DE4327764A1 - Air suspension system - Google Patents

Abstract

An air suspension system is proposed which is provided with a lifting axle control. For operation of the lifting axle (3) individual valves (12, 13) can be operated merely by a pulse and precautions are taken in the form of one or more slide valves in combination with main valves so that the valve position attained at any one time is maintained even in the absence of current. As a result, the lifting axle (3) remains in its position attained at any one time even when the current is shut off or fails, thereby saving current. The air suspension system is preferably intended for commercial motor vehicles with three axles. <IMAGE>

Description

State of the art

The invention relates to an air suspension system according to the Genus of the main claim. Such an air suspension system is known (literature: WABCO, ECAS electronic level control for air-sprung commercial vehicles, March 1990).

In the case of known air suspension systems, the control was initially included Air spring valves designed purely mechanically. But soon electromechanical controls were developed. The Be ease of use increased and there were lifting and lowering operations relieved. The most advanced development in this direction is an electronically controlled air suspension system.

With such an electronically controlled system, the driving comfort increased. With low spring rates and low natural frequencies the cargo is protected. It is the air consumption during the Reduced ride. Different levels can be set by automa table readjustment are observed. There are also additional functions such as lift axle control, traction help and overload protection without any problems to integrate.  

However, the known system has the disadvantage that the with Magnetven valve devices equipped as pilot valves in the Switch positions are usually under power. To the holder of the order switch position, constant power consumption is required. In order to the power requirement of the known system is relatively high. At The valves fail if the power supply is switched off or fails their basic position back.

Advantages of the invention

The present invention has for its object this to avoid part and create an air suspension system whose Power consumption is lower.

This object is achieved according to the invention by the characterizing Features of the main claim solved.

The air suspension system has the advantage that electri without supply sher energy a set switched switching position will hold.

Advantageous further developments of the subject matter of the main claim result from the features of the subclaims.

drawing

Several selected embodiments of the invention are shown in FIG Drawing shown and in the description below explained. Show it

Fig. 1 shows a preferred embodiment of an air suspension system for a utility vehicle with three axles, of which one axle is a lift axle, Fig. 2 shows a modification of the design according to Fig. 1, Fig. 3 shows a second variant of the design according to Fig. 1 and Fig. 4 to 9 exemplarily various details of the air suspension system according to the invention.

Description of the embodiments

The exemplary embodiment of the air suspension system of a commercial vehicle according to the invention shown symbolically in FIG. 1 has, for example, a steerable front axle 1 and a rear double axle. The double axle comprises a driven axle 2 and a non-driven axle 3 . The non-driven axle 3 can be arranged in relation to the direction of travel in front of or behind the driven axle 2 and can accordingly be referred to as a leading axle or as a running axle. In the illustrated embodiment, the non-driven axle 3 can be raised and is therefore also referred to as the lifting axle 3 . The lift axle 3 can be raised when the vehicle is lightly loaded. The air suspension system essentially has a compressed air supply device 4 , a central 3/2-way solenoid valve 5 , a downstream 2/2-way solenoid valve 6 for the front axle 1 and a downstream 2/2-way solenoid valve 7 for the axle 2 as well as two air bellows 8 and 9 or 10 and 11 , but also three valve devices 12 , 13 and 14 symbolically shown in FIG. 1 for monitoring two air bellows 15 and 16 and an air bellows 17 of the lifting axle 3 . The valve devices 12 , 13 , 14 can be integrated in a common lift axle valve block 26 . The valve devices 12 , 13 , 14 can be actuated with the aid of electrical means. In Fig. 1, the electrical means of symbolic electrical magnets 112 , 113 , 114 are gebil det. For the sake of clarity, the air bellows 17 is referred to below as the bellows 17 .

A displacement sensor 18 is arranged on the front axle 1 and a displacement sensor 19 is arranged on the driven axle 2 . Both displacement transducers 18 and 19 are connected to an electronic control unit of a controller 83 , with the corresponding electrical connecting lines not being shown for reasons of clarity. Finally, there are two venting points 20 and 21 in the system, a pressure ratio valve 22 and a pressure switch 23 on the driven axle 2 .

A connecting line 61 connects the air bellows 10 , 11 of the driven axle 2 to the valve device 13 . If necessary, the pressure ratio valve 22 can be provided in the course of the connecting line 61 . If necessary, the pressure ratio valve 22 can be dispensed with.

From the compressed air supply device 4 leads a Druckversor supply line 87 to the valve devices 12 , 13 , 14th A ventilation line 88 connects the valve devices 12 , 14 to the ventilation point 21 . A vent line 90 leads from the Ven tileinrichtung 13 via the valve device 14 in the vent line 88th A lift axle line 62 leads from the Ventileinrich device 13 to the bellows 15 , 16 of the lift axle 3rd

In the area of the front axle 1 and the driven axle 2 , the system works in the manner customary for air suspensions. This working method is known and is therefore not described in detail here.

By partially venting the air bellows 15 , 16 can be achieved that the non-driven axis 3 is relieved and the driven axis 2 is loaded more heavily. Venting the air bellows 15 , 16 and additionally venting the bellows 17 leads to a lifting of the lift axle 3 .

