FR2831504A1 - HYDRAULIC TANK FOR HYDRAULIC CIRCUIT WITH INCREASED SUPPLY SECURITY AND BRAKING SYSTEM COMPRISING SUCH A TANK - Google Patents

Abstract

The invention relates primarily to a brake fluid supply tank for an electrohydraulic braking circuit, said fluid being drawn from the tank using a hydraulic pump. According to the invention, the tank comprises: at least one chamber (28, 29); a fill opening (7); at least one outflow port (9); and means (13) of returning the fluid contained in a circuit (11), which is supplied by said tank, by means of the outflow port (9). The aforementioned return means (13) comprise a conduit (17) that connects the inside (5) of the tank to the circuit (11) in an impervious manner. The longitudinal end (25) of the conduit (17) is disposed in the tank and separated from a lower wall (31) thereof by a distance (d). Moreover, the longitudinal end (25) of the conduit (17) co-operates with a volume (V) of liquid which is defined by the camber (28, 29), thereby enabling the immersion of said longitudinal end (25) during the normal operation of the circuit.

Description

<Desc / Clms Page number 1>

Hydraulic reservoir for hydraulic circuit with increased supply security and braking system comprising such a reservoir
The present invention relates mainly to a hydraulic fluid reservoir for a hydraulic circuit with increased supply security and braking system comprising such a reservoir, and more particularly to a reservoir for supplying brake fluid to an electrohydraulic braking circuit. , said liquid being sucked from said reservoir by a hydraulic pump.

 A hydraulic reservoir for an electro-hydraulic braking system of known type supplies in normal operation, during a braking phase, the suction braking circuit by means of a hydraulic pump of the brake fluid in said reservoir, such a reservoir will be called electro-hydraulic tank. The electrohydraulic reservoir comprises an envelope defining an interior volume in communication with the external environment by a filling orifice placed on the upper part of the reservoir and allowing the brake fluid to be filled with the reservoir. The filling orifice is capable of being closed by leaktight sealing means, for example a plug, fixedly mounted for example by screwing on a sleeve extending from the periphery of the filling orifice towards the outside.

 The electrohydraulic reservoir also has a drainage opening arranged in the lower part of the reservoir and connected in leaktight manner by a pipe to a hydraulic pump driven for example by an electric motor, the pump sucking the brake fluid from the reservoir and sending it under pressure to brakes arranged at the vehicle wheels. The reservoir also includes means ensuring the return of part of the brake fluid contained in the braking circuit in the reservoir after a braking phase, formed of a pipe sealingly passing through the upper part of the reservoir and extending therefore from the inside of the tank to the outside of the tank, the end disposed outside the tank being tightly connected to the braking circuit

<Desc / Clms Page number 2>

 by a pipeline.

 The lower end of the pipe placed in the reservoir of the pipe must be permanently immersed in the brake fluid to avoid the risk of the appearance of an emulsion or in other words air in the brake fluid of the makes the brake system operate at high pressure, the presence of air interfering with the operation of the brake system.

 However, when the level of brake fluid contained in the reservoir is low but sufficient not to be detected by a level detector and in the event of strong acceleration, the lower end of the pipe may no longer be submerged in the brake fluid or at least in part, which may affect the operation of the braking system. The same problem can also appear in the event of severe braking or when the vehicle is on a road with a steep drop.

 It is therefore an object of the present invention to provide a hydraulic fluid reservoir ensuring the immersion of the lower end of a return conduit with hydraulic fluid.

 It is also an object of the present invention to provide a hydraulic fluid reservoir limiting the appearance of air bubbles in the brake fluid and therefore ensuring proper operation of the circuit supplied by said reservoir.

 These aims are achieved by a hydraulic fluid reservoir comprising a filling orifice, a flow orifice, means for returning the hydraulic fluid to the reservoir formed by a conduit connecting a hydraulic circuit to a volume defined in the reservoir, the cooperation of said conduit with the volume defined in the tank allowing immersion of the lower end of the conduit during normal operation of the hydraulic circuit.

 In other words, it is a reservoir replenished by a conduit sealingly passing through the upper wall of the reservoir and penetrating for a certain length into a chamber delimited in the reservoir isolating the open end of the conduit from the air contained in the tank, in

<Desc / Clms Page number 3>

 particularly when varying the inclination of the surface of the hydraulic fluid.

