Braking device for a vehicle and vehicle with such a braking device

Abstract

The invention relates to a braking device (2) for a vehicle with at least one brake disc (4) which is rotatable about an axis of rotation (6) and which comprises at least one friction layer (8) subject to wear, which forms a braking surface (10), with at least one braking means (12) which bears against the friction layer (8) of the brake disc (4) when the vehicle is braking, with at least two wear indicators (14) which are arranged in the braking surface (10) of the friction layer (8), which have the same wear indicator spacing (R) radially to the axis of rotation (6) with respect to the axis of rotation (6), which are user-detectable until a critical friction layer thickness of the friction layer (8) is reached or undershot, with at least one planar, disc-shaped covering means (16) which is fixed in a rotationally fixed manner with respect to the vehicle,which is arranged to run substantially parallel to the brake disc (4) and to be spaced apart from the brake disc (4) without contact, and which comprises at least one viewing window (18) which extends in the shape of a circular segment around the axis of rotation (6) and whose distance from the axis of rotation (6) corresponds to the wear indicator distance (R), wherein at least one of the at least one viewing window (18) comprises a position on the covering means (16) and a segment length in the circumferential direction with respect to the axis of rotation (6), through which at least one of the at least two wear indicators (14) can be detected by the user.

Description

The invention relates to a brake device for a vehicle and to a vehicle having such a brake device.Vehicles, in particular motor vehicles, comprise brake devices at their wheels in order to decelerate a movement of the vehicle. During operation of the vehicle, in particular during braking of the vehicle, a braking means of the braking device is applied contacting and generating wear to a braking surface of a contact body, for example a brake disc. Due to the prevailing friction between the brake means and the brake disc, it can never be entirely avoided that particles are released from the friction layer of the brake disc or of the brake means during braking and the brake disc is subject to wear.Known brake disks consist entirely of gray cast iron or brake disks coated with a hard material, such as stainless steel.The coated brake disks can comprise a base body which consists, for example, of gray cast iron and which is coated with a friction layer of hard material and / or a similar material. Friction layer thicknesses of coated brake disks are very low and can comprise 100 μm to 300 μm.In the known brake disks, the friction layer serves as a braking surface on which a braking means of the braking device can be placed in contact during braking of the vehicle.Because of the in some cases very low friction layer thicknesses, it is difficult to visually ascertain by a user whether the friction layer has to be worn out and the brake disk has to be replaced or processed, or whether the brake disk can be used even further. For this purpose, very precise tools, such as a micrometer screw or a similarly precise tool, must be used, which proves to be time-consuming and cumbersome.In order to be able to estimate wear more quickly, brake disks for vehicles are known in which wear indicators are arranged in the friction layer. These can be user-detected, so that these can be detected exclusively by a visual examination without using measurement tools. It can thus easily be determined whether the friction layer is still sufficiently thick.In order to protect brake disks from dirt and fluidized foreign bodies, such as stones, in known motor vehicles, cover means in the form of cover plates are provided on the inner side of the brake disk, which faces the vehicle center.In the known cover plates it has proven disadvantageous that when checking wear indications of the brake disc, the latter is covered by the covering means. To check the wear indicator, the brake disk must be removed, which is time-consuming.In order to facilitate checking wear indicators, covering means are known which comprise small viewing windows through which the wear indicators can be seen. For this purpose, the brake disk must be rotated into an inspection position in which the viewing window and wear indicator overlap one another in a direction parallel to the axis of rotation. If the vehicle is fixed in such a way that the wheel units cannot be rotated, this proves to be impractical or at least more difficult.An object of an exemplary embodiment of the invention is to propose a brake device in which it is possible to check a wear indicator of a brake disk of a brake device independently of the position of the brake disk.This object is achieved by a brake device for a vehicle having at least one brake disk which is rotatable about an axis of rotation and which comprises at least one friction layer which is subject to wear and forms a brake surface, having at least one brake means which, when the vehicle is braked, bears in contact with the friction layer of the brake disk and generates wear, having at least two wear indicators which are arranged in the brake