Disc brake for a commercial vehicle

Abstract

Disc brake for a commercial vehicle with a brake calliper (1) which spans a brake disc (3) and in which a brake application device which can be actuated by a brake cylinder (16, 17) is arranged, by means of which brake pads (4, 4') positioned in a vehicle-side brake carrier (2) can be pressed against the brake disc (3) on both sides during braking, wherein the brake calliper (1) is mounted on sliding guides (5) fastened to the brake carrier (2) in an axially displaceable manner with respect to a rotational axis (D) of the brake disc (3), and each brake pad (4, 4') has a pad carrier plate (11) which carries a friction pad (11') and has a pad retaining spring (10) on which a pad retaining bracket (8) which is fastened to the pad and spans a mounting opening (28) of the brake calliper (1) is supported, characterized in thatthat at least on the lining carrier plate (11) of the reaction-side brake lining (4') on its side facing the lining retaining spring (10) there is provided a hump-shaped vibration stop (12) which is covered by the lining retaining bracket (8) and spanned by the lining retaining spring (10), which has a flat surface on its side facing the lining retaining bracket (8) and bears with its side edges against the lining retaining spring (10) during a pivoting movement of the brake calliper (1) occurring during driving operation, wherein the dimension of the vibration stop (12) is smaller than the associated width of the lining retaining bracket (8), wherein a gap (23) is formed between the vibration stop (12) and the lining retaining spring (10) in the overlap area with the lining retaining bracket (8), and wherein the lining retaining spring (10) in the rest state of the brake calliper (1) is not yet at the edges of the vibration stop (12) for When the pad retaining bracket (8) is moved so far against the brake pad (4'),that the pad retaining spring (10) comes into contact with the edges of the vibration stop (12), a free span (29) of the pad retaining spring (10) is reduced to a width (30) of the vibration stop (12) and has a drastically increased spring rate upon further deflection.

Description

[0001] The invention relates to a disc brake for a commercial vehicle according to the preamble of claim 1.

[0002] A generic disc brake is known, for example, from DE 199 03 620 C1, as well as from DE 10 2007 046 945 A1, DE 10 2006 051 965 A1 and DE 39 19 179 A1, each of which discloses a brake pad whose pad carrier plate has an elevation on its side facing the pad retaining spring.

[0003] Such disc brakes, preferably air-operated, are used in heavy commercial vehicles, where they are exposed to extreme vibration during operation. This is due to the vehicles' very diverse operating conditions, sometimes on very poor road surfaces, widely varying loading conditions (fully loaded on one side, empty on the other), and frequently inadequate maintenance, resulting in operation with, for example, defective shock absorbers.

[0004] The design of the vehicle's suspension and damping system, which is intended to ensure comfort and load protection on the one hand, and driving stability and robustness under harsh operating conditions on the other, can only be achieved satisfactorily through compromises. This means that the disc brakes, along with the attached brake cylinders, often have to withstand very strong vibration loads.

[0005] Such vibration stresses can occur in various ways. First, vertical vibrations or shocks are imposed on the wheels as vertical movements due to uneven road surfaces and obstacles such as railroad crossings. Such vertical accelerations can reach up to 25 times the acceleration due to gravity.

[0006] In addition, horizontal accelerations occur during driving, which represent a lesser load than vertical impacts. These horizontal accelerations occur when cornering, but also in a more pronounced form when impacting sideways with road curbs and road edges caused by road surface damage. The maximum loads from horizontal accelerations are estimated to be three to five times the acceleration due to gravity.

[0007] Furthermore, rotational accelerations caused by oscillating movements of the vehicle axle must be considered. These typically occur with rigid axles and are generated by the compression of one wheel on the axle while the other wheel rebounds. The vehicle wheel, and thus also the associated disc brake, experiences back-and-forth rotational accelerations perpendicular to the longitudinal axis. In principle, however, even the strong compression or rebound of just one of the two wheels can cause corresponding rotational accelerations.

[0008] The rotational accelerations resulting from the pendulum movements of the vehicle axle are superimposed, above all, on the vertically acting vibrations and lead to considerable stress and, under certain circumstances, damage to the disc brake and its fastening.

