FR2495080A1 - HYDRAULIC BRAKE INSTALLATION FOR UTILITY VEHICLE TRAILERS - Google Patents

Abstract

Hydraulic braking system for trailers of commercial vehicles, the brake cylinders of which are supplied by means of a brake valve mounted in the commercial vehicle, by means of which the brake lines connected to the brake cylinders by the intermediate of a coupling device can optionally be supplied with brake pressure or connected to a hydraulic fluid reservoir by means of a return line. A shut-off valve 12, 13 is mounted in the brake lines 7, 9 behind and in front of the coupling 8 of said brake lines, this valve being held in the open position on the side facing towards the front. coupling 8 of the brake lines by the pressure prevailing in the lines against an elastic preload. The pressure in the brake lines is always maintained at a level exceeding the elastic preload applied to the stop valve 12, 13. (CF DRAWING IN BOPI)

Description

Hydraulic brake installation for trailers of

commercial vehicles.

  The present invention relates to a hydraulic braking installation for trailers of commercial vehicles, whose brake cylinders are fed via a brake valve mounted in the commercial vehicle, valve by means of which the brake lines connected to the cylinders of brake via a coupling device can optionally be supplied with brake pressure or connected to a reservoir of hydraulic fluid

by means of a return pipe.

  Trailer brake systems shall be constructed in such a way that the trailer brakes can be operated reliably at any time during their service. This requirement is met during normal service of the vehicle train because the commercial vehicle brake line is coupled to the trailer brake line via a coupling. When detaching the trailer from the utility vehicle, the trailer brakes are immediately activated regardless of the operating pressure of the commercial vehicle. In general, this result is achieved by starting a mechanical or hydraulic accumulator attached to the braking system of the trailer. In the case

  o the trailer is detached from the commercial vehicle in sepa-

  the brake lines from each other at the coupling, there are no complications. But the

  separation of the trailer from its service car

  however, kills a case of danger that can not be foreseen. It is sufficient that the brake lines that are

  always in the coupling separate from each other.

  But if the brake lines separate from the coupling, one side of the braking system is open, on the side of the trailer or on the side of the commercial vehicle, and there is then the great danger that hydraulic oil flows in significant amount from the brake line which is open and a hydraulic fluid supply system

  who is in communication with the conduct that is no longer

  leakage may not work. This produces on the one hand a dangerous roadway pollution and on the other hand can lead to the shutdown of important devices (such as the installation of the brake control) of the vehicle train.

  the, o a strong reduction in its operational safety.

  That is why the subject of the invention is an

  the hydraulic braking system of commercial vehicle trailers so that, even when the brake lines separate from the coupling, there are no consequences

  detrimental to the operational safety of the service vehicle

  vice or the trailer and that the danger of pollution of the

be very small.

  This problem is solved by the fact that a stop valve is mounted in the brake lines at the rear and the front of the coupling of said brake lines, this valve being kept in the open position on the side facing the coupling of the brake lines by the pressure in the lines against prestressing

  2G elasticity, and the fact that the pressure prevailing in the driving

  brake is always maintained at a level exceeding the

  elastic preload applied to the shut-off valve.

  Thanks to the assembly according to the invention of a valve

  stop which can be brought to its position of

  against elastic prestressing in

  respective sections of the brake lines and through the application

  according to the invention, the pressure prevailing in the brake lines between each valve and the coupling, this effect is obtained according to which, when the

  brake lines are separated from the coupling, the pressure

  which holds the shut-off valve in the open position

  abruptly and the shut-off valve sets itself in

  the broken brake line closes securely and effectively prevents

the output of the hydraulic fluid.

  According to a preferred embodiment of the invention,

  The stop valve is a 2/2-way distributor which is designed as a drawer which is biased on one side by a pressure transfer member and on its other side by another

  control spring. This embodiment presents the advantage

  particular to greatly simplify the balancing of the shut-off valve adjusting forces which act one

against each other.

  To be able to maintain in all circumstances the pressure prevailing in the brake pipes to a level which exceeds the prestressing force of the control springs is mounted in the brake valve disposed on the service vehicle, that is to say in the return line that returns to the hydraulic fluid reservoir, a non-return valve

  subjected to the prestressing of a spring and preferably

  corn. Advantageously, the spring devices, the pressure control members and the limit pressure of the non-return valve can be tuned to each other. An embodiment of the installation of

  trailer braking according to the invention which proves particularly

  It is particularly advantageous if the stop valve mounted in the brake line of the trailer is connected in position.

  closing to a hydraulic accumulator which can be

  ge via the brake line and a nonreturn valve. In this case, the stop valve of the trailer brake system fulfills another important function. In this case, the separation of the trailer or the brake line on the side of the trailer leads, on the one hand, according to the operating mode of the stop valve indicated above, to the closing of the driving section of the trailer. brake which is separated, and secondly to the simultaneous application to the trailer brakes of the pressure of a hydraulic accumulator. This measure simultaneously increases the safety of the operation of

  the braking system of the trailer and the vehicle train

cles.

