WO2002097294A1

WO2002097294A1 - Parking brake caliper and parking brake

Info

Publication number: WO2002097294A1
Application number: PCT/IT2001/000271
Authority: WO
Inventors: Giovanni Mario Tironi; Enrico Battista Ongaretti
Original assignee: Freni Brembo S.P.A.
Priority date: 2001-05-28
Filing date: 2001-05-28
Publication date: 2002-12-05

Abstract

The caliper body (12) houses a pair of pads (18) for cooperating with the disk (16), and a winding element (34) which is rotatable relative to an axis (42) and comprises means (36) for locking an end of a tensile element (32). Moreover, resilient means (46) are operatively interposed between the winding element (34) and the caliper body (12). A thrust member (52), operatively connected to the winding element (34), is movable along a translation axis perpendicular to the axis (42) of rotation of the winding element (34) and parallel to a longitudinal axis (X) of the caliper. A pair of gears, driven by the winding element (34) is interposed between the winding element (34) and the thrust member (52).

Description

"Parking brake caliper and parking brake" DESCRIPTION

The subject of the present invention is a parking- brake caliper for a vehicle and, in particular, a mechanically-operated caliper.

According to a further aspect, a subject of the present invention is a parking brake for a vehicle.

It is known to provide disk braking systems; in these systems, the parking brake usually comprises a mechanically-operated caliper, in combination with a hydraulic caliper and acting on the same disk.

Known mechanically-operated calipers generally comprise a lever having one end articulated to the caliper body and the other end connected to a tensile element . The tensile element is operatively connected to an operating device housed in the passenger compartment of the vehicle, for example, a hand lever or an electric actuating device .

Action on the tensile element brings about a pivoting movement of the lever which in turn is converted into a pressure of the pads against the so-called braking band of the disk.

Each type of vehicle has its own obstructions and structures which require the caliper to be very versatile in order to suit the characteristics imposed by vehicle manufacturers. In particular, the constructional selections made by the manufacturer of the vehicle dictate the orientation which the tensile element must have when it reaches the caliper body. In order to define the orientation of the tensile element relative to the caliper body, a longitudinal axis extending perpendicular to the pads can be defined in every caliper. It is correspondingly possible to have vehicles in which the tensile element of the parking- brake extends along axes parallel or perpendicular to the longitudinal axis of the caliper.

For example, there are known mechanical calipers in which the cable extends along an axis parallel to the longitudinal axis of the caliper and the caliper- operating lever pivots in a plane perpendicular to this axis. These calipers require, amongst other characteristics, for example, a pulley transmission, and have considerable structural complexity which leads to high manufacturing costs. In addition to structural complexity, known calipers have the disadvantage that they are not sufficiently versatile to permit the provision of a single caliper type suitable for any direction of entry of the operating tensile element. Moreover, known calipers have disadvantages relating to their capacity to take up the wear of the disk. In fact, the angular travel of the lever is limited, in the two extreme positions respectively, by a travel limiter which the lever abuts in rest conditions, and by the position of alignment of the tensile element with the lever, which corresponds to the maximum travel of the tensile element. In order to take up the wear of the disk, known calipers consequently have complex and sophisticated mechanisms for taking up play. It is clear from the foregoing that there is a need to have a parking-brake caliper of simple construction such that it can be operated by a tensile element arriving along a longitudinal axis relative to the caliper. In the second place, there is also clearly a need to be able to use a caliper of a single type for any vehicle, that is, a caliper of a type which can be adapted to any direction of entry of the tensile element . Finally, there is also clearly a need for simple and effective taking-up of the wear of the disk. The aim of the present invention is to devise and to provide a parking-brake caliper and a parking brake which satisfy the above-mentioned requirements and at the same time overcome the disadvantages mentioned with reference to the prior art . This aim is achieved by means of a parking-brake caliper for a vehicle of the type specified above and according to Claim 1.

This aim is also achieved by means of a parking brake according to Claim 18. Further characteristics and the advantages of the caliper and of the parking brake according to the invention will become clear from the following description of preferred embodiments, given below by way of non-limiting example with reference to the appended drawings, in which:

Figure 1 is a perspective view of a parking-brake caliper according to the invention,

Figure 2 is a front view of the caliper of Figure 1, taken on the arrow II, Figure 3 is a view of the caliper of Figure 1 which is taken from above in accordance with the arrow III and in which some elements have been omitted in order to show others,

Figure 4 is a partial longitudinal section, that is, a view of the caliper of Figure 3 partially sectioned on the line IV-IV,

Figure 5 is a transverse section, that is, a view of the caliper of Figure 3 sectioned along the line V-V,

Figure 6 shows a possible variant of the caliper of Figure 4, and Figure 7 shows a transverse section of the caliper of Figure 6.