[0009] Previously considered remedies involve enlarging the sliding guide system, but this would require a guide rail length that far exceeds the available installation space. A more rigid attachment to the brake carrier and its more stable dimensions are also not feasible due to the limited installation space.

[0010] DE 8615015 U1 deals with a disc brake in which the spring characteristic of the pad retaining spring is changed depending on the load on the brake calliper by a corresponding configuration of the upper edge of the pad carrier plate assigned to the pad retaining spring.

[0011] The invention is based on the object of further developing a disc brake of the generic type in such a way that its service life is increased and its operational reliability is improved.

[0012] This object is achieved by a disc brake having the features of claim 1.

[0013] The invention now effectively prevents the damage previously caused by pendulum movements of the axle, particularly in the case of already worn sliding guide bearings, so that the operational reliability of the disc brake is improved overall.

[0014] Since the previously large distance between the pad retaining spring and the retaining bracket has now been reduced, the pivoting movement that occurs is limited with the lowest possible forces.

[0015] By forming a defined stop zone on the brake pad carrier, a so-called vibration stop, the characteristics of the pad retaining spring are influenced in such a way that, when driving freely, a first stage of the spring force is effective, which is uncritical with regard to possible residual drag torques of the brake.

[0016] However, when the brake calliper is pivoted, the pad retaining spring comes into contact with the vibration stop after only a short stroke, so that the free span of the pad retaining spring is drastically reduced and the spring stiffness is increased accordingly.

[0017] When the brake calliper is pivoted even further, the retaining bracket contacts the pad carrier plate via the pad retaining spring, which is now completely flattened, and transfers an impulse force caused by the blocking of the pivoting movement via the pad carrier plate to contact surfaces on the brake carrier opposite the pad retaining spring, against which the brake pad, i.e. the pad carrier plate, rests.

[0018] In addition to the frictional damping effect of the pad retaining spring, a damping effect of the pad carrier plate is utilized, which is particularly effective when the pad carrier plate is made of a cast iron material with a low modulus of elasticity.

[0019] According to a further idea of ​​the invention, it is provided that the sliding guide bearings, i.e. the fixed and loose bearings, by means of which the brake calliper is held displaceably on the brake carrier, are arranged and designed taking into account the mass distribution of the completely assembled brake calliper in such a way that even when taking into account extreme center of gravity positions and displacement positions of the brake calliper, the center of gravity lines characterizing the center of gravity positions run within the guide length of the fixed bearing, wherein the completely assembled brake calliper includes a flanged-on brake cylinder.

[0020] Further advantageous embodiments of the invention are characterized in the subclaims.

[0021] An embodiment of the disc brake and the brake pad according to the invention is described below with reference to the attached drawings.

[0022] They show: Fig. 1 a cross section through a disc brake according to the invention in an operating position Fig. 2 the disc brake after Fig. 1 in another operating position Fig. 3 a brake pad according to the invention in mounted position in a front view Fig. 4 a partial section of the disc brake in a perspective top view.

[0023] In the Fig. 1 and Fig. 2 shows a disc brake for a commercial vehicle, with a brake calliper 1 spanning a brake disc 3, which is fastened to a vehicle-side brake carrier 2 so as to be axially displaceable with respect to a rotational axis D of the brake disc 3.

[0024] For this purpose, two sliding guides 5 are provided, one of which serves as a loose bearing and the other, in the Fig. 1 and Fig. 2, are designed as fixed bearings.

[0025] The sliding guide 5 has a guide bar 22 which is firmly connected to the brake carrier and on which the brake calliper 1 slides.

[0026] In a housing 18 of the brake calliper 1, an application device is positioned, with a brake lever 6 which can be actuated via a brake cylinder 16 and with which brake pads 4, 4' can be pressed against the brake disc 3 on both sides.

[0027] In addition to the brake cylinder 16, which is used exclusively for service braking, a combination brake cylinder 17 is also provided, with which the disc brake can be switched to a parking brake function.

[0028] While the Fig. 1 represents an operating position of the disc brake in which unworn brake pads 4, 4' are used, is shown in the Fig. 2 shows an operating position, with worn brake pads 4, 4'.