With regard to the control of the lifting axle 3 , it is essential to the invention that the magnets 112 , 113 , 114 need only be briefly energized in each case so that the valve devices 12 , 13 move into their new switching position and then also after the current has been switched off remain in this new switch position.

If the lifting axle 3 is to be raised, this can be done with an appropriate switch 60 on the dashboard. The air spring bellows 15 and 16 of the lifting axle 3 are vented by the solenoid is energized for a short time 114, whereby the valve device 14 b is in a locking position 14 during the time of energization. At the same time the valve device 13 is driven via a symbolically represent supplied control air line 84, whereby the direction Ventilein 13 a venting position 13 assumes b.

The operation of the valve devices 12 , 13 , 14 is, for the sake of a better overview, only roughly described with reference to FIG. 1, but is still explained in detail with reference to FIGS. 4 to 7.

After the current pulse supplied to the magnet 114 has been switched off, the valve device 14 is put back into a through position 14 a by a symbolically illustrated spring 85 . The valve device 13 remains in the vent position 13 b.

When the valve device 13 is in its ventilation position 13 b, the air bellows 15 , 16 are connected to the ventilation point 21 via the lift axle line 62 , via the valve device 13 , via the ventilation line 90 , via the valve device 14 and finally via the ventilation line 88 , and the in the air spring bellows 15 , 16 compressed air can escape to the outside through this vent 21 . Only during the short current pulse supplied to the magnet 114 is the Ventilein device 14 in the blocking position 14 b and the ventilation of the air bellows 15 , 16 is not possible during this time.

Simultaneously with the venting process for the bellows 15 and 16 of the electric solenoid is energized, the valve means 12 relatively short 112 and the valve device 12 is subject to change in its venting position 12 b for the lifting bellows 17th In the ventilation position 12 b of the compressed air supply device 4 via the pressure supply line 87 and via the valve device 12, the bellows 17 is supplied with compressed air, ie the bellows 17 is ventilated. The valve device 12 remains in its ventilation position 12 b and the valve device 13 remains in its ventilation position 13 b until the command to lower the lift axle 3 is given on the dashboard. A current pulse is sufficient to switch over. For holding these positions 12 b, 13 b no more energy is required.

The described process of lifting the lifting axle 3 is automatically prevented if the driven axle 2 would be overloaded. The respective axle load on axle 2 is identified by means of the pressure switch 23 .

To lower the lifting axle 3 , the switch 60 is used to give the command to lower it. For this purpose, the magnet 113 receives current briefly, and the valve device 13 thereby switches to a working position 13 a. If the valve device 13 is in the working position 13 a, the air bellows 15 , 16 are via the lift axle line 62 , via the valve device 13 , via the connecting line 61 and via the pressure ratio valve 22 with the air spring bellows 10 , 11 and with the 2/2 way -Magnetic valve 7 connected. The valve device 12 is connected to the valve device 13 via a symbolically illustrated control air line 24 and then switches, depending on the pressure, into a venting position 12 a. The valve device 13 is in its working position 13 a permanent connection between the bellows 10 and 11 of the driven axle 2 and the air bellows 15 and 16 of the lift axle 3 , so that the air bellows 15 , 16 are refilled. The valve device 12 remains permanently in its (drawn) venting position 12 a so that the bellows 17 is relieved.

After completion of the lowering process of the lifting axle 3 , the normal level of the vehicle body is readjusted using the solenoid valves 5 , 6 and 7 .

The lifting axle 3 is automatically lowered when the pressure switch 23 gives a signal to the controller 83 that the driven axle 2 is overloaded.

The lifting axle 3 is usually lifted when the vehicle body is unloaded or lightly loaded, because then the driven axle 2 is completely sufficient to support the vehicle body.

It is also possible to use the more or less partial ventilation of the air bellows 15 , 16 of the lift axle 3 as a starting aid. The traction help is to be understood as the increase in the axle load of the driven axle 2 . The traction help can also be used when the vehicle body is loaded. A certain overload of the driven axle 2 by a certain permissible overload value of about 30% is often permissible, since the starting aid is only required for a short time and only at low speeds.

For the starting aid in the embodiment shown in FIG. 1, by briefly energizing the magnet 114, the ventilation of the air bellows 15 , 16 is initiated, as already described. With increasing ventilation of the air bellows 15 , 16 , the driven axle 2 is increasingly loaded. If the permissible overload value is exceeded, the magnet 114 is energized again, which actuates the valve device 14 in the blocking position 14 b. As a result, the ventilation of the air bellows 15 and 16 of the lift axle 3 is interrupted. The magnet 114 must be continuously energized for the duration of the starting aid. The corresponding load conditions are identified via the pressure switch 23 . Since the starting aid is of course only required for a short time, the power consumption required is negligible.

Fig. 2 shows a further advantageous embodiment of the air suspension system.

