FR2487268A1 - DEVICE FOR CONTROLLING A PNEUMATIC SUSPENSION TRAIN AXLE WITH A VERTICAL DISPLACEMENT OF A UTILITY MOTOR VEHICLE - Google Patents

Abstract

THE INVENTION RELATES TO A CONTROL DEVICE FOR A PNEUMATIC SUSPENSION AND VERTICAL DISPLACEMENT TRAILED AXLE. THE DEVICE CONTAINS FOR THE DRIVING AXLE A PRESSURE REGULATION VALVE 5, A PRESSURE LIMITATION VALVE 23, A NON-RETURN VALVE 7 AND A DISTRIBUTOR VALVE 8 AND FOR THE SUPPLY AXLE A LEVEL 10 REGULATION VALVE AND A DISTRIBUTOR VALVE 15, THESE COMPONENTS COOPERATING SO AS TO ACT, DEPENDING ON THE LOAD EXERCISING ON THE AXLES, EITHER ON THE LIFTING DEVICE 18 OF THE SUPPORT AXLE OR ON THE BELLOWS 1, 2 OF ITS SUSPENSION PNEUMATIC. APPLICATION TO UTILITY VEHICLES.

Description

The present invention relates to a device for controlling an axle

  air-suspension and vertical-displacement supplementary train of a commercial motor vehicle in connection with a steel spring suspension drive axle, this device comprising a pressure limiting valve, a dispensing valve, a throttle check valve and lever-operated pressure control valve

  mounted on the driving axle as well as a valve

  butrice and a level control valve, ordered

  by a linkage, mounted on the extra axle.

  Back up axles placed behind drive axles are increasingly sought after in the commercial vehicle market because of the possibility of absorbing an additional payload and a relatively low additional cost. This is why they are frequently installed later on

existing vehicles.

  Preferably, the suspension of the axle of ap-

  point is a pneumatic suspension, especially when the drive axle is mechanical suspension. The advantage of a pneumatic suspension of the auxiliary axle with respect to a steel spring suspension thereof is the desired distribution of the load between the axles, to which the pneumatic pressure of the axle extra can adapt each time. Indeed, the

  axle load transmission is effected

  kills from about 95% of the allowable load of

  the driving axle and one thus ensures good conditions

  traction. A controlled lift device allows the auxiliary axle to be raised to increase the load on the drive axle and therefore to increase the driving force exerted on the road and also to save the tires of the axle

  when the vehicle is partially

loaded.

  Air suspension vehicles generally have a level control valve which always maintains the vehicle chassis height constant regardless of the load. then

  the combination of a mechanical suspension for the

  engine and a pneumatic suspension for the

  In addition, such an arrangement can not be used.

  On the contrary, the auxiliary axle must adapt to the strokes, depending on the load, of the drive axle with mechanical suspension, because otherwise one could not regulate a determined proportion of distribution of the loads on the two axles. The aim of the invention is to ensure that the permissible load for the driving axle is not exceeded and that the drive capacity of the driving axle can be optimally used. practically to the nominally maximum limit of the

axle load.

  This problem is solved according to the invention in that a pressure kept constant by the pressure limiting valve is applied to the valve of

  pressure regulation, in that this regulating valve

  pressure pressure, proportional to the position of a linkage responsive to the axle load and which produces, after exceeding a predetermined pressure value corresponding to approximately 95, 4

  the permissible load of the driving axle, the switching

  of the distributor valve of the driving axle of

  so that the actuating valve, possibly

  of the lifting device of the axle of

  the point is placed in a vent condition and compressed air is supplied to the level regulating valve, placed on the auxiliary axle, thereby conveying,

  depending on the load, compressed air in the

  flutters of the air suspension until a predetermined spacing interval is established between the vehicle frame and the auxiliary axle

depending on the load.

  When this condition is reached and when the extra axle is lowered, it must no longer be produced, due to load variations during operation on both axles, position switching and tilting. of the extra axle. For this reason, according to another characteristic of the invention, the auxiliary axle does not

  can be raised only by manual switching control

  of the actuating valve and the distribu-

towing axle.

  Other advantages and features of the invention will be highlighted later in the

  description, with reference to the attached single drawing

  which represents an arrangement scheme of the device of

  booster axle control according to the invention.

  In the accompanying drawing, there is shown schematically the control device of a trailing axle booster, provided with pneumatic springs 1 and 2 and

  cooperating with a drive axle 3 equipped with a suspension

  mechanical suspension with steel springs. This diagram shows the function of the air suspension and the device

  axle lift and the posi-

  the valves and valves in the con-

  step-up where the extra axle is lowered.

  In Drincipe it is expected that the booster axle will be loaded only after the drive axle

  has reached approximately 95% of its rated load.

  This result is obtained in that the pneumatic springs

  1 and 2 of the auxiliary axle remain without pressure until the regulator, that is to say the pressure regulating valve 5, actuated by the driving axle 3 via a lever linkage 4, establish a Pans pressure which corresponds to 95% of the permissible axle load. This pressure is applied by means of a pipe 6 in which is connected a non-return check valve 7, a 3/2 way distributor valve 8 which it

  switches when it reaches the limit value

  mentioned above. A pipe 9 connects this dispensing valve 8 to a level control valve 10. From the pipe 9 a pipe 11 terminates at an actuating valve 12 of the lifting device. The pipes 9 and 11, after switching of the dispensing valve 8, are supplied with air at a constant pressure limited by the valve of

pressure limitation 23.

