staircases.

[0038] The output value of the target current intensity can be understood as the value from which the next target current intensity is determined, taking this into consideration. For example, the time interval T Δp In the differential pressure control performed therein, at least one more quantity can be identified, which is additionally taken into consideration when determining the target current intensity in consideration of the output value. In particular, a first target brake pressure p which should be adjusted simultaneously within the first wheel brake cylinder 10 during a specified comparison time interval. 1target From this, a deviation of at least one measured or estimated first actual brake pressure p1 in the first wheel brake cylinder 10 can be identified. Then, taking the identified deviation into account, an offset value for the target current intensity of the current signal 52 can be determined. In this case, the target current intensity of the current signal 52 can be determined as the sum of the output value of the target current intensity and the offset value. The determination of the target current intensity described herein can favorably compensate for component tolerances and / or degradation phenomena of the brake system.

[0039] As an optional developmental form, time interval T ΔpDuring differential pressure control performed in the first wheel brake cylinder 10, at least one measured or estimated first actual brake pressure p1 in the first wheel brake cylinder 10 is simultaneously adjusted to a first target brake pressure p in the first wheel brake cylinder 10. 1target This allows for the determination of periods (continuously) that differ by at least one specified minimum pressure deviation. If the specified period exceeds a specified time threshold, preferably, for the specified or determined valve-closing time, the target current intensity of the current signal 52 is determined so that at least one second wheel inlet valve 22 is switched to a closed state for the valve-closing time specified or determined by the current signal 52 output to it. In this way, the first target brake pressure p to be adjusted in the first wheel brake cylinder 10 is determined simultaneously. 1target This prevents a relatively large deviation of the first actual brake pressure p1 in the first wheel brake cylinder 10 from occurring over a period of time exceeding a time threshold.

[0040] Preferably, time interval T Δp At the beginning of the differential pressure control performed, a first target brake pressure p to be adjusted within the first wheel brake cylinder 10 is determined by equation (Equation 1), i.e., specified or determined by equation (Equation 1). 1target The second target brake pressure p to be adjusted within the designated or determined second wheel brake cylinder 12 2target The target differential pressure Δp is the difference between the two. target This will be decided.

[0041] In the first braking process schematically shown in Figure 3a, the required vehicle deceleration a is achieved by regenerative mode Φ between times t1 and t2. rThis can be achieved by at least one electric motor operating on a t-axis and a first wheel brake cylinder 10 assigned to the first axle of the vehicle. Thus, the first wheel outlet valve 20 located behind the first wheel brake cylinder 10 is held closed from time t1, while the second wheel outlet valve 24 located behind the second wheel brake cylinder 12 is controlled to remain open between times t1 and t2. In this case, differential pressure control is performed as described above between times t1 and t2.

[0042] From time t2, the required vehicle deceleration a is determined by regenerative mode Φ. r This can be performed by only one electric motor operating at a certain speed, a first wheel brake cylinder 10, and a second wheel brake cylinder 12 assigned to the second axle of the vehicle. Thus, the second wheel outlet valve 24 located behind the second wheel brake cylinder 12 is held closed from time t2 (the same as the first wheel outlet valve 20 located behind the first wheel brake cylinder 10). Additionally, brake fluid can also be pumped into the brake system from at least one reservoir chamber 34 located behind the first wheel outlet valve 20 and the second wheel outlet valve 24 by a non-zero pump rotation speed n of at least one pump 36 of the brake system. However, unlike the prior art described above, the pressure increase in the second wheel brake cylinder 12 resulting from time t2 does not cause (almost) any pressure decrease in the first wheel brake cylinder 10.

[0043] In the second braking process shown by the coordinate system in Figure 3b, a vehicle deceleration a that is not equal to zero is required from time t0, but this vehicle deceleration occurs between times t0 and t1 in the regenerative mode Φ rIt can still be produced by at least one electric motor operating in the same manner. However, compared to the first braking process, much faster braking of the vehicle is required. In the second braking process as well, the required vehicle deceleration a, which is not equal to zero, is produced between times t0 and t1 by the regenerative mode Φ r By at least one electric motor operating and only by the first wheel brake cylinder 10 of the first axle, and from time t2, regenerative mode Φ r This can be accomplished by at least one electric motor operating on a first wheel brake cylinder 10 and a second wheel brake cylinder 12 on a second axle. A first target brake pressure p is to be adjusted within the first wheel brake cylinder 10. 1target and a second target brake pressure p to be adjusted within the second wheel brake cylinder 12 2target It is determined accordingly.