Unless otherwise stated, identical or equivalent parts are provided with the same reference symbols in all the figures. The following exemplary embodiments are largely constructed in the same way as the first exemplary embodiment according to FIG. 1, with the exception of the deviations essentially specified below. Details of the various exemplary embodiments can be combined with one another.

Fig. 2 shows an extension of the system of FIG. 1. There is also a preloaded check valve 81 and a make-up valve 25 , of which the check valve 81 serves as a retention pressure valve. The check valve 81 is located in the ventilation line 88 leading to the ventilation point 21 . A Lei device 89 leads from the pressure supply line 87 via the make-up valve 25 and opens before the check valve 81 in the vent line 88th Both valves 81 and 25 are integrated with the Ventileinrich lines 12 , 13 and 14 in a common lift axis valve block 27 . The lift axle valve block 27 otherwise corresponds to the lift axle valve block 26 shown in FIGS . 1, 4 and 5. With the help of the two valves 81 and 25 , a safety residual pressure in the bellows 17 or in the air bellows 15 and 16 can be maintained. In the event of a possible leak, the previously determined residual pressure is filled up again via the make-up valve 25 .

Fig. 3 shows a third advantageous embodiment.

FIG. 3 shows an installation which is derived from the design according to FIG. 1. A lift axle valve block 31 is expanded here by two valves 28 and 29 compared to the lift axle valve block 26 according to FIG. 1. In addition, in the supply line for the air bellows 8 and 9 of the front axle 1 there is also a directional solenoid valve 30 which, in its one (drawn) position 30 a, has a throttle passage between the left and right air bellows 8 and 9 of the front axle 1 and which in its Stromum switch position 30 b connects both air bellows 8 and 9 with each other and with the supply line. It can also be seen that there is no direct connection between the two air bellows 15 and 16 of the lift axle 3 .

The air bag 11 of the left vehicle side is controlled by a 2/2-way solenoid valve 91 , and a 2/2-way solenoid valve 92 controls the pressure of the right air bag 10 . The 2/2-way solenoid valves 91 , 92 correspond in their function to the 2/2-way solenoid valve 7 of Fig. 1, with the difference that in the embodiment shown in Fig. 3, the left and right side of the axis 2 can be controlled with the separate valves 91 , 92 . Depending on the position of the valve devices of the lifting axles Ven valve block 31 , the right bellows 15 is connected via a Druckver ratio valve 94 with the bellows 10 and the bellows 16 via a pressure ratio valve 95 with the bellows 11 the. The pressure ratio valves 94 , 95 correspond in their function to the pressure ratio valve 22 shown in FIG. 1. Just as in Fig. 1 on the pressure ratio valve 22 who can, the pressure ratio valves 94 , 95 , depending on the requirement, can be omitted.

A separate and independent regulation of the pressures of the air bellows 10 , 11 , 15 , 16 on the left and on the right side of the vehicle is possible with the system shown in FIG. 3. In order to be able to regulate both sides of the vehicle separately, the displacement sensor 19 shown in FIG. 1 is replaced by two displacement sensors 98 , 99 shown in FIG. 4.

In the embodiment shown in FIG. 3, the valve devices 13 , 14 serve to control the left air bellows 16 . The valves 28 , 29 shown symbolically are piloted by the solenoid valves 113 , 114 contained in the valve devices 13 , 14 and serve to control the right air bellows 15 . The valve 28 has a through position 28 a and a blocking position 28 b, and the valve 29 has a working position 29 a and a vent position 29 b.

If the lifting axle 3 carry part of the load, then the Ven valve devices 12 , 13 , 14 , 28 , 29 are in the positions shown in FIG. 3 Darge 12 a, 13 a, 14 a, 28 a, 29 a.

To lift the lifting axle 3 , the magnet 114 is first energized briefly and the valve device 14 switches during the current flow of the magnet 114 into the blocking position 14 b. As a result, the valve device 13 in the venting position 13 b, the valve 28 in the blocking position 28 b and the valve 29 in the venting position 29 b actuated. After completion of the energization of the magnet 114 of the valve device 14, the spring shown symbolically 85 performs the valve means 14 in the passage position 14 a back, and a spring 97 is also shown symbolically drives the valve 28 back into its passage position 28 a. The valve devices 13 and 29 , however, remain in their venting positions 13 b, 29 b. As a result, the air bellows 15 , 16 are vented and the bellows 17 is ventilated by briefly energizing the magnet 112 , as a result of which the lifting axle 3 is raised.

If the air suspension bellows 15 , 16 are to be vented only slightly for the starting aid, the venting just described can be interrupted at any time by energizing the magnet 114 again, for example when the pressure switch 23 signals an impending overload of the driven axle 2 .

To drain the lift shaft 3, the magnet 113 is the Ventileinrich tung 13 briefly energized, whereby the valve device 13 to the working position 13 a, the valve 29 in the working position 29 a and the valve device 12 are actuated in its venting position 12 a. As a result, the bellows 17 is vented, the air bellows 15 is coupled again to the air bellows 10 and, accordingly, the air bellows 16 is connected again to the air bellows 11 .

FIG. 4 shows an example of a detail of the pneumatic shock absorbing system.