[0029] Each brake pad 4, 4' consists of a pad carrier plate 11 and a friction pad 11' fastened thereon, which in the braking position contacts the brake disc 3.

[0030] On the one mounting opening 28 ( Fig. 4) facing the upper side, a pad retaining spring 10 is fastened to the pad carrier plate of each brake pad 4, 4', with which, in cooperation with a pad retaining bracket 8, the brake pad 4, 4' is held under pretension in the brake carrier 2, wherein the brake pad 4, 4' rests with its side opposite the pad retaining spring 10 on contact surfaces 7, 7' of the brake carrier 2.

[0031] As the Fig. 4 very clearly shows, the pad retaining bracket 8 spans the mounting opening 28 and is held in a pocket formed in a projection 19 of the housing 18 and, on the other hand, by support cams 20 formed on a saddle back 15. In the connection area with the support cam 20, the pad retaining bracket 8 has an opening through which the support cam 20 passes, with two opposing cranked legs 25 which are connected to one another by a web 26, so that a frame 9 is formed overall.

[0032] A bolt 21 is guided through the support cam 20, which rests against the legs 25 and is secured by a split pin 27. In the Fig. 1 and Fig. 2 shows the position lines 13, 14 of the center of gravity of the fully assembled brake caliper 1 with brake cylinder 16, but without brake pads 4, 4', brake carrier 2, and guide rails 22. Position line 13 indicates the center of gravity with the brake cylinder 16, and position line 14 indicates the center of gravity of the brake caliper 1 with a combined brake cylinder 17.

[0033] It can be seen that the respective center of gravity lies within the overlap area of ​​the sliding guide 5 or the guide bar 22.

[0034] In the Fig. 3 shows the reaction-side brake pad 4' assigned to the saddle back 15, with the friction pad 11' as the front side.

[0035] According to the invention, a hump-shaped vibration stop 12 is provided on the side of the pad carrier plate 11 facing the pad retaining spring 10, specifically mirror-symmetrical to an axis of symmetry S that runs transversely to the longitudinal extent of the brake pad 4'. The vibration stop 12 is smaller in size than the width of the pad retaining bracket 8.

[0036] A gap 23 is formed between the pad retaining spring 10 and the vibration stop 12, which gap is dimensioned so large that even with maximum tolerances of the brake pad 4', the brake carrier 2, the brake calliper 1 and the pad retaining bracket 8, the pad retaining spring 10 does not yet come into contact with the edges of the vibration stop 12 when the brake calliper 1 is at rest.

[0037] The effectiveness of the vibration stop is primarily evident in the reaction-side brake pad 4'. However, the opposite, action-side brake pad 4 is sensibly designed in the same way, since the problems described also arise here, albeit in a less severe form.

[0038] In the Fig. 3 shows two different positions of the pad retaining bracket 8. On the one hand, the normal driving position is shown in solid line, in which the pad retaining spring 10 rests with its preload force determined by its span between support points 24 on the pad carrier plate 11, without touching the vibration stop 12.

[0039] The dashed representation of the contour of the vibration stop 12 shows the reduced distance when the pad retaining bracket 8 is moved so far against the brake pad 4' as a result of the pivoting brake caliper 1 that the pad retaining spring 10 comes into contact with the edges of the vibration stop 12. A free span 29 of the pad retaining spring 10 is now reduced to the width 30 of the vibration stop 12 and exhibits a drastically increased spring rate upon further deflection.

[0040] Since the stroke of the pad retaining spring that can be executed under these conditions is less than 1 mm, the pad retaining bracket 8 comes into full contact with the vibration stop 12 upon further pivoting movement of the brake caliper 1 via the pad retaining spring 10, which is then pressed flat. The remaining kinetic energy of the brake caliper 1 is now dissipated in the form of an impact pulse from the pad retaining bracket 8 via the vibration stop 12 to the pad carrier plate 11 and through this via the contact surfaces 7 to the brake carrier 2 connected to the vehicle axle.

[0041] In the Fig. 4 shows the pad retaining bracket 8, the lateral legs 25 of which divert radially acting supporting forces.