With reference to the drawings, a parking-brake caliper for a vehicle is generally indicated 10. The caliper comprises a caliper body 12 provided with guides 14 for the mounting of the caliper on non- rotating portions of the vehicle, not shown.

The caliper body 12 is constituted by two portions 12a and 12b joined together by threaded connections 13. A first portion 12a comprises seats for coupling with the guides, and a second portion 12b, also referred to as the bridge, extends from the first portion. When the caliper body is mounted on fixed portions of the vehicle, the second portion or bridge is such as to be arranged astride a disk 16 associated with a wheel of the vehicle and rotated thereby.

The portion of the caliper body 12 which is arranged astride the disk 16 houses a pair of pads 18. The pads are of conventional structure, each having a main surface 19 to be arranged parallel to a braking band 20 of the disk 16.

For simplicity of description, an axis X perpendicular to the surface 19 of the pads 18 will be referred to below by the term "longitudinal axis of the caliper" . When the caliper body 12 is mounted on the fixed portion of the vehicle and is arranged astride the disk 16, as shown, for example, in Figure 3 and in Figure 4, each pad 18 is arranged on one of the two sides of the disk in a manner such as to cooperate therewith in order to exert the braking force on the vehicle.

In particular, the pads 18 are suspended, in conventional manner, on two pins 22 fitted in the caliper body 12 along axes perpendicular to the main surface 19 of the pads 18, that is, parallel to the longitudinal axis X of the caliper.

Resilient means, which are not shown since they are of substantially known type, are fitted between the pins

22 and the pads 18 to keep the pads 18 constantly bearing on the pins 22 as well as constantly removed from the disk 16.

The caliper body 12 also comprises a cover 26 which is positioned so as to close a chamber 28 defined inside the caliper body and, in particular, inside a first portion 12a thereof. A seat 30, through which a tensile element 32 can extend, is also provided in the region of the cover 26.

The tensile element 32 has an end that is operatively connected to a parking-brake operating device which is not shown and is constituted, for example, by a hand-operated lever housed in the passenger compartment of the vehicle, or by an electric actuating device.

The other end of the tensile element is fitted inside the chamber 28 where actuating means that transmit the force exerted by the tensile element 32 to the pads 18 are housed.

The tensile element is advantageously formed by a cable constituted by an outer sheath, not shown, inside which there is a core constituted by the tensile element itself.

The actuating means advantageously comprise a winding element 34 around which a portion of the tensile element 32, in particular, the portion inside the chamber 28, is wound. Locking means 36 are provided for fixing the end of the tensile element to the winding element 34. The locking means are constituted, for example, by a pin 38 which is fitted in a ring 40 formed at the end of the tensile element 32 and is locked in seats formed in the winding element.

In the embodiment shown, the tensile element is arranged to be wound around the winding element 34 through about 360° and the portion of the tensile element entering the caliper body 12 is arranged to have an orientation parallel to the longitudinal axis X of the caliper.

The winding element 34 extends substantially along an axis 42 of symmetry about which the winding element can rotate relative to the caliper body 12. In the embodiment shown, the winding element 34 is in the form of a pulley or sheave which has a seat 44 around its periphery for housing the tensile element 32.

Moreover the axis 42 about which the winding element 34 can rotate is perpendicular to the longitudinal axis X of the caliper.

Resilient means 46 are provided between the winding element 34 and the caliper body 12, for example, in the form of a spiral spring having one end interacting with the caliper body 12 and one end interacting with the winding element 34.

The actuating means also comprise a pair of gears driven by the winding element 34. The pair of gears has a first gear 48 rotating about the rotation axis 42 of the winding element 34 and driven thereby and a second gear 50 driven by the first gear 48 and rotating about the longitudinal axis X of the caliper.

In the embodiment shown in Figures 1-5, the pair of gears is constituted by a pair of cylindrical gears in which the first gear 48 is constituted by a circular crown gear fixed for rotation with the winding element, about the axis 42.

The second gear 50 is constituted by a cylindrical gear which has an external toothed sector meshing with the toothed sector of the first gear 46 and an inner threaded portion constituting a female thread.

In addition to the above-described elements, the actuator means comprise a thrust member 52 operatively connected to the winding element 34 and movable along a translation axis perpendicular to the rotation axis 42 of the winding element and substantially coinciding with the longitudinal axis X of the caliper.

The thrust member 52 is constituted by a rod housed inside the caliper body 12 along the said longitudinal axis X. The rod has a central threaded portion 54 coupled with the female thread formed inside the second gear 50.

In a portion of the rod 52 there is a slot 56. The slot extends along an axis parallel to the longitudinal axis X of the caliper and, in the embodiment shown, extends through the entire diameter of the rod.