surface of the friction layer and which comprise the same wear indicator distance radially with respect to the axis of rotation with respect to the axis of rotation, which wear indicators distance can be detected by the user until a critical friction layer thickness of the friction layer, at which the friction layer is virtually removed, is reached or undershot, and which wear indicators are removed after the critical friction layer thickness of the friction layer has been reached or undershot, having at least one planar, disk-shaped cover means which is fixed in a rotationally fixed manner with respect to the vehicle, which extends substantially parallel to the brake disc and is spaced apart from the brake disc in a contactless manner and which comprises at least one viewing window which extends in the form of a segment of a circle about the axis of rotation and whose distance from the axis of rotation corresponds to the wear indicator distance, wherein at least one of the at least one viewing windows comprises a position on the covering means and a segment length in the circumferential direction with respect to the axis of rotation, by means of which, when the brake disc is fixed in a rotationally fixed manner, at least one of the at least two wear indicators can be detected by the user through the viewing window from the side of the covering means facing away from the brake disc.Because the brake device comprises a covering means, the brake disk can be protected from damage, in particular due to stone chipping, whereby the service life of the brake disk can be increased.Because the covering means comprises at least one viewing window which comprises a position on the covering means and a segment length in the circumferential direction with respect to the axis of rotation, which can always be user-detected at least one of the at least two wear indicators, it is no longer necessary to rotate the brake disc, for example into an inspection position.As a result, even in an arrangement of the vehicle in which the wheels and, as a result, also the brake disc, are fixed in a rotationally fixed manner, at least one of the at least two wear indicators can be detected. A rotationally fixed attachment of the wheels or of the brake disks can be the case, for example, when the vehicle is parked on a fixed underlying surface or is arranged on a lifting platform, in which the vehicle is lifted via support means attached to the wheels.To detect the wear indicator through the viewing window, the wear indicator and viewing window are aligned with one another along a parallel to the axis of rotation. This arrangement is ensured in that the viewing window is at the same distance from the axis of rotation as the wear indicator. In this case, the respective distance from the axis of rotation can be measured in each case up to the center line of the wear indicator or of the viewing window, or from an edge of the wear indicator or of the viewing window which is closest to the axis of rotation.The viewing window can be designed in any desired manner from a technical point of view, provided that it follows the function that the wear indicator can be detected by the user from the side of the covering means facing away from the brake disc. For example, the viewing window can be formed by a transparent region in the cover plate.The brake device can be designed in a simple and cost-effective manner if at least one of the at least one viewing window of the covering means comprises a continuous opening which extends parallel to the axis of rotation and is at least as wide or wider than one of the at least two wear indicators. In such a case, the covering means may comprise a punch part.Because the viewing window comprises a continuous opening, it is possible to easily detect the wear indicator. Even in cases where the viewing window becomes clogged, for example, by particles during the course of use of the motor vehicle, the viewing window can be quickly and easily released again, for example, by using a fluid under pressure, such as water or air.In order to configure the length of the segment, in particular a segment of a circle, of the at least one viewing window in an optimized manner, it can be provided that the at least two wear indicators are arranged on the brake disc so as to be uniformly spaced apart from one another, and that the covering means comprises at least one viewing window which extends in the form of a segment of a circle around the axis of rotation at an angle which is equal to or greater than 360° divided by the number of wear indicators, or that the covering means comprises at least two viewing windows, wherein in each case two adjacent viewing windows are separated from one another and spaced apart from one another by a web section of the covering means, and wherein the viewing windows and the web section or sections arranged therebetween extend in total in the form of a segment of a circle at least by an angle around the axis of rotation which is equal to or greater than 360° divided by the number of wear indicators.If the brake device comprises at least two wear indicators which are uniformly spaced apart from one another, when using exactly two wear indicators these comprise a spacing of 180° from one another. In