BRAKE CONTROL DEVICE FOR MOTOR VEHICLES AND VEHICLES INCLUDING SUCH A DEVICE

Abstract

The invention relates to a braking control device (1) for a motor vehicle, characterized in that said device (1) comprises: – a cam carrier (3) mounted for rotation and comprising at least one cam (5); – two cylinders (9) in each of which is mounted a piston (11), each piston (11) having two ends: a first end (11a) which, together with the cylinder (9), defines a hydraulic pressure chamber (13), and a second end (11b) configured to bear against the cam (5), each of said pistons (11) being configured to move according to the position of said cam (5), varying the volume of the associated chamber (13); the chambers (13) of each of said cylinders (9) are, on the one hand, connected to each other and to a control pressure inlet (17), and on the other hand, configured to be connected to a braking element of a wheel of the vehicle. [Fig. 1]

Description

Title of the invention: BRAKE CONTROL DEVICE FOR MOTOR VEHICLES AND VEHICLE INCLUDING SUCH A DEVICE

[0001] The present invention relates to the general field of motor vehicles and more particularly to the field of braking systems and the anti-lock braking system, better known by the acronym ABS (from the German: "Antiblockier sy s tem").

[0002] An anti-lock braking system is a braking assistance system used on moving vehicles which has the function of limiting wheel lock-up and loss of vehicle control, for example when there is a loss of grip between the vehicle's wheels and the road surface.

[0003] Anti-lock braking systems were initially designed to help drivers maintain control of their vehicles when braking in conditions of poor traction (rain, snow, ice, gravel, etc.). Such a system allows, in particular, for maintaining vehicle steering control in order to perform a possible evasive maneuver, while optimizing braking distance, which increases considerably when the wheels lock and / or the tires slip on the road surface.

[0004] A vehicle wheel anti-lock system generally includes a speed sensor for each wheel of the vehicle, an electronic control unit and a hydraulic brake pressure control system, the hydraulic brake pressure control system being configured to control the contact and pressure exerted by braking components, such as brake pads, on the wheel's brake disc to slow down, or even stop, its rotation.

[0005] Thus, during emergency braking of the vehicle, if the anti-lock braking system detects, via the associated speed sensor, the locking of a wheel meaning that the braking pressure is too high given the available grip, the anti-lock braking system will then reduce the pressure exerted by the braking components on the wheel, until the wheel is unlocked.

[0006] However, as soon as the wheel regains traction, the braking pressure will increase again to optimize braking performance, until the wheel locks up again. Therefore, the system regulates the braking pressure around the point of wheel lockup through a rapid succession of locking and unlocking cycles.

[0007] Several variations or versions of anti-lock braking systems can thus be found wheels: - a so-called generic or standard version which equips most current vehicles, and which generally includes a high-pressure pump, a hydraulic distributor, sensors, etc.; - a so-called simplified or low-cost version of the standard version in which the high-pressure pump is replaced by an accumulator and solenoid valves.

[0008] However, whether it is the standard or simplified version of anti-lock braking systems, these systems remain too expensive and complex for certain types of vehicles, for example of the type associated with micromobility, such as light vehicles and / or those without a license.

[0009] Moreover, an anti-lock braking system for vehicles without a license, therefore generally limited in terms of their speeds, does not require an anti-lock braking system whose complexity, performance and costs are disproportionate to this type of vehicle.

[0010] It is therefore necessary to find a device that can reproduce the functions of an anti-lock braking system, for example to improve the braking capabilities of micromobility vehicles, license-free and / or electric vehicles, at a cost related to these types of vehicles.

[0011] The present invention thus aims to remedy at least one of the aforementioned drawbacks by proposing a new type of braking control device for motor vehicles, characterized in that said device comprises: - a cam carrier which is rotatably mounted and which includes at least one cam; - at least two hollow cylinders in each of which a piston is mounted movable, each piston having two opposite ends: a first end which delimits with the cylinder a hydraulic pressure chamber, and a second end configured to be in contact with said at least one cam of the cam carrier, each of said pistons being configured to move according to the position of said at least one cam, varying the volume of the associated pressure chamber; the pressure chambers of each of said cylinders are, on the one hand, hydraulically connected to each other and to a control pressure inlet, and on the other hand, configured to be hydraulically connected to a braking element (for example separate) of a wheel of the vehicle.

