Parking safety device for a motor vehicle

Abstract

Parking safety device (1) for a motor vehicle (2), comprising at least the following components: - a gear wheel (3) which, in the state of the parking safety device (1) being mounted in a motor vehicle (2), is rotationally fixed to at least one vehicle wheel (4, 5) in such a way that the vehicle wheel (4, 5) in question can only be rotated if the gear wheel (3) can be rotated; and - a parking brake (7) which frictionally engages the relevant vehicle wheel (4,5), where the parking brake (7) acts directly on the gear wheel (3), the parking brake (7) is formed as a loop band (9) encircling a partial circumference (8) of the gear wheel (3) and furthermore, a parking lock (6) is provided, which, as a separate locking means, can be brought into such a positive engagement with the gear wheel (3), on which the parking brake (7) also acts, that the gear wheel (3) is then not rotatable, characterized in that the parking lock (6) and the parking brake (7) are operated by means of a single common actuator (10).

Description

[0001] The invention relates to a parking safety device for a motor vehicle, as well as a motor vehicle with such a parking safety device.

[0002] Parking safety devices for motor vehicles are known from the prior art, in which a parking lock and a parking brake are arranged as redundant systems due to legal requirements, in order to reliably prevent the vehicle from rolling away. The parking lock acts positively on a gear wheel in a drive train upstream of the vehicle wheels in the torque flow. The gear wheel is preferably part of a switchable transmission, so that a parking position, usually indicated by a P, can be set via a gearshift, for example by means of a gear lever. In the parking position, the gear wheel is then locked or blocked by the parking lock, and due to the rotationally fixed connection to at least one vehicle wheel, this wheel is thus locked. The vehicle cannot then roll away.In parallel, the parking brake acts by friction, for example by means of at least one brake pad pressed onto a brake disc of a vehicle wheel, locking at least one of the vehicle wheels. This parking brake is usually operated via a separate lever, such as the handbrake or an electric parking brake (usually marked with a P in a circle that illuminates when engaged, with a concentric subcircle symbolizing a brake pad on either side).

[0003] Furthermore, a centrally synchronized transmission is known, for example, from DE 10 2015 211 367 A1, which has a brake acting on a transmission input shaft. Additionally, a transmission output shaft of the transmission is held rotationally fixed by a coupling of the transmission input shaft to the transmission output shaft, while the brake acts on the transmission input shaft.

[0004] DE 10 2008 000 645 A1 discloses a band brake for a transmission in which a band brake interacts with a special axial cylindrical section of a loose gear of a countershaft of a partial transmission.

[0005] Due to the increasing automation of motor vehicles, by-wire systems are in growing demand. In the initial phase, this primarily concerns functions that assist autonomous parking, specifically the parking brake and parking lock. While both the parking lock and parking brake are available on the market, the sum of these individual systems, with a total of three separate energy sinks (e.g., electric motors) and energy sources, is quite expensive and space-consuming. For example, the electric motors for the parking brake are typically located directly at the relevant vehicle wheels. This necessitates a complex signal wiring structure running from the point of operation, usually in or near the driver's cabin, to the location of the parking brake, for example, at the rear axle wheels.

[0006] Based on this, the present invention aims to overcome, at least partially, the disadvantages known from the prior art. The features of the invention are defined in the independent claims, for which advantageous embodiments are shown in the dependent claims. The features of the claims can be combined in any technically meaningful way, whereby the explanations in the following description and features from the figures, which comprise supplementary embodiments of the invention, can also be used.

[0007] The invention relates to a parking safety device for a motor vehicle, comprising at least the following components: - a gear wheel which, in the state of the parking safety device being mounted in a motor vehicle, is rotationally fixed to at least one vehicle wheel in such a way that the vehicle wheel in question can only rotate if the gear wheel is rotatable; and - a parking brake which locks the relevant vehicle wheel by friction.

[0008] The parking safety device is characterized primarily by the fact that the parking brake acts directly on the gear wheel.

[0009] The parking safety device proposed here includes a parking brake, so that the parking safety device, with the parking brake acting as a redundant locking means, is configured with a (separate or integrated) parking lock and, in conjunction with a parking lock, meets the globally standardized legal requirements. The transmission, particularly preferably the switchable transmission, is usually located close to a drive motor of the powertrain and / or close to the driver's cab of the vehicle. This results in shorter signal paths for operating the parking safety device compared to previously known solutions with wheel-mounted parking brakes.

