Method for operating an electric locking actuator, electric locking actuator for a car parking brake function, and motor vehicle wheel brake with an electric parking brake function

Abstract

A method for operating a locking actuator for a parking brake function (34), which comprises - a pawl wheel (38); - a parking pawl (46); - a parking pawl actuator (42) for displacing the parking pawl (46) from a basic position in the direction of the pawl wheel (38) with an actuation force; - a counter spring (54) which presses or pulls the parking pawl (46) in the direction of the basic position, comprising the steps of - rotating the pawl wheel (38) in a first direction of rotation (74) until the parking pawl (46) is free; - displacing the parking pawl (46) with a test force (78) which is smaller than the actuation force; - checking the rotational freedom of the pawl wheel (38).

Description

[0001] Description

[0002] Method for operating an electric locking actuator, electric locking actuator for an automotive parking brake function and motor vehicle wheel brake with electric parking brake function

[0003] The invention relates to a novel method for operating an electric locking actuator for a parking brake function of a wheel brake of a motor vehicle according to the preamble of claim 1. Furthermore, an electric locking actuator for a parking brake function of a wheel brake of a motor vehicle as well as a novel electrically actuated wheel brake for a motor vehicle are presented.

[0004] A well-known electric drive actuator for commercially available electric parking brakes on motor vehicle wheel brakes is systematically defined as self-sufficient and, for the electric parking brake function, has a separate electric motor actuator (electric motor-gearbox assembly) that is designed to be automatically self-locking without current for parking by means of structural means based on internal friction in the parking brake actuator drive train. In combined vehicle wheel brake systems that provide a service brake function and an electric parking brake function (EPB), this automatically self-locking parking brake electric motor drive also competes with a secondary service brake actuator whose service brake actuator drive train is defined as de-energized—without structural self-locking. The service brake actuator is typically configured as a hydraulic piston-cylinder assembly.

[0005] In contrast, DE 196 15 186 C1 proposes a particularly efficiently rationalized and combined purely electrically actuated motor vehicle wheel brake of the disc brake type, comprising the electric electric motor gear actuator for the electric service brake function as well as for the electric parking brake function, in that the same drive train of this electric motor gear actuator is structurally shown to be de-energized and is used for all braking functions.

[0006] DE 10 2018 109 465 A1 does not integrate a wheel brake, and the actuator system lacks brake clamping force generation. Instead, an automatically locking motor vehicle drivetrain is presented using improved methods, including a space-saving design, for determining the state of a spindle-driven transmission lock. Its locking kinematics are such that the transmission lock is automatically engaged or disengaged with a parking lock gear by an electric motor—i.e., when the spindle parking lock actuator is driven. To determine an additional state between the engaged and disengaged parking pawl, the axially displaced positioning of the spindle is detected by a sensor using a measuring coil.

[0007] DE 10 2018 118 258 A1 corresponds to a certain extent to the technology of the transmission lock according to DE 10 2018 109 465 A1, but as a replacement for the measuring coil, an axially directed internal bore is assigned to the spindle drive in order to provide an inductive sensor in a space-saving manner and to use it for sensing purposes.

[0008] From DE 10 2020 213 916 A1 an electromechanical motor vehicle wheel brake is known, comprising a brake housing module and an actuator module with drive and transmission drive train, which is controlled electrically or electronically via a control unit and to which at least one actuating means is assigned, which, with a transmission means, is suitable and intended to act on at least one associated motor vehicle friction lining for the purpose of releasable friction cooperation with a rotatably mounted brake rotor.

[0009] Fig. 3 of EP 1 032 773 B1 illustrates a positively locked, currentless electric parking lock for an electrically combined disc brake design, and the combined electric disc brake system suffers from the lack of suitable diagnostic capabilities. The invention is based on the object of specifying an improved method for operating a locking actuator for a parking brake function or a parking lock with increased safety. Furthermore, an improved locking actuator for a parking brake function and an improved electrically actuated wheel brake are to be specified. Based on the deficient prior art, the object of the present invention is to provide a novel, improved method for operating an electric locking actuator for an electric parking brake function of a motor vehicle wheel brake.Furthermore, a novel electric locking actuator for a parking brake function of a wheel brake of a motor vehicle is desired. A novel electrically combined actuated wheel brake with an electric parking brake function for a motor vehicle is also to be provided.

