DE3016783A1 - Floating caliper disc brake - has auxiliary piston actuating adjacent shoe via expander mechanism supported on caliper - Google Patents

Abstract

The floating-caliper disc brake has a main cylinder on the caliper at one side of the disc, while on the other side is a mechanism between the caliper and shoe, taking up the brake clearance. This comprises an auxiliary cylinder of smaller cross- section than the main one and supplied from the same source. The piston (12) of the auxiliary cylinder actuates the shoe (16) adjacent to it via an expander mechanism (13,14,18,24,32) supported on the caliper (15) and whose axial force amplification factor is great enough only to achieve a self-locking action, taking into account the force exerted by the auxiliary piston in the release direction. The pressure source (29) is connected to the main cylinder only above a predetermined threshold pressure. Thus above the latter the expander mechanism transmits the force from the main cylinder from the caliper directly to the shoe.

Description

The invention relates to a floating caliper partial lining disc

brake with one arranged on one side of the disk on the floating caliper Main piston-cylinder arrangement and with one on top of the main piston-cylinder arrangement facing away from the disc side arranged between the floating caliper and the brake shoe Brake clearance overcoming device which has an auxiliary piston-cylinder arrangement with a much smaller cross-sectional area than the main piston-cylinder arrangement has and of the same pressure wave as the main piston-cylinder arrangement is fed.

From DE-AS 14 80 335 is already a floating caliper-like partial lining disc brake known, in the case of piston-cylinder arrangements on opposite sides of the brake disc are provided with significantly different effective areas.

The small piston can be locked by a friction lock to prevent it from falling back. so that he is in its extended position with the large clamping force generated by the large piston Position can remain.

The invention is based on this known partially lined disc brake, works however. with a pure floating saddle.

The aim of the present invention is to provide a brake of the To procure the type mentioned at the beginning, which is characterized by greater operational reliability and a smaller space requirement on the side facing away from the actuating device of the saddle, i.e. within the bowl of the vehicle wheel. In particular should with a relatively small volume requirement and with the precisely enough for this Forces the brake clearance on the side facing away from the actuating device the brake disc are overcome, whereupon subsequently due to self-locking a rigid abutment for the reaction forces generated with the main piston actual operating forces should be present.

For Loiang's task, the invention provides that the piston of the ilfs piston-cylinder arrangement, the adjacent brake shoe via one on the floating caliper supported spreader actuated, its axial force amplification factor only is as great as it is considering for achieving self-rogue the force exerted by the auxiliary piston is required in the brake release direction, and that the pressure source is only applied to the main piston-cylinder arrangement above a predetermined threshold pressure can be connected, so that above this predetermined threshold pressure the spreading device the force of the main piston-cylinder arrangement from the floating caliper on the Brcmsbacke transmits immediately. Because of this design, a very small auxiliary piston be used because he just needs to apply those forces that are necessary for Movement of the spreader and the associated brake shoe are required. As soon as the brake shoe is in contact with the brake disc, i.e. the brake clearance has been overcome the main piston takes effect and transmits its reaction forces the caliper and the spreading device directly on the one facing away from it Brake shoe. The self-locking of the spreading device according to the invention is therefore of special meaning. The self-locking properties of the spreader can can be increased significantly by rough surfaces or serrations.

During the actual braking process, the one facing away from the main piston is turned away Brake shoe primarily purely mechanical via the self-locking of the spreading device supported on the brake caliper. The effective area of the auxiliary piston can therefore be ignored on the direct mechanical support of the brake shoe on the brake caliper will.

A particularly advantageous practical embodiment of the invention characterizing is characterized in that the piston of the auxiliary piston-cylinder arrangement over an expanding wedge drive at least two radially displaceable expanding jaws acts, which in turn k or tonusförrntg avls are formed and between the saddle and the back cover.

The spreader is here so by two connected in series Spreader drives formed to double force deflection from the axial to the radial and to achieve again from the radial to the axial direction.

An advantageous practical implementation of the idea of the invention is characterized in that the cylinder of the small piston is arranged in the saddle and has a flange that engages behind the saddle on the inside and is on the disk side has a wedge or conical surface on which the complementary wedge or conical surface the spreading jaws are in contact. In this embodiment, the application forces are immediate transferred from the caliper via the flange and the expanding jaws to the brake shoe. The surfaces of the expanding jaws on the disk side can expediently be flat and rest against an intermediate plate. The expanding jaws and the intermediate plate should be biased towards each other by springs, so even when not actuated Brake, all parts of the adjuster are cleanly against one another. The intermediate plate rests directly on the outer brake shoe.

It is particularly useful when in the hydraulic supply line to Main piston-cylinder arrangement, a threshold valve is switched on, which only opens above the predetermined threshold pressure. The threshold of the valve is set so that it only opens when the inlet pressure has risen that far is that the auxiliary piston the necessary adjustment to overcome the Has performed the brake clearance. This is e.g. after a pressure build-up to 3 to 5 bar the case. If this pressure is exceeded, the valve opens and releases the Free flow of pressure medium to the main actuating piston. Such valves are known per se (DE-GBM 18 96 381) [ To after a braking a return of the spreading device and the auxiliary piston in its starting position to achieve, the spreader by a spring arrangement; on her unspread Able to be biased. For this purpose, the two radially opposite one another can be used Spreading jaws be biased towards each other by a spring.