[0010] The parking safety device is preferably designed as a unit that can be integrated into a drivetrain. This unit can be delivered as a single piece, although necessary connecting elements may be supplied separately, or mounting clips may need to be removed before or during installation. Alternatively, the parking safety device is assembled from individual components only when installed in the drivetrain of a motor vehicle. Preferably, the gear wheel is always a separate component, which, for example, forms a single component of a transmission, such as a switchable transmission.

[0011] The gear wheel is preferably permanently and rigidly connected to a transmission output shaft, so that the gear wheel and the at least one vehicle wheel are permanently in a torque flow. This means that the vehicle wheel cannot rotate unless the gear wheel also rotates, although usually at a different speed. The movement of the gear wheel and the at least one vehicle wheel is thus coupled to each other. In an alternative embodiment, the gear wheel is only connected to the transmission output shaft in a torque-transmitting manner in a parked position or at least temporarily, depending on the gear selected. Thus, the aforementioned coupling of movement between the at least one vehicle wheel and the gear wheel applies only, or at least in the parked position.

[0012] The parking brake here is not designed to interact with a service brake, such as a disc or drum brake on at least one of the vehicle's wheels. Instead, the parking brake interacts with the transmission wheel. The parking brake is friction-based, for example, as a brake block that can be pressed onto the transmission wheel. The transmission wheel is then locked in both directions of rotation. No relative rotation is possible between the transmission wheel and at least one of the vehicle's wheels (beyond the usual play and mechanical compliances in the intervening section of the drivetrain). Thus, at least one of the vehicle's wheels is locked.

[0013] The parking safety device is installed in a motor vehicle in addition to, or includes, a parking lock. The parking lock is, for example, of conventional design, preferably acting on the same transmission as the parking brake. The parking brake thus provides a redundant locking mechanism for the motor vehicle, thereby fulfilling the legal requirements. According to the inventive embodiment of the parking safety device, the parking brake is formed as a loop band encircling a partial circumference of the transmission gear.

[0014] In this embodiment, a large friction surface is formed for the parking brake, resulting in a high frictional force and / or a low area-specific frictional load acting on the gear wheel. The gear wheel preferably has teeth (and tooth gaps) distributed around its circumference. In a preferred embodiment, the friction surface is formed by the tooth tips of the gear wheel's teeth. The partial circumference preferably comprises more than two-thirds, and particularly preferably more than three-quarters, of the circumference. In an advantageous embodiment, compared to a previously known embodiment with an externally arranged parking brake, only minimal additional installation space is required in the area of ​​the gear wheel, since the sling strap utilizes the clearance typically available in the partial circumference, and only the sling strap's abutment and actuating lever require minimal additional installation space.This additional installation space is often freely available within a gearbox, subject to the installation space specifications of the vehicle manufacturer.

[0015] According to the embodiment of the parking safety device according to the invention, a parking lock is further provided which, as a separate locking means, can be brought into such a positive engagement with the gear wheel, on which the parking brake also acts, that the gear wheel is then not rotatable.

[0016] The law does not require that the parking lock and the parking brake act on at least one locked wheel at different points (directly or indirectly). Rather, it is sufficient to integrate the parking locking device into the transmission of the drivetrain. This must be done in such a way that if one locking device fails, the other still adequately fulfills its function.

[0017] The parking lock is designed, for example, as is known from the prior art. The parking lock used here is designed for positive engagement with the gear wheel, the gear wheel having a plurality of recesses or protrusions, such as teeth and tooth gaps, distributed around its circumference. The parking lock has, for example, a pin or a (pivoting) pawl that engages in such a recess or acts against such a protrusion. The gear wheel is then blocked, i.e., locked, in both directions of rotation. In some embodiments, a certain amount of play is provided, so that rotation about the wheel axis by the amount of this play is possible. No relative rotation is possible between the gear wheel and the at least one vehicle wheel (beyond the usual play and mechanical compliances in the intermediate part of the drive train).This means that at least one wheel of the vehicle is locked in place; specifically, by means of the parking lock alone, without the involvement of the parking brake.

[0018] A parking safety device with two redundant locking devices is thus formed, with these locking devices arranged close to each other by acting on the same gear wheel. This results in very short signal paths for operating the parking safety device compared to previously known solutions.

[0019] According to the invention, the parking brake is designed as a loop band as described above, wherein the loop band only encircles a portion of the gear wheel and the remaining circumference forms a gap for the mounting space and / or movement space of the parking lock or its engagement means, such as a hinged pawl. This requires very little installation space.