[0010] Using an integrated wheel brake system or parking brake operating method according to the invention with an electric locking actuator for the parking brake function, one or more brake pads are pressed against an associated brake rotor (brake drum or brake disc) by means of an electric motor with a gear (actuator) and actuating device, preferably a spreading device with a defined, predetermined brake application force, to activate the electric parking brake, the brake pad(s) are pressed against a corresponding brake rotor (brake drum or brake disc), and the application force / holding force is held in a currentless, positively locked manner. When parking, the set application force flow of the described friction brake is therefore "self-contained" and also positively locked. In other words, the respective wheel brake of the friction brake type is, to a certain extent, "locked or pre-tensioned" by means of the actuator force, and the electric motor or the transmission is controlled by means of the electrically switchable, ieAn electrically actuated parking pawl or parking brake pawl is positively locked via a control and / or regulating unit, without the need for current to be applied for parking. This is because the parking pawl, by definition, engages in a switchable and positively locking manner with the actuator drive train in the form of a ratchet wheel or gear with undercut teeth. This engagement takes place in a correctly positioned, controlled or regulated manner precisely when the switchable parking pawl of the wheel brake is in the correct alignment with the cavity between two projections, i.e. between two ratchet wheel teeth / gear teeth, so that the holding force is transferred from the parking pawl during parking, and at the same time the parking pawl is automatically held in the locked position.

[0011] The parking brake actuation is released when the ratchet wheel is moved in the tensioning direction by the electric motor and the parking pawl is pushed out of its positive engagement, i.e. becomes free. For this purpose, a mechanical return mechanism acts on the parking pawl, which preferably has at least one elastoelement (e.g. an elastic tension and / or compression spring), which may be designed as a counter spring. The elastoelement is particularly preferably provided with a defined elastic preload force and basically applies or holds the parking pawl in the unactuated release position with the preload force. An (elastically preloaded) counter spring can thus be provided and intended to push a parking brake-actuated parking pawl back into its unactuated initial position when the parking brake actuation is released, if an undercut tooth profile of a ratchet wheel allows or releases the necessary clearance for a pawl return movement.

[0012] The activation and release of the parking brake as described above during parking operation is fundamentally desired and, in this sense, also occurs fundamentally satisfactorily in trouble-free and error-free operation. However, the invention is also subject to an important safety precaution to prevent malfunctions in the event of a fault (e.g. due to breakage of a counter spring 54) in the sense of a countermeasure. Without a safety precaution, the spring break mentioned as an example could cause an unwanted locking of a wheel brake when the vehicle is in motion. In particular, during service braking controlled by an electric motor, the brake pads are applied while the vehicle is moving (service brake) by the electric motor with gear and spreading unit with respect to the brake rotor, i.e., spread apart, for example, within the brake drum.The present invention detects and avoids hazards caused by a defect (problematic case of unwanted blocking / locking) using a special testing method. This is because, during vehicle operation, each service wheel brake must be released without power, and any inhibition of the brake actuation mechanism during vehicle operation (during service braking) must be excluded and prevented. To relieve the brake load, the electric motor or the spreader unit is retracted, and the brake pads are returned to the unbraked starting position or braking standby position by one or more brake pad return springs.

[0013] Particularly from an FMEA perspective, i.e., for example, in connection with a defective return mechanism of an electrically switchable parking pawl (e.g., due to environmental influences, wear, jamming, a damaged or fatigued (broken or missing) elasticity / counter spring), it is conceivable in principle that a parking pawl could engage uncontrollably and automatically without the driver requesting the parking brake or automatically requesting the electric parking brake. Under certain boundary conditions, such as vibration or shock (which may occur during vehicle use) with a system defect, there is therefore a fundamental possibility that the parking pawl could engage undesirably.However, undesired and, moreover, positively locked parking brake intervention can fundamentally endanger vehicle driving safety during vehicle operation, which is efficiently, safely and sustainably excluded by the present invention.