such a case, it is sufficient if the length of the circle segment also extends over 180° with respect to the axis of rotation.If, for example, three wear indicators are provided which are uniformly spaced apart from one another, they have a spacing of 120° with respect to the axis of rotation. In such a case, it is sufficient if the at least one viewing window extends one around the axis of rotation at an angle of 120°.This can ensure that at least one of the wear indicators is visible from the outside through the viewing window.Furthermore, the at least necessary arc length about the axis of rotation can be covered by a single viewing window or can be ensured in total by a plurality of viewing windows which are spaced apart from one another by a web section in each case. If a plurality of viewing windows are used, the rigidity of the covering means can be kept high on account of the web sections arranged therebetween.In a development of the last-mentioned embodiment, it proves to be advantageous if at least two of the at least two viewing windows comprise the same circle segment length in the circumferential direction with respect to the axis of rotation or a circle segment length in the circumferential direction with respect to the axis of rotation which repel one another.In such a case, it is possible to arrange viewing windows with a smaller circular segment length and viewing windows with a comparatively larger circular segment length on the covering means.The arrangement of the viewing windows on the covering means can in principle be effected as desired. It has proven to be advantageous if these are arranged mirror-symmetrically to a horizontal running through the axis of rotation. During operation of the brake device, in particular when the wheel and the brake disk arranged thereon are immovably fixed, it can never be avoided that one of the wear indicators is arranged in the region of the brake means, i.e. is covered by the brake means.In such a case, a point-symmetrical arrangement of at least one of the viewing windows with respect to the axis of rotation with respect to the braking means proves to be possible. This can ensure that, if only two wear indicators are provided, at least one of the wear indicators is visible if the other wear indicator is covered by the brake means.It has proven to be advantageous if the web sections in the circumferential direction with respect to the axis of rotation comprise a length which is smaller than the diameter of the wear indicator in the circumferential direction with respect to the axis of rotation.If the web sections in the circumferential direction with respect to the axis of rotation comprise a length which is smaller than the diameter of the wear indicator in the circumferential direction with respect to the axis of rotation, a wear indicator can be detected by the user even if this is overlapped by the web section. This ensures that in no case can a complete overlap take place, in which case the wear indicator is completely covered by the web section.Embodiments of the brake device are conceivable in which at least one of the at least one viewing window comprises a straight or rounded edge region at at least one of its ends situated in the circumferential direction with respect to the axis of rotation.If the edge region of the viewing window is rounded, it can comprise a radius which corresponds to the radius of the wear indicator, if the wear indicator is formed, for example, in a rounded manner.If the edge region of the viewing window is formed in a straight line, it can run parallel to a radial through the axis of rotation.In order to improve the rigidity of the covering means, it proves to be advantageous if the covering means comprises at least one reinforcing device which has at least one channel-shaped depression in the covering means, in particular in the region of the at least one web section, and / or the at least one collar region which is arranged on the side of the covering means facing away from the brake disc and is shaped in the direction away from the brake disc and which surrounds the axis of rotation partially, in particular adjoining at least one viewing window, or completely circumferentially.The groove-shaped depression in the covering means can comprise, for example, a bead. As a result, the rigidity of the covering means can be increased. The at least one collar region can be stamped and / or deep-drawn. The collar region can firstly increase the rigidity of the covering means and secondly reduce the risk that small stones can pass through the viewing window in the direction of the brake disc. In such a case, it has proven to be particularly advantageous if the at least one collar region is arranged adjacent to one of the viewing windows.In order to further reduce the risk of damage to the brake disc by stones passing through the viewing windows, the brake device can comprise at least one closure means which can be releasably arranged in or on at least one of the at least one viewing window.At least one closure means can be provided for each viewing window. In addition, it is also conceivable for the at least one closure means to be arranged in a plurality of, in particular all, viewing windows. In such a case, the closure means