[0020] According to the embodiment of the parking safety device according to the invention, the parking lock and the parking brake are actuated by means of a single common actuator.

[0021] In this embodiment, only a single common actuator is provided for both the parking lock and the parking brake. This is feasible due to their close proximity. The legal requirement for redundant parking safety devices is also not violated if at least one of the two locking mechanisms is self-holding in the locked position. For example, the parking lock is self-closing and is held in an open position (i.e., not engaged) by the actuator. To engage the parking lock, the actuator is simply moved out of this open position. The parking lock then automatically engages the gear wheel in a locking position. This can also be implemented analogously, alternatively, or additionally with the parking brake, which must therefore be actively held in an open position by the actuator.It should be noted that at least the active keeping open by means of the actuator can be carried out without supplying electrical energy, i.e. without energy.

[0022] According to an advantageous embodiment of the parking safety device, the actuator comprises a spindle and a spindle nut, wherein a corresponding spindle thread is designed to be self-locking in such a way that a switching state is held without energy.

[0023] In this simple embodiment, a self-locking spindle thread achieves energy-free holding of a switching state. This means that no electrical energy is required to maintain the current position of the spindle and / or the spindle nut. However, mechanical energy storage devices, such as springs, can certainly be used. Their energy output is stored again when they are adjusted, for example, when the spring is compressed, so that overall they can be considered to operate without energy consumption, even though the restoring energy must then be supplied, for example, electrically, during switching.

[0024] According to an advantageous embodiment of the parking safety device, the actuator is used to - in a first position only the parking lock or only the parking brake, and - in a second position, the parking lock and the parking brake are engaged with the gear wheel in such a way that the vehicle wheel in question is locked.

[0025] In this advantageous embodiment, the usual two switching states can be represented despite the use of only a single actuator. Once the first position is reached, only one of the two locking devices is engaged. Preferably, this is the parking pawl, thus increasing the probability that the engaging element of the parking pawl, for example, the latch, will engage in the corresponding recess, for example, a tooth gap, if the vehicle rolls a short distance before the parking brake is applied because the driver releases the foot brake, i.e., the driving brake for controlled deceleration of the vehicle. If the driver does not do this, or if the parking brake is applied first, the parking pawl could engage next to a recess, for example, on a tooth head. If the parking brake then fails, the vehicle will roll a little further. However, this is also a sufficiently reliable and permissible way to secure the vehicle while parked.

[0026] According to a further aspect, the invention relates to a motor vehicle comprising a drive train, a transmission and at least one vehicle wheel, wherein a torque can be transmitted from the drive train to the vehicle wheel by means of the transmission, wherein the transmission comprises at least one gear wheel which is switched into the torque flow at least in a parking mode such that the vehicle wheel is rotationally fixed with the at least one gear wheel, so that the vehicle wheel in question can only be rotated when the gear wheel is rotatable.

[0027] The motor vehicle is characterized in particular by the fact that at least one gear wheel can be locked by means of a parking brake, preferably by means of a parking locking device according to an embodiment as described above.

[0028] The motor vehicle is, for example, a passenger car, a truck, or a motorized two-wheeler. The motor vehicle has a drivetrain which includes at least one drive unit, for example, an internal combustion engine and / or an electric motor. The torque available from the drive unit is transmitted via a transmission to at least one wheel of the vehicle, the drive wheel. The transmission described here is preferably a selectable transmission. Alternatively, the transmission is a fixed transmission, i.e., with an unchangeable gear ratio, a differential, or a slip clutch. Preferably, the transmission is already equipped with an actuator that can be controlled by an electrical signal, so that the wiring required for the parking safety device is minimal.

[0029] The parking safety device proposed here is preferably designed as described above and integrated into the transmission, with the parking lock and parking brake preferably acting on a single (common) gear wheel. Alternatively, the parking safety device is designed differently in that the parking lock acts on a first gear wheel and the parking brake acts on a second gear wheel, different from the first. In a further alternative, at least the parking brake acts directly on a transmission shaft, preferably the transmission output shaft. For the gear wheels or the relevant transmission shaft, however, the same applies as described above for the single gear wheel, namely that rotation of at least one vehicle wheel is only possible when the parking lock and parking brake are released. For further details, please refer to the above description of the parking safety device.