 The main object of the invention is a hydraulic fluid reservoir, comprising at least one chamber a filling orifice at least one flow orifice, means for returning the hydraulic fluid contained in a circuit supplied by said reservoir via the flow orifice, said means being formed by a conduit sealingly connecting the interior of the reservoir to said hydraulic circuit, said conduit comprising a longitudinal end in the reservoir separated from a bottom wall of said reservoir by a distance, a level minimum filling of the reservoir being predetermined, characterized in that the longitudinal end of the conduit cooperates with a volume of hydraulic fluid determined by the chamber allowing the immersion of said longitudinal end of the conduit in normal operation of the braking circuit.

 The invention also relates to a reservoir characterized in that it advantageously comprises a first chamber comprising the flow orifice and a second chamber, said second chamber being sealed from the first chamber, said second chamber delimiting the volume of hydraulic fluid and in that the second chamber receives the lower end of the conduit through its upper end through which it communicates with the first chamber.

 The invention also relates to a tank characterized in that the second chamber is sealed from the first chamber by at least one wall of height relative to the bottom wall of the tank, said height being at least equal to the distance separating the end of the conduit of the lower wall of the tank.

 The invention also relates to a tank characterized in that the second chamber has a height advantageously between 20 mm and 40 mm, and even more advantageously equal to 30 mm and in that the end of the conduit is separated from '' a distance advantageously between 10 mm and 20 mm, and even more advantageously equal to 15

<Desc / Clms Page number 4>

 mm from the bottom wall of the tank.

 The invention also relates to a tank characterized in that the second chamber has a relatively smaller volume than the volume of the first chamber.

 The invention also relates to a reservoir characterized in that the second chamber is of substantially cylindrical shape.

 The invention also relates to a reservoir characterized in that the conduit advantageously penetrates with a length between 10 mm and 20 mm, and even more advantageously equal to 15 mm in the second chamber with a diameter advantageously between 15 mm and 25 mm, and even more advantageously equal to 20 mm.

 The invention also relates to a tank characterized in that the second chamber is sealed from the first chamber by the height wall for a level of hydraulic fluid contained in the first chamber corresponding at most to the height of the wall .

 The invention also relates to a tank characterized in that the height of the wall of the second chamber corresponds to the minimum filling level.

 The invention also relates to a tank characterized in that the second chamber is integrally formed with the bottom wall of the tank.

 The invention also relates to a reservoir characterized in that it comprises means for detecting a level of brake fluid below the minimum level.

 The invention also relates to an electro-hydraulic braking system comprising a hydraulic circuit supplying at least during a braking command to the brakes arranged at the wheels of a vehicle carrying said brakes, said circuit being supplied by a

<Desc / Clms Page number 5>

 tank characterized in that said tank is a tank according to any one of the preceding claims.

 The preferred embodiment of the reservoir according to the present invention comprising a second chamber defined in the interior volume of the reservoir has the advantage of isolating the open end of the hydraulic fluid make-up pipe contained in the reservoir from the rest of the interior volume and thus in the event of a break in the hydraulic connection between the hydraulic circuit and the tank, to avoid siphoning off all of the hydraulic fluid contained in the tank and to allow detection of this break by conventional means with which tanks of the type are already fitted known, for example the brake fluid level detection device.

The present invention will be better understood with the aid of the description which follows and of the appended figures for which:
Figure 1 is a sectional view of a first embodiment of a tank according to the present invention;
Figure 2 is a sectional view of the preferred embodiment of a tank according to the present invention
Figure 3 is a diagram of an electrohydraulic braking system comprising a reservoir according to the present invention.

 The same references will be used for the elements having substantially the same shape and substantially the same function.

 In Figure 1, we can see a first embodiment of a tank according to the present invention comprising an envelope 3 defining an interior volume 5 and placed in communication with the outside by a filling orifice 7 disposed on the upper part of the tank 1 and capable of being sealed in a sealed manner by watertight means, for example a plug (not shown). The tank 1 also includes

<Desc / Clms Page number 6>

 a flow orifice 9 allowing the liquid contained in the reservoir 1 to flow towards a hydraulic circuit, the reservoir also comprises means 13 for returning the liquid to the reservoir coming from the hydraulic circuit 11 at the end of a phase of braking, said means being arranged in the upper part of the tank and sealingly passing through an upper wall 15 of the tank 1. The means 13 are formed, in the embodiment shown, by a pipe 17 comprising a first tubular part 19 of greater length of longitudinal axis X sealingly passing through the upper wall 15 of the tank. The first part 19 is provided with a first longitudinal end 21 disposed outside the tank 1 connected to a second tubular part 23 of shorter length relative to the first part 19 in a manner substantially orthogonal to the axis X. The first part 19 of greater length also has a second longitudinal end 25 opposite the first longitudinal end 21, arranged inside the tank 1 and serving for the flow of the liquid coming from the hydraulic circuit 11 into the tank 1. The hydraulic circuit is connected to the pipe 17 by a conduit 24 tightly connected to the second portion of smaller length 23.