The slot can receive a pin 58 housed in the caliper body 12, perpendicular to the longitudinal axis X of the caliper. In the embodiment shown, the pin 58 is an extension of an axle of the winding element 34, extending along the axis 42 about which the winding element 34 and the first gear 48 rotate.

A further portion of the rod constituting the thrust member 52 extends towards the pads 18, forming a head 60. The head 60 is arranged in contact with a plate 62 supporting one of the pads 18.

The operation and the mounting of a parking-brake caliper according to the present invention are described below.

During the mounting of the caliper on the vehicle, the pads 18 are spaced apart by a predetermined distance greater than the thickness of the disk 16 and, in particular, of its braking band 20.

As soon as the caliper body is mounted on a fixed portion of the vehicle, for example, the suspension, and is arranged astride the disk, the tensile element 32 is put under tension, reacting against the resilient means 46 fitted between the winding element 34 and the caliper body 12. The tension applied by the tensile element 32 keeps the pad in the rest position. As a result, when the parking brake is not operated, that is, when it is not necessary to exert a braking force on the disk 16, the caliper assembly is kept in the rest condition by the tensile element 32.

Unlike calipers of the prior art, the winding element 34 does not in fact have a travel limiter. Calipers of the prior art in fact have a tensile element acting on a lever the rest position of which is defined by a travel limiter. As a result, when the lever is in the rest position it is in abutment with the travel limiter and the tensile element is completely unloaded.

In contrast with the arrangement described above, the caliper of the present invention provides for the resilient means 46 which, in the embodiment in question are constituted by the spiral spring disposed between the winding element 34 and the caliper body 12, to be preloaded when the caliper is mounted on the corresponding fixed portion of the vehicle. Similarly, the tensile element 32 is under tension so as to keep the pads in the rest position. When the parking brake is operated, the tensile element 32 is subjected to a pulling force directed outwardly relative to the caliper body 12. This pulling force brings about rotation of the winding element 34 about the axis 42 through an angle such as to press the pads 18 onto the disk 16.

The caliper 10 as described above is a so-called floating caliper, that is, a caliper in which, during the braking operation, the caliper body floats or slides relative to the fixed portion of the vehicle on which it is mounted. The rotation of the winding element 34 in fact brings about rotation of the first gear 48 therewith, and rotation of the second gear 50.

As a result of the rotation of the second gear 50 and of the coupling between the female thread inside the second gear and the threaded portion 54 , the thrust member 52 translates along the longitudinal axis X of the caliper. The presence of the pin 58 in the slot 56 prevents the threaded portion 54, and consequently the thrust member 52, from following the female thread in its rotation about the axis X.

The thrust member 52 consequently exerts a thrust against one of the pads 18. Finally, as a result of this thrust, the caliper body 12 is moved or floats until both of the pads 18 come into contact with and press against the braking band 20 of the disk 16, acting thereon with equal and opposite forces .

When the braking action terminates, the resilient means 46 which are loaded as a result of the rotation of the winding element 34, return the winding element to the rest position.

It can be appreciated from the foregoing description that the provision of a parking-brake caliper having a winding element 34 for the tensile element 32 satisfies the above-mentioned requirements and overcomes the disadvantages mentioned with reference to the prior art.

In particular, the caliper according to the present invention satisfies the above-mentioned requirement to limit structural complexity, nevertheless providing a caliper in which the tensile element can have an axial orientation relative to the caliper, that is, an orientation parallel to the longitudinal axis X of the caliper.

Moreover, the caliper according to the invention enables the direction of entry of the tensile element to be varied, for example, from the above-mentioned axial direction to a direction perpendicular to the longitudinal axis X of the caliper, simply by setting the angular position of rest of the winding element 34. This variation does not involve any variation of the structural elements constituting the caliper, except for the seat 30.

The direction of entry of the tensile element is therefore fully adaptable to the vehicle manufacturer's requirements .

In addition to the foregoing, the provision of a caliper having a winding element for the tensile element enables the wear of the disk, which progresses with use, to be taken up. When the parking brake is operated, for example, by means of the lever housed in the passenger compartment, the winding element 34 rotates until the pads are in contact with and pressing against the disk . The angle of rotation of the winding element 34 is determined by the travel which the thrust member 52 has to perform, in the first place to take up the play and the wear of the disk and, in the second place, to press the pads onto the disk. Only when this angle is too large is it necessary, for example, to adjust the position of the cable relative to the caliper. The operation described above may be slightly different if the parking brake is operated by an electric device which, in some cases, avoids adjustment of the cable and/or taking-up of play by not returning to the starting position. A further advantage of the caliper shown, in which the caliper body 12 is formed in two parts, lies in the versatility with which the caliper can also be adapted to disks of various thicknesses, simply by replacing the second portion 12b or bridge. Clearly, variations and/or additions may be provided for the embodiment described and illustrated.

