Brake caliper comprising a piston in which a spacer is fixed, forming a thermal barrier

Abstract

The invention relates to a brake caliper (2) for a brake disc braking device (4), comprising a brake control chamber (21) adapted to be open towards the brake disc (4), in which is slidably mounted a piston (5) which has an internal chamber (51) adapted to be open towards the brake disc (4), said internal chamber (51) comprising a spacer (6) which is made of a thermally insulating material, said spacer (6) being projecting from the piston (5), towards the brake disc (4), the spacer (6) and the piston (5) comprising fastening means (52, 62, 71) for fixing the spacer (6) in the internal chamber (51) of the piston (5), the fastening means (52, 62, 71) comprising an elastic ring (71) positioned so as to block in translation the spacer (6) in the internal chamber (51) of the piston (5). Figure for the summary: Fig. 2

Description

Title of the invention: BRAKE CALIPER COMPRISING A PISTON IN WHICH IS FIXED A SPACER FORMING A THERMAL BARRIER

[0001] The present invention relates to an improved cooling braking device.

[0002] The present invention relates to a brake caliper for a braking device brake disc, comprising a brake control chamber adapted to be opened towards the brake disc, in which a piston is slidably mounted, said piston comprising an internal chamber adapted to be opened towards the brake disc, said internal chamber comprising a spacer which is made of a thermally insulating material, said spacer comprising a portion extending projecting from the internal chamber of the piston, towards the brake disc, the spacer and the piston comprising means for fixing the spacer in the internal chamber of the piston.

[0003] The aerodynamics of a vehicle is strongly impacted by the openings which are formed in the wheel rim to cool the braking system; closing the wheel rim further increases the temperature of the braking system in the event of high stresses and in particular the temperature of the hydraulic fluid.

[0004] Thus, during steep descents of mountain passes, the brakes are under heavy stress, the discs and the hydraulic braking fluid can reach very high temperatures which can cause the braking device to malfunction, and in particular create the appearance of air bubbles in the hydraulic fluid if it exceeds the maximum operating temperature, causing it to boil.

[0005] The main problem that risks causing the hydraulic braking fluid to boil comes from the temperature of the brake disc which is under-supplied with fresh air due to a wheel fairing that promotes aerodynamics, causing the disc to reach a temperature of 700°C, transmitting part of this heat to the brake pads which will raise the temperature of the brake caliper and the hydraulic fluid contained in the caliper.

[0006] Document FR3114134 discloses a brake caliper which includes a spacer which is made of a thermally insulating material and which is positioned between the brake caliper piston and the first of the two brake pads.

[0007] But in this document, different embodiments are disclosed which are difficult to implement and which present safety problems in the event of breakage of the spacer during the operation of the braking device.

[0008] The device according to the invention makes it possible to remedy these drawbacks.

[0009] It includes a brake caliper for a disc brake device, comprising a brake control chamber adapted to be open towards the brake disc, in which a piston is slidably mounted, said piston comprising an internal chamber adapted to be open towards the brake disc, said internal chamber comprising a spacer which is made of a thermally insulating material, said spacer comprising a part extending in projection from the internal chamber of the piston, towards the brake disc, the spacer and the piston comprising fixing means for fixing the spacer in the internal chamber of the piston, the fixing means comprising an elastic ring positioned so as to block the spacer in translation within the internal chamber of the piston.

[0010] According to a first characteristic of the invention, an internal lateral wall of the piston delimiting said internal chamber and an external lateral wall of the spacer each comprise a groove, said two grooves being positioned opposite one another, the elastic ring being positioned in said two grooves.

[0011] According to a second characteristic of the invention, the elastic ring is formed by a conical elastic ring, a corrugated elastic ring or a snap ring.

[0012] According to a third characteristic of the invention, the spacer protrudes 2 mm from the internal chamber of the piston.

[0013] According to a fourth characteristic of the invention, the spacer extends to the bottom of the internal chamber of the piston.

[0014] According to a fifth characteristic of the invention, the piston is made of steel and the spacer is made of bakelite.

[0015] The present invention also relates to a vehicle which includes a braking device with at least one of the preceding characteristics.

[0016] The present invention also relates to a braking device comprising a brake caliper having at least one of the preceding characteristics and a vehicle comprising such a braking device.

[0017] The attached drawings illustrate the invention:

[0018] [Fig-1] represents a perspective view of a braking device according to the invention.

[0019] [Fig.2] represents a partial cross-sectional view, along a vertical cutting axis, of the braking device according to a first embodiment of the invention.

[0020] [Fig.3] represents a partial cross-sectional view, along a vertical cutting axis, of the braking device according to a second embodiment of the invention.

[0021] [Fig.4] represents a partial cross-sectional view, along a vertical cutting axis, of the braking device according to a third embodiment of the invention.

[0022] With reference to figures 1 and 2, the braking device 1 comprises a brake caliper 2 equipped with two friction pads 3 and a brake disc 4.

[0023] The brake caliper 2 comprises clamping means adapted to, during a braking command, move a first friction pad 31 against a first friction track 41 of a first face of the brake disc 4, this first friction causing the brake caliper 2 to move in the opposite direction and consequently, to move it by a second friction pad 32 against a second friction track 42 of a second face of the brake disc 4 and this as known from the state of the art for a so-called floating brake caliper 2.

