Braking system, in particular a by-wire braking system, comprising a master cylinder, in particular a tandem master cylinder

Abstract

The invention relates to a master cylinder intended to form part of a braking system, the master cylinder, in particular a TMC, being formed of a base body having a substantially cylindrical shape, the base body defining therein an inner space in which at least one piston moves under the thrust of a mechanical actuator, the inner space of the master cylinder being able to be placed in communication, on the one hand, by at least one inlet pipe, with a brake fluid reservoir, and, on the other hand, by at least one outlet pipe, with at least one hydraulic brake circuit connected to an electronic controller, or ESP, acting on the brakes, the master cylinder being characterised in that at least one suction valve is provided, the suction valve being arranged in the base body, in the path of the liquid between the brake fluid reservoir and the at least one outlet pipe.

Description

FR 2504021 of 15 / 04 / 2025 Description Title of the invention: Braking system, in particular by wires, comprising a master cylinder, in particular a tandem master cylinder

[0001] [The present invention relates to a braking device comprising a master cylinder, in particular a tandem master cylinder (TMC), as well as to a master cylinder or a TMC of this kind.

[0002] The braking system is a critical component for vehicle safety, ensuring effective deceleration and control under various driving conditions. Traditional braking systems, particularly those using a master cylinder, especially a tandem master cylinder, without an additional mechanism, often face limitations in fluid transfer efficiency under specific operating conditions. Conventional master cylinder designs rely on pistons moving within sealed areas to move brake fluid, which can lead to flow restriction, especially under extreme conditions. Thus, in very low temperatures, the viscosity of the brake fluid increases, further restricting its movement within the system. This restriction can lead to reduced braking efficiency and increase the risk of brake failure.

[0003] Current braking systems primarily utilize a master cylinder and associated components that operate based on hydraulic principles. Existing solutions do not adequately address the problem of fluid viscosity in cold temperatures or the need to increase fluid intake during emergency situations. This is particularly true for wired systems, where relying on electrical signals to actuate the brakes introduces specific difficulties that the present invention also aims to overcome.

[0004] Thus, we would like to improve the ability of current braking systems to operate effectively under adverse conditions, particularly in the case of so-called cable or wire systems, in which the connection between the brake pedal and the master cylinder is entirely electrical and in which, in the event of an electrical fault, the driver loses the ability to mechanically press the master cylinder to generate the pressure necessary for braking on the piston.

[0005] The present invention aims to overcome the drawbacks of the prior art by providing a braking system comprising a master cylinder, in particular a TMC, formed of a substantially cylindrical base body defining within it an internal space in which at least one piston moves under the pressure of a mechanical actuator, the internal space of the master cylinder being in communication on the one hand, by at least one inlet pipe, with a brake fluid reservoir, and on the other hand, by at least one outlet pipe, with at least one hydraulic braking circuit, acting on the brakes, by being connected to an electronic controller, or ESP, the movement of the mechanical actuator being controlled either by a mechanical link between the actuator and the brake pedal, or by an electrical link, known as wired, characterized in that at least one suction valve is provided, disposed in the base body,in the fluid path between the brake fluid reservoir and the outlet pipe, and the ESP includes a pump capable of creating a vacuum to open the suction valve.

[0006] By incorporating a suction valve, the ESP can supplement, or even replace in the most critical situations, the piston's function of pressurizing the fluid, particularly if the actuator fails, thus acting on the brakes. Specifically, this ensures that even when the brake fluid viscosity increases, the system can maintain optimal fluid flow and pressure. Similarly, in the event of an electrical fault, the backup mode can be activated, providing a significant supply of brake fluid to guarantee effective braking.

[0007] A series of simulation tests were conducted which made it possible to evaluate the performance of the braking system according to the invention including the additional valves, by comparing it to traditional systems without this improvement and the result is a marked improvement in the braking response and in safety, particularly in extreme conditions and emergency situations.

[0008] This improves the fluid intake capacity of the braking system. In particular, we obtain a braking system with improved braking performance and greater ease of use, and which is also particularly well suited to so-called wire braking.

[0009] Thus, according to a preferred embodiment, the movement of the mechanical actuator is controlled by an electrical unit receiving a signal from the brake pedal, via an electrical wire, with which the electrical unit determines the braking force and controls, accordingly, by means of an electric motor, the corresponding action of the actuator.