can comprise a web-like region which is formed, in particular in the circumferential direction about the axis of rotation, and comprises the projecting region which is each configured to correspond, in particular to complement, to the viewing windows and can engage in the latter.It has proven to be advantageous if the covering means and / or the closure means comprises a metal, a plastic or a carbon fiber composite material and in particular comprises a deep-drawn part, a bent stamped part or an injection-molded part.If the covering means and / or closure means comprise a metal, the covering means can be designed to be particularly heat-resistant.If the covering means and / or the closure means comprise a plastic or a carbon fiber composite material, the covering means can be designed to be reduced in weight.The covering means can in principle be fixed at any desired location and with any desired component on the motor vehicle. In one embodiment of the brake device, it proves to be advantageous if the brake device comprises at least one brake caliper which is fixed in a fixed position with respect to the vehicle and in addition the brake means and / or the cover means are fixed.Finally, the object is achieved by a motor vehicle having at least one brake device having at least one of the aforementioned features.Further features, details and advantages of the invention are evident from the appended patent claims, from the drawing and from the following description of a preferred embodiment of the brake device.The drawing shows: FIG. 1 is a plan view of a schematic representation of the brake device.FIG. 1 shows a braking device for a vehicle, which is provided overall with the reference numeral 2. The brake device 2 comprises a brake disc 4 which is rotatable about an axis of rotation 6. The brake disk 4 is concealed in the illustration according to FIG. 1 and is illustrated by a dashed line. The brake disc 4 comprises a friction layer 8 which is subject to wear and forms a brake surface 10.In addition, the brake device 2 comprises a brake means 12 which, during the braking of the vehicle, bears in contact and in a wear-generating manner against the friction layer 8 of the brake disc 4. In the exemplary embodiment shown in FIG. 1, three wear indicators 14 are provided in the brake disc 4, which wear indicators are arranged in the brake surface 10 of the friction layer 8. These comprise the same wear indicator distance R radially to the axis of rotation 6 with respect to the axis of rotation 6. The wear indicators 14 can be detected by the user until a critical friction layer thickness of the friction layer 8 is reached or undershot, at which the friction layer 8 is virtually removed. When the critical friction layer thickness of the friction layer 8 is reached or undershot, the wear indicators 14 are abraded.In addition, the brake device 2 comprises a flat, disk-shaped covering means 16 which is fixed in a rotationally fixed manner with respect to the vehicle. The covering means 16 is arranged so as to extend substantially parallel to the brake disc 4 and without contact with the brake disc 4. In the exemplary embodiment shown in FIG. 1, a plurality of viewing windows 18 are arranged in the covering means 16, which viewing windows are each extended in the form of a segment of a circle around the axis of rotation 6 and whose respective distance from the axis of rotation 6 corresponds to the wear indicator distance R. At least one of the at least one viewing window 18 has a position on the covering means 16 and a segment length in the circumferential direction with respect to the axis of rotation 6, by means of which, when the brake disc 4 is fixed in a rotationally fixed manner, at least one of the wear indicators 14 can be detected by the viewing window 18 from the side of the covering means 16 facing away from the brake disc 4.In the exemplary embodiment shown in FIG. 1, the wear indicators 14 have such an arrangement on the brake disc 4 that they are arranged on the brake disc 4 so as to be uniformly spaced apart from one another. The three wear indicators 14 are arranged offset relative to one another by 120° in each case with respect to the axis of rotation 6. The viewing windows 18 are formed by through-openings which are at least as wide or wider than the wear indicators 14.FIG. 1 shows an embodiment of the braking device 2 in which the respective circle segment length and arrangement of the individual viewing windows 18 are arranged and formed mirror-symmetrically with respect to a horizontal running through the axis of rotation 6.The features of the invention disclosed in the above description, in the claims and in the drawing can be essential both individually and in any combination in the realisation of the invention in its various embodiments within the scope of the following claims.List of reference characters2 Braking device 4 Brake disc 6 Axis of rotation 8 Friction layer 10 Braking surface 12 Braking means 14 Wear indicator 16 Covering means 18 Viewing window 20 Web section R Wear indicator distance

Claims