[0014] The present invention thus makes a significant contribution to the electrically automated (status) monitoring of an electric wheel brake of a passenger car, and thus a special contribution to increased vehicle driving safety, by systematically avoiding both design and methodologically, so that the invention represents a safety system that guarantees that, during vehicle operation, an accidental or otherwise undesired parking brake locking of a wheel brake cannot occur, with undesirable consequences such as undesired friction buildup, undesired braking torque, undesired continuous braking, or an undesired locked wheel. The driving stability of a vehicle is ensured in all cases by the present invention, and the state of the wheel brake / parking brake can be reliably detected electrically, preferably automatically, by the present invention.The corresponding information about the detected (parking) brake status or about a specific parking pawl is available in the connected control and / or regulation unit (e.g. EPB + ESC-ECU) and can be integrated, communicated and shared with third parties on request in the networked on-board network or vehicle system, for example with other, also peripheral, electrical control units, with apps and / or with a vehicle driver and / or in other ways as required and / or desired - or according to the respective (software) configuration, for example for the purpose of electrically automated, in particular for driverless vehicle control, computer-supported further processing and / or for automatic function monitoring by a service company, vehicle manufacturer or similar.

[0015] With regard to the method, this object is achieved according to the invention by a method having the features of claim 1. The method serves to operate a locking actuator for parking brake function, which comprises a ratchet wheel or parking lock wheel, a parking pawl and a parking pawl actuator for displacing the parking pawl from a home position towards the ratchet wheel with an actuating force, as well as a counter spring which pushes or pulls the parking pawl towards the home position. The method comprises the steps of rotating the ratchet wheel in a first direction of rotation until the parking pawl is free, displacing the parking pawl with a test force which is less than the actuating force, and checking the rotational freedom of the ratchet wheel.

[0016] In summary, the present invention makes it possible for the first time to present a particularly innovative, safely rationalized (synergistic), efficient brake-by-wire solution that satisfies all legal requirements and FMEA specifications for electrically combined car wheel brakes (car service brake + integrated parking brake). This brake-by-wire solution can be implemented without a hybrid supply because a single electromotive-based actuating device is sufficient for the purpose of wheel-specific electrical brake application force generation (for the service brake function and also for the parking brake function), which defines the same electromotive geared motor drive train (MGU) for all braking functions (service brake function and parking brake function), which is basically configured to be self-locking-free.In other words, compared to currently commercially available hydraulic combined car wheel brakes (drum brakes or disc brakes) with an integrated electric parking brake, it makes it possible to rationalize complex brake hydraulics as well as a self-locking, currentless electric parking brake motor drive train. The invention systematically creates added value, reduces previously required hardware expenditure, promotes environmental friendliness (i.e., sustainability), and, at the same time, releases weight savings and rationalizing synergy effects that are entirely in the interest of all automotive customers, shareholders, and stakeholders.

[0017] The ratchet wheel or parking lock wheel has a large number of undercut teeth, whereby the parking pawl engages in a tooth gap of the ratchet wheel to carry out the parking brake functionality.

[0018] The ratchet free state refers to the state in which the parking pawl is not in contact with the ratchet wheel during rotation and restricts its rotational movement.

[0019] Advantageous features, effects and embodiments of the invention emerge from subclaims and a description based on the drawing.

[0020] The invention is based on the idea that unintentional locking of the parking pawl while driving should be prevented at all costs. The integrity of the counter spring should be guaranteed at all times during vehicle operation.

[0021] As has now been recognized, this goal can be achieved by testing spring integrity via the residual spring force. This ensures that the parking pawl will remain in the unlocked position, even in the event of vibration or shock.

[0022] Advantageously, when checking the rotational freedom of the ratchet wheel, the ratchet wheel is rotated at least once in a second rotational direction opposite to the first direction of rotation. This reliably checks that the parking pawl does not engage the ratchet wheel.

[0023] In an advantageous embodiment of the method, the ratchet wheel is rotated at least once in both directions of rotation.

[0024] The rotation of the ratchet wheel is preferably torque-limited. The actuator motor torque can be so great that it could break any extended pawl against the parking lock gear. Limiting this torque ensures that the mechanical integrity of the parking pawl and ratchet wheel is maintained in the event of a defective counter spring.