[0024] The clamping means comprise a piston 5 mounted to slide in a brake control chamber 21 formed in the caliper 2.

[0025] The caliper 2 has conduits which supply the brake control chamber 21 with hydraulic fluid to actuate the movement of the friction pads 3 against the friction tracks of the brake disc 4 during said brake control.

[0026] The piston 5 having an internal chamber 51 adapted to be open in the direction of the friction plates 3 and which is adapted to contain a spacer 6 made of a thermally insulating material.

[0027] The spacer 6 protrudes 2 mm from the internal chamber 51 of the piston 5, so as to exert pressure on the first friction pad 31 when braking is activated, without the piston 5 being too close to the first friction pad 31 to limit the heat transfer from the temperature of the friction pads 31 to the piston 5.

[0028] The spacer 6 is present to thermally insulate the first friction pad 31 from the piston 5 and consequently limit thermal heating of the hydraulic fluid.

[0029] The small 2 mm protrusion of the internal chamber 51 of the piston 5 of the spacer 6 ensures the safety of the operation of the braking device, because in the event of breakage or any other damage to the spacer 6, the piston 5 is able to resume its function of pressing against the first friction pad 31 when braking is activated without the conduction temporarily resulting in a significant variation in the depressurization of the brake pedal, which could create the impression of no longer having brakes.

[0030] The spacer 6, in addition to having thermal insulation qualities with a very low conductivity coefficient, must also play a role as a vibration insulator so as not to amplify braking noises.

[0031] Different materials can be considered such as a titanium alloy, stainless steel and preferably, bakelite.

[0032] The term bakelite designates a material formulated by a laminate consisting of layers of high-strength cotton fabric, impregnated with phenolic resin, agglomerated hot under high pressure, providing both low thermal conduction and high heat resistance.

[0033] To ensure good retention of the spacer 6 in the internal chamber 51 of the piston 5, a first groove 52 is provided, formed along the internal side wall of the internal chamber 51 of the piston 5, and a second groove 62 is formed along the external side wall of the spacer 6, with the first groove 52 being positioned opposite the second groove 62, and an elastic ring is positioned in both grooves.

[0034] In [Fig.2] a first embodiment is shown where the elastic ring is formed by a conical elastic ring 71.

[0035] In [Fig.3] a second embodiment is shown where the elastic ring is formed by a corrugated elastic ring 72.

[0036] In [Fig.4] a third embodiment is shown where the elastic ring is formed by a stop ring 73.

[0037] In the third embodiment, the stop ring 73 is crushed during the mounting of the spacer 6 in the piston 5, so that the second groove 62 can have the same depth as the first groove 52.

[0038] In the first two embodiments, the elastic ring is entirely contained in the second groove 62 when the spacer 6 is mounted in the piston 5, so that the second groove 62 must have a depth equal to the width of the arm of the elastic ring, the first groove 52 remaining of shallower depth.

[0039] In these three embodiments, there is always a piston 5 which receives only small modifications which makes the installation of such a spacer 6 very simple, not modifying the overall design of the caliper 2.

[0040] The size of the spacer 6 is also favorable to form a good thermal insulator for the hydraulic fluid, making it possible to achieve the objective of keeping the fluid below 150°C without too much difficulty.

Claims

Claims

1. Brake caliper (2) for a braking device (1) with a brake disc (4), comprising a brake control chamber (21) adapted to be open towards the brake disc (4), in which a piston (5) is slidably mounted, said piston (5) comprising an internal chamber (51) adapted to be open towards the brake disc (4), said internal chamber (51) comprising a spacer (6) which is made of a thermally insulating material, said spacer (6) comprising a portion extending projecting from the internal chamber (51) of the piston (5), towards the brake disc (4), the spacer (6) and the piston (5) comprising fixing means (52, 62, 71, 72, 73) for fixing the spacer (6) in the internal chamber (51) of the piston (5), characterized in that the fixing means (52, 62, 71, 72, 73) comprise an elastic ring (71, 72,73) positioned so as to block the spacer (6) in translation in the internal chamber (51) of the piston (5), characterized in that the spacer (6) protrudes 2 mm from the internal chamber (51) of the piston (5) and in that the spacer (6) is made of bakelite.,

2. Brake caliper (2) according to claim 1, characterized in that an internal lateral wall of the piston (5) delimiting said internal chamber (51) and an external lateral wall of the spacer (6) each comprise a groove (52, 62), said two grooves (52, 62) being positioned opposite one another, the elastic ring (71, 72, 73) being positioned in said two grooves (52, 62).

3. Brake caliper (2) according to claim 1 or 2, characterized in that said elastic ring (71, 72, 73) is formed by a conical elastic ring (71), a corrugated elastic ring (72) or a snap ring (73).

4. Brake caliper (2) according to any one of the preceding claims, characterized in that the spacer (6) extends to the bottom of the internal chamber (51) of the piston (5).

5. Brake caliper (2) according to any one of the preceding claims, characterized in that the piston (5) is made of steel.

6. Braking device (1) comprising a brake caliper (2) according to any one of the preceding claims.

7. Vehicle comprising a braking device (1) according to the preceding claim.

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