Brake comprising a fluid expansion reservoir

Abstract

The invention relates to a disc brake (1) comprising a cylinder (25) filled with a liquid, typically a brake fluid, characterized in that it comprises an expansion reservoir (31) which is permanently hydraulically connected to the cylinder (23).

Description

DESCRIPTION TITLE: BRAKE WITH A FLUID EXPANSION TANK TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a brake comprising a fluid expansion tank. PREVIOUS STATE OF THE ART

[0002] It is known, on the one hand, to manufacture hydraulic disc brakes comprising a hydraulic circuit filled with brake fluid, including a variable-volume cylinder connected, when not braking, to a brake fluid reservoir open to the atmosphere. The connection to the brake fluid reservoir ensures pressure equalization, particularly during variations in the cylinder's internal volume resulting from piston movement due to brake pad and disc wear. Furthermore, the brake fluid lubricates the mechanical parts pressing within the cylinder, such as the piston and / or the brake pad wear compensation mechanism. Such brakes are described in US 2024 / 409076 and GB 2 307 525.

[0003] It is known, on the one hand, to manufacture electric disc brakes whose cylinder is filled with brake fluid but lacks a hydraulic circuit and therefore a reservoir open to the atmosphere. The Plaintiff discovered that pressure variations in the cylinder of such a brake disrupt its proper operation, and in particular the position of the piston when not braking.

[0004] Furthermore, it is known that dry electric disc brakes, i.e. filled with air, cause premature wear of unlubricated parts.

[0005] It is therefore an object of the present invention to provide a brake comprising a variable-volume chamber, referred to hereafter as a cylinder, in which the internal pressure is controlled. It is also an object of the present invention to provide such a brake in which the internal mechanical parts of the cylinder are lubricated. DESCRIPTION OF THE INVENTION

[0006] These objectives are achieved by a brake according to the invention equipped with an expansion tank. The invention aims to overcome all or part of the drawbacks of the prior art. In this regard, the invention relates to a disc brake comprising a cylinder filled with a fluid, typically brake fluid, characterized in that it includes an expansion tank permanently hydraulically connected to the cylinder.

[0007] The invention also relates to a brake characterized in that the expansion vessel comprises a body delimiting an internal cavity.

[0008] The invention also relates to such a brake characterized in that the expansion vessel comprises means dividing the internal cavity delimited by the body into a first volume connected to atmospheric pressure and a second volume separated from the first volume.

[0009] The invention also relates to such a brake characterized in that the expansion vessel comprises a flexible wall dividing the internal cavity delimited by the body into a first volume connected to atmospheric pressure and a second volume separated from the first volume.

[0010] The invention also relates to such a brake characterized in that the expansion vessel has a lid and in that a periphery of the flexible wall dividing the internal cavity delimited by the body into a first volume connected to atmospheric pressure and a second volume separate from the first volume is pinched between the body of the expansion vessel and the lid.

[0011] The invention also relates to such a brake characterized in that the expansion vessel has a chimney for fixing to a brake caliper.

[0012] The invention also relates to such a brake characterized in that the chimney has a channel connecting the second volume to a channel opening into a cylinder of the caliper.

[0013] The invention also relates to such a brake characterized in that the flexible wall has folds.

[0014] The invention also relates to such a brake characterized in that it comprises a floating caliper equipped with an electric geared motor.

[0015] The invention also relates to a method for manufacturing a brake forming a parking and / or emergency brake with purely electromechanical operation and without connection to a hydraulic braking circuit, referred to as a purely electromechanical brake, said method comprising: - on the one hand, the supply of a so-called mixed brake, designed to operate electromechanically as a parking brake and hydraulically as a service brake, and on the other hand, the supply and fitting by screwing of an expansion vessel into a hydraulic control inlet or a bleed screw inlet of said mixed brake, The said mixed brake is thus converted to form the said purely electromechanical brake. BRIEF DESCRIPTION OF THE FIGURES

[0016] The present invention will be better understood upon reading the description of non-limiting examples of embodiments, with reference to the attached figures, which illustrate: - [Fig. 1]: an isometric view of a parking brake according to the preferred embodiment of the invention; - [Fig. 2]: a cross-sectional view of the brake in figure 1; - [Fig. 3]: a cross-sectional view of an expansion vessel whose internal volume is mainly filled with liquid; - [Fig. 4]: a cross-sectional view of an expansion vessel from figure 3 whose internal volume is mainly filled with air. DETAILED DESCRIPTION OF AT LEAST ONE IMPROVEMENT METHOD

[0017] For clarity, identical elements are identified by identical reference symbols from one figure to another.