 The reservoir 1 also includes indications of minimum level m and maximum level M of brake fluid contained in the reservoir prescribed by the manufacturer of the braking system for the correct functioning of the braking circuit. The indications m and M are advantageously marked on a side wall 24 of the reservoir 1 connecting the lower wall 31 to the upper wall 15 of the reservoir in sealed manner, by indications for example engraved or in relief. In addition, the reservoir 1 comprises means for detecting (not shown) a level of brake fluid lower than the minimum level m, these detection means are for example formed by a conductive float forming part of an electrical circuit, in the event of a brake fluid level in the reservoir less than equal to the level m, the float interrupts the flow of current in the electrical circuit causing the lighting of an indicator light or the emission of an audible signal in the cabin.

<Desc / Clms Page number 7>

The tubular part 19 extends over a certain length in the direction of a bottom wall 31 of the tank in a chamber 29 of volume V formed in the tank and is separated from the bottom wall 31 by a distance d, the distance d being determined, as well as the minimum level m so as to ensure in operation under normal conditions of the braking system, the immersion of the second end 25 of tubular part 19 in the brake fluid despite variations in the level of the brake fluid in acceleration or deceleration
In Figure 2, we can see the preferred embodiment of a tank according to the present invention comprising an envelope 3 defining an interior volume 5 and placed in communication with the outside by a filling orifice 7 disposed on the upper part of the reservoir 1 and capable of being sealed off, for example a plug (not shown). The reservoir 1 also comprises at least one flow orifice 9 allowing the liquid contained in the reservoir 1 to flow towards a hydraulic circuit, the reservoir also comprises return means 13 for the liquid in the reservoir coming from the hydraulic circuit 11 to the end of a braking phase, said means being arranged in the upper part of the tank and sealingly passing through an upper wall 15 of the tank 1. The means 13 are formed, in the embodiment shown, by a pipe 17 comprising a first tubular part 19 of greater length of longitudinal axis X passing in leaktight manner the upper wall 15 of the tank. The first part 19 is provided with a first longitudinal end 21 disposed outside the tank 1 connected to a second tubular part 23 of shorter length relative to the first part 19 in a manner substantially orthogonal to the axis X. The first part 19 of greater length also includes a second longitudinal end 25 opposite the first longitudinal end 21, disposed inside the tank 1 and serving for the flow of the liquid coming from the hydraulic circuit 11 in the tank 1 and distant from the lower wall 31 of the reservoir with a distance d, advantageous between 10mm and 20mm and more advantageously equal to 15mm. The hydraulic circuit is connected to the pipe 17 by a conduit 24 connected in leaktight manner to the second part more

<Desc / Clms Page number 8>

 short length 23.

 The reservoir 1 also includes indications of minimum level m and maximum level M of brake fluid contained in the reservoir prescribed by the manufacturer of the braking system for the correct functioning of the braking circuit. The levels m, M are advantageously marked on a side wall 24 of the tank 1 connecting the bottom wall 31 to the top wall 15 of the tank in a sealed manner, by indications for example engraved or in relief. In addition, the reservoir 1 includes means for detecting (not shown) a brake fluid level below the minimum level m, these detection means are for example formed by a conductive float forming part of an electrical circuit, in the event of a brake fluid level in the reservoir less than equal to the level m, the float breaks the flow of current in the electrical circuit causing the lighting of an indicator light or the emission of an audible signal in the cabin.

The reservoir according to the present invention comprises a first chamber 28 provided in its lower part with the flow orifice 9 and a second chamber 29 separated in leaktight manner from the first chamber 28 by at least one wall 26, advantageously of tubular shape whose the upper end is distant from the lower wall 31 by a distance h, the wall 26 is advantageously formed integrally with the lower wall
31 of the tank.

