Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60G—VEHICLE SUSPENSION ARRANGEMENTS
  • B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
  • B60G17/02—Spring characteristics, e.g. mechanical springs and mechanical adjusting means
  • B60G17/04—Spring characteristics, e.g. mechanical springs and mechanical adjusting means fluid spring characteristics
  • B60G17/052—Pneumatic spring characteristics
  • B60G17/0523—Regulating distributors or valves for pneumatic springs
  • B60G17/0526—Distributor units, e.g. for retractable wheels
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60G—VEHICLE SUSPENSION ARRANGEMENTS
  • B60G2204/00—Indexing codes related to suspensions per se or to auxiliary parts
  • B60G2204/40—Auxiliary suspension parts; Adjustment of suspensions
  • B60G2204/47—Means for retracting the suspension
  • B60G2204/4702—Means for retracting the suspension pneumatically
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60G—VEHICLE SUSPENSION ARRANGEMENTS
  • B60G2300/00—Indexing codes relating to the type of vehicle
  • B60G2300/02—Trucks; Load vehicles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60G—VEHICLE SUSPENSION ARRANGEMENTS
  • B60G2600/00—Indexing codes relating to particular elements, systems or processes used on suspension systems or suspension control systems
  • B60G2600/02—Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60G—VEHICLE SUSPENSION ARRANGEMENTS
  • B60G2600/00—Indexing codes relating to particular elements, systems or processes used on suspension systems or suspension control systems
  • B60G2600/60—Signal noise suppression; Electronic filtering means
  • B60G2600/604—Signal noise suppression; Electronic filtering means low pass