Around the spreading device against external pollution, which is sensitive to contamination To shield influences, it should be through an annular protective cap between the The cylinder flange and the intermediate plate must be sealed. The cylinder flange and the intermediate plate are preferably round, so that the attachment of the Protective cap is possible in a simple manner.

It is particularly advantageous if the brake application movement of the auxiliary piston is limited by a stop on the expanding jaws. The attack is supposed to be in the released state of the brake at a distance equal to the brake clearance from that Auxiliary piston -being. Since the application and release movements of the expanding jaws are the same, the size of the movement determines the existing brake clearance.

Although in the preferred embodiment of the invention two series-connected If there are wedge drives, only the wedge angle of the expanding jaws should be the self-locking condition meet, the wedge angle of the located between the auxiliary piston and the expanding jaws Wedge drive, however, does not. This preferred embodiment ensures that the reaction force from the actuation force of the main piston via the expanding jaws is supported directly on the saddle and the transmission link between the auxiliary piston and the spreading jaws are not loaded.

In view of the problem discussed above, the wedge angle lies of the expanding wedge drive preferably between 30 and 600 and preferably at 450, while the wedge angle of the expanding jaws between 10 and 200 and preferably should be at 150 l.i.een.

The invention is illustrated in the following example with reference to the drawing described; 1 shows a schematic axial section of an inventive Floating caliper partial covering disc brakes and FIG. 2 shows a schematic section of the Schwcllenventils 28 according to Fig. 1 According to Fig. 1 is on the inside of a disc 19 a main piston-cylinder arrangement 27 is formed in that in one on the saddle 15 formed cylinder, a main actuating piston 17 is arranged axially displaceable which is from the pitch operated master cylinder 29 via a threshold valve 28 and the supply line 26 can be acted upon with brake pressure.

The saddle 15 engages around the outside or inside in a manner not shown the brake disk 19 on the one facing away from the main actuation device 27 On the side of the disk 19, the caliper 15 has a central bore in the area of the brake shoes 16 30, into which a small cylinder 20 is inserted, which via a line 31 is acted upon directly by the master cylinder 29. Located in the cylinder 20 a small piston 12, which has a wedge drive via a plunger with a ball head 32 13 is applied, the between two diametrically opposite expanding jaws 14 is provided. The expanding jaws 14 have a wedge-shaped or conical outer surface l8, while the surface facing the brake shoes 16 is flat and against an intermediate plate 23, which acts on the outer brake shoe 16 directly.

The wedge or conical surface 18 lies on the complementary inner surface 24 of a flange 21 which is formed on the cylinder 20 and the saddle 15 inside engages behind. Bores 33 in the expanding jaws 14 accommodate tension springs 22, which bias the intermediate plate 23 and the flange 21 towards one another. The annular gap between the flange 21 and the intermediate plate 23 is all around by an elastic Protective cap 25 covered.

Around approaches to the expanding jaws 14 in the area of the ball head 32 if a spring washer is placed B4, the expanding jaws 14 are softer against the ball head 32 tension and return it to its original position after actuation can.

Axial stops 36 on the expanding jaws 14 limit the axial movement of the auxiliary piston 12 in the direction of the braking.

disk 19.

The operation of the brake according to the invention is as follows: When When the brake pedal 35 is depressed, initially only a low pressure of, for example, builds up 3 to 5 bar, which acts on the auxiliary piston 12- directly and via the Wedge drive 13 and the wedge or conical surfaces 18, 24 the.

outer brake shoe 1 moves in the direction of the brake disc 19, until it comes to the system there .. If the pressure increases further, the wave valve opens 28 and also acts on the main piston 17, which due to its considerable larger area transmits a much greater force to the saddle 15 than the Auxiliary piston 12.

Due to the self-locking on the wedge surfaces 18, 24, however, it is prevented that the greater force of the piston 17 pushes the small piston. 12 into its cylinder 20 lets back away.

The wedge angle 1 of the wedge drive 13 shown in FIG preferably selected so large that no self-locking occurs at this point. The wedge angle 9 of the wedge surfaces 18, 24, on the other hand, is chosen so small that there in Brake release direction a self-locking occurs. In this way the ball head 32 of the auxiliary piston 12 is only slightly loaded during braking.

The distance between the auxiliary piston 12 and the stops 36 lies in the brake release position shown in Figure 1 in the order of magnitude of the clearance, so that after it has been overcome, the auxiliary piston 12 rests against the stops 36 and the spreading instinct is thus neutralized.

The two are in the brake release position shown in FIG radially opposite expanding jaws 14 on the axis of the arrangement to one another at. This creates a defined end position for the brake shoes in the brake release position ensured.