[0010] According to another embodiment, the brake pedal sends a signal to the ESP via an electrical wire, with which the ESP determines the braking force and, consequently, controls the corresponding action of the ESP pump via an electric motor.

[0011] The two embodiments above can be combined with each other, or implemented individually.

[0012] Preferably, the master cylinder is a TMC and respective suction valves are integrated between the liquid reservoir and respective outlet pipes.

[0013] According to a favorable embodiment, the master cylinder includes at least one brake fluid inlet pipe from the reservoir into the internal space of the master cylinder in which at least one piston moves, at least one suction valve being disposed in the at least one inlet pipe.

[0014] Preferably, a bypass channel is provided between the inlet pipe, upstream of the valve, and the internal space of the cylinder.

[0015] According to another favorable embodiment, at least one bypass channel is formed in the basic body between at least one inlet pipe and at least one outlet pipe, and at least one suction valve is disposed in at least one bypass channel. FR 2504021 of 15 / 04 / 2025

[0016] According to a favorable embodiment, the at least one bypass channel consists of a main through hole between the outside of the base body and the at least one outlet pipe, and an auxiliary through hole extending between the at least one inlet pipe and the main through hole.

[0017] Preferably, at least one suction valve is disposed in the main through hole.

[0018] Preferably, the main through hole has a longitudinal axis parallel to that of at least one inlet pipe.

[0019] According to one embodiment, the main through hole extends from the upper side of the master cylinder and is closed on top by a plug or cover.

[0020] According to another embodiment, the main through hole extends from the lower side of the master cylinder and is closed from below by a plug or cover.

[0021] The present invention also relates to a master cylinder intended to be part of a braking system according to the invention, the master cylinder, in particular TMC, being formed of a basic body of substantially cylindrical shape defining within it an internal space in which at least one piston moves under the push of a mechanical actuator, the internal space of the master cylinder being able to be made to communicate on the one hand, by at least one inlet pipe, with a brake fluid reservoir, and on the other hand, by at least one outlet pipe, with at least one hydraulic braking circuit acting on the brakes, by being connected to an electronic controller, or ESP, characterized in that it is provided with at least one suction valve, disposed in the basic body, in the path of the fluid between the brake fluid reservoir and at least one outlet pipe.

[0022] As an example, preferred embodiments of the invention are shown in the figures.

[0023] Figure 1 is a schematic representation of a vehicle with a mechanical braking system including a booster; FR 2504021 of 15 / 04 / 2025

[0024] Figure 2 is a schematic representation of a vehicle with a so-called wire braking system;

[0025] Figure 3 is a longitudinal cross-sectional view of a tandem master cylinder (TMC) according to a first embodiment of the invention;

[0026] Figure 4 is a cross-sectional view of another embodiment of a TMC according to the invention;

[0027] Figure 5 is a cross-sectional view of yet another embodiment of a TMC according to the invention;

[0028] Figure 6 is a larger scale view of part of Figure 5;

[0029] Figure 7 is a perspective view of the TMC from Figure 3, associated with a brake fluid reservoir;

[0030] Figure 8 is a perspective view of the TMC from Figure 4, associated with a brake fluid reservoir;

[0031] Figure 9 is a perspective view of the embodiment of Figure 5, associated with a brake fluid reservoir.

[0032] Figure 1 schematically represents a motor vehicle in which the driver acts (F pe dai) on a pedal P to control, via an electrical unit, a booster B (Fout = F pedal + Fbooster) acting on a primary piston moving in an internal space of a TMC 1 having two outlet tubes 13 and 14 respectively primary and secondary in communication with the hydraulic braking circuits C1 and C2, under the control of an ESP, which act on the brake calipers 40.

[0033] In the event that the actuator and / or booster fails, the driver still has the option of pushing the piston directly (a function known as "push thru").

[0034] The ESP receives a braking signal from the pedal, via a sensor and the electrical unit, and based on this signal, the ESP can command a pump to actuate the opening of two suction valves, respectively 15 primary and 16 secondary, arranged in the TMC 1, between the fluid reservoir 10 and two respective inlet pipes 11 primary and 12FR 2504021 of 15 / 04 / 2025 secondary, so that, in case of emergency or failure of the actuator, it can hydraulically control or supplement the braking.