[0012] Said brake control device thus makes it possible to regulate the pressure exerted on the wheel braking components without having to use a high-pressure pump, an accumulator and / or solenoid valves, while improving the response time of pressure regulation, particularly when the vehicle wheels are locked and it is necessary to reduce the pressure in the pressure chamber to unlock said wheels. Furthermore, the device has the advantage of generating less mechanical noise than prior art systems or devices.

[0013] According to one possible feature, said device includes a motor for rotating said cam carrier. This motor, for example an electric one, is a simple and inexpensive way to control the rotation of the cam carrier, and therefore the position of the cams, all while being fast enough to allow a reduction in pressure at the pressure chamber (and thus in braking pressure), thereby enabling the wheel associated with said pressure chamber to be unlocked. Furthermore, having a motor directly linked to the cam carrier allows for increased response times in initiating the movement of the cam carrier, and therefore improved pressure regulation at the pressure chambers (and thus better responsiveness of the braking components of the associated wheels).

[0014] According to another possible feature, said device includes a pressure limiting device, said pressure chambers being connected to each other via said pressure limiting device, said pressure limiting device including said control pressure inlet.

[0015] The pressure limiting device, or pressure limiter, is a device that distributes the control input pressure evenly among the different pressure chambers, thus ensuring that the braking force exerted by each braking component on a wheel of the vehicle is equivalent. The pressure limiting device is also configured to prevent the pressure in the pressure chambers from exceeding a predetermined threshold value.

[0016] According to another possible feature, said device is configured so that the cam carrier rotates under certain predetermined conditions until one of said pistons moves in the direction of the cam carrier and the volume of the hydraulic pressure chamber increases.

[0017] Advantageously, the triggering of the device, by rotating the cam carrier, and the variation of the volume of the pressure chambers is controlled by the detection of the blocking of a wheel associated with the pressure chamber of the device.

[0018] According to another possible feature, the second end of the piston is configured in such a way that the contact, between said second end and said at least one cam, is substantially point contact. Advantageously, the contact area between the second end of the piston and the cam is minimized, in order to reduce friction forces between these elements, and therefore wear, and to optimize the rotation of the cam carrier (and the cam), as well as the movement of the piston.

[0019] According to another possible feature, the second end of the piston is substantially in the shape of a hemisphere or a semi-ellipse. The second end of the piston advantageously has shapes that minimize the contact area with the cam, in order to reduce friction forces between these elements, thus reducing wear, and to optimize the rotation of the cam carrier (and the cam), as well as the movement of the piston.

[0020] According to another possible feature, said at least one cam has a continuous profile. The cam profile is advantageously continuous, meaning that it does not have abrupt variations, in particular to limit wear on the cam and the end of the piston, but also to make the piston movements more regular and continuous (and by extension limit sudden variations in the volume of the associated pressure chamber), and avoid among other things the generation of noise.

[0021] According to another possible feature, the cam profile comprises a concave portion and two convex portions framing said concave portion. Such a geometry of the cam profile, or cam circumference, allows a progressive movement of the piston on the cam according to its angular position and to define a frequency and a duty cycle of wheel unlocking.

[0022] According to another possible feature, said cam carrier comprises at least two separate cams, each of said cams being configured to cooperate respectively with one of said pistons. Advantageously, each piston is associated with a separate cam from the cam carrier. This helps, among other things, to limit the application of opposing forces by the pistons on the same cam, which could disrupt the rotation of the cam carrier (and by extension the cam) and accelerate cam wear.

[0023] According to another possible feature, said at least one cam and / or the second end of the piston include a surface treatment to minimize friction, for example a layer of Polytetrafluoroethylene (or PTFE).

[0024] The interface between said at least one cam and / or the second end of the piston can also be configured to allow oil lubrication, thus limiting friction, and also heating of said elements.

[0025] The invention also relates to a motor vehicle, for example thermal, electric or hybrid, characterized in that said vehicle includes a braking control device as defined above.