[0025] Once the ratchet wheel is free to rotate, the current supply to the parking pawl actuator is stopped. The functionality of the counter spring has been successfully verified, and the parking brake can continue to operate safely.

[0026] In a preferred embodiment of the method, if the rotational freedom of the ratchet wheel could not be determined or verified, this is checked again for plausibility. If the rotational freedom still cannot be determined or verified, this wheel brake is reported as defective. The vehicle then only drives with three brakes. The automobile manufacturer or the customer preferably decides on the next steps.

[0027] In a preferred embodiment, the test force corresponds to the equivalent force of the vibration requirements to be met. The resulting force corresponds to a mechanical shock of a maximum defined vibration requirement. This preferably corresponds to a 50g shock in the actuation direction of the parking pawl. The spring force should always be greater than this force.

[0028] With regard to the locking actuator for the parking brake function, the above-mentioned object is achieved according to the invention by a locking actuator for the parking brake function having the features of claim 7. The locking actuator for the parking brake function comprises a ratchet wheel, a parking pawl, a parking pawl actuator for displacing the parking pawl from a home position in the direction of the ratchet wheel with an actuating force, a counter spring which pushes or pulls the parking pawl in the direction of the home position, and a control and / or regulating unit which is configured to carry out a method described above.

[0029] In a preferred embodiment, the locking actuator for the parking brake function is electrically configured with at least one coil, which is supplied with an actuating current to move the parking pawl. The actuating current is selected to be sufficiently large to exert a desired actuating force on the parking pawl.

[0030] In further preferred embodiments, the locking actuator for the parking brake function can be designed according to a hydraulic or pneumatic operating principle and actuate the parking pawl hydraulically or pneumatically.

[0031] In a preferred embodiment, the counter spring is a compression spring.

[0032] The locking actuator for the parking brake function preferably has a housing, with the counter spring, designed as a compression spring, supported on a base of the housing. The base has an opening through which the parking pawl can be axially displaced.

[0033] With regard to the electrically actuated wheel brake, the above-mentioned object is achieved according to the invention by a locking actuator for the parking brake function as described above. The wheel brake can be designed as a drum brake or a disc brake.

[0034] The advantages of the invention lie in the fact that the described method can be used to determine the reliable functionality of the electrically actuated wheel brake. The functionality or integrity of the counter spring can be checked without the need to measure the coil's inductance. Under suitable conditions, it is possible to detect the movement of the parking pawl using an inductance measurement in the coil. However, this is very complex to develop and implement.

[0035] The proposed, more cost-effective solution can prevent unintentional locking of the brake while driving, which would otherwise lead to safety-critical driving situations. The method can be used with a variety of electrically actuated wheel brakes with a locking actuator for the parking brake function.

[0036] An embodiment of the invention is explained with reference to the drawing. The drawing shows, in many cases in highly schematic sketches:

[0037] FIG. 1 schematically shows a combined electric service and parking brake in a preferred embodiment as a drum wheel brake system including a preferred embodiment of a locking actuator for the parking brake function,

[0038] FIG. 2 shows a flowchart of a method in a preferred embodiment,

[0039] FIG. 3 shows schematically the locking actuator for the parking brake function in a first method step,

[0040] FIG. 4 shows a schematic view of the locking actuator for the parking brake function in a second method step, FIG. 5 shows a schematic view of the locking actuator for the parking brake function in a third method step, and

[0041] FIG. 6 shows a schematic view of the locking actuator for the parking brake function in a fourth method step.

[0042] The invention is provided with corresponding reference numerals in the drawing.