In Fig. 1, the valve devices 12 , 13 , 14 of the lift axle valve block 26 are shown symbolically so that their operation within the air suspension system can be seen as clearly as possible. In FIG. 4, the same lift axles valve block 26 is shown on a different scale again, so that details of the valve means 12, 13, 14 can exhibit better.

In Fig. 1, the valve devices 12 , 13 , 14 are in the position in which the bellows 17 is vented and the air bellows 15 , 16 are connected and ventilated with the air bellows 10 , 11 , so that the lifting axle 3 is part of the load of the vehicle body. In FIG. 4, the valve means 12, 13, 14 are shown in the position in which they are located for lifting the lift axle 3 and at the raised lift axle 3. The state shown in FIG. 1 and the other state shown in FIG. 4 can be maintained without current. Only a short current pulse is required to switch over.

As FIG. 4 shows the valve means 12 includes a solenoid valve 212 and a main valve 312 will. The valve device 13 comprises a solenoid valve 213 and a main valve 313 . The valve device 14 further comprises a solenoid valve 214 and a main valve 314 .

The main valve 312 has a venting position 312 a ( 12 a) and a venting position 312 b ( 12 b); the main valve 313 has a working position 313 a ( 13 a) and a venting position 313 b ( 13 b); the main valve 314 has a through position 314 a ( 14 a) and a blocking position 314 b ( 14 b). In this paragraph, the same function corresponding to those used in FIG. 1 are given in parentheses.

The lift axis valve block 26 also includes a slide valve 101 shown in FIG. 4 and a slide valve 102 . The slide valves 101 , 102 are not shown in FIG. 1 for the sake of clarity. The solenoid valves 212 , 213 , 214 each have a relief position labeled 212 a, 213 a and 214 a and a pressure position labeled 212 b, 213 b and 214 b, respectively. The valves 101 , 102 each have a first position 101 a or 102 a and a second position 101 b or 102 b. A control line 66 leads from the solenoid valve 213 to the valves 101 , 102 . A control line 67 leads from the solenoid valve 214 to the slide valve 101 and to the main valve 314 . A control line 68 leads from the solenoid valve 212 to the slide valve 102 . The slide valve 101 is connected to the main valve 313 via a control line 69 . A Steuerlei tung 70 connects the spool valve 102 to the main valve 312th

Are the valves of the lift axle valve block 26 in the position shown in FIG. 4, the bellows 15 , 16 of the lift axle 3 via the lift axle line 62 , via the main valve 313 , via the ventilation line 90 , and via the main valve 314 connected to the vent line 88 , whereby the air spring bellows 15 , 16 are vented. In the switching position shown, the pressure supply line 87 is connected to the bellows 17 via the main valve 312 , so that the bellows 17 can lift the lifting axle 3 . The lift axle 3 remains in the raised position without any of the solenoid valves being energized.

To lower the lift axle 3 , ie to ventilate the air bellows 15 , 16 and vent the bellows 17 , the magnet 113 of the solenoid valve 213 is briefly energized, as a result of which the solenoid valve 213 switches briefly to its pressure position 213 b. The pressure supply line 87 is connected via the valve 213 to the control line 66 . By the signal pressure in the control line 66 who the slide valves 101 , 102 in the second position 101 b and 102 b adjusted. In the second position 101 b, the Druckversor supply line 87 is connected via the slide valve 101 to the main valve 313 , which causes the main valve 313 to get into the working position 313 a. If the slide valve 102 is in the second position 102 b, the control line 70 is relieved, where it passes through the main valve 312 with the aid of a symbolically represented spring into the venting position 312 a. In the working position development 313 a, the air bellows 15 , 16 are connected via the main valve 313 to the connecting line 61 leading to the air bellows 10 , 11 of the driven axle 2 , so that the air bellows 15 , 16 are driven in accordance with that in the air bellows 10 , 11 the axis 2 prevailing pressure can be vented. In this position, the pressure in the air bellows 15 , 16 together with the pressure in the air bellows 10 , 11 is controlled by the 2/2-way solenoid valve 7 shown in FIG. 1. Via the main valve 312 located in the ventilation position 312 a, the bellows 17 is vented.

To initiate the ventilation of the air bellows 15 , 16 and vent the bellows 17 , the magnet 113 of the solenoid valve 213 must be energized briefly. Subsequently, further energization is not required. Even if the solenoid valve 213 returns to the discharge position 213 a, the slide valve 101 remains in the second position 101 b, so that the pressure in the pressure supply line 87 via the control line 69 holds the main valve in the working position 313 a.