[0026] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of a particular embodiment of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings, in which: - Fig. 1 illustrates a very schematic view of a braking control device according to the invention for a motor vehicle; - [Fig.2] is a very schematic partial and side view of a cam holder of the device of [Fig.1]; - [[Fig.3]] is a schematic and cross-sectional view of the cam holder of [Fig.2],

[0027] In the following description, the term "include" is synonymous with "include" and is not limiting in that it permits the presence of other elements in the device (and / or vehicle), or the structure to which it relates. It is understood that the term "include" includes the terms "consist of".

[0028] Fig. 1 thus illustrates a very schematic view of a braking control device 1 intended to equip a motor vehicle, for example thermal, hybrid or electric.

[0029] The braking control device 1 comprises: - a cam carrier 3 which is rotatably mounted and which includes at least one cam 5, and for example two as in the embodiment described herein; - a motor 7 to drive the said cam carrier 3 in rotation; - at least two hollow cylinders 9 in each of which is mounted movable a piston 11, said piston 11 comprising an end lia delimiting with the cylinder 9 a hydraulic pressure chamber 13; - a pressure limiting device 15, or pressure limiter, said pressure chambers 13 being connected to each other via said pressure limiting device 15, and by pipes 16.

[0030] It will be noted that the term "cam" means the part of the cam carrier 3 configured to be in contact with said at least one piston 11, the cam can thus be an added part on the cam carrier 3 or unitary with said cam carrier 3, as long as the cam 3 has a shape or profile allowing the position of the piston 11 to vary according to the angular position of the cam and / or the cam carrier, the movement of the piston 11 resulting in a variation of the volume of the associated pressure chamber 13.

[0031] Each of the pistons 11 thus has two opposite ends 1la and 11b: the end lia, called the first end, delimiting with the cylinder 9, an internal volume, which corresponds to the hydraulic pressure chamber 13, and a second end 11b configured to be in contact with one of said cams 5 of the cam carrier 3.

[0032] Each of the pistons 11 is advantageously configured to cooperate with a cam 5 separate from the cam carrier 3. Each piston 11 is thus configured to move, for example in translation, within the cylinder 9 according to the stroke allowed by the cam 5, that is to say, according to the mechanical cooperation between the second end 11b of piston 11 and cam 5, and among other things depending on the angular position of cam 5.

[0033] Thus, each of said pistons 11 is configured to move according to the angular position of the cam 5, which has the effect of modifying the volume of the associated pressure chamber 13 of the cylinder 9 and the piston 11.

[0034] Furthermore, each of the ends 1la and 11b delimits an isolated or sealed volume with respect to each other, for example by means of one or more seals mounted on the body of the piston 11 and sealing between the piston 11 and the cylinder 9 surrounding said piston 11.

[0035] Said device 1 further includes a control pressure inlet 17, said control pressure inlet 17 being arranged at the level of said pressure limiting device 15.

[0036] It will be noted that the control pressure inlet 17 is configured to be connected to a control element enabling the braking to be activated by increasing the pressure in the device 1, in particular at the level of the pressure limiting device 15, and then, via the pipes 16, at the level of the pressure chambers 13.

[0037] Furthermore, the pressure chambers 13 of each of said cylinders 9 are, on the one hand, hydraulically connected (by means of the pipes 16) to each other via the pressure limiting device 15, and on the other hand, configured to be hydraulically connected to a braking element (not shown) of a wheel of the vehicle, for example by hydraulic connections 19.

[0038] It should be noted that the braking element to which a pressure chamber 13 is connected can be a caliper in the case of disc brakes or a master cylinder in the case of drum brakes.

[0039] Increasing the pressure in the pressure chambers 13 makes it possible, in particular, to increase the braking pressure and activate the braking components in a regulated manner, and to slow down, or even stop, the rotation of the wheel. The device 1 is thus configured to regulate the pressure exerted on the wheel braking components (and the pressure exerted by them), and therefore to control the intensity of the braking applied to the wheels.

[0040] It should be noted that the pressure limiting device 15, or pressure limiter, is a device for distributing the control inlet pressure evenly between the different pressure chambers 13. The pressure limiting device 15 is also configured to prevent the pressure in the pressure chambers 13 from exceeding a predetermined threshold value.

[0041] The cam carrier 3 is, for its part, a rotatably mounted shaft configured to carry one or more cams 5 intended to cooperate with one or more pistons 11. The engine 7, for example electrical, is thus in mechanical cooperation, via a mechanical interface, such as gears, with one end of the cam carrier 3 to drive said cam carrier 3 (and by extension the cams 5) in rotation on itself.