Fig. 2 shows schematically the internal structure of the threshold valve 28. One with a check valve. 37 equipped valve plate 38 is through a spring 39 against the pressure from the master cylinder 29 against an annular one Valve seat 40 biased so that only above one by the force of the spring 39 certain threshold pressure the valve plate 38 from the annular valve seat 40 lift off and -soden passage to the supply line 26 to the master cylinder 15 can be released. The check valve 37 acts in the opposite direction and gives when loosening the brake, i.e. a central opening when the pressure in the master cylinder 29 drops 41 in-the valve plate 38 free. The check valve is in the opposite direction like die'Ventilplatte 38 acted upon by a further spring 42, which, however is made much weaker than the spring 39.

As can be seen particularly clearly from the drawing, the Device according to the invention very flat, so that it is particularly suitable for housing suitable within the bowl of a vehicle wheel.

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Claims (15)

Floating caliper partially lined disc brake Patent claims 5 Floating caliper partially lined disc brake with a main piston-cylinder arrangement arranged on one side of the disk on the floating caliper and with a disk side facing away from the main piston-cylinder arrangement brake clearance overcoming device arranged between the floating caliper and the brake shoe, which is an auxiliary piston-cylinder arrangement with a much smaller cross-sectional area than the main piston-cylinder arrangement, coming from the same pressure source as the. Main piston-cylinder arrangement is fed, thereby g e k e n n z e i c h -n e t that the piston (12) of the auxiliary piston-cylinder arrangement is adjacent to it Brake shoe (16) via a spreading device (13) supported on the floating caliper (15) 14, 18,24, 32) actuated, the axial force amplification factor of which is only as large as as it is for the achievement of one Self-locking taking into account the force exerted by the auxiliary piston (12) is required in the brake release direction, and that the pressure source (29) is only above a predetermined threshold pressure can be connected to the main piston-cylinder arrangement, so that above this predetermined threshold pressure the spreading device (13, 14, 18, 24, 32) the force the main-piston-7-cylinder arrangement of the floating pad} on the brake shoe directly transmits. 2. Brake according to claim 1, characterized in that g e k e n n z e i c h -n e t, that the cross-sectional area of the auxiliary piston-cylinder arrangement is just large enough as is the case for advancing the associated brake shoe (16) below the threshold pressure is required. 3. Brake according to claim 1 or 2, characterized in that g e k e n n. -Z e i c h n e t that the piston (12) of the auxiliary piston-cylinder arrangement via an expanding wedge drive (13) acts on at least two radially displaceable expanding jaws (14) which in turn are wedge-shaped or cone-shaped and are located between the saddle (1.5) and the brake shoe (16) extend. 4. Brake according to one of the preceding claims, dadruch g e k e n n z e i c h n e t that the cylinder (20) of the small piston (12) in the saddle (15) is arranged and a. the saddle (15) has inside rear engaging flange (21), the disc side has a wedge or conical surface (24) on which the complementary The wedge or conical surfaces (18) of the expanding jaws (14) are in contact. 5. Brake according to claim 4, characterized in that g e k e n n z e i c h -n e t, that the disc-side surfaces of the expanding jaws (14) are flat and on an intermediate plate (23) are in contact. 6. Brake according to claim 4 and 5, characterized in that g ek e n n -z e i c h n e t that the expanding jaws (14) and the intermediate plate (23) by springs (24) on one another are too biased. 7. Brake according to one of the preceding claims, characterized in that g e k E n n z e i c h n e t, -that in the hydraulic supply line (26) to the main piston-cylinder arrangement (27) a threshold valve (28) is switched on, welcfics only above the predetermined Threshold pressure opens. 8. Brake according to one of claims 3 to 7, characterized in that g e -k e n n z e i c h n e t that the spreading device (13, 14, 18, 24, 32) by a spring arrangement (34) is biased towards its unspread position. 9. Brake according to claim 2 and 8, characterized in that g e k e n n -z e i c h n e t that the two radially opposite expanding jaws (14) through a spring (34) are biased towards one another. 10. Brake according to one of claims 4 to 9, characterized in that g e -k e n n z e i c h n e t that the spreading device (13, 14, 18, 24, 32) by an annular Protective cap .825) between the cylinder flange (21) and the intermediate plate (23) is sealed. 11. Brake according to claim 10, characterized in that it g e k e n n z e i c h -n e t that the cylinder flange (21) and the intermediate plate (23) are round. 12. Brake according to one of claims 2 to 11, characterized in that g e -k e n n z e i c h n e t that the brake application movement of the auxiliary piston (12) by a Stop (36) on the expanding jaws (14) is limited. 13. Brake according to one of claims 2 to 12, characterized in that g e -k e n n z e i c h n e t that the wedge angle (ß) of the expanding jaws (14) the self-locking condition fulfilled, the wedge angle (i) of the wedge drive (13), however, not. 14. Brake according to one of claims 2 to 13, thereby g e k e n n z e i c h n e t that the wedge angle (of the expanding wedge drive (13) between 30 and 60 ° and preferably 450. 15. Brake according to one of claims 2 to 14, characterized in that g e -k e n n z e i c h n e t, - that the wedge angle (ß) of the expanding jaws (14) between 10 and 200 and preferably 150.