[0018] Figure 1 shows the preferred embodiment of a brake 1 according to the present design, comprising a yoke 3 and a floating caliper 5. The yoke is equipped with means for mounting it on a motor vehicle chassis. The caliper 5 is mounted to slide relative to the yoke on guide pins 7. The caliper 5 has a caliper nose 9 and an arch 11 that straddles a brake disc which is rotationally fixed to a wheel of a vehicle, typically a rear wheel. The yoke also straddles the brake disc. An outer brake pad 13, fitted with a friction lining, is carried by the caliper nose 9. The caliper 5 is equipped with a piston 17 which is moved, on command, by an electric geared motor 19 via a wear compensation device 21 for the brake pads and the disc. The piston 17, pushed by the device 21, exerts a force, on command, on an inner pad 23, in the direction of a main face of the brake disc.In the advantageous, non-limiting example shown, the piston 17 is housed in a cylinder 25, the sealing being ensured by a square gasket 27 surrounding the piston 17 and by a torii gasket 29 disposed in a groove of the caliper 5 and compressed by the geared motor 19.

[0019] According to the invention, the cylinder 25 is connected to an expansion vessel 31, for example, by a channel 33 formed in the wall of the stirrup 5. The expansion vessel 31, illustrated in Figures 3 and 4, comprises a body 35, for example cylindrical, delimiting an internal cavity divided into two volumes by a flexible membrane or wall 37. The flexible wall 37 is watertight and is made of a material compatible with the liquid filling the cylinder 25, advantageously an elastomer. The body 35 of the expansion vessel 31 has a chimney 39 delimiting a central channel 41 opening into the channel 33. A cover 43 closes the internal cavity while pinching the periphery of the flexible wall 37, thus ensuring a seal between the first volume 45 and the second volume 47 of the cavity.An opening and / or a micro-perforated membrane, not shown, allows the opening to the atmosphere of a first volume 45 of the internal cavity, which is hermetically sealed from the channel 41, and a second volume 47 by the flexible membrane 37. The second volume 47 of the internal cavity is connected to the channel 41. The flexible wall 37 advantageously protects the second volume 45 from pollution by atmospheric contaminants, such as dust or liquid or gaseous water. Advantageously, the flexible membrane 37 has folds facilitating its deployment, as illustrated in Figure 4, or its folding, as illustrated in Figure 3. Advantageously, a seal, for example a torigue, surrounds the chimney 39 to confine the fluid, typically brake fluid, within the cylinder 25, the channel 33, the channel 41, and the second volume 47. The expansion vessel 31 is secured to the caliper 5 by the chimney 39, for example, by screwing. K646.

[0020] As can be understood and illustrated in the figures, the expansion vessel 31 is advantageously fixed and connected to the caliper via a threaded opening, which is connected to the cylinder 25, pre-existing in a given hydraulic caliper. Advantageously, the chimney 39 has a thread that complements the tapping of the opening into which it is screwed. As illustrated, for example, in Figures 1 and 2, it is thus possible to fix the expansion vessel to the pressure inlet of a standard caliper designed for hydraulic service braking, or to the location of its bleed screw. This provides an electromechanical parking brake that does not require connection to a hydraulic braking circuit. This parking brake can, for example, be mounted as a second brake on a wheel, in addition to a conventional combined brake performing both service and parking functions, to increase parking braking safety.It can also be mounted in addition to a brake performing only service braking, to ensure the parking and emergency function on its own, or even on an unbraked wheel or shaft.

[0021] Alternatively, the flexible wall 37 is supplemented or replaced by a movable piston separating the first and second volumes.

[0022] When the disc and the pads 13, 23 are new, the piston 17 is in a retracted position as illustrated in Figure 2. Excess brake fluid is located in the second volume 47 as illustrated in Figure 3. When the pads 13, 23 are applied to the friction tracks of the brake disc, the piston 17 moves towards the disc, causing an increase in the volume of cylinder 25 and drawing brake fluid from the second volume 47, causing the first volume 45 to expand. The increase in the volume of cylinder 25 is exacerbated by wear on the pads 13, 23 and the disc; the wear compensation device 21 also moves the piston 17 out of cylinder 25. The expansion tank is in a configuration illustrated in Figure 4.When replacing worn pads 13, 23 with new pads, the piston 17 is pushed back into the cylinder 25, towards the left in Figure 2. This reduces the available volume of the cylinder 25, with the brake fluid flowing towards the second volume 47 as illustrated in Figure 3.