[0042] This rotation of the cam carrier 3 and the cams 5 modifies the angular position of the cam 5, and therefore the point of the cam 5 on which the second end 11b of the piston 11 is supported, consequently causing a displacement of the piston 11, towards the cam carrier 3 or towards the pressure chamber 13 (and therefore a variation of the volume of the chamber, as well as of the pressure value of the associated pressure chamber).

[0043] Said cams 5, for their part, are parts mounted or arranged on the cam carrier 3 and configured to rotate with it when the cam carrier 3 changes its angular position. Each cam 5 has a contour or profile, called a cam profile, which varies according to the angular position, and which allows a greater or lesser displacement of the piston 11 (and therefore a variation in the pressure value in the pressure chamber).

[0044] Fig. 2 illustrates a very schematic, enlarged and partial side view of a cam holder 3 of the device 1. The cams 5 thus have a partially circular contour, part of the profile (or contour) of the cam 5 being recessed from the outer contour of the cam holder 3.

[0045] Fig. 3 illustrates, for its part, a schematic and cross-sectional view, along axis A, of the cam carrier 3 and the cam 5. Moreover, the profile of each of the cams 5 is advantageously a continuous profile, that is to say that the profile does not have abrupt variations, but only progressive variations.

[0046] Furthermore, the profile of each of the cams 5 comprises a concave portion 5a and two convex portions 5b framing said concave portion 5a, as well as a circular portion 5c. The concave portions 5a and convex portions 5b are recessed relative to the circular portion 5c of the cam 5. The profile of the cam 5, for example, has substantially lobed shapes.

[0047] It should also be noted that the two cams 5 advantageously have the same cam profile, and that there is, for example, no angular phase shift between said cams 5.

[0048] Thus, depending on the angular position of the cam 5, the piston 11 moves in translation in the cylinder 9 due to the modification of the position of the second end 11b of the piston on the profile of the cam 5. There is thus a change in altitude of the piston 11 (therefore of its position) induced by the concave portions 5a or convex portions 5b of the cam 5 with respect to the circular portion 5c.

[0049] It will be noted that the dimensions of said concave 5a, convex 5b and circular 5c portions of the cam 5 allow among other things to define a frequency and a duty cycle for wheel unlocking.

[0050] The second end 11b of the piston 11 has substantially the shape of a hemisphere or a semi-ellipse, so it is possible to assimilate the contact between said second end 11b and said at least one cam 5 to a substantially point contact.

[0051] It will be noted that the cam 5 and / or the second end 11b of the piston 11 advantageously include a surface treatment to minimize friction, for example a layer of Polytetrafluoroethylene (or PTFE).

[0052] Said device 1 is also configured so that the cam carrier 3 rotates under certain predetermined conditions until one of said pistons 11 moves in the direction of the cam carrier 3 and the volume of the associated hydraulic pressure chamber 13 increases.

[0053] It will be noted that the triggering of device 1, by the rotation of the cam carrier 3, and the variation of the volume of the pressure chambers 13 is controlled by the detection of the blocking of a wheel associated with the pressure chamber 13 of device 1.

[0054] Thus, when the device 1 is mounted in a motor vehicle, each of the pressure chambers 13 is connected to a wheel braking element, and the control pressure inlet 17 is connected to the vehicle's braking control element, such as a brake pedal.

[0055] The device 1 is initially in the rest position, the pressure in the pipes 16, the pressure limiting device 15 and the pressure chambers 13 is constant, said pressure is for example substantially equal to 1 bar.

[0056] The pistons 11 are supported on the cams 5, pushed back to the maximum, that is to say that the second end 11b of the pistons 11 is supported on the circular portion 5c of the associated cam 5, the volume of the pressure chambers 13 being minimal.

[0057] Then when there is braking, via the brake pedal, the pressure in the device 1 increases progressively, until the pressure applied at the level of the pressure limiting device 15 exceeds a predetermined threshold value.

[0058] The increase in pressure in the device 1, and in particular at the level of the pressure chambers 13, of course causes the braking elements to be triggered, and the associated wheels to be braked.

[0059] Then, when the pressure in device 1 exceeds the predetermined threshold value, the pressure limiting device 15 blocks the control pressure input 17. There is thus braking, by means of said braking elements, but at a constant amplitude, the pressure in device 1 no longer being able to increase.

