FR2651196A1 - TRAILER CONTROL VALVE FOR BRAKES OF MOTOR VEHICLES. - Google Patents

Abstract

In addition to its usual piloting, a trailer control valve can be controlled by a solenoid valve. The solenoid valve (27) provides a further boost in control pressure in a control chamber (17). It thus becomes possible to obtain a further increase in the brake pressure applied to the trailer by a brake line passing through a coupling head (11), preferably as a function of signals from sensors installed between the towing vehicle and the trailer, so that the brakes of both parts of the road train can be better matched to each other.

Description

The invention relates to a trailer control valve for installations

  motor vehicle braking system, comprising a double seat valve which controls the pressure in a downstream brake line, since it allows the pressure of a supply source to enter the brake line by reducing it further. or less, and which is switchable by the pressures prevailing in the various braking circuits of the

towing vehicle.

  Such a trailer control valve is known (DE-AS 1 963 879). For road trains equipped with such a known trailer control valve, there is often the problem of mutually agreeing the braking of the towing vehicle and the braking of the trailer. Even if the useful and working faces in the trailer control valve have been designed perfectly, it is often the case that

braking is not optimal.

  One of the aims of the invention is to avoid this inconvenience

  venient. For this purpose, according to the invention, a trailer control valve as defined at the beginning is essentially characterized by

  what one of the braking circuits is connected through an electri-

  trovanne to a control chamber provided in the tap of

  trailer control and that the solenoid valve, when its electro-

  magnet is not energized, allows the brake circuit pressure of the towing vehicle acting as control pressure to operate without influencing it and, when switched, establishes a direct connection between the supply pressure source and the chamber by closing the connection port of the

  relevant braking of the towing vehicle.

  Compared to the state of the art, a trailer brake valve thus produced has the advantage that the agreement of the

  braking of the tractor and that of the trailer is better achievable.

  Another advantage is that the means for producing the exact chord are relatively simple and can be electrically connected to suitable sensors exposed to the forces exerted.

between the tractor and the trailer.

  Other features and advantages of the invention

  will be clearer from the following description of a

  non-limiting embodiment, as well as the single figure of the accompanying drawing, which is an axial section of a control valve

trailer according to the invention.

  The trailer control valve 1 shown in the drawing comprises a body 2 which has a connection (connection port) 3 for a supply line 4 coming from a supply pressure source 40, two connections 5 and 6 for service braking circuits I and II respectively, a connector 7 for a stop braking circuit III and two connectors 8 and 9 for a supply coupling head 10 and

  a brake line coupling head 11 respectively.

  The interior of the trailer control valve is essentially designed as shown and described in DE-AS 1 963 879 corresponding to the state of the art. It should be noted, more exactly, that the body 2 contains at its center a double seat valve 12, having a shutter 12 'and two movable seats 13 and 14, because of their arrangement on the pistons 15 and 16. The piston 15, incorporated in the upper part of the body 2, delimits a control chamber 17 and is exposed on its upper side to the pressure of the braking circuit I, which can move the piston 15 against the force of a spring 18 provided on the rear side of the piston. The other piston 16 is disposed in the lower part of the body 2 and defines by its lower side a control chamber 18 in which the pressure of the braking circuit II prevails. Its upper side forms the movable wall of a control chamber 19, on which the stop braking circuit III is connected via the

connection 7.

  The double seat valve 12 connects firstly an alternating pressure chamber 20, provided in the middle in the trailer control valve 1, through a hollow piston rod 21, to an external air connection 22 and can on the other hand - after switching - connecting a supply air chamber 23 to the alternating pressure chamber 20. The latter communicates through the connection 9 with the brake line coupling head 11, while the chamber supply air 23 is connected by a

  channel 24 formed in the valve body at the air connection of

  3. A shutter 26 of a stop valve 25 can enter the body channel 24 to cut or throttle the link

for supply air.

  Body 2 is surmounted by a proportional solenoid valve

  27, through which a channel 28 connecting the connection 5

  from the braking circuit I to the control chamber 17 of this circuit.

  The solenoid valve 27 has a double seat valve 29 which is switchable by an electromagnet armature 30. The armature 30 is fixed by means of two disks 31 and 32 to a reaction surface, constituted in this example by a membrane of reaction 33 'of

  annular shape, which is clamped in the body of the solenoid valve 27.

  The two discs 31 and 32 have openings for the passage of air and the lower disc 32 carries a seat 34 for the double seat valve 29. A second valve seat 35 is integral with the

  body and a double shutter is designated by reference 36.

  A spring 37, provided under the frame 30, and a spring 38, provided under the double shutter 36, tend to maintain these two bodies in the position shown. The spring 37 also ensures that the electromagnet closes only the seat of the portion of the double valve forming the exhaust valve from a minimum force. A supply air channel 39

  establishes a connection between the inlet 3 and the solenoid valve 27.