To raise the lifting axle 3 , the magnets 112 , 114 are briefly energized. As a result, the solenoid valves 212 , 214 briefly reach the pressure position 212 b, 214 b. As a result, the pressure in the pressure supply line 87 via the solenoid valve 214 and via the control line 67 can adjust the slide valve 101 to the first position 101 a, and it can also the pressure in the pressure supply line 87 via the valve 212 and via the control line 68 operate the slide valve 102 in its first position 102 a. As a result, the control line 69 is relieved and the main valve 313 is in its venting position 313 b, whereby the bellows 15 , 16 are vented ent. Simultaneously with energizing the electromagnet 112 , the slide valve 102 is in the first position 102 a, and it can adjust the pressure in the pressure supply line 87 via the slide valve 102 and the control line 70, the main valve 312 in its ventilation position 312 b, so that the bellows 17 is connected to the pressure supply line 87 , is thereby aerated and can lift the lift axle 3 . Even if the main valve 314 is briefly actuated into the blocking position 314 b when the lifting axle 3 is raised, the main valve 314 immediately switches back to the through position 314 a as soon as the magnet 114 is no longer energized. The magnets 112 , 114 need only be energized briefly to initiate the lifting of the lifting axle 3 . In order to raise the lifting axle 3 completely or to hold it up, no current supply to the magnets is required. The lift axle 3 also remains up if, for example, the power fails or the ignition is switched off.

The so-called traction help is initiated in the same way as lifting the lifting axle 3 . Since the traction help can also be carried out when the vehicle is heavily loaded, care must be taken that the driven axle 2 is not loaded beyond the predetermined overload value. As soon as the pressure switch 23 signals that this overload value has been reached, the magnet 114 is energized again, as a result of which the main valve 314 is switched into the blocking position 314 b, so that further bleeding of the air bellows 15 , 16 is prevented. The magnet 112 remains de-energized for the starting aid. In order to prevent the air spring bellows 15 , 16 from being vented too far, the electromagnet 114 must be energized during the entire starting aid once the overload value has been reached. However, since the starting aid is naturally only required for a short time, this energization of the electromagnet 114 does not play a role. The traction help is ended by briefly energizing the electromagnet 113 again and by switching off the current for the magnet 114 .

FIG. 5 shows a detail of the lifting axles valve block 26.

Showing further details of the presented in FIGS. 1 and 4 Darge Liftachsen-valve block 26, an 26 extending cross section through the lifting axles valve block in a different scale, in FIG. 5 are shown in part. The control line 67 and the vent line 88 extend in sections below the cross section shown and are therefore shown in broken lines in sections.

As FIG. 5 shows, the main valve 313 comprises the Ventileinrich tung 13, a valve member 122, a valve member 124, a circumferential edge of the valve 126, a sealing body 128 and a valve spring 130.

The valve members 122 , 124 are axially displaceably mounted in a block 26 in the lift axle valve block, which is stepped several times. The sealing body 128 is, for example, a flat rubber disk connected to the valve member 122 . The sealing body 128 is arranged so that when the valve member 122 against the valve edge 126 is actuated, the connecting line 61 is blocked against the lift axis line 62 and against the ventilation line 90 . The valve spring 130 or the pressure in the connecting line 61 strives to actuate the valve member 122 with the sealing body 128 against the valve edge 126 .

The main valve 313 of the valve device 13 is a kind of Sitzven valve. The circumferential sealing edge 126 serves as the first valve seat for the valve body 122 . The sealing body 128 serves as a valve seat for the second valve body 124 . A first controllable valve cross section 136 is formed between the valve body 122 and the sealing edge 126 and a second controllable valve cross section 138 is formed between the valve body 124 and the sealing body 128 .

A control pressure prevailing in the control line 69 acts on the valve member 124 . A corresponding magnitude of the control pressure in the control line 69 can bring the valve member 124 against the sealing body 128 of the valve member 122 . The second valve cross section 138 is closed. This blocks the connection in the direction of the vent line 90 . In addition, the control pressure in the control line 69 can act on the valve member 124 on the Ven valve member 122 against the force of the valve spring 130 , so that the valve member 122 lifts off the valve edge 126 , whereby the first valve cross section 136 opens and the lift axis line 62 with the Connecting line 61 is connected. In this position, the valve cross section 138 is blocked in the direction of the ventilation line 90 . As already explained with reference to FIG. 4, the control pressure in the control line 69 can bring the main valve 313 into the working position 313 a, in which the first valve cross section 136 opens and the second valve cross section 138 is closed. If the control line 69 is relieved of pressure, the first valve cross section 136 is closed, the second valve cross section 138 is open, and the main valve 313 is in the ventilation position 313 b, in which the air can escape from the lift axle line 62 into the ventilation line 90 . FIG. 5 shows the valve members 122, 124 corresponding in position to the position of the vent shown in Fig. 4313 b.

In Fig. 5, the magnets 113 , 114 are not energized, so that the solenoid valves 213 , 214 are in the Fig. 4 with 213 a, 214 a be marked relief positions. In these switching positions shown, the control line 66 and the control line 67 are relieved of pressure via the solenoid valves 213 , 214 in the direction of the vent line 88 .

When the solenoid 113 of the solenoid valve 213 is energized , an armature of the solenoid valve 213 serving as a control element 154 , with reference to FIG. 5, is actuated upward, as a result of which the connection of the solenoid valve 213 in the direction of the vent line 88 is blocked and the connection becomes released from the pressure supply line 87 in the direction of the control line 66 . The solenoid valve 214 has a corresponding function. Here too, when the magnet 114 is energized, a control member 156 is actuated upward. As a result, the connection is blocked in the direction of the vent line 88 , and the control line 67 is connected to the pressure supply line 87 . By energizing the electromagnet 114 , a signal pressure can be built up in the control line 67 .