[0060] Subsequently, if at least one of the vehicle's wheels is detected as blocked (i.e., the wheel has a zero rotation speed), for example by means of a sensor, then the motor 7 is activated and the cam carrier 3 is rotated.

[0061] The rotation of the cam carrier 3 causes the angular position of the cam 5 to change, bringing the second end 11b of the piston 11 to the concave position 5a, the piston 11 then moves in rectilinear translation towards the cam carrier 3 (under the effect of the pressurized fluid in the pressure chamber 13).

[0062] This movement of the piston 11 also causes an increase in the volume of the pressure chamber 13, and therefore a decrease in the pressure within said chamber 13, which results in a reduction of the braking pressure exerted on the braking component, and thus, by extension, on the wheel. This reduction in braking pressure causes the wheel to unlock.

[0063] The motor 7 then returns the cam carrier 3 to its rest position, then drives said cam carrier 3 in rotation in the opposite direction so that the other piston 11 is positioned at the level of the concave part 5a of the other cam 5, thus unlocking the other wheel.

[0064] The motor 7 is activated, and the camera carrier 3 is rotated, as long as a blocked wheel is detected, until the device 1 is deactivated. The device 1 may also include a locking system allowing the camera carrier 3 to be locked in the rest position, as long as the motor 7 is not activated.

[0065] In an alternative embodiment of the invention not shown, the cam holder 3 comprises a single cam and the two pistons 11 bear against a single cam, said cam comprising several concave and / or convex portions. As before, rotation of the cam allows the pressure value in the pressure chambers associated with each of the pistons in contact with said cam to be varied.

[0066] In another embodiment not shown, there is oil lubrication between the cam 5 and / or the second end 11b of the piston 11, in order to minimize friction between these elements 5 and 11b.

Claims

Demands

1. Braking control device (1) for a motor vehicle, characterized in that said device (1) comprises: - a cam carrier (3) which is rotatably mounted and which includes at least one cam (5); - at least two hollow cylinders (9) in each of which a piston (11) is movablely mounted, each piston (11) having two opposite ends: a first end (1a) which delimits with the cylinder (9) a hydraulic pressure chamber (13), and a second end (11b) configured to bear against said at least one cam (5) of the cam carrier (3), each of said pistons (11) being configured to move according to the position of said at least one cam (5), varying the volume of the associated pressure chamber (13);the pressure chambers (13) of each of said cylinders (9) are, on the one hand, hydraulically connected to each other and to a control pressure inlet (17), and on the other hand, configured to be hydraulically connected to a braking element of one wheel of the vehicle.

2. Device (1) according to the preceding claim, characterized in that said device (1) comprises a motor (7) for rotating said cam carrier (3).

3. Device (1) according to any one of the preceding claims, characterized in that said device (11) comprises a pressure limiting apparatus (15), said pressure chambers (13) being connected to each other through said pressure limiting apparatus (15), said pressure limiting apparatus (15) comprising said control pressure inlet (17).

4. Device (1) according to any one of the preceding claims, characterized in that said device (1) is configured so that the cam carrier (3) begins to rotate under certain predetermined conditions until one of said pistons (11) moves in the direction of the cam carrier (3) and the volume of the hydraulic pressure chamber (13) increases.

5. Device (1) according to any one of the preceding claims, characterized in that the second end (11b) of the piston (11) is configured such that the contact, between said second end (11b) and said at least one cam (5), is substantially punctual.

6. Device (1) according to any one of the preceding claims, characterized in that the second end (11b) of the piston (11) is substantially in the shape of a hemisphere or a half-ellipse.

7. Device (1) according to any one of the preceding claims, characterized in that said at least one cam (5) has a continuous profile.

8. Device (1) according to any one of the preceding claims, characterized in that the cam profile comprises a concave portion (5a) and two convex portions (5b) framing said concave portion (5a).

9. Device (1) according to any one of the preceding claims, characterized in that said cam carrier (3) comprises at least two separate cams (5), each of said cams (5) being configured to cooperate respectively with one of said pistons (11).

10. Motor vehicle, characterized in that said vehicle comprises a braking control device (1) according to any one of claims 1 to 9.

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