[0035] Figure 2 schematically represents a motor vehicle in which the driver acts on a pedal P to control, via an electrical unit, a booster acting (Fout=FBWA) on a primary piston moving in an interior space of a TMC 1 having two outlet tubes 13 and 14 respectively primary and secondary in communication with the hydraulic braking circuits, under the control of an ESP.

[0036] The BWA actuator is not mechanically linked to the pedal, and its movement is controlled by an electric motor controlled by the electrical unit 41 on the basis of a signal received from a sensor 42 which determines, from the stroke of the pedal and the force applied by the driver, the desired braking.

[0037] In the event that the actuator is faulty, the driver does not have the option of pushing the piston directly (the so-called "push thru" function is not available).

[0038] The ESP receives a braking signal from the pedal, via a sensor and the electrical unit, and based on this signal, the ESP can command a pump to actuate the opening of two suction valves, respectively 15 primary and 16 secondary, arranged in the TMC 1, between the fluid reservoir 10 and two respective inlet pipes 11 primary and 12 secondary of vertical axis, so that, in case of emergency or failure of the actuator, it can hydraulically control or supplement the braking.

[0039] Figure 3 shows that the TMC 1 has two pistons 7 primary and 8 secondary moving back and forth in the space 9 inside the cylinder under the push of an actuator (not shown) to create hydraulic pressure transmitted to respective brake circuits, via the two outlet pipes 13 primary and 14 secondary and the ESP controller.

[0040] Two inlet pipes, 11 primary and 12 secondary respectively, connect the brake fluid reservoir 10 to the interior space 9. FR 2504021 of 15 / 04 / 2025

[0041] In addition, two bypass channels 5 and 6 are planned, respectively primary and secondary, which connect the inlet pipes, upstream of the valves, to the interior space 9.

[0042] These two channels, 5 and 6, each open into the internal space and allow brake fluid to flow from the reservoir into this space when both pistons are in their rest position, not being pushed by the actuator, and no braking is required. Thus, during normal system operation, they ensure the fluid supply for brake application when the two pistons, under the action of the actuator, increase the pressure in the internal space.

[0043] On the other hand, there is a respective suction valve 15 and 16 in each inlet pipe, allowing, when the ESP operates its integrated pump, to open communications between the tank and the outlet pipes which are not prevented by the position of the plunged pistons.

[0044] On the other hand, in the case of normal piston operation, these valves allow by suction to increase the quantity of brake fluid which is sent into the internal space, which improves the flow of brake fluid and therefore the effectiveness of braking.

[0045] Figure 7 shows TMC 1 from Figure 3 in perspective view.

[0046] Figures 4 and 8 show, respectively, a cross-sectional view of the primary manifold and piston and a perspective view, another embodiment of a tandem master cylinder according to the invention. The liquid reservoir 10 supplies the vertically oriented primary inlet manifold 11, which is connected, via an auxiliary channel 20 extending horizontally, to a main channel 21 parallel to the inlet manifold 11. The main channel 21 also opens into the primary outlet manifold 13. Furthermore, although not visible in the figures, the primary inlet manifold 11 opens into the internal space 9. The same arrangement is provided for the secondary manifold and piston. FR 2504021 of 15 / 04 / 2025

[0047] A suction valve 15 is disposed in the main channel 21, in the path of the liquid between the auxiliary channel and the outlet pipe.

[0048] The main channel 21 also opens outside the TMC, on the upper side. It is closed by a watertight plug 22, easily accessible from the top of the TMC. The plug can be screwed in. The plug's function is to hold the valve in position. In addition, the skirt 23 of the plug, which bears against the valve 15, is at least partially hollowed out, for example, by a notch, a hole, or the like, to allow the passage of liquid between the valve and the channel 20.

[0049] According to this embodiment, when valve 15 is open, the brake fluid can flow directly from the brake fluid reservoir to the outlet pipe 13. Thus, the ESP, by activating its pump to open the valves, can ensure that the brakes are actuated by the fluid even if the pistons remain blocked opposite the inlet pipes, thereby enabling emergency braking. If the pistons are not blocked opposite the inlet pipes, the ESP can supplement the fluid flow created by the pressure exerted by the piston on the fluid entering the interior space through the inlet pipes with an additional flow passing through valve 15, which is opened for this purpose by the ESP.This additional flow is particularly welcome in extreme conditions where the viscosity of the fluid is high, such as in very cold weather or for particular emergency braking situations, to draw in more fluid and thus increase the flow of brake fluid passing through and out of the outlet pipe towards the brakes.

