FLUID DISTRIBUTION SYSTEM TO THE REAR BRAKES OF A MOTOR VEHICLE

Abstract

A system for distributing fluid to the rear brakes of a motor vehicle, comprising a distributor (8) having a fluid inlet port (30) connected to two outlet ports (32), each leading to a wheel brake, and comprising an inlet pipe connected to the inlet ports (30), this distributor having, between the inlet port (30) and the outlet ports (32), calibrated flow-limiting passages (40, 42) having a reduced passage diameter that is less than half the diameter of the inlet pipe. Figure 4

Description

Title of the invention: SYSTEM FOR DISTRIBUTING FLUID TO THE REAR BRAKES OF A MOTOR VEHICLE

[0001] The present invention relates to a system for distributing fluid to the rear brakes of a motor vehicle, as well as to a motor vehicle equipped with such a circuit distribution system.

[0002] A known type of hydraulic braking circuit, presented in particular by document FR-A-1541048, includes a master cylinder controlled by a brake pedal which acts directly on the front wheel brakes, and on the rear brakes via a correction device in order to adjust their braking level relative to the front brakes.

[0003] Depending on the vehicle's load and acceleration, the value of the rear brakes is reduced to avoid rear wheel lock-up and the risk of an accident.

[0004] Furthermore, for a simple and economical braking circuit, without an electronic system for individual pressure control of each brake, it is known to have in series on the circuit to the rear wheels, first an individual retarding device having a calibrated bore with a reduced fluid passage cross-section, and then, after an intermediate conduit, a fluid distributor comprising an inlet, and two outlets to the two brakes of the rear wheels of the vehicle.

[0005] During sudden braking with a rapid pressure increase in the master cylinder, the reduced passage section of the retarder device forms a nozzle limiting the high flow of fluid filling the rear brakes, giving a shift in the pressure increase and braking torque on the rear axle, with a delay of a few thousandths of a second compared to the front axle.

[0006] This offset ensures that the front wheel brakes come on first before the rear wheels, which ensures vehicle stability and safety.

[0007] However, this type of individual delay device has two connections to the upstream and intermediate pipelines, and its own system for attaching it to the vehicle. The entire set of components requires space under the vehicle body, adds weight to the vehicle, and involves costs related to manufacturing and parts management, as well as labor time for attaching the device and connecting the pipelines.

[0008] Moreover, this type of delay device, which generally includes upstream and downstream pipes and intermediate boreholes aligned on the same axis, does not offer the possibility of easily making bends in the passages which would add a further limitation of high flow rates.

[0009] The present invention is specifically intended to avoid these problems of the prior art.

[0010] To this end, it proposes a system for distributing a fluid to the rear brakes of a motor vehicle, comprising a distributor having a fluid inlet bore connected to two outlet bores each to a wheel brake, and comprising an inlet pipe connected to the inlet bores, this system being notable in that the distributor has, between the inlet bore and the outlet bores, calibrated flow limiting passages having a reduced passage diameter, which is less than half the diameter of the inlet pipe.

[0011] An advantage of this distribution system is that with a single component, by forming inside bores with the reduced section distributing symmetrically the pressure towards the two rear brakes, we achieve both the distribution of the fluid towards these brakes, and with the calibrated passages of the nozzles which brake a strong flow of fluid during a sudden braking by giving a slight time shift in the braking power of the rear wheels.

[0012] It is then necessary to supply a single component, the distributor, which can have a size and weight equivalent to those of the distributors already in use, without having to provide another location in the vehicle for the mounting and connection of another independent component. This reduces size, weight, and costs by simplifying component procurement and limiting assembly time.

[0013] In addition, the distributor naturally having bends to supply two brakes on the sides of the vehicle, makes it easy to make these bends in the calibrated passages of the fluid, which add braking of high flow rates.

[0014] The distribution device, according to the invention, may further comprise one or more of the following characteristics, which may be combined with each other.

[0015] Advantageously, the inlet drilling is extended by a calibrated inlet passage.

[0016] Advantageously, the outlet holes are aligned and connected to each other by a calibrated outlet passage.

[0017] In this case, advantageously, the calibrated inlet passage and the calibrated outlet passage have identical diameters.

[0018] Moreover, advantageously, the calibrated inlet passage and the calibrated outlet passage are perpendicular.

[0019] Moreover, advantageously, the calibrated output passage is arranged symmetrically with respect to the axis of the calibrated input passage.

[0020] The invention also relates to a motor vehicle comprising a hydraulic braking circuit, remarkable in that it includes a distribution system, comprising any one of the preceding characteristics.