A brake device (2) for a vehicle having at least one brake disc (4) which is rotatable about an axis of rotation (6) and which comprises at least one friction layer (8) which is subject to wear and forms a brake surface (10), having at least one brake means (12) which, during braking of the vehicle, bears in contact with the friction layer (8) of the brake disc (4) and generates wear, having at least two wear indicators (14) which are arranged in the brake surface (10) of the friction layer (8) and which comprise, radially with respect to the axis of rotation (6) with respect to the axis of rotation (6), the same wear indicator distance (R) which is sufficient until a critical friction layer thickness of the friction layer (8) at which the friction layer (8) is virtually removed has been reached or undershot, The wear indicator can be detected by a user and which are abraded after reaching or falling below the critical friction layer thickness of the friction layer (8), with at least one flat, disc-shaped covering means (16) which is fixed in a rotationally fixed manner with respect to the vehicle, which is arranged running substantially parallel to the brake disc (4) and at a distance from the brake disc (4) without contact and which comprises at least one viewing window (18) which extends in the form of a segment of a circle around the axis of rotation (6) and the distance from the axis of rotation (6) of which corresponds to the wear indicator distance (R), wherein at least one of the at least one viewing window (18) comprises a position on the covering means (16) and a segment length in the circumferential direction with respect to the axis of rotation (6), through which, when the brake disc (4) is fixed in a rotationally fixed manner, at least one of the at least two wear indicators (14) can be detected by the user through the viewing window (18) from the side of the covering means (16) facing away from the brake disc (4).Brake device (2) according to claim 1, characterised in that at least one of the at least one viewing window (18) of the covering means (16) comprises a continuous opening which extends parallel to the axis of rotation (6) and is at least as wide or wider than at least one of the at least two wear indicators (14).Brake device (2) according to Claim 1 or 2, characterized in that the at least two wear indicators (14) are arranged on the brake disc (4) so as to be uniformly spaced apart from one another, and in that the covering means (16) comprises at least one viewing window (18) which extends in the form of a segment of a circle at an angle about the axis of rotation (6) which is equal to or greater than 360° divided by the number of wear indicators (14), or in that the covering means (16) comprises at least two viewing windows (18), wherein in each case two adjacent viewing windows (18) are separated from one another and spaced apart from one another by a web section (20) of the covering means (16), and wherein the viewing windows (18) and the web section or sections (20) arranged therebetween extend in total in the form of a segment of a circle at least by an angle about the axis of rotation (6) which is equal to or greater than 360° divided by the number of wear indicators (14).Brake device (2) according to claim 3, characterised in that at least two of the at least two viewing windows (18) comprise the same circle segment length in the circumferential direction with respect to the axis of rotation (6) or a circle segment length in the circumferential direction with respect to the axis of rotation (6) which differs from one another.Brake device (2) according to one of the preceding claims, characterized in that the web sections (20) in the circumferential direction with respect to the axis of rotation (6) comprise a length which is smaller than the diameter of the wear indicator (14) in the circumferential direction with respect to the axis of rotation (6).Braking device (2) according to one of the preceding claims, characterized in that at least one of the at least one viewing window (18) comprises a rectilinear or rounded edge region at at least one of its ends situated in the circumferential direction with respect to the axis of rotation (6).Brake device (2) according to one of the preceding claims, characterized in that the covering means (16) comprises at least one reinforcing device which has at least one channel-shaped depression in the covering means (16), in particular in the region of the at least one web section (20), and / or the at least one collar region which is arranged on the side of the covering means (16) facing away from the brake disc (4) and is shaped in the direction away from the brake disc (4) and which surrounds the axis of rotation (6) partially, in particular adjoining at least one viewing window (18), or completely circumferentially.Brake device (2) according to one of the preceding claims, characterized byat least one closure means which can be releasably arranged in or on at least one of the at least one viewing window (18).Brake device (2) according to one of the preceding claims, characterized in that the covering means (16) and / or the closure means comprise a metal, a plastic or a carbon fibre composite material and in particular comprise a deep-drawn part, a bent stamped part or an injection-moulded part.Motor vehicle having at least one brake device (2) according to one of Claims 1 to 9.

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