Definitions

• the invention refers to a lift axle control unit to be used in a lift axle suspension system of a commercial vehicle, further to a lift axle suspension system comprising such a lift axle control unit, and a vehicle, in particular a commercial vehicle, comprising such a lift axle suspension system.
• a lift axle suspension system of a commercial vehicle comprises in general suspension bellows (like the other axles) for damping and for adjusting the distribution of the axle load between the axles of the vehicle, and additionally one or more lift bellows capable for lifting the axle in order to detach the wheels of the lift axle from ground; further, pneumatic valves for controlling these bellows are provided.
• a lift axle suspension system in a commercial vehicle enables the following functions:
• This override can be initialized manually or by a control unit.
• a damping delay is provided for maintaining the axle position during road undulations. Further it is often preferred to keep the lift axle during an ignition off condition in its lowered position in order to avoid theft of wheels.
• Valve assemblies often comprise solenoid valves for receiving electrical signals and relay valves to enlarge the volume flow. Raising or lowering the axle is achieved through pneumatically actuated valves, which in turn receive appropriate pneumatic and/or electrical signals.
• Existing lift axle control valve assemblies can be comprised of essentially a combination of a spool valve, a damping reservoir, a Solenoid valve and a switch, e.g. a double throw pressure switch; the axle control valve assembly works e.g. with an external electrical relay and two external relay valves.
• One disadvantage of those prior art lift axle control valves are the high costs of manufacture due to separate cast bodies for the individual valves (lift axle control valve and relay valve) and piping to join them together.
• a further disadvantage of the known art lift axle control valve can be seen in the fact that load detection is performed through a double throw pressure switch. This results in more inconsistency of pressure sensing and it affects the reliability of the system.
• a still further disadvantage of the known art is that a lowering of the lift axle during ignition off condition has to be achieved through an external electrical relay. This affects the reliability of the system.
• the WO2012140672A2 discloses a lift axle control valve assembly comprising a stack arrangements of layers including several pneumatic valves to be connected to a reservoir and to lift bellows and suspension bellows.
• the lift axle control unit according to the invention is defined in claim 1. Further a lift axle suspension system comprising this lift axle control unit, air bellows and a lever arrangement and a vehicle comprising this lift axle suspension system are provided.
• the present invention enables an integration of the following functions in a modular way:
• these elements are integrated in a multi-layer modular construction.
• both lift axle control valve and load detection valve are achieved by a single control unit. So the protection for dust and water entry has to be provided only in single exhaust port of present invention.
• an electrical position sensing system which replaces the pneumatic load detection system in the prior art which requires the complex pressure differential mechanism.
• the vehicle load condition is for example identified by position of a cam in the load detection valve.
• the function of the damping reservoir in the prior art is to provide the damp- ing delay for load detection.
• the electronic control unit provides the damping delay in reduced size; the damping delay can be realized and adjusted by the electronic control unit which performs a low pass filtering and then outputs the control signal to a solenoid valve.
• the electrically actuated pneumatic valve device can in particular comprise only one single solenoid valve, preferably for both relay valves, i.e. the first relay valve of the suspension bellow and the second relay valve of the lift bellow.
• the lift axle control valve assembly enables a reduced plumbing on the vehicle.
• a spool valve and pressure differential valve are preferably not necessary.
• the preferred multilayer construction permits flexibility in connecting the air passages between the functional groups of components, said layers being preferably flat bodies with cavities and passages, which results in simplified manufacture and hence reduced costs.
• Fig. 1 is an electro-pneumatic diagram of a suspension system according to the prior art
• Fig. 2 is an electro-pneumatic diagram of a suspension system according to an embodiment of the invention.
• Fig. 3 is a first sectional view of a lift axle control unit according to an embodiment of the invention in a plane comprising the relay valves,
• Fig. 4 is a second sectional view of the lift axle control valve of figure 3 in a plane comprising the control unit and the solenoid valve,
• Fig. 5 is a flow chart of the signal processing in an electronic control unit according to an embodiment of the invention.
• lift axle control system 101 of the prior art comprises two devices, both shown in dashed lines: a lift axle control valve 102 and a load detection valve 103. Further a pressurized air reservoir 111 , suspension bellows 14 and lift bellows 16 are provided.
• the a lift axle control valve 102 comprises a spool valve 105, a differential pressure valve 106, a first solenoid valve 107 for receiving an ignition signal IG, a second solenoid valve 108 for receiving an electric override signal TA and for enabling a manual override, a relay valve 109, a damping reservoir 110 and a small orifice (throttle) 112.
• the delivery pressure 700 of said load detection valve 103 is given as control input 550 to the lift axle control valve 102.
• the control input 550 is then given to damping reservoir 110 through said small orifice 112.
• the control pressure from damping reservoir 110 is given to pressure differential valve 106 through first solenoid valve 107 and second solenoid valve 108 for load de- tection.