  Operation To start, the trailer control valve is switchable - from the neutral position shown in the drawing - in the conventional way, in the braking direction, in three ways: 1) By raising the service brake pressure in the braking circuit I, which causes the pressure in the control chamber 17 to rise, the downward movement of the piston 15 with the valve seat 13 and the lifting of the shutter 12 'of the valve seat 14 , so that supply air can flow from the supply air chamber 23

  at the braking line coupling head 11.

  2) By raising the pressure in the service brake circuit II, which causes the pressure in the control chamber 18 to rise. The piston 16 with the valve seat 14 rise and the shutter 12 'reaches the seat 13 and is lifted from the seat 14. Supply air flows from the chamber 23

  to the brake line coupling head 11.

  3) Under the effect of a drop in the pressure in the stop braking circuit III. The control chamber 19 usually has the supply pressure. When the parking brake is operated, the pressure in the braking circuit III is reduced to the zero pressure. Lowering the supply pressure makes

  mount the piston 16 with the seat 14 under the pressure of

  in the supply air chamber 23, with the result

  that the shutter 12 'reaches the seat 13 and is raised from the seat 14.

  Supply air flows from chamber 23 to the head

  braking line coupling 11.

  According to the invention, this conventional switching mode is improved in that the pressure of the circuit of

  Braking I does not act exclusively in the control chamber 17.

  Indeed, according to the invention, the pressure in the chamber of

  command 17 can be varied.

  The proportional solenoid valve 27 is controlled by operating signals provided by electronics to which sensors connected between the tractor and the trailer are connected so that the braking of the two parts of the road train can

  better be tuned to each other.

  Therefore, in the case where, according to the operating signals, the brake pressure applied to the trailer must become higher than the pressure applied to it so far,

  the solenoid valve 27 is energized. Excitatory current intensity

  average value produces a certain magnetic force.

  The excitation current can come from a current regulation

  constant or adequate modulation.

  Anyway, the force exerted on the armature 30 causes the closure of the valve 34/36 and the opening of the inlet valve 35/36 of the solenoid valve. As a result, supply air enters through the channel 39 and the inlet valve 35/36 opened in the control chamber 17, with the result that the pressure possibly existing in this chamber is relieved, up to the force exerted on the underside of the diaphragm 33 is balanced with the force exerted from above and which is due to the pressure of the braking circuit I - closed by the valve 34/36 - and the magnetic force . When the dimensions of the solenoid valve 27 are fixed in advance, it is thus possible to obtain a corresponding rise in the pressure beyond the braking pressure of the trailer established by the braking circuit I. It should be noted that the force magnetic pressure and the pressure applied each time by the solenoid valve 27 balance each other by the

  reaction surface formed in this example by the membrane 33.

  The invention provides the advantages described below.

  1) The control air of a pilot circuit

  I) braking is sent through the solenoid valve 27.

  2) The solenoid valve 27 is electrically controlled, preferably via an electronic device. It is however also possible to replace the solenoid valve 27 with a

pneumatically operated valve.

  3) The membrane 33 of the solenoid valve 27 is loaded on one side by the service braking circuit and on the other side by the pilot pressure, which reigns in the control chamber 17, for the trailer control valve 1 The membrane is solicited in

  more by the force of the electromagnet.

  4) The increase of the pressure of the brake line on the brake line coupling head with respect to the pilot pressure from the service braking circuit (for example of the braking circuit I), which elevation is predetermined by the size of the solenoid valve 27, is possible in a large

range of variation.

  5) In case of absence of excitation current of the electro-

  valve 27, the latter does not represent an obstacle for the transmission of the control pressure of the braking circuit I. This pressure is transmitted unhindered to the chamber of

  control 17 from the connector 5 and through the channel 28.

  Instead of the electromagnet armature 30 described, another energy generator may be employed, for example a

  a cylinder driven by a pressure fluid or an engine.

  All the characteristics indicated in the description

  and the claims that will follow or are represented

  on the drawing, may be essential for the invention, also

  well individually than in any combination.

Claims (3)

  1. Trailer control valve for motor vehicle brake installations, comprising a double seat valve which controls the pressure in a brake line arranged   downstream, because it leaves the pressure of a food source   penetration in the brake line by reducing it more or less, and which is switchable by the pressures prevailing in the various braking circuits of the towing vehicle, characterized in that one (I) of the braking circuits (I, II , III) is connected through a solenoid valve (27) to a control chamber (17) provided in the trailer control valve (1) and that the solenoid valve (27), when its electromagnet is not energized, leaves acting without influencing the brake circuit pressure of the towing vehicle acting as control pressure and, when switched, establishing a direct connection between the supply pressure source and the control chamber (17), closing the connection port of the braking circuit concerned of the towing vehicle.   2. Trailer control valve according to claim   cation 1, characterized in that the solenoid valve (27) is a proportional electromagnetic valve and comprises a reaction surface (reaction membrane 33) integral with the armature (30) and by which the force of the equilibrium is balanced each time electromagnet and   the pressure applied by the solenoid valve (27).   3. Trailer control valve according to claim   cation 1, characterized in that a cylinder driven by a pressure fluid or a motor is used in place of the armature   electromagnet (30) as an energy generator.