[0030] According to an advantageous embodiment of the motor vehicle, the parking safety device is designed such that the actuator can be moved into a first position and a second position according to an embodiment as described above, wherein the first position can be adjusted and / or released by means of a gear shift, and wherein the second position can be adjusted and / or released by means of a separate parking lever.

[0031] In this advantageous embodiment, the two familiar switching states can be represented despite the use of only a single actuator. This is achieved in one way, namely as described above, with a first position and a second position of the actuator. Furthermore, these switching states can be set in a manner familiar to the driver, namely, firstly, by moving the gear selector from a driving position, for example, reverse (R) or forward (D), to park (P). The driver can then manually engage the second locking device using a separate control element, and preferably an algorithm implemented in the vehicle's on-board computer.

[0032] The invention described above is explained in detail below against the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is in no way limited by the purely schematic drawings, although it should be noted that the drawings are not dimensionally accurate and are not suitable for defining size relationships. It is illustrated in Fig. 1: Parking safety device in an open position; Fig. 2: Parking safety device in a first position; Fig. 3: Parking locking device in a fully closed position; and Fig. 4: a drive train in a motor vehicle with a parking safety device.

[0033] Unless explicitly stated otherwise, ordinal numbers used in the preceding and following descriptions serve only to clearly distinguish the components and do not indicate any order or ranking.

[0034] In the Fig. Figures 1 to 3 show a parking locking device 1 in which a parking lock 6 and a parking brake 7 act on a single common gear wheel 3. The parking lock 6 is designed with a self-closing pawl 24, in which a closing spring 25 prevents the pawl 24 from pivoting clockwise, i.e., towards the gear wheel 3, as shown in the illustration, when the actuator 10 acts against the closing spring 25, and forces it to pivot when the actuator 10 does not act against the closing spring 25. For example, the closing spring 25 forces the pawl 24 towards the gear wheel 3 by means of a corresponding cam track (not shown).

[0035] The gear wheel 3 has a circumferential external toothing corresponding to the pawl 24, where the tooth gap 21 relevant in the present rotational position of the gear wheel 3 and a tooth 22 of the two adjacent teeth are designated. Fig. In position 1, the pawl 24 is not engaged, allowing the gear wheel 3 to rotate freely. Fig. 2 and Fig. 3 the pawl 24 is deflected into the tooth gap 21 and thus blocks a rotational movement of the gear wheel 3.

[0036] The parking brake 7 comprises a sling strap 9 which wraps around a partial circumference 8 of the gear wheel 3 such that sufficient installation space remains for the parking lock 6. Furthermore, the abutment 26 and the brake lever 27 are arranged in such a way that conventionally available installation space is utilized. If the brake lever 27 is removed from the Fig. 1 and in Fig. 2. Position shown, according to the illustration, clockwise into the Fig. When the position shown in Figure 3 is tilted, the loop band 9 tightens and acts as a frictional locking device on the gear wheel 3. In this embodiment, the loop band 9 interacts with the tooth heads 23 of the external teeth of the gear wheel 3. Alternatively, it interacts with a special shoulder (offset parallel to the teeth 22) or a special groove (machined into the teeth 22).

[0037] Only a single actuator 10 is provided here, which acts on both the parking lock 6 and the parking brake 7. In the example shown, the actuator is designed with a translationally movable spindle 11 and a translationally fixed spindle nut 12. The spindle 11 acts against the parking lock 6 (as in Fig. 1 shown) or against the brake lever 27 (as shown in Fig. 3 shown). Preferably, the spindle thread (not shown) is designed to be self-locking, so that the spindle 11 can be held in a position without requiring any energy.

[0038] In Fig. 1. The parking lock 6 is held open in the position shown, referred to here as the zero position. If necessary, the parking brake 7 is also actively held open. Alternatively, the parking brake 7 is self-releasing. In this zero position, the gear wheel 3 is freely rotatable.

[0039] In Fig. In step 2, the spindle 11 is moved into the first position of the actuator 10, so that the parking lock 6 engages positively with the gear wheel 3. The gear wheel 3 is now locked. However, the parking brake 7 is not yet engaged.

[0040] In Fig. In step 3, the spindle 11 is moved into the second position of the actuator 10, so that the parking brake 7 is now also engaged (frictionally) with the gear wheel 3. The gear wheel 3 is now redundantly blocked by means of the parking lock 6 and the parking brake 7, thus locking the vehicle 2 (compare Fig. 4) reliably prevented from rolling away.