• the damping reservoir 110 and orifice 112 is used to reduce the air consumption by avoiding frequent air exhaust in bump road conditions.
• the first solenoid valve 107 is getting the signal from dashboard.
• the second solenoid valve 108 is used for traction assistance to manual override the axle irrespective of load condition.
• the pressure differential valve 106 is actuating the spool valve 105 to charge the lift bellow 16 by delivery port 800 or suspension bellow 14 by another delivery port 900.
• the supply pressure from reservoir 111 is supplied to supply ports 600 for the load detection valve 103 and to port 500 for the lift axle con- trol valve 102.
• the relay valve 109 gets activated through the spool valve 105, then the delivery air of relay valve 109 feeds to suspension bellows 14 connected to delivery port 900.
• the second solenoid 108 gets the signal TA from dashboard, it switches from the position shown in Fig.1 to the other position. This switches the pressure differential valve 106 into its other position and actuates the spool valve 105 to the other, second position.
• the lift bellow 16 is charged from the supply pressure at 800 from reservoir 111.
• the supply air at port 500 from auxiliary reservoir 11 is passing through first solenoid valve 107 as shown in Fig 1 and through second solenoid valve 108 as shown in Fig1 to activate the pressure differential valve 106 and subsequently spool valve 105 as shown position and to charge the suspension bellow 14 through relay valve 109 corresponding to the control pressure 550 received from load detection valve 103 for achieving the axle in lowered position during ignition off condition.
• the lift bellow 16 can be discharged through the common exhaust 130.
• Figure 2 discloses one embodiment of an inventive lift axle suspension system 30 comprising a lift axle control unit 1 , suspension bellows 14, lift axle bellows 16 and a reservoir (pressure tank) 2 containing pressurized air with supply pressure p2.
• the proposed lift axle control unit 1 has one supply port 100, which in fig. 2 is shown twice only for reasons of illustration in this scheme, further a first delivery port 220 to charge the suspension bellow 14, a second delivery port 250 to charge the lift bellow 16 and a common exhaust 300.
• Internal first pressure lines 41 are connected to the supply port 100.
• An electronic control unit 4 is assembled in the lift axle control unit 1 to control a solenoid valve 5 to charge either the suspension bellow 14 or lift bellow 16.
• the electronic control unit receives an ignition input signal S1 from vehi- cle battery through an ignition key.
• a ground signal S3 is connected to a vehicle battery.
• a traction assistance input signal S2 is received from
• This traction assistance input signal S2 may e.g. be output if a reverse gear is used, in order to enable better maneuverability.
• a position sensing system 8 is assembled in the integrated load detection valve 3 to detect the vehicle load conditions. Output from the position sensing system 8 is given as load condition sensing signal S4 to the electronic control unit 4.
• the electronic control unit 4 actuates the solenoid valve 5 via an elec- trie control signal S5 depending on the ignition input signal S1 , traction assis- tance input signal S2 and load condition sensing signal S4 to charge or deplete the lift bellow 16 and suspension bellow 14.
• the supply pressure in reservoir 2 is connected to the lift axle control unit 1 in single supply port 00.
• the supply pressure p2 in single supply port 100 is given via the first pressure lines 41 to first relay valve 6 and second relay valve 7 whereupon the first relay valve 6 is connected to the first pressure line 41 via the pressure port 641 an the second relay valve 7 is connected via the pressure port 741.
• the first pressure lines 41 are also connected to the load detection valve 3 via the pressure port 341 which modulates the pres- sure and gives a modulated pressure p3, p3 ⁇ (smaller or equal to) p2, via a second line 42 to the solenoid valve 5 with respect to vehicle load conditions.
• the load detection valve 3 and the solenoid valve 5 are thereby connected via the pressure ports 342 and 542.
• the load detection valve 3 comprises a self balancing mechanism 301 , which limits the supply pressure to a predefined value.
• the first relay valve 6 charging the suspension bellow 14 via fourth pressure line 44 through the pressure port 644 and the first delivery port 220 depending on the control pressure from load detection valve 3. Additionally the first relay valve 6 comprises a self balancing mechanism 601 , which limits the supply pressure to a predefined value.
• the second relay valve 7 is charging the lift bellows 16 via fifth pressure line 45 through pressure port 745 and second delivery port 250. The pressure in lift bellow 16 is depleted to atmosphere through the second relay valve 7 in the position as shown in Fig. 2 and common exhaust 300 which is connected via pressure port 701.
• the electronic control unit 4 actuates the solenoid valve 5 via the electronic control signal S5 when it receives the traction assistance input signal S2 from dashboard or the electrical load condition sensing signal S4 from the position sensing system 8 in the presence of the ignition signal S1.
• the solenoid valve 5 switches from the shown position in Fig. 2 to its second, actuated position.
• the pressure in the suspension bellow 14 is depleted to atmosphere through the first delivery port 220, first relay valve 6 and common exhaust 300.
• the lift bellow 16 charged to supply pressure at port 100 through the second relay valve 7 and delivery port 250.
• the lift axle control unit 1 comprises a multilayer construction with levels 51 , 52, 53, 54, 55 stacked together and fixed by bolts (or screws) 57, whereas also nuts are possible, which do not extend to the section planes of Fig. 3 and 4.
• FIG. 3 the sectional view in a plane of the integration of first relay valve 6 and second relay valve 7 in the is shown.