 The chamber 29 delimits a volume V and is arranged opposite the portion of greatest length 19 of the pipe 17 for returning liquid to the reservoir 1 and receives the second longitudinal end 25 of the tubular portion 19, the height h of the second chamber 29 being at least equal to the distance d separating the end 25 of the pipe 17 from the bottom wall (31) of the tank.

 The second chamber 29 is advantageously of smaller volume than the volume of the smaller first chamber (28).

<Desc / Clms Page number 9>

 The second chamber 29 is sealingly isolated from the first chamber 28 for a level of liquid contained in the first chamber 28 less than the height h of the second chamber 29 and is in communication with the first chamber 28 by an upper end 28 open receiving the end 25 of the pipe 17.

 The pipe 17 penetrates from a distance advantageously between 10 mm and 20 mm and more advantageously equal to 15 mm in the second chamber (29) having a diameter advantageously between 15 mm and 25 mm, and even more advantageously equal to 20 mm and height h advantageously between 20 mm and 40 mm, and even more advantageously equal to 30 mm.

 Advantageously in the event of rupture of the conduit 24 connecting the pipe 17 to the braking circuit 11, the brake fluid contained in the reservoir is sucked in by the end 25 of the tube 19 via the chamber 29 as long as the level of liquid brake is greater than the height h of the side wall 26 of the chamber 29. Then the chamber is isolated from the rest of the reservoir, and only the chamber 29 continues to empty through the pipe 17.

The height h of the side wall 26 of the chamber 29 advantageously corresponds to the minimum level m of brake fluid required for the proper functioning of the braking system, allowing detection of the rupture of the conduit 24, that is to say of the fact that the chamber 29 has been siphoned and therefore of an anomaly in the braking system. In fact, when the chamber 29 is siphoned off the level of brake fluid in the entire reservoir decreases until this level corresponds to the height h of the chamber 29 then only the level of liquid contained in the chamber 29 continues to drop. In the case where the level m and the height h correspond, the liquid level detector will detect, when the chamber 29 is being siphoned, the drop in the brake fluid level to the level m
The reservoir is advantageously made in two parts, a lower part and an upper part connected to each other in a sealed manner, for example by gluing or by welding.

<Desc / Clms Page number 10>

 It is also conceivable that the second chamber 29 is manufactured independently, and then fixed on the inner face of the lower wall 31 of the tank 1 before the lower part is fixed on the upper part of the tank.

In FIG. 3, an electro-hydraulic braking system 30 can be seen comprising a reservoir 1 according to the present invention, the reservoir 1 supplies the braking circuit 11 by means of a hydraulic pump 33 for example actuated by an electric motor and controlled by a computer 35 which, upon detection of a braking will on the part of the driver, sends the order to the pump to draw liquid into the reservoir 1 through the flow orifice 9 and the 'Send under pressure in brakes 37 arranged at the wheels. The braking system 30 also comprises a master cylinder 39 supplied by a reservoir 41, serving in normal operation for simulating the mechanical reaction of the braking circuit 11 and in degraded operation for supplying brake fluid under pressure of the brakes 37 The master cylinder being
The electro-hydraulic tank 1 is advantageously made of transparent plastic, advantageously by molding.

 We will now explain how the reservoir shown in FIG. 2 ensures permanent immersion of the second longitudinal end 25 of the longer part 19 of the means 13 for returning the liquid to the reservoir and a minimum operating volume of the circuit. braking.

 In the event of sudden acceleration of the vehicle, the level of the brake fluid which is substantially horizontal in most cases, is then in a position which is substantially inclined relative to the horizontal, for example by an angle of 45. The second chamber 29 even allows, in the limit operating condition, that is to say when the brake fluid level is at minimum level m, complete immersion of the first longitudinal end 21 of the pipe 17. The immersion is d '' all the better assured

<Desc / Clms Page number 11>

 when the brake fluid level is above the minimum level m.

 In the event of sudden braking, during which the level of the brake fluid is also inclined relative to the horizontal, the second chamber 29 plays the same role as in the event of sudden acceleration.

 In the case of rupture of the pipe 24 connecting the braking circuit 11 to the pipe 17, part of the brake fluid contained in the reservoir 1 is sucked by the pipe 17 through the chamber 29 until the brake fluid level reaches the level m, the chamber 29 is then sealed off from the rest of the reservoir 1 and only the chamber 29 continues to be siphoned off. Consequently, the reservoir still contains sufficient brake fluid to ensure normal braking of the vehicle and the rupture of the conduit connecting the circuit to the reservoir is then detected by the level detector which informs the driver, the driver must then have it repaired. the rupture of the conduit.