As already shown in FIG. 4, the connections between the pressure supply line 87 , the ventilation line 88 and the control line 69 can be controlled via the slide valve 101 .

The slide valve 101 comprises a valve body 132 formed in the form of a spool valve which is axially displaceably mounted in a bore 26 provided in the lifting axis Ven valve block.

A signal pressure in the control line 66 acts on the end of the control slide 132 with the aim, based on FIG. 5, of actuating the control slide 132 to the right. A signal pressure in the control line 67 also acts on the control slide 132 with the endeavor to actuate the control slide 132 in the opposite direction, based on FIG. 5, to the left. As already symbolically shown in FIG. 4, the slide valve 101 is adjusted to its position 101 b via the signal pressure in the control line 66 , in which the pressure supply line 87 is connected to the control line 69 . And a corresponding signal pressure in the control line 67 can actuate the control slide 132 to the left, so that the slide valve 101 reaches the first position 101 a, in which the control line 69 is connected to the vent line 88 . Seals 134 made of an elastomer material are also provided in the bore for mounting the control slide 132 . The seals 134 ensure mutual sealing of the various connections of the slide valve 101 and for friction between the control slide 132 and the lift axis valve block 26 in which the control slide 132 is mounted. The friction between the spool 132 and the lift axles valve block 26 is sized so that the spool stops in each position 132, without any shock to the control slide can be adjusted from its position 132nd However, the friction is also such that the signal pressure in the control line 66 or in the control line 67 can bring the control slide 132 into the desired switching position.

As FIG. 5 clearly shows, the main valve 313 is a so--called pressure-operated poppet valve. With the main valve 313 , large cross sections can be opened or closed by the control pressure in the control line 69 . The pressure actuated main valve 313 has the advantage that it works reliably and is easy to adjust. The same applies to the main valves 312 and 314 , which are constructed in a similar manner to the main valve 313 . The solenoid valves 212 , 213 , 214 are also inexpensive to manufacture, operate reliably, require only a small amount of current to actuate the control members 154 and 156, and are small in size. The slide valve 102 is constructed in the same way as the slide valve 101 . Since only small amounts of air have to be controlled with the solenoid valves 212 , 213 , 214 and with the slide valves 101 , 102 , these valves can be made small.

By briefly energizing the solenoid valve 213 or the solenoid valve 214 , the control slide 132 of the slide valve 101 can be brought into the desired position. Depending on the position of the control slide 132 , the control pressure acts in the control line 69 , or the control line 69 is relieved of pressure. Accordingly, the main valve 313 is in the desired position 313 a or 313 b. The main valve 313 remains in the desired position, even if the solenoid valves 213 , 214 are de-energized. The main valve 313 remains in the respective position 313 a or 313 b until the control valve 132 is adjusted by briefly energizing the solenoid valve 213 or 214 .

It can be seen that no solenoid valves are energized in this way when the lift axle 3 is raised and the lift axle 3 is lowered.

Fig. 6 shows a section of a modified lift axis valve block 26 '.

Here includes a main valve 313 'in the lift axis valve block 26 ' slidably mounted valve member 124 ', a rubber valve seat 128 ' be, a controllable valve cross section 138 'and if necessary a valve spring 130 '.

The control pressure in a control line 69 'actuates the valve member 124 ' against the valve seat 128 'and thus closes the valve cross section 138 '. Without control pressure in the control line 69 ', the pressure in the ventilation line 90 ' or the valve spring 130 'can lift the valve member 124 ' from the valve seat 128 '. As a result, the valve cross section 138 'is open, and the air can give way to the vent line 90 '.

Fig. 7 shows a section of another modified lift axle valve block 26 ''.

The lift axle valve block 26 '' comprises a valve member 124 '' which, when the control line 69 is depressurized, rests on a valve seat 126 '' with the aid of a spring 130 '' and closes a valve cross section 138 ''. When the control pressure is present in the control line 69 '', the valve cross section 138 '' between the valve member 124 '' and the valve seat 126 '' is open, and the lines 62 '', 90 '' are connected to one another.

Depending on whether the valve cross section 138 'or 138 ''should be opened or closed at pressure in the control line 69 ' or 69 '', the embodiment according to FIG. 6 or FIG. 7 may be preferred.

When the power supply is switched off, the lifting axle 3 remains in the position in which it is currently located. This also applies to a power failure due to a defect.

It is with the type of lift axle actuation according to the invention possible at any time to use this as a starting aid.

By using spool valves (e.g. spool valve 101 ), valves with a small nominal size can be realized because the spool valves only have to perform pilot control tasks.

By combining seat and slide valves, you can choose the use of the solenoid valves as a pulse valve or - when starting help - as a continuously energized solenoid valve.

In FIG. 8, yet another type of he inventive air suspension system finally is exemplified.