  The level regulating valve 10 is connected by a lever mechanism 13 to the booster axle. A pipe 14 from the level regulating valve 10 connects it to a distributor valve 15 switching or vent control. This valve is connected to a side, via a pipe 16, with the two pneumatic springs 1 and 2; these are also

  connected by a pipe 26 to the braking system.

  On the other hand a pipe 17 divided into two branches leads respectively to a lifting device 18 of the booster axle and to the actuating valve 12 of this lifting device 18. The actuating valve 12 is connected, Via a pipe 19, to a pressure source 20 which is supplied by a source of compressed air 25 and upstream of which is connected

a discharge pit 21.

  From the pipe 19 part a pipe 22 leading to

  the pressure relief valve 23. that it applies

  that, by means of a bypass pipe 24, it is possible to have a value of 5.7 (+0.3) bar, on the one hand to the 3/2 way distributor valve 8 and else

  part of the pressure regulating valve 5.

  The level 10 control valve shall be set to be in the locked position up to 90% of the permissible load of the driving axle 3 and in the filling position when this value is exceeded. The level regulating valve assures the supply of air to the auxiliary axle, that is to say that air is blown into the pneumatic springs 1 and 2. The actuating valve 12 a been switched by the

  limited constant pressure in pipe 11, that is,

  to say that the lifting device 18, the pipe 17 and the

  valve 15 are put into a vent condition and that the axle of

point is lowered.

  The pressure relief valve 23 must be

  set to a pressure which corresponds to the pressure of

  pneumatic pension of the auxiliary axle subjected to the

  age eligible. This pressure is simultaneously the

  inlet pressure at the pressure regulating valve 5.

  For about 95% of the nominal load of the

  If engine 3, it is established at the output of the regulator, that is to say, the pressure regulating valve 5, a pressure determined. This pressure constitutes the switching pressure of the 3/2-way distributor valve 8, by which the auxiliary axle is supplied with air while the lifting device is brought into

  the position of vent, that is to say of descent.

  We then encounter the following situations: 1) The vehicle is empty and the extra axle is on the ground: the level 10 control valve and the

  actuating valve 12 are still in the condition of being

  wind. The pneumatic springs 1 and 2 and the lifting bellows 18 are thus under pressure. The device

  lift 18 can be operated by means of the control valve.

12.

  2) The vehicle is empty or partially loaded and the booster axle is on the ground: The valve 12 is actuated and the lifting device 18 thereby

  supplied with air, and the extra axle is relieved of

  that the driving axle 3 undergoes an additional load.

  3) The vehicle is partially loaded, the lifting device 18 supplied with air (ie the raised auxiliary axle raised), and when the load reaches% of the maximum permissible value for the driving axle

  3, the pressure regulating valve 5 establishes a pressure

  which causes switching of the distribution valve

  3/2-way valve 8. The actuating valve 12 of the dis-

  Positive lift is activated and switches to

  venting, or axle descent, and the operating bellows of the lifting device 18 is placed in the vent condition. Simultaneously, the connection connection

  of the 3/2-way distributor valve 15

  mutation or vent placed between the regulator valve

  level 10 and the air springs 1 and 2 are de-

  loaded with pressure and this dispensing valve 15 is actuated by its spring. When the axle load

  motor exceeds 955 of the permissible value, the check valve

  Level 10 control switches to open condition and provides air supply to the air springs

  1,2 of the extra axle. It transmits a charge jus-

  that, by lifting the chassis, the lever 13

  of the level 10 control valve goes into the

  locking position. The lifting device 18 can

  only be operated when needed.

  4) In the vehicle, the loads on the driving axle and the auxiliary axle have reached the maximum permissible values and the vehicle is then overloaded. The lifting device 18 can only be operated if necessary because the pressure

  constant established through the distribution valve

  3/2 way bushing 8 is applied to the valve 12 of ac-

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  the lifting device and makes the maneuver difficult. The level regulating valve 10 is placed in the open condition because of the

  overload. However, the pressure of the res-

  pneumatic spells 1 and 2 is limited to the value by the pressure relief valve 23, the additional load is absorbed only by the drive axle. We are thus sure to make maximum use of

tractive force.

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REVEI'TDICATIONS

  1 - Device for controlling an extra drag axle, with pneumatic suspension and vertical displacement, of a utility vehicle in connection with a

  suspension axle with steel springs, this disc

  positive having a pressure limiting valve,

  a dispensing valve, a non-return valve of

  and a lever-operated pressure control valve mounted on the driving axle and a distributor valve and a level control valve, controlled by a linkage, mounted on the auxiliary axle, characterized in that that a pressure maintained constant by the pressure limiting valve (23) is applied to the pressure regulating valve (5), in that this pressure regulating valve (5) establishes a pressure proportional to the position of the pressure the tringer (4) responsive to the axle load and which produces, after exceeding a predetermined pressure value corresponding to about? the permissible load of the driving axle (3), the switching of the 3/2 way distributor valve (8) of the driving axle so that the actuating valve (12), possibly supplied with air, of the lifting device (18) and (15) of the auxiliary axle is set

  in a vent condition and that compressed air is applied

  to the level regulating valve (10), placed on the auxiliary axle, which thus causes, according to the load, compressed air in the bellows (1, 2) of air suspension until it is established

  between the vehicle chassis and the auxiliary axle

  predetermined range of spacing according to the

  ge. 2 - Control device according to claim 1, characterized in that the booster axle can not be

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  noted that by manual control by switching of

  said actuating valve (12) and the valve

  tributrice (15) of the booster axle.