[0023] Advantageously, cylinder 25 and the second volume 47 are filled with brake fluid such as DOT 4 brake fluid (acronym for "Department Of Transportation" or Minister of Transportation of the United States of America), DOT 5, DOT 5.1, mineral brake fluid, oil or similar, at atmospheric pressure.

[0024] The expansion tank also prevents brake fluid pressure from building up when the brake fluid temperature increases. It should be noted that at a constant temperature, the sum of the volumes of cylinder 25 and the second volume 47 is constant.

[0025] It should be noted that the fluid filling cylinder 25 acts as a lubricant and corrosion protector for the mechanisms immersed within cylinder 25, and not as a hydraulic fluid for transmitting forces and pressures. The degradation of its hydraulic performance, and in particular its boiling point, is less critical than the performance of the brake fluid in a hydraulic brake. Thus, the use of an expansion vessel 31 without a flexible wall 37 does not fall outside the scope of the invention. In this latter case, the internal cavity delimited by the wall 35 of the expansion vessel 31 forms a single volume.

[0026] The brake 1 according to the invention is a parking brake, a parking and emergency brake, a service brake, or a parking and service brake. In this patent, a parking brake is understood to be a brake intended to hold a motor vehicle, such as a car, stationary. Advantageously, the brakes 1 are mounted on at least one axle, for example, on the wheels of the rear axle of a vehicle, or on the wheels of the front and rear axles. The implementation of other brakes to displace the brake according to the invention in addition to the brake according to the invention K646 on the same axle and / or on the same disc does not fall outside the scope of the present invention. Advantageously, as illustrated, the brake according to the invention is a disc brake with a floating caliper. However, brakes with fixed calipers include an expansion tank 31 and do not fall outside the scope of the present invention.

[0027] Cylinder 25 and second volume 47 are advantageously filled with fluid, typically brake fluid, on the brake assembly line 1.

[0028] The invention is applicable to the automotive industry. LIST OF DIGITAL REFERENCES

[0029] 1 brake 3 screed 5th caliper 7th column 9 stirrup nose 11 stirrup arch 13 outdoor skate 17 piston 19 geared motor 21 wear compensation device 23 indoor skate 25 cylinder 27 square joint 29 O-ring 31 expansion vessel channel 33 35. Body of the expansion vessel 37 flexible membrane 39 chimney K646 channel first volume expansion tank lid second volume seal

Claims

K646 DEMANDS 1. Disc brake (1), comprising a cylinder (25) filled with a fluid, typically a brake fluid, characterized in that it comprises an expansion tank (31) permanently hydraulically connected to the cylinder (25).

2. Brake (1) according to claim 1 characterized in that the expansion vessel (31) comprises a body (35) delimiting an internal cavity.

3. Brake (1) according to claim 2 characterized in that the expansion vessel (31) comprises means dividing the internal cavity delimited by the body (35) into a first volume (45) connected to atmospheric pressure and at least a second volume (47) separated from the first volume (45).

4. Brake (1) according to claim 3 characterized in that the expansion vessel (31) comprises a flexible wall (37) dividing the internal cavity delimited by the body (35) into a first volume (45) connected to atmospheric pressure and a second volume (47) separated from the first volume (45).

5. Brake (1) according to claim 4 characterized in that the expansion vessel (31) has a lid (43) and in that a periphery of the flexible wall (37) dividing the internal cavity delimited by the body (35) into a first volume (45) connected to atmospheric pressure and a second volume (47) separated from the first volume (45) is pinched between the body (35) of the expansion vessel (31) and the lid (43).

6. Brake (1) according to any one of the preceding claims, characterized in that the expansion vessel (31) comprises a chimney (39) for attachment to a brake caliper (5). K646 7. Brake (1) according to claim 6 characterized in that the chimney (39) has a channel (41) connecting the second volume (47) to a channel (33) opening into a cylinder (25) of the caliper (5).

8. Brake (1) according to claim 4, 5, 6 or 7 characterized in that the flexible wall (37) has folds.

9. Brake (1) according to any one of the preceding claims characterized in that it comprises a floating caliper equipped with an electric geared motor (19).

10. Brake (1) according to claim 9 characterized in that said brake is a parking brake.

11. A method for manufacturing a brake according to any one of claims 6 to 10, forming a parking and / or emergency brake with purely electromechanical operation and without connection to a hydraulic braking circuit, referred to as a purely electromechanical brake, said method comprising: - on the one hand, the supply of a so-called mixed brake, designed to operate electromechanically as a parking brake and hydraulically as a service brake, and on the other hand, the supply and screw-fitting of an expansion vessel (31) into a hydraulic control inlet or a bleed screw inlet of said mixed brake, said mixed brake being thus converted to form said purely electromechanical brake.

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