The section of the air suspension system shown in FIG. 8 corresponds to the section of the air suspension system shown in FIG. 4, the lift axle valve block 26 being replaced by a modified lift axle valve block 47 .

The bellows 15 and 16 of the lifting axle 3 and the lifting bellows 17 associated lifting axle valve block 47 has three parallel solenoid valves 48 , 49 and 50 and three pressure-controlled main valves 51 , 52 and 53 . The main valves is connected upstream of a 51 and 53 between the operating as pilot valves solenoid valves 48 and 49 and the main valves 51, 53 arranged, common spool valve 54th The solenoid valves 48 , 49 , 50 correspond in their design and function to the solenoid valves 212 , 213 , 214 , and the main valves 51 , 52 , 53 also correspond in design and function to the corresponding main valves 312 , 313 , 314 .

The slide valve 54 is pressure actuated from its one (left) side, on its other side a spring 55 is arranged for resetting. On the side of the spring 55 there is also a lock 56 with a locking piston 57 which can be actuated on the one hand by compressed air and on the other hand by spring force. The slide valve 54 is designed as a 3/2-way valve.

The lift axle valve block 47 has, in addition to its connection for the lift axle line 62 leading to the air bellows 15 and 16 and for the lifting bellows 17 , a connection for the pressure supply line 87 containing the pre-pressure and a connection for the spring bellows 10 and 11 of the driven axis with the air 2 connecting connecting line 61 .

The solenoid valves 48 , 49 , 50 , like the solenoid valves 112 , 113 , 114, each have three connections and two switching positions 48 a, 49 a, 50 a and 48 b, 49 b, 50 b.

When the pulse solenoid valve 48 is briefly energized, it switches to its pressure position 48 b, in which it can reach a control pressure on the left side of the slide valve 54 via a control line 73 . As a result, the slide valve 54 switches from a first position 54 a shown symbolically in FIG. 8 to a second position 54 b likewise shown symbolically. In addition, in this second position 54 b, the latch 56 occurs in activity. Because of this switching, control pressure is then applied to the main valves 51 , 53 via a control line 71 leading from the slide valve 54 to the main valves 51 , 53 , and the main valve 51 is pressed into the ventilation position 51 b and the main valve 53 into its ventilation position 53 b . The bellows 17 is ventilated and the air bellows 15 and 16 of the lift axle 3 are vented. Lift axis 3 is raised. The fact that the slide valve 54 is locked, the solenoid valve 48 can be switched off again without the position of the lifting axle 3 changed, ie the lifting axle 3 remains raised. The control pressure in the control line 71 is maintained even after the end of the current pulse for the solenoid valve 48 .

To lower the lift axle 3 , the solenoid valve 49 is briefly energized. During energization, the solenoid valve 49 is in the pressure setting 49 b. As a result, the locking piston 57 is pressurized via a control line 74 , the lock 56 of the slide valve 54 is released, the control line 71 is relieved of pressure, the main valve 53 goes back into the working position 53 a and the main valve 51 is again under the force of a symbolically illustrated return spring back into its venting position 51 a. The bellows 17 is vented and the bellows 15 and 16 are pressurized ge. The lift axle 3 is lowered. During the current pulse, the main valve 52 switches briefly to the blocking position 52 b, which, however, since it is short, is not disturbing.

In order to trigger the start-up aid, the solenoid valve 50 is continuously energized. Characterized the main valve 53 is switched b via a control line 72 to control pressure in its venting position 53rd The air bellows 15 and 16 of the lift axle 3 are vented. As soon as the lift axle 3 is sufficiently relieved, the solenoid valve 49 is then also continuously energized to shut off the ventilation. This duration of current supply to the two solenoid valves 50 and 49 is, however, seen from the nature of a starting aid as a whole only of short duration, so that the resulting power consumption remains low. If the two solenoid valves 50 and 49 are then de-energized again after the start-up has been completed, all the valves assume the positions shown in FIG. 8 again.

Fig. 9 shows a detail of the lifting axles valve block 47.

In Fig. 9 a cross-section through the lift axle valve block 47 is shown, the cross-section of the vent line 88 extends in sections below the cross-section shown, which is why the vent line 88 is shown in dashed lines there. FIG. 9 shows the slide valve 54 in the first position 54 a according to FIG. 8.

The slide valve 54 has a valve body or control slide 148 slidably mounted in a bore 47 provided in the lift axle valve block. If the control slide 148 , as shown in FIG. 9, is shifted to the left, the control line 71 is connected to the vent line 88 , which corresponds to the first position 54 a. When the control slide 148 is on the right, the control line 71 is connected to the pressure supply line 87 , which corresponds to the second position 54 b.

The signal pressure in the control line 73 pushes the control slide 148 to the right. When the control slide 148 is shifted to the right, a spring 150 presses the locking piston 57 into a shoulder 152 which runs around the control slide 148 like a groove. As a result, the control slide 148 is held in its right position, even if the control line 73 is depressurized again when the current pulse supplied to the solenoid valve 48 has ended.