[0043] A combined electric motor vehicle wheel brake system / wheel brake 2 of the drum brake type, sketched as an example in Fig. 1, basically has one, two, or more brake shoes or brake linings 6, which can be metered by means of an actuating unit or spreading unit 10 for the purpose of implementing a service brake request or a parking brake request, or can be brought into frictional engagement with an associated brake rotor, such as in particular into engagement with a brake drum (not shown), with a predetermined contact force / application force. A method or device according to the invention - locking actuator for a parking brake function 38 - can also be used in a wheel brake system that defines one or more brake discs (not shown). The (brake) application force or a brake load can be sensed via the control and / or regulating unit 48 with the aid of a brake force sensor and / or brake torque sensor (hereinafter referred to as brake load sensor 14 for short).The directly, indirectly detected or determined load is used as information in the electrical control and / or regulating unit 48 of the wheel brake for controlling and / or regulating a clamping force as well as for monitoring the wheel brake function. The use of said brake load information may, in principle, relate both to a parking brake function on the one hand and to a service brake function on the other. The electrically actuated wheel brake 2 has an electric motor 18 for the purpose of motor-driven clamping force generation. The electric motor 18 drives a motor shaft 26, which is coupled to the spreading unit 10 via a gear 30. A preferably redundant motor position sensor 22 (referred to as MOPS) is used for motor monitoring or control and / or regulating.The term motor position in the sense of the invention can refer both to the current motor speed, motor shaft rotational position and, starting from a reference position, to a concretely executed number of motor shaft rotations in one or the other direction of rotation 74,90.

[0044] The electrically actuated wheel brake 2 further comprises a locking actuator for a parking brake function 38. At least one electrical switching module or the entire locking actuator can be provided as a separate subassembly in a separate housing 62. The locking actuator for the parking brake function 38 comprises, on the one hand, a ratchet wheel 38 that can generally rotate with the motor shaft 26, or can be located elsewhere on or in the transmission. It is generally sufficient for the ratchet wheel 38 to be present as a downstream gear component on a transmission shaft, and for the transmission shaft to participate in the transmission power flow of the actuator via at least one meshing transmission gear.

[0045] Furthermore, the locking actuator for the parking brake function 38 comprises a parking pawl actuator 42 for a parking pawl 46. In the preferred embodiment shown, the parking pawl 46 is mounted in a rotationally fixed manner on or in a housing, armature, or holder of the wheel brake. The parking pawl 46 is guided so as to be translationally displaceable relative to the wheel brake. Accordingly, the parking pawl actuator shown with switching positions serves to move the parking pawl 46, guided in a translationally transverse manner as required, from a rearward basic position into an advanced engaged position, in which the parking pawl 46 engages the ratchet wheel 38 and blocks it so as to be rotationally fixed. For the purpose of a kinematically alternative design, a parking pawl (not shown) can be pivotable relative to the ratchet wheel 38, with the result that a limited pivoting movement may be performed for electrical switching.

[0046] The parking pawl actuator 42 has at least one electrical coil 44 which is addressed in a defined manner by the control and / or regulating unit 42 and which is briefly energized with a defined predefined actuation current by means of a current pulse for electrical switching, ie for kinematically moving, shifting or pivoting the parking pawl 46.

[0047] The position change caused by the current pulse and the positive engagement of the rotationally fixed parking pawl 46 in an associated cavity of the ratchet wheel 38 hold the wheel brake in its applied position. The electric actuator is blocked from release because rotation of the ratchet wheel 38, and thus the rotation of the actuator, motor shaft 26, etc., is inhibited in a positive and currentless manner. Consequently, the wheel brake, with its application force, is held in a positive, currentless manner in the parking brake function. The applied position of brake pads 6, with their contact pressure against the brake rotor / brake drum, is thus fixed in a positive, currentless manner. This is how the parking brake functionality is realized.

[0048] With such an electrically actuated wheel brake 2, it is important that the rotation of the ratchet wheel 38 is prevented reliably so that the motor vehicle can be shut off or parked reliably and the brake is not released unintentionally. However, it is also important that the parking pawl 46 does not engage the ratchet wheel 38 unintentionally, for example while driving, which would result in the brake being locked. A locking actuator for the parking brake function 34 is assigned an electrical control and / or regulating unit 48, which monitors or controls the wheel brake in question and, in particular, its parking brake function, i.e., release and actuation. For this purpose, the control and / or regulating unit 48 is essentially electrically connected to the sensor system, electric motor 18, motor position sensor 22, and parking pawl actuator 42.The electrical control and / or regulating unit 48 is further designed, suitable and intended to carry out an operating method explained in detail below.