• the first layer 51 is the top layer of the single device stack arrangement of lift axle control unit 1 ; the top layer 51 serves as a lid for closing the valve arrangement
• the second layer 52 serves as an air passage layer and comprises flow passages of pressure lines 41 and 43, said flow passages being designed as cavities 43a, 41a in the second layer 52.
• the sectional views of figures 3 and 4 not all air conduits and air passages are visible; in particular, the con- nections between the cavities 43a, 41a and the first pressure line 41 are not visible.
• the sectional views may show separated lines 41 and separated lines 43 which are three dimensional lines extending through this device.
• the third layer 53 serves as a valve layer and comprises the first relay valve 6 and second relay valve 7 as shown in Fig 3.
• the fourth layer 54 comprises the flow passages between the first relay valve 6 and second relay valve 7.
• the fifth layer 55 supports a cam arrangement 1050 connected to the load dependent lever arrangement 1100 as shown in Fig.3.
• the first relay valve 6 is depleting the suspension bellow 14 shown in
• Fig. 2 as shown in the construction of the first relay valve 6 in Fig. 3.
• the lift bellow 16 shown in Fig. 2 is charged to supply pressure by the second relay valve 7 as shown in the construction of Fig. 3.
• the sectional view of load detection valve 3 discloses an adjustable screw arrangement 1010 in the second layer 52 to define the pressure values at different load conditions.
• Fig. 4 is showing the construction of third layer 53 with solenoid valve 5 and load detection valve 3.
• the delivery pressure of load detection valve 3 is supplied via the second pressure line 42 realized as a cavity 42a in the third layer 53 to the solenoid valve 5.
• the air flow direction is indicated by arrows.
• the electronic control unit 4 is assembled in third layer 53 as shown in Fig. 4 to actuate the solenoid valve 5 which is assembled in the third layer 53.
• the lever arrangement 1100 shown in Fig. 4 is connected to vehicle axle of vehicle 1000 to detect the vehicle load conditions.
• the rotation of lever arrangement 1100 is e.g. directly proportional to vehicle load conditions.
• the electronic control unit 4 assembled in third layer 53 as shown in Fig. 4, having the control algorithm for damping delay in order to reduce the air consumption by avoiding frequent exhaust in suspension bellow 14 shown in Fig. 2.
• the input signals S1 of ignition, traction assistance input signal S2 of manual override, and the load signal S4 which are inputted into the electronic control unit 4 as shown in Fig. 2 are monitored for a defined duration in said algorithm for the damping delay to ensure the required action of actuating or deactivating the solenoid valve 5 assembled in layer 53 as shown in Fig. 4.
• the electronic control unit 4 preferably executes a logical operation on basis of the input signals S1 , S2, S4 and actuates the solenoid valve 5 via an electric control signal S5 to lift the axle in dependence of the statuses of these signals S1 , S2, S4.
• This is shown in the flow chart of Fig. 5, whereupon in a first step F0 the electronic control unit 4 is e.g. initialized.
• a second step F1 the electronic control 4 unit checks if the signals S1 , S2, S4 are available. Therefore the electronic control unit 4 periodically monitors these signals S1 , S2, S4. If these signals S1 , S2, S4 are available their statuses, e.g. ignition “on” or manual override "active", are checked in a further step F2.
• a step F3 the electronic control unit 4 checks the statuses of the sig- nals S1 , S2, S4 for a damping delay time t_damp, which may be a predefined time delay set in the electronic control unit 4 to avoid frequent exhaust of the suspension bellows 14.
• t_damp the electronic control unit 4 checks whether the statuses of the signals S1 , S2, S4 are changing. If so the changing of the signal is considered as noise or an unwanted change and the signals S1 , S2, S4 will maintain at their previous states. If the statuses are not changing during the damping delay time t_damp the signals S1 , S2, S4 are stored, e.g. in a memory unit, and are processed further in step F4. After the statuses are checked the damping delay counter is reset to zero.
• the electronic control unit 4 compares an axle height position indicated by the load condition sensing signal S4 with a predetermined value hjhresh and decides on basis of this comparison, if the lift axle has to be lifted or not. The result of this comparison is referenced to by "comp(S4)".
• the electronic control unit 4 can perform a low pass filtering (LP) either of this comparison result "comp(S4)" or on the sensing signal S4 before the comparison is carried out, in order to avoid the above mentioned unnecessary switching in case of e.g. a bumpy road.
• LP low pass filtering
• the result of this low pass filtering leads to a Boolean value which is referenced to by "LP(comp(S4))” or “comp(LP(S4)) depending on when the low pass filtering is carried out. This leads to an overall Boolean operation:
• step F3 the electronic control unit 4 checks the stored statuses of the signals S , S2, S4 for a predefined amount of time, the damping time t_damp, and then further processes these signals S1 , S2, S4 in a step F1.4 to actuate the solenoid valve 5 depending on the Boolean operation (Eq. 1) as it is done in step F4.
• a last step F5 the delay counters are reset and the current statuses of the signals S1 , S2, S4, S5 are updated.
• valve 6 601 self balancing mechanism of valve 6

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Vehicle Body Suspensions (AREA)

Priority Applications (2)

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Cited By (6)

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Citations (6)

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• 2014
  • 2014-04-23 WO PCT/IB2014/000598 patent/WO2014181160A1/en active Application Filing
  • 2014-04-23 BR BR112015027727-6A patent/BR112015027727B1/pt not_active IP Right Cessation
  • 2014-04-23 CN CN201480023895.9A patent/CN105392646B/zh not_active Expired - Fee Related

Patent Citations (6)

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