 The reservoir shown in FIG. 1 also ensures the immersion of the end 25 of the pipe 17 but does not guarantee a safety volume when the return duct 24 is broken, nor does it guarantee detection of this rupture by detection means, including the tank is conventionally equipped.

A reservoir has been made allowing a safe supply of hydraulic fluid to a hydraulic circuit, in particular a safe supply of brake fluid to an electro-hydraulic brake circuit, reducing the appearance of air bubbles in suspension in the fluid. of brake-
It is understood that a tank supplying both the master cylinder and the hydraulic pump does not depart from the scope of the present invention.

 It is understood that the reservoir according to the present invention applies to any system having the same requirements as the electrohydraulic braking systems.

<Desc / Clms Page number 12>

 The present invention is particularly applicable to the automotive industry.

 The present invention applies mainly to the braking system industry for motor vehicles and in particular for passenger cars.

Claims (12)

 CLAIMS 1. Hydraulic fluid reservoir, comprising at least one chamber (28,29), a filling orifice (7), at least one flow orifice (9), return means (13) for the hydraulic fluid contained in a circuit (11) supplied by said reservoir via the flow orifice (9), said means (13) being formed by a conduit (17) sealingly connecting the interior (5) of the reservoir to said hydraulic circuit (11), said conduit (17) having a longitudinal end (25) in the tank separated from a bottom wall (31) of said tank by a distance (d), a minimum filling level (m) of the tank being predetermined characterized in that the longitudinal end (25) of the conduit (17) cooperates with a volume (V) of hydraulic fluid determined by the chamber (28,29) allowing the immersion of said longitudinal end (25) of the conduit ( 17) in normal operation of the braking circuit. 2. Tank according to claim 1 characterized in that it advantageously comprises a first chamber (28) comprising the flow orifice (9) and a second chamber (29), said second chamber (29) being sealed of the first chamber (28), said second chamber (29) delimiting the volume (V) of hydraulic fluid and in that the second chamber (29) receives the lower end (25) of the conduit (17) through its upper end by which it communicates with the first chamber (28). 3. Tank according to claim 2 characterized in that the second chamber (29) is sealed from the first chamber (28) by at least one wall (26) of height (h) relative to the bottom wall (31) of the tank, said height (h) being at least equal to the distance (d) separating the end (25) of the duct (17) from the bottom wall (31) of the tank. <Desc / Clms Page number 14> 4. Tank according to claim 3 characterized in that the second chamber (29) has a height (h) advantageously between 20 mm and 40 mm, and even more advantageously equal to 30 mm and in that the end ( 25) of the duct is separated by a distance (d) advantageously between 10 mm and 20 mm, and even more advantageously equal to 15 mm from the bottom wall (31) of the reservoir. 5. Tank according to claim 2,3 or 4 characterized in that the second chamber (29) has a relatively smaller volume than the volume of the first chamber (28). 6. Tank according to any one of claims from 2 to 5 characterized in that the second chamber (29) is of substantially cylindrical shape. 7. Tank according to claim 6 characterized in that the conduit (17) advantageously penetrates with a length between 10 mm and 20 mm, and even more advantageously equal to 15 mm in the second chamber (29) advantageously of diameter between 15 mm and 25 mm, and even more advantageously equal to 20 mm. 8. Tank according to any one of claims from 3 to 7 characterized in that the second chamber (29) is sealingly isolated from the first chamber (28) by the wall (26) of height (h) for a level hydraulic fluid contained in the first chamber corresponding at most to the height (h) of the wall (26). 9. Tank according to any one of claims from 3 to 8 characterized in that the height (h) of the wall (26) of the second chamber (29) corresponds to the minimum level (m) of filling. 10. Tank according to any one of claims from 2 to 9 <Desc / CRUD Page number 15>  characterized in that the second chamber (29) came integrally with the bottom wall (31) of the tank. 11. Reservoir according to any one of the preceding claims, characterized in that it comprises means for detecting a level of brake fluid below the minimum level (m). 12. Electrohydraulic braking system comprising a hydraulic circuit supplying at least during a braking command to the brakes arranged at the wheels of a vehicle carrying said brakes, said circuit being supplied by a tank characterized in that said tank is a tank according to any one of the preceding claims.