[0021] The invention will be better understood, and other features and advantages will become more apparent upon reading the following description given by way of example, with reference to the accompanying drawings in which:

[0022] [Fig. 1] shows the rear part of a hydraulic braking circuit comprising a prior art distribution system;

[0023] [Fig.2] presents in axial section the individual delay device of this circuit;

[0024] [Fig.3] shows in axial section the distributor of this circuit; and

[0025] [Fig.4] shows in axial section a distributor of a distribution system according to the invention.

[0026] Fig. 1 shows the rear part of a braking circuit of a motor vehicle, comprising successively, coming from a control master cylinder delivering a pressure P, an upstream pipe 2, an individual retarding device 4, then an intermediate pipe 6 connected to a distributor 8 which distributes symmetrically via two final pipes 10 the pressure to drum brakes 12 of the rear wheels.

[0027] Fig. 2 shows the individual delay device 4 comprising an elongated machined metal body having an axial bore, comprising at each end a threaded part 22 receiving a screwed end 20 for clamping one end of a pipe 2, 6.

[0028] The axial bore has in its central part a calibrated passage having a reduced calibrated diameter forming a nozzle 26, which is framed by two connecting bores 24 to the tips 20 having a diameter substantially equivalent to that of the pipes 2, 6.

[0029] In this way, during a large flow rate, a substantially free passage of the fluid is obtained in the pipes 2, 6 and in the connecting bores 24, but which is slowed down in the calibrated passage of reduced diameter 26. During sudden braking, a slightly delayed pressure rise is obtained in the rear brakes 12 compared to the front brakes.

[0030] Fig. 3 shows the distributor 8 having an inlet bore 30 aligned with the intermediate pipe 6, which opens into a perpendicular bore comprising two outlets 32 arranged symmetrically with respect to the axis of this inlet bore, delivering the fluid identically to the two final pipes 10.

[0031] The inlet drilling 30 and the outlet drilling 32 having identical diameters equivalent to the pipes 6, 10, does not slow down the passage of the fluid.

[0032] Fig. 4 shows a distributor 8 arranged similarly between the two rear wheel brakes 12, in a circuit not having an individual upstream retarding device.

[0033] The distributor 8 has the inlet hole 30 and outlet holes 32 arranged directly opposite the screwed ends 20, which have a diameter equivalent to that of the pipes 6, 10.

[0034] However, the inlet bore 30 is extended by a first calibrated inlet passage of reduced diameter 40, which opens into a perpendicular calibrated outlet passage 42 arranged symmetrically with respect to the axis of this inlet, extending on each side by the outlet bore 32.

[0035] The calibrated passages 40, 42 advantageously have a diameter that is less than half of the inlet and outlet bores 30, 32, which gives a reduced passage section of at least 75% providing a limitation of the high flow rate during a sudden rise in pressure of the incoming fluid.

[0036] In addition, since the calibrated passages 30, 32 are perpendicular, this change in orientation of the fluid in small diameters results in a slightly greater braking of the flow during a sudden rise in pressure.

[0037] It is thus easy to obtain a precise calibration of the restriction of the calibrated passages 40, 42, formed by the nozzles on the same part combining the functions of symmetrical distribution of the fluid to the two brakes of the rear wheels 12, and of timing of a few thousandths of a second of the action requested from these rear brakes.

[0038] A single pipe 6 from the master cylinder is used, which is not interrupted on the rear part of the braking circuit, and a single component, the distributor 8, to be positioned and fixed under the body of the vehicle, which simplifies this installation, reduces the size and mass, increases reliability by reducing the number of connections, and decreases the costs of parts and assembly labor.

Claims

Demands

1. A system for distributing fluid to the rear brakes (12) of a motor vehicle, comprising a distributor (8) having a fluid inlet bore (30) connected to two outlet bores (32) each to a wheel brake (12), and comprising an inlet pipe (6) connected to the inlet bores (30), characterized in that the distributor comprises between the inlet bore (30) and the outlet bores (32) calibrated flow limiting passages (40, 42) having a reduced passage diameter which is less than half the diameter of the inlet pipe (6).

2. Distribution system according to claim 1, characterized in that the inlet bore (30) is extended by a calibrated inlet passage (40).

3. Distribution system according to claim 2, characterized in that the outlet holes (32) are aligned and connected to each other by a calibrated outlet passage (42).

4. Distribution system according to claims 2 and 3, characterized in that the calibrated inlet passage (40) and the calibrated outlet passage (42) have identical diameters.

5. Distribution system according to claim 4, characterized in that the calibrated inlet passage (40) and the calibrated outlet passage (42) are perpendicular.

6. Distribution system according to claim 4 or 5, characterized in that the calibrated outlet passage (42) is arranged symmetrically with respect to the axis of the calibrated inlet passage (40).

7. Motor vehicle comprising a hydraulic braking circuit, characterized in that this braking circuit is equipped with a distribution system, according to any one of the preceding claims.

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