[0049] The method according to the invention, the embodiment of which is described in more detail below by way of example in connection with FIGS. 4-6, furthermore always ensures that the unactuated actuator drive train with unactuated parking pawl 46 always remains in its unlocked position, so that a fundamentally released brake is met as an initial prerequisite or requirement for an electric car wheel brake of the service brake type.

[0050] FIG. 2 shows a flowchart of a preferred embodiment of the method. FIG. 3 shows the switchable locking actuator for the parking brake function 34, illustrated as an assembly / module in its own housing 62, in a state in which the parking brake is activated. The parking pawl 46 engages positively with the ratchet wheel 38. To enable this, the electric locking actuator for the parking brake function 34 has the parking pawl actuator 42 with its electromagnetic coil 44, which, when supplied with a predetermined current that is greater than or equal to an actuation current, serves to move the magnetic armature of the parking pawl 46 from a home position into the engaged position illustrated in FIG. 3. The locking actuator for the parking brake function 34 also has at least one restoring elasticity. The elasticity can, in principle, be implemented in any desired design.For example, the elasticity is structurally provided as a counter spring 54 in order to move the parking pawl 46 into a home position to release the actuated parking brake or to hold the parking pawl 46 in its home position (i.e., the release position) when the coil 44 is de-energized. For example, the elasticity is clamped between the parking pawl 46 and the housing 62 with a defined elastic preload force. In the embodiment as a counter spring 54, the elasticity may, on the one hand, rest on a base 58 of the housing 62, wherein an opening 66 may also be formed in the said base 58 as an outlet for the parking pawl 46. Finally, it is understood that the elasticity may, on the other hand, rest in, on or on a seat of the parking pawl 46.

[0051] The procedure explained below is preferably performed when the parking brake is released or during the parking brake release process. For example, the vehicle is parked and the driver wants to drive off, ideally automatically.

[0052] In a first method step 70 (see FIG. 2), which is shown in FIG. 4, the ratchet wheel 38 is electrically rotated in a first rotational direction 74 by the electrical control and / or regulating unit 48 until the parking pawl 46 is freely movable in the transverse direction without a positive undercut and does not engage with the ratchet wheel 38, or automatically comes out of the positive-locking, rotationally fixed engagement with the ratchet wheel 38. This occurs, for example, due to the elastically prestressed elasticity, which fundamentally permanently applies a defined prestressing force to the parking pawl, and wherein a line of action of the elastic spring prestressing force always points in the release direction. Consequently, the permanent spring force / prestressing force of the elasticity acts as a restoring means. Parallel to this or simultaneously, the parking pawl actuator 42 is supplied with a current that is lower than the actuation current.The actuation current is a current applied to the coil 44 with a magnitude such that the electromagnetically applied actuating force of the parking pawl actuator 42 is sufficient to overcome the elastically applied, defined pretensioning force of the elasticity, i.e., the parking pawl 46 is displaced with electromagnetically applied force in the engagement direction for positive engagement with the ratchet wheel 38. It is understood that the electrical control and / or regulating unit 48 observes and / or monitors the various applied electrical currents (electric motor, coil, etc.). As a result, a function and / or position sensing of the parking pawl 46 is possible. With regard to the electric motor 18, the motor current can also be monitored, whereby this can additionally include the polarity due to a change in the direction of rotation in the first or second direction. During the low (test) current application, two opposing currents act on the parking pawl 46, i.e.competing forces, namely 1. an electromagnetically generated test force 78, which is caused by the comparatively low current supply to the parking pawl actuator 42, and 2. the spring force 82 exerted by the elasticity / counter spring 54 with the opposite direction of action on the parking pawl 46. Since the test current, which correlates with the test force 78, is smaller than the actuation current, the parking pawl 46 should not move in the direction of engagement with the ratchet wheel 38 when the counter spring 54 is present or properly preloaded.Only in the case of a defect such as a stiff pawl actuator, if the elasticity is completely missing, elasticity is broken, elasticity is worn or slightly jammed, or in the case of defect conditions with comparable symptoms (which result in the retention force exerted by the elasticity / counter spring 54 being insufficient), can the parking pawl 46 be displaced in the engagement direction to the ratchet wheel 38 or be engaged in an undesirable form-fitting engagement during this energization of the parking pawl actuator 42.