[0044] However, during differential pressure control, the measured or estimated first actual brake pressure p1 in the first wheel brake cylinder 10 simultaneously adjusts to a first target brake pressure p in the first wheel brake cylinder 10. 1target If it is confirmed to be smaller by at least one specified limit deviation than the target differential pressure Δp, then preferably, for the specified or determined transition time, target However, according to equation (equation 2), the first actual brake pressure p1 in the first wheel brake cylinder 10, which has been measured or estimated, and the second target brake pressure p to be adjusted in the second wheel brake cylinder 12 are... 2target It is determined as the difference between and . Therefore, the second target brake pressure p which should be adjusted in the second wheel brake cylinder 12 at the same time 2target Therefore, it is possible to reliably prevent deviations from occurring that exceed the limit deviation of the second actual brake pressure p2 in the second wheel brake cylinder 12.

[0045] To adjust the first actual brake pressure p1 present in the first wheel brake cylinder 10 and the second actual brake pressure p2 present in the second wheel brake cylinder 12, a time interval T Δp a new target differential pressure Δp target is adjusted / regulated by the differential pressure control described above. For this purpose, even in the second braking process of Figure 3b, considering the determined target differential pressure Δp target the target current intensity or the output value of the target current intensity of the current signal 52 is selected from a value range including at least three current intensity values. The arrow 64 in the coordinate system of Figure 3b newly indicates that only a relatively small deviation of the first actual brake pressure p1 in the first wheel brake cylinder 10 from the first target brake pressure p 1target to be adjusted in the first wheel brake cylinder 10 occurs. Therefore, different from the prior art described above, during the differential pressure control executed in the time interval T Δp no "soft" braking operation element 28 occurs.

[0046] It should be mentioned that the differential pressure control executed in the two braking processes omits the exchange between the overflow of at least one second wheel inlet valve 22 and the underflow of at least one second wheel inlet valve 22. Considering the determined target differential pressure Δp target it is not necessary to determine the target current intensity or the output value of the target current intensity of the current signal 52 from a value range including at least three current intensity values.

Explanation of Signs

[0047] 10 First wheel brake cylinder 12 Second wheel brake cylinder 14a, 14b Brake circuit 16 Control device 16a Electronic device 18 First wheel inlet valve 20 First wheel outlet valve 22 Second wheel inlet valve 24. Second wheel outlet valve 26 Master brake cylinder 28 Brake operation elements, brake pedal 30 Brake booster 32 Brake fluid reservoir 34 Storage chambers, low-pressure storage chambers 36 pumps 38 Pump motor 40 Diverter Valve 42 High-pressure switching valve 44 Brake operation element sensors 46 Sensor signals 48 Pressure Sensor 50 Pressure sensor signal 52 Current Signal 60 Arrows 62 Arrows 64 Arrows

Claims

1. A control device (16) for the regenerative braking system of a vehicle, The required vehicle deceleration (a) is achieved in regenerative mode (Φ ｒ ) is designed and / or programmed to query or determine whether it can be partially generated by a brake system or at least one electric motor of the vehicle, and optionally includes electronic equipment (16a) in differential pressure control mode, in which differential pressure control mode, The target differential pressure of the first wheel brake cylinder (10) of the brake system assigned to the first axle of the vehicle and the target differential pressure of the second wheel brake cylinder (12) of the brake system assigned to the second axle of the vehicle are - A first target brake pressure (p) to be adjusted within the designated or determined first wheel brake cylinder (10) １ｔａｒｇｅｔ ), or the measured or estimated first actual brake pressure (p) in the first wheel brake cylinder (10) １ )and, —A second target brake pressure (p) to be adjusted within the designated or determined second wheel brake cylinder (12) ２ｔａｒｇｅｔ ) It can be determined as the difference between them. In a control device that can output a current signal (52) to at least one wheel inlet valve (22) positioned in front of the second wheel brake cylinder (12) of the brake system, taking into account the determined target differential pressure, and thereby control the at least one wheel inlet valve (22) by the output current signal (52), A control device characterized in that the electronic device (16a) in the differential pressure control mode is further designed and / or programmed to determine the target current intensity of the current signal (52) in consideration of the determined target differential pressure, by allowing the electronic device (16a) to select a target current intensity of the current signal (52) or an output value of the target current intensity from a range of values ​​including at least three current intensity values, taking the determined target differential pressure into consideration.