[0050] Figure 8 shows the embodiment of Figure 4 represented in perspective. Figure 8 shows only one plug; the secondary part could also similarly include a bypass tube and a plug not shown in Figure 8.

[0051] Figures 5 and 9 show a third embodiment in which the main channel 2T extends open at the bottom of the TMC and is closed below by a sealed plug 22'. According to this embodiment, a more direct flow from the brake fluid reservoir (FR 2504021 dated 15 / 04 / 2025) towards the outlet pipe 13 is obtained when the valve 15 is open. The plug 22' is screwed in place.

[0052] In the embodiment shown in Figures 5 and 9, the cap directly withstands the brake fluid pressure. In the embodiment shown in Figures 4 and 8, the cap indirectly withstands the brake pressure.

[0053] The TMC's basic body can be made of aluminum. The valve bodies can be made of metal, particularly steel.

Claims

FR 2504021 of 15 / 04 / 2025 Demands

1. [Master cylinder intended to be part of a braking system, the master cylinder, in particular TMC, being formed of a basic body of substantially cylindrical shape defining within it an internal space in which at least one piston moves under the pressure of a mechanical actuator, the internal space of the master cylinder being able to be made to communicate on the one hand, by at least one inlet pipe, with a brake fluid reservoir, and on the other hand, by at least one outlet pipe, with at least one hydraulic braking circuit acting on the brakes, by being connected to an electronic controller, or ESP, characterized in that it is provided with at least one suction valve, disposed in the basic body, in the path of the fluid between the brake fluid reservoir and at least one outlet pipe.

2. Master cylinder according to claim 1, characterized in that the master cylinder is a TMC and respective suction valves are integrated between the liquid reservoir and respective outlet pipes.

3. Master cylinder according to claim 1 or 2, characterized in that the master cylinder comprises at least one brake fluid inlet pipe, from the reservoir, into the internal space of the master cylinder in which at least one piston moves, at least one suction valve being disposed in the at least one inlet pipe.

4. Master cylinder according to claim 3, characterized in that a bypass channel is provided between the inlet pipe, upstream of the valve, and the internal space of the cylinder.

5. Master cylinder according to claim 1 or 2, characterized in that at least one bypass channel is formed in the base body between at least one inlet pipe and at least one outlet pipe, and at least one suction valve is disposed in at least one bypass channel.

6. Master cylinder according to claim 5, characterized in that the at least one bypass channel consists of a main through hole FR 2504021 of 15 / 04 / 2025 between the outside of the base body and the at least one outlet pipe, and an auxiliary through hole extending between the at least one inlet pipe and the main through hole.

7. Master cylinder according to claim 6, characterized in that at least one suction valve is disposed in the main through hole.

8. Master cylinder according to claim 7, characterized in that the main through hole extends from the upper side of the master cylinder and is closed on top by a cover.

9. Master cylinder according to claim 7, characterized in that the main through hole extends from the lower side of the master cylinder and is closed from below by a cover.

10. A braking system comprising a master cylinder, in particular a TMC, according to any one of the preceding claims, formed of a basic body of substantially cylindrical shape defining within it an internal space in which at least one piston moves under the pressure of a mechanical actuator, the internal space of the master cylinder being in communication, on the one hand, by at least one inlet pipe, with a brake fluid reservoir, and on the other hand, by at least one outlet pipe, with at least one hydraulic braking circuit acting on the brakes, being connected to an electronic controller, or ESP, the movement of the mechanical actuator being controlled either by a mechanical link between the actuator and the brake pedal, or by an electrical link, known as a wired link, characterized in that at least one suction valve is provided, disposed in the basic body,in the path of the fluid between the brake fluid reservoir and the outlet pipe, and the ESP includes a pump capable of creating a vacuum to open the suction valve

11. System according to claim 10, characterized in that the movement of the mechanical actuator is controlled by an electrical unit receiving from the brake pedal, via an electrical wire, a signal with which the electrical unit determines the braking force and controls, accordingly, by an electric motor, the corresponding action of, the actuator.FR 2504021 of 15 / 04 / 2025

12. System according to claim 10 or 11, characterized in that the brake pedal sends to the ESP, via an electrical wire, a signal with which the ESP determines the braking force and, consequently, controls, by means of an electric motor, the corresponding action of the ESP pump. ]

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