[0053] It was recognized that the drive force necessarily exerted on a stationary parking pawl 46 in order to move it from a standstill is greater than the drive force which is sufficient after it breaks away to uniformly move / displace the moving parking pawl 46 further (a distinction between friction at rest and friction in motion is to be provided as an improvement). Accordingly, it is proposed that a so-called "breakaway force" be taken into account. It is added that this, as well as stick-slip effects, can be automatically detected with further improved control and regulation, e.g. in conjunction with a correspondingly improved, further developed electronic control and / or regulating unit 48, and that disturbing influences orObstacles are therefore automatically detected during the process, learned, and stored in a microprocessor / memory, and any disturbances can therefore be automatically filtered out or compensated for in future recurring actuation processes for the purpose of compensation, without departing from the invention. In a second method step 86, which is shown in FIG. 5, the freedom from disturbances of the parking pawl function or the rotational freedom of the ratchet wheel 38 is checked or tested (verified). Accordingly, an operating method for the automatic electrical or electronic verification of proper function of the parking brake is defined. The coil 44 of the parking pawl actuator 42 is supplied with test current by the control and / or regulating unit 48.The electric motor 18 is reversely energized by the control and / or regulating unit 48 such that the ratchet wheel 38 begins to rotate, specifically in the second rotational direction 90, which is defined exactly opposite to the first rotational direction 74. The automated IO check using the electrical control and / or regulating unit 48 is carried out as follows: With the elastically preloaded elasticity / counter spring 54 intact, the spring force F_Spring applied to the parking pawl 46 is - as can be seen - always greater than the force F_coil generated by the test current, with the consequence that the parking pawl 46 does not move, or at most moves imperceptibly, in the direction of the ratchet wheel 38. Because the parking pawl 46 does not move or moves very slightly in the direction of the ratchet wheel 38, there is no inhibition by form closure. Consequently, the vehicle wheel brake can relax and the ratchet wheel 38 can rotate unhindered and freely in the second direction 90.

[0054] With the aid of a motor position sensor 22 (called MOPS) or by means of a motor control system implemented in the control and / or regulating unit 48, the rotation of the ratchet wheel 38 is monitored, detected and consequently electrically and automatically verified as to whether it is released in a rotation-free manner.

[0055] In a third method step 94 shown in FIG. 6, if the rotational freedom of the ratchet wheel 38 has been determined, the actuation current is reduced to zero.

[0056] According to the invention, it is preferred that the operating method according to the invention or the electric locking actuator according to the invention, for the purpose of embodying an electric parking brake function for light passenger car applications, is present in (or at) preferably a motor vehicle drum brake. This can, in principle, be any drum brake type, such as in particular a simplex drum brake, but particularly preferably a servo drum brake, such as in particular a duo-servo drum brake. Furthermore, alternatively, the invention can be embodied in or at a motor vehicle disc brake. Primarily suitable for this are floating-caliper disc brakes with or without hammerhead-shaped friction linings, as well as the proven pin-slider disc brake types.In particular for heavy and medium-heavy passenger car applications such as SUVs, flatbed trucks, delivery vans, mobile homes or similar applications, it may be an alternative if the invention is embodied for and in a centrally integrated drum-in-hat motor vehicle drum brake in conjunction with a motor vehicle disc brake as a service brake.