The winding element 34, which is shown in the form of a pulley or sheave, may be of different shapes and sizes. As an alternative to the embodiment shown in the drawings, the caliper body may, for example, be formed in a single piece.

Moreover, Figures 6 and 7 show a possible variant in which the pair of gears is a pair of bevel gears. This solution provides for a structure substantially similar to that shown in Figures 1 to 5 and the reference numerals of the two embodiments are consequently the same.

In addition to this solution, further variants which enable the rotation of the winding element 34 to be converted into a translation of the thrust member 52 may be provided.

The shape, number, and size of the resilient means 46 may also differ from those shown whilst being such as to exert a biasing force on the winding element 34.

The thrust member 52 and, in particular, the head 60, provided may differ from those shown in Figure 4. In fact, in this drawing, the head 60 is shown screwed onto the rod that constitutes the thrust member 52, but the coupling between the rod and the head could be achieved by welding or by means of a ball joint.

With reference to the shape of the thrust member 52 , the slot 56 may not extend through the entire diameter of the rod constituting the thrust member. Moreover, the pin 58 may not be fixed relative to the axis 42 about which the winding element rotates .

In order to satisfy contingent and specific requirements, a person skilled in the art may apply to the above-described preferred embodiment of the parking- brake caliper, many modifications, adaptations and replacements of elements with other functionally equivalent elements without, however, departing from the scope of the appended claims .

Claims

1. A vehicle parking-brake caliper (10) comprising: a caliper body (12) which is provided with elements for the mounting of the caliper (10) on non-rotating portions of the vehicle and which can be arranged astride a disk (16) associated with a wheel of the vehicle, a pair of pads (18) for cooperating with the disk (16) in order to exert the braking force on the vehicle, actuating means which, when operated by a tensile element (32) , exert on each of the pads (18) forces directed towards the opposed pad, characterized in that the actuating means comprise a winding element (34) for the tensile element (32) , the winding element (34) being mounted on the caliper body (12) and rotatable about an axis (42) .

2. A caliper according to Claim 1 in which the winding element (34) extends substantially along an axis (42) of symmetry.

3. A caliper according to Claim 2 in which the winding element (34) is mounted on the body (12) so as to rotate about the axis of symmetry (42) .

4. A caliper according to Claim 2 or Claim 3 in which the axis (42) is perpendicular to a longitudinal axis (X) of the caliper (10) , the longitudinal axis (X) being perpendicular to the pads (18) .

5. A caliper according to at least one of the preceding claims in which the winding element (34) comprises means (36) for locking an end of the tensile element (32) .

6. A caliper according to at least one of the preceding claims in which resilient means (46) are operatively interposed between the winding element (34) and the caliper body (12) .

7. A caliper according to at least one of the preceding claims in which the winding element (34) comprises a pulley having a seat (44) for housing the tensile element (32) .

8. A caliper according to at least one of the preceding claims in which the actuating means also comprise a thrust member (52) operatively connected to the winding element (34) and movable along a translation axis perpendicular to the rotation axis (42) of the winding element (34) and parallel to a longitudinal axis

(X) of the caliper, the longitudinal axis (X) being perpendicular to the pads (18) .

9. A caliper according to Claim 8 in which the actuating means comprise a pair of gears driven by the winding element (34) and operatively interposed between the winding element and the thrust member (52) .

10. A caliper according to Claim 9 in which the pair of gears comprises a first gear (48) rotating about the axis (42) and driven by the winding element (34) .

11. A caliper according to Claim 9 in which the pair of gears comprises a second gear (50) driven by the first gear (48) and rotating about the longitudinal axis (X) .

12. A caliper according to Claim 9 in which the pair of gears is a pair of cylindrical gears.

13. A caliper according to Claim 9 in which the pair of gears is a pair of bevel gears.

14. A caliper according to Claim 9 in which the actuating means also comprise a male-and-female screw coupling operatively interposed between the pair of gears and the thrust member (52) .

15. A caliper according to Claims 11 and 14 in which the second gear (50) comprises a female thread engaging a threaded portion (54) of the thrust member (52) .

16. A caliper according to Claim 15 in which the thrust member (52) comprises a slot (56) which extends along an axis parallel to the longitudinal axis (X) of the caliper and can house a pin (58) arranged perpendicular to the axis (X) .

17. A caliper according to Claim 16 in which the pin (58) is an extension of an axle of the winding element, extending along the axis (42) about which the winding element (34) rotates.

18. A parking brake comprising a caliper according to at least one of Claims 1 to 17.