[0041] In Fig. 4 is a parking safety device 1, for example as in Fig. 1 to Fig. Figure 3 shows the vehicle 2 mounted in a motor vehicle 2. The motor vehicle 2 comprises a drive train 13, in which a drive unit 18 is connected to at least two of the vehicle wheels, here the front left wheel 4 and the front right wheel 5, for the propulsion of the motor vehicle 2 along the longitudinal axis 20, transmitting torque. A transmission 14 is interposed, so that a torque flow 15 is transmitted via the (relevant here, because it is used for a parking position, for example as in Fig. Figure 3 shows a lockable gear wheel 3 leading to the vehicle wheels 4 and 5. The vehicle wheels 4 and 5 cannot rotate when the gear wheel 3 is blocked by the parking lock 6 and / or the parking brake 7. Thus, the vehicle 2 is reliably prevented from rolling away. A gearshift 16 and a parking lever 17 are shown schematically in a driver's cab 19, preferably in a conventional configuration. For example, the first position can be selected by setting the gearshift lever to P using the gearshift 16, so that in one embodiment of the parking locking device 1 according to Fig. 1 to Fig. 3 the parking lock 6 is engaged with the gear wheel 3. By actuating, for example pulling, the parking lever 17, the second position can be selected in a corresponding example, so that in an embodiment of the parking locking device 1 according to Fig. 1 to Fig.3 the parking brake 7 is engaged with the gear wheel 3.

[0042] The parking safety device proposed here achieves low complexity and preferably requires only a single actuator. Reference symbol list 1 Parking safety device 2 motor vehicles 3 Gear wheel 4 left vehicle wheel 5 right vehicle wheel 6 Parking restrictions 7 Parking brake 8 Partial scope 9 loop tape 10 Actuator 11 Spindle 12 Spindle nut 13 Powertrain 14 gearboxes 15 Torque flow 16 Gearbox 17 parking levers 18 Drive unit 19 Driver's cab 20 Longitudinal axis 21 tooth gap 22 teeth 23 Tooth head 24 jack 25 Closing spring 26 abutments 27 brake levers

Claims

[1] Parking safety device (1) for a motor vehicle (2), comprising at least the following components: - a gear wheel (3) which, in the state of the parking safety device (1) being mounted in a motor vehicle (2), is rotationally fixed to at least one vehicle wheel (4, 5) in such a way that the vehicle wheel (4, 5) in question can only be rotated if the gear wheel (3) can be rotated; and - a parking brake (7) which frictionally engages the relevant vehicle wheel (4,5), where the parking brake (7) acts directly on the gear wheel (3), the parking brake (7) is formed as a loop band (9) encircling a partial circumference (8) of the gear wheel (3) and furthermore, a parking lock (6) is provided, which, as a separate locking means, can be brought into such a positive engagement with the gear wheel (3), on which the parking brake (7) also acts, that the gear wheel (3) is then not rotatable, characterized by , that the parking lock (6) and the parking brake (7) are operated by means of a single common actuator (10). [2] Parking safety device (1) according to claim 1, wherein the actuator (10) comprises a spindle (11) and a spindle nut (12), wherein a corresponding spindle thread is designed to be self-locking such that a switching state is held without energy. [3] Parking safety device (1) according to claim 1 or 2, wherein, by means of the actuator (10), in a first position only the parking lock (6) or only the parking brake (7) is engaged, and in a second position the parking lock (6) and the parking brake (7) are engaged with the gear wheel (3) in such a way that the vehicle wheel (4,5) in question is locked. [4] Motor vehicle (2) comprising a drive train (13), a transmission (14) and at least one vehicle wheel (4, 5), wherein a torque can be transmitted from the drive train (13) to the vehicle wheel (4, 5) by means of the transmission (14), wherein the transmission (14) comprises at least one gear wheel (3) which is engaged in the torque flow (15) at least in a parking position such that the vehicle wheel (4, 5) is rotationally fixed to the at least one gear wheel (3) so that the vehicle wheel (4, 5) is only rotatable when the gear wheel (3) is rotatable. characterized by , that at least one gear wheel (3) can be locked in place by means of a parking locking device (1) according to one of the preceding claims. [5] Motor vehicle (2) according to claim 4, wherein the parking safety device (1) is designed according to claim 6, wherein the first position is adjustable by means of a gear shift (16), and wherein the second position is adjustable and / or reversible by means of a separate parking lever (17).

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