[0057] List of reference symbols

[0058] 2 electrically operated wheel brakes

[0059] 6 brake pad

[0060] 10 Spreading unit

[0061] 14 Brake force / brake load sensor

[0062] 18 electric motor

[0063] 22 Engine position sensor

[0064] 26 Motor shaft

[0065] 30 gearboxes

[0066] 34 Locking actuator for parking brake function

[0067] 38 ratchet wheel

[0068] 42 Parking pawl actuator

[0069] 44 coil

[0070] 46 parking handle

[0071] 48 Control and / or regulation unit

[0072] 50 process steps

[0073] 54 Counter spring

[0074] 58 Floor

[0075] 62 housings

[0076] 66 Opening

[0077] 70 process steps

[0078] 74 first direction of rotation

[0079] 78 test force

[0080] 82 spring force

[0081] 86 Process step

[0082] 90 second direction of rotation

[0083] 94 third procedural step

Claims

Patent claims 1 . A method for operating an electric locking actuator for a parking brake function (34), which comprises - a ratchet wheel (38); - a parking handle (46); - a parking pawl actuator (42) for displacing the parking pawl (46) from a basic position in the direction of the ratchet wheel (38) with an actuating force; - an elasticity, in particular a counter spring (54), which pushes or pulls the parking pawl (46) towards a basic position; and with an electronic control and / or regulating unit (48), characterized by the steps Rotating the ratchet wheel (38) in a first rotational direction (74) until the parking pawl (46) is free; Moving the parking pawl (46) with a test force (78) which is less than the actuation force; - Check the rotational freedom of the ratchet wheel (38).

2. Method according to claim 1, characterized in that when checking the rotational freedom of the ratchet wheel (38), the ratchet wheel (38) is rotated at least once in a second rotational direction (90) opposite to the first rotational direction (74).

3. Method according to claim 1 or 2, characterized in that the rotation of the ratchet wheel (38) takes place with torque limitation.

4. Method according to one or more of the preceding claims, characterized in that when the ratchet wheel (38) is free to rotate, the actuation of the parking pawl actuator (42) is terminated.

5. Method according to one or more of the preceding claims, characterized in that the level of the test force corresponds to the equivalent force of the vibration requirements to be ensured.

6. Method according to one or more of the preceding claims 1 - 5, characterized in that it is provided for the purpose of a software-supported and in particular automated, and furthermore in particular automatic, functional check of a correct function of an electric parking brake function in conjunction with a, preferably electric, motor vehicle drum brake or in conjunction with a, preferably electric, motor vehicle disc brake.

7. Locking actuator for a parking brake function (34), comprising - a ratchet wheel (38); - a parking handle (46); - a parking pawl actuator (42) for displacing the parking pawl (46) from a basic position in the direction of the ratchet wheel (38) with an actuating force; - an elasticity, in particular a counter spring (54), which pushes or pulls the parking pawl (46) towards the basic position; and - an electronic control and / or regulating unit (48).

8. Locking actuator for a parking brake function (34) according to one or more of the preceding claims, characterized in that the electronic control and / or regulating unit (48) is designed and configured to carry out an operating method according to one of claims 1 - 5.

9. Locking actuator for a parking brake function (34) according to one or more of the preceding claims, characterized in that the parking pawl actuator (42) is electrically connected to the control and / or regulating unit (48) and is designed with at least one coil (44) which is supplied with an actuating current for displacing the parking pawl (46) by means of the control and / or regulating unit (48).

10. Locking actuator for a parking brake function (34) according to one or more of the preceding claims 1-9, characterized in that the elasticity with a defined preload force is present in such a way that the parking pawl (46) is permanently subjected to preload force by the elasticity.

11. Locking actuator for a parking brake function (34) according to one or more of the preceding claims, characterized in that the elasticity is designed as a compression spring.

12. Locking actuator for a parking brake function (34) according to one or more of the preceding claims, characterized in that the parking pawl actuator (42) is present as an independently represented subassembly in its own housing (62).

13. Locking actuator for a parking brake function (34) according to one or more of the preceding claims, characterized in that the elasticity is elastically clamped between a bottom (58) of a housing (62) and the parking pawl.

14. Locking actuator for a parking brake function (34) according to one or more of the preceding claims, characterized in that the parking pawl actuator (42) is provided integrated on or in a motor-gearbox assembly (MGU) of an electric brake actuator of a wheel brake (2).

15. Motor vehicle wheel brake (2), comprising a locking actuator for a parking brake function (34) according to one or more of the preceding claims 7-14.

16. Motor vehicle wheel brake (2) according to claim 15, characterized in that the wheel brake (2) is designed as a motor vehicle drum brake.

17. Motor vehicle wheel brake (2) according to claim 15, characterized in that the wheel brake (2) is designed as a motor vehicle disc brake.

18. Motor vehicle wheel brake (2) according to one or more of claims 15 - 17, characterized in that the wheel brake (2) is designed as a Drum-in-hat motor vehicle drum brake designed for an electric parking brake function in conjunction with a motor vehicle disc brake as a service brake.

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