2. The control device (16) according to claim 1, wherein the electronic device (16a) in the differential pressure control mode is designed and / or programmed to determine the target current intensity of the current signal (52) or the output value of the target current intensity according to a specified continuous function having the range of values ​​including the at least three current intensity values, depending on the determined target differential pressure.

3. The electronic device (16a) additionally adjusts the first target brake pressure (p) to be adjusted in the first wheel brake cylinder (10) simultaneously after the start of the differential pressure control mode. １ｔａｒｇｅｔ ) from the at least one first actual brake pressure (p) in the first wheel brake cylinder (10) measured or estimated during a specified comparison time interval １ The control device (16) according to claim 1 or 2, which is designed and / or programmed to determine an offset value of the target current intensity of the current signal (52) taking into account the respective deviations of the current signals (52), and to determine the target current intensity of the current signal (52) as the sum of the output value of the target current intensity and the offset value.

4. The electronic device (16a) additionally, after the start of the differential pressure control mode, measures the first actual brake pressure (p) in the at least one measured or estimated first wheel brake cylinder (10). １ ) the first target brake pressure (p) which should be adjusted simultaneously within the first wheel brake cylinder (10) １ｔａｒｇｅｔ The control device (16) according to claim 1 or 2, which is designed and / or programmed to identify a period that is different by at least one specified minimum pressure deviation, and if the identified period exceeds a specified time threshold, to determine the target current intensity of the current signal (52) for a specified or determined valve-closing time such that the at least one wheel inlet valve (22) is switched to a closed state for a valve-closing time specified or determined by the current signal (52) output to the wheel inlet valve.

5. The electronic device (16a) is designed and / or programmed to determine the target differential pressure as the difference between the first target brake pressure (p １ｔａｒｇｅｔ ), which should be adjusted within the first wheel brake cylinder (10) specified or determined, and the second target brake pressure (p ２ｔａｒｇｅｔ ), which should be adjusted within the second wheel brake cylinder (12) specified or determined, at the beginning of the differential pressure control mode. However, when the first actual brake pressure (p １ ) within the first wheel brake cylinder (10) measured or estimated is less than the first target brake pressure (p １ｔａｒｇｅｔ ) to be adjusted within the first wheel brake cylinder (10) simultaneously by at least one specified limit deviation, the electronic device (16a) determines the target differential pressure as the difference between the first actual brake pressure (p １ ) within the first wheel brake cylinder (10) measured or estimated and the second target brake pressure (p ２ｔａｒｇｅｔ ) to be adjusted within the second wheel brake cylinder (12) during the specified transition time. The control device (16) according to claim 1 or 2.

6. A regenerative braking system for a vehicle, The control device (16) according to claim 1 or 2, A first wheel brake cylinder (10) is assigned to the first axle of the vehicle, A second wheel brake cylinder (12) is assigned to the second axle of the vehicle, A regenerative braking system comprising: at least one wheel inlet valve (22) positioned in front of the second wheel brake cylinder (12);