[0042] Under extreme load, which can occur as a result of impact loading, the lateral legs 25 yield slightly. As a result, the strut 26 connecting the lateral legs 25 is pressed against the support cams 20, so that the lateral legs 25 no longer absorb the load exclusively as bending stress, but rather a significant portion as tensile stress, which is directly transferred from the connecting strut 26 to the support cams 20.

[0043] This measure enables the particularly cost-effective and service-friendly fastening of the pad retaining bracket 8 by means of a transverse bolt 21 without a complex and installation space-restricting design and dimensioning of the pad retaining bracket 8. List of reference symbols 1 brake caliper 2 brake carriers 3 brake disc 4 brake pad 4' brake pad 5 Sliding guide 6 brake levers 7 Radial contact surfaces of the brake carrier 8 pad retaining brackets 9 Frame of the pad retaining bracket 10 pad retaining spring 11 Pad carrier plate 11' friction lining 12 Vibration stop on the pad carrier driving position / pivoted brake calliper 12' Vibration stop on the pad carrier driving position / pivoted brake caliper 13 Center of gravity of the brake caliper service brake cylinder 14 Center of gravity of the brake caliper combination brake cylinder 15 saddle back 16 service brake cylinders 17 combination brake cylinders 18 housings 19 Housing projection 20 support cams 21 bolts 22 Guide pin 23 gap 24 Support point of the pad retaining spring on the pad carrier 25 side legs of the pad retaining bracket frame 26 Connecting strut of the pad retaining bracket frame 27 Splint 28 Mounting opening 29 wingspan 30 width

Claims

[1] Disc brake for a commercial vehicle with a brake calliper (1) which spans a brake disc (3) and in which a brake application device which can be actuated by a brake cylinder (16, 17) is arranged, by means of which brake pads (4, 4') positioned in a vehicle-side brake carrier (2) can be pressed against the brake disc (3) on both sides during braking, wherein the brake calliper (1) is mounted on sliding guides (5) fastened to the brake carrier (2) in an axially displaceable manner with respect to a rotational axis (D) of the brake disc (3), and each brake pad (4, 4') has a pad carrier plate (11) which carries a friction pad (11') and has a pad retaining spring (10) on which a pad retaining bracket (8) which is fastened to and spans a mounting opening (28) of the brake calliper (1) is supported, characterized bythat at least on the lining carrier plate (11) of the reaction-side brake lining (4') on its side facing the lining retaining spring (10), a hump-shaped vibration stop (12) is provided which is covered by the lining retaining bracket (8) and spanned by the lining retaining spring (10), which has a flat surface on its side facing the lining retaining bracket (8) and bears with its side edges against the lining retaining spring (10) during a pivoting movement of the brake calliper (1) occurring during driving operation, wherein the dimension of the vibration stop (12) is smaller than the associated width of the lining retaining bracket (8), wherein a gap (23) is formed between the vibration stop (12) and the lining retaining spring (10) in the overlap area with the lining retaining bracket (8), and wherein the lining retaining spring (10) is not yet at the edges of the vibration stop in the rest state of the brake calliper (1) (12) comes into contact, whereby, when the pad retaining bracket (8) is moved so far against the brake pad (4'),that the pad retaining spring (10) comes into contact with the edges of the vibration stop (12), a free span (29) of the pad retaining spring (10) is reduced to a width (30) of the vibration stop (12) and has a drastically increased spring rate upon further deflection. [2] Disc brake according to claim 1, characterized by that the pad retaining bracket (8) has a frame (9) surrounding a passage opening for a brake calliper-side support cam (20), with two opposite lateral legs (25) which are connected to one another by a connecting strut (26). [3] Disc brake according to one of the preceding claims, characterized by that a bolt (21) which is held in a displacement-proof manner and which is supported on the upper side of the frame (9) facing away from the brake calliper (1) is guided through the support cam (20). [4] Disc brake according to one of the preceding claims, characterized bythat the center of gravity of the completed brake calliper (1) with brake cylinders (16, 17) and the application device lies within the length of the sliding guide (5) designed as a fixed bearing.

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