  The invention advantageously provides that the

  st stop is constituted by a 3/2-way distributor which supplies the hydraulic accumulator via a non-return valve integrated in the shut-off valve when it is in its switching position which controls the braking system of the trailer, and which forms a non

  throttled between the trailer brake cylinder and the

  hydraulic emulator when in its switching position

  which closes the brake line. It is thus possible to provide a particularly simple way of controlling the brakes of the trailer. The invention furthermore provides that the shut-off valve which is integrated in the braking system of the trailer is coupled to a device for separating the trailer by means of which it is necessarily brought to its position of

  closing when the trailer is separated.

  Finally, it is advantageous that the shut-off valves and the non-return valve integrated in the pipe of

  back are mounted in the same housing.

  The invention will now be explained in greater detail.

  tail with several examples and with re-

  reference to the attached schematic drawings in which:

  Figure 1 is a schematic diagram of a first

  first embodiment of the hydraulic braking system

trailers, and

  Figure 2 is a schematic diagram of a second

  of embodiment of the hydraulic braking system

than trailers.

  Hydraulic trailer braking system

  1 shown in FIG. 1 comprises an accumulator S of pressurized fluid and a constant pressure pump P which is driven in any manner, which supplies the accumulator S with pressurized fluid coming from a return tank or from a tank of hydraulic fluid HFT, via a check valve R. The accumulator S is connected to a brake supply line 2 through which the pressure fluid is sent under constant pressure to a valve 1. The brake valve 1 is constituted for example in the form of a 3/3-way distributor which is, according to the

  figure i and when it is submitted to the action of a

  pel 3, in a position in which the pipe connection

  4 is connected with the hydraulic fluid reservoir

  through a return line. 5. In the

  return line 5 is integrated a non-return valve 5 re-

  and prestressing a spring so that the pressure in the return line can be

  always maintained at a certain level.

  The connection of the brake line 4 is connected to a tractor or commercial vehicle brake line 7 which is connected to a brake line 9 of the trailer via a brake line coupling. The brake line 9 of the trailer reaches a cylinder

  brake 11 of the trailer by means of a valve adapted

  load gauge 10. In sections 7 and 9 of the brake line are respectively integral stop valves 12

  or 13 constituted in the form of 2/2-way distributors, res-

  respectively constituted in the form of control drawers. The distributor 12 or 13 is on the one hand biased in the closed position by means of an adjustable spring device 14 or 15 and on the other hand subjected to the action of a pressure regulating member 16 or 17 which is in connection respectively with the brake line section disposed between the distributor 12

  or 13 and the coupling of brake lines 8 via

  18 or 19. The pressure determined by the adjustable non-return valve 6 in the brake lines 7 and 9 is at a level exceeding that

  of the adjustable spring device 14 or 15, so that the

  12 or 13 dimmers return to their switching position

  When the brake valve 1 is in the position shown.

  When a braking force FB is applied to the brake valve, the brake lines 7 and 9 are then subjected to increasing pressure from the accumulator S and

  the brake cylinder 11 of the trailer is then actuated.

  When the trailer or the brake lines 7 or 9 are unhitched, the pressure falls in the section of the brake line that has been removed or has been interrupted.

  pressure in the control pressure line

  pective 18 also falls abruptly and the pressure regulating member 16 or 17 can no longer overcome the force of the

  adjustable spring device 14 or 15, so that the disc

  Timer 12 or 13 is pushed back into its closed position B. This prevents the pressurized fluid from escaping from a brake line subjected to pressure. In the case where the brake pipe of the commercial vehicle or the driving of

  the braking system of the trailer braking system is in

  communication with a pressure source or with a

  work, breaking of the brake line has no further negative effect on the operational safety or operating capacity of the installation. Of another

  side, it can be avoided thanks to the hydraulic braking

  trailer shown in Figure 1 the pollution of the

  hydraulic fluid, which makes it possible to exclude

  the traffic on the roadway is endangered.

  Figure 2 represents another form of realization

  a trailer hydraulic braking system which

  is very similar to the installation shown in Figure 1.