7. A method for operating a vehicle's regenerative braking system, Vehicle deceleration (a) requested by the driver of the vehicle and / or the automatic speed control device of the vehicle is controlled in regenerative mode (Φ ｒ A step of determining whether the braking system operating in the above-mentioned manner or at least one electric motor of the vehicle can cause only a portion of the event, If the vehicle deceleration (a) can be partially caused by the at least one electric motor, the step of performing differential pressure control of the wheel brake cylinders (10, 12) of the brake system is included, and the step of performing the differential pressure control is A substep for determining the target differential pressure of the first wheel brake cylinder (10) of the brake system assigned to the first axle of the vehicle and the second wheel brake cylinder (12) of the brake system assigned to the second axle of the vehicle, - A first target brake pressure (p) to be adjusted within the designated or determined first wheel brake cylinder (10) １ｔａｒｇｅｔ ), or the measured or estimated first actual brake pressure (p) in the first wheel brake cylinder (10) １ )and, —A second target brake pressure (p) to be adjusted within the designated or determined second wheel brake cylinder (12) ２ｔａｒｇｅｔ ) The difference between them is determined as the target differential pressure in the substep, A method comprising the substep of controlling at least one wheel inlet valve (22) positioned in front of the second wheel brake cylinder (12) of the brake system by a current signal (52) output to the at least one wheel inlet valve (22) taking into consideration the determined target differential pressure, A method comprising the substep of determining the target current intensity of the current signal (52) in consideration of the determined target differential pressure, wherein the target current intensity of the current signal (52) or the output value of the target current intensity can be selected from a range of values ​​including at least three current intensity values, in consideration of the determined target differential pressure.

8. The method according to claim 7, wherein the target current intensity of the current signal (52) or the output value of the target current intensity is determined according to a specified continuous function having the range of values ​​including the at least three current intensity values, depending on the determined target differential pressure.

9. During differential pressure control, the first target brake pressure (p) to be adjusted simultaneously within the first wheel brake cylinder (10) １ｔａｒｇｅｔ ) from the at least one first actual brake pressure (p) in the first wheel brake cylinder (10) measured or estimated during a specified comparison time interval １ The method according to claim 7 or 8, wherein the offset value of the target current of the current signal (52) is determined by taking into consideration the respective deviations of the above, and the target current intensity of the current signal (52) is determined as the sum of the output value of the target current intensity and the offset value.

10. During the differential pressure control, the first actual brake pressure (p) in the first wheel brake cylinder (10) is measured or estimated by the first wheel brake cylinder (10). １ ) are each simultaneously adjusted within the first wheel brake cylinder (10) to the first target brake pressure (p １ｔａｒｇｅｔ The method according to claim 7 or 8, wherein a period differing by at least one specified minimum pressure deviation is identified, and if the identified period exceeds a specified time threshold, the target current intensity of the current signal (52) is determined such that the at least one wheel inlet valve (22) is switched to a closed state for the specified or determined period by the current signal (52) output to the wheel inlet valve.

11. At the start of the differential pressure control mode, a first target brake pressure (p) is set to be adjusted within the designated or determined first wheel brake cylinder (10). １ｔａｒｇｅｔ ) and a second target brake pressure (p) to be adjusted within the designated or determined second wheel brake cylinder (12) ２ｔａｒｇｅｔ The target differential pressure is determined as the difference between the first actual brake pressure (p) in the first wheel brake cylinder (10) that has been measured or estimated. １ ) simultaneously adjusts the first target brake pressure (p) to be adjusted within the first wheel brake cylinder (10). １ｔａｒｇｅｔ If the target differential pressure is less than at least one specified limit deviation than the first actual brake pressure (p) in the first wheel brake cylinder (10) during the specified or determined transition time, then during the specified or determined transition time, the target differential pressure will be less than the first actual brake pressure (p) in the first wheel brake cylinder (10) that was measured or estimated. １ ) and the second target brake pressure (p) to be adjusted within the second wheel brake cylinder (12) ２ｔａｒｇｅｔ The method according to claim 7 or 8, which is determined as the difference between ) and ).

12. During the differential pressure control, the vehicle deceleration (a) is in regenerative mode (Φ ｒ The motor brake torque applied to the vehicle by the at least one electric motor operating at ) and the first target brake pressure (p) that can be generated by the first wheel brake cylinder (10) １ｔａｒｇｅｔ ) and, if achievable by, the second target brake pressure (p ２ｔａｒｇｅｔ ) is determined to be equal to zero, otherwise the second target brake pressure (p ２ｔａｒｇｅｔ ) comprises the vehicle deceleration (a), the motor brake torque, and the first target brake pressure (p １ｔａｒｇｅｔ The method according to claim 7 or 8, determined by taking into consideration the following:

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