  The same references designate in Figure 2 the same ele-

  or elements operating in the same way. The difference

  The difference between this embodiment and that shown in FIG. 1 lies in the conformation of the installation of the trailer and in particular in the modified conformation of the stop valve 13 'of the trailer. This stop valve 13 '

  is embodied in this embodiment in the form of a

  3/2-way tribulator which, in the switching position A 'which is shown, feeds a hydraulic accumulator 20 of the trailer via a non-return valve 21 and a charging line 22. the rest, this second mode of

  realization of the hydraulic braking system of trailers

  that works in the same way as the installation

  shown in Figure 1. The peculiarity of this embodiment

  the case where the trailer is detached from the utility vehicle.

  re. In the case where the brake line 9 of the trailer is

  breaks, the pressure prevailing in the pressure line of com-

  Mande 19 falls abruptly at atmospheric pressure, and it follows that the distributor 13 'is pushed to its position B' by the adjustable spring device 15. In this position

  the brake line of the trailer is uncoupled from the

  braking system of this trailer and it is established

  a fluid connection between the hydraulic accumulator 20

  and the brake cylinder. The trailer thus automatically undergoes

  immediate braking and is done simultaneously

  that no leakage of hydraulic fluid can occur

  re by the brake line 9 which is broken.

  The distributor 13 'is advantageously coupled to a breaking cable whose function, in case of separation of the trailer from the commercial vehicle or the towing vehicle,

  is to obligatorily bring the distributor 13 'into its posi-

  B '. By using the dispenser, it is thus possible to avoid mounting a special security device against a

  separation from the fact that this distributor fulfills the function.

  The valves 12, 13 or 13 'therefore operate simultaneously as safety devices against pipe rupture and

  against the detachment of the coupling.

  The level of the pressure in the brake line can be adjusted by means of the non-return valve 6

  on a value which is for example about 5 bars.

Claims (8)

R E V E N D I C A T I 0 N S   1. - Hydraulic brake installation for trailers of commercial vehicles, the brake cylinders of which are supplied by means of a brake valve   mounted in the commercial vehicle, a valve by means of which   51e the brake lines connected to the brake cylinders via a coupling device may be at   choices fed - at brake pressure or connected to a   see hydraulic fluid by means of a return line, characterized in that a shut-off valve (12, 13; 13 ') is mounted in   the brake lines (7, 9) at the rear and front of the   coupling (8) of said brake lines, this valve being held in the open position on the side facing the coupling   (8) brake lines by the pressure prevailing in the con-   against elastic prestressing, and that the pressure in the brake lines is still   maintained at a level exceeding the elastic prestress   connected to the stop valve (12, 13; 13 ').   2. - Hydraulic braking installation according to claim 1, characterized in that the stop valve (12, 13) is a 2/2-way distributor which is produced under   shape of a drawer urged on one side by a device with   the fate (14, 15) and on its other side by a pressure regulating member (16, 17); which is connected with the respective section of brake line (7 or 8) via a line control pressure (18, 19).   3. - Hydraulic braking system according to   any of claims 1 and 2, characterized in that   a non-return valve (6) subjected to prestressing   a spring is mounted in the return line (5).   4. - Hydraulic braking system according to   any of claims 1 and 3, characterized in that   that the spring devices (14 or 15), the regulating   pressure (16 or 17) and the limit pressure of the non-return valve (6) can be tuned to each other. 5. Hydraulic braking system according to   any of claims 1 to 4, characterized in that   that the shut-off valve (13 ') fitted in the brake line (9) of the trailer is connected in the closed position (B') to a hydraulic accumulator (20) which can be loaded via the pipe brake (9) and a valve of no return (21).   Hydraulic brake system according to claim 5, characterized in that the shut-off valve   (13 ') consists of a 3/2-way distributor which supplies   installs the hydraulic accumulator (20) via a non-return valve (21) integrated in the distributor (13 ') when   it is in its switching position (A ') which controls the   braking system (9) of the trailer, which forms a link   unstressed between the brake cylinder (11) of the trailer   and the hydraulic accumulator (20) when in its switching position (B ') which closes the brake line (9). 7. - Hydraulic braking system according to   any of claims 5 and 6, characterized in that   that the shut-off valve (13 ') which is integrated into the   braking of the trailer is coupled to a separating device   the trailer by means of which it is necessarily brought to its closed position (B ') when there is separation of the trailer.   8. - Hydraulic braking system according to   any of claims 1 to 7, characterized in that   the shut-off valves (12, 13; 13 ') and the non-return valve   return (6) integrated in the return pipe (5) are mounted in the same housing.