To return the control slide 148 to its left position, signal pressure in the control line 74 is briefly sufficient. As a result, the locking piston 57 is lifted off the shoulder 152 and the spring 55 can actuate the control slide 148 to the left.

As with the slide valve 101, the seals 134 can also be provided with the slide valve 54 , in order to seal the connections to one another better.

It should also be noted that the lift axis valve block 47 can be expanded by the check valve 81 shown in FIG. 2 and the make-up valve 25 , like the design according to FIG. 1. Likewise, a modification to separate control of the left and right vehicle side also possible in the exemplary embodiment shown in FIG. 8, as shown for the type according to FIG. 1 in FIG. 3. A combination of both expansions is possible for the type according to FIG. 8.

The advantage of the design according to FIG. 8 over that according to FIGS. 1 to 5 is that here only a single slide valve 54 is necessary instead of the two slider valves 101 , 102 and that the locking position of the slide valve 54 is stable. In addition, it is advantageous that only a single current pulse is required to lower the lifting axle 3 .

The main valves 51 , 53 , 312 , 313 can be switched from one switching position to the other switching position by short current pulses supplied to the respective solenoid valves 48 , 49 , 50 , 212 , 213 , 214 . It is also important to know that the Hauptven tile 51 , 52 , 53 , 312 , 313 , 314 are of their type valves that have a basic switching position and only then, while a control pressure acts on them, leave their basic switching position . As soon as the control pressure drops, the main valves 51 , 52 , 53 , 312 , 313 , 314 immediately fall back into their basic switching position. In the air suspension system proposed here, it is ensured that the control pressure acts on the main valves 51 , 53 , 312 , 313 until a new current pulse arrives in order to switch off the control pressure acting on the respective main valve 51 , 53 , 312 , 313 , so that the corresponding main valve 51 , 53 , 312 , 313 can fall back into its basic switching position.

While the main valves 51 , 53 , 312 , 313 remain in their desired switching position, no compressed air is consumed, but only a small amount during the changeover.

Since no compressed air and no electrical energy are required to keep the main valves 51 , 53 , 312 , 313 switched, it is also possible, for example, to keep the lift axle 3 raised for weeks when the vehicle is parked. Any small loss of compressed air due to leaks can be compensated for by pressure accumulators provided in the compressed air supply device 4 .

The exemplary embodiments described relate to a utility vehicle with three axles. However, the number of axes is arbitrary. The air suspension system can also be used on other vehicles, where there is a between an axle and a vehicle body Air bellows there. The proposed air suspension system is also in vehicles, e.g. B. a trailer with only a single axle and an air bellows applicable. Here is the air suspension system for example, be provided for the height of the vehicle body to keep at a set level for a long time without constantly electrical or pneumatic energy would have to be supplied.  

Depending on how and what is to be controlled, the air handling system comprises at least one valve device. The Ventileinrich device has, for example, a main valve with a single changeable valve cross section 138 'or 138 '', as shown in FIGS. 6 and 7, or the valve device has a main valve with, for example, two variable valve cross sections 136 , 138 , as in Fig. 5 shown. The position of the at least one valve body 132 , 148 determines the control pressure acting on the at least one valve member 122 , 124 , 124 ', 124 ''. The position of the valve body 132 , 148 can be adjusted with the aid of electrical means 48 , 49 , 112 , 113 , 114 . If the setting position is set, no further supply of electrical energy is required to hold this setting position of the valve body 132 , 148 . Set with the in FIG. 5 and to the in the Fig. Shifter shown as an example valve 101 9 and 54 can be seen in the control line 69 or 69 ', 69' ', 71 a control pressure. No energy is required to maintain the control pressure, ie in particular neither electrical nor pneumatic energy supply. With the control pressure in the control line 69 , 69 ', 69 '', 71 , a valve device with a Ven valve member 124 ' or 124 '', as shown in FIGS . 6 and 7 by way of example, or a valve device with two valve members 122 , 124 , as shown in FIG. 5 by way of example, who the. Without further energy supply, the at least one valve cross section 136 or 138 or 138 'or 138 ''can be held in the selected switching position, ie open or closed.

In the illustrated exemplary embodiments, the actuating position of the valve body 132 , 148 is set in that the electrical means comprise at least the control element 154 and / or the control element 156 , with which an actuating pressure can be controlled, the actuating pressure of the actuating position of the valve body 132 or 148 is adjustable. There is also the possibility that the electrical means comprise an electromagnet with a magnet coil and a magnet armature, the magnet armature being able to act directly mechanically on the valve body 132 , 148 without the interposition of a pneumatic signal pressure. However, it is also possible for the valve body 132 , 148 to be used as a magnet armature and to be acted upon directly by the magnet coil. Those skilled in the art can produce these simplified embodiments without the need for a pictorial representation. The pneumatic adjustment of the valve body pers 132 , 148 shown in the illustrated exemplary embodiment with the aid of the signal pressure has the advantage that the very simple, inexpensive solenoid valves 213 , 214 can be used.

In the present application, the movable valve parts of the main valves 312 , 313 , 314 as "valve members" 122 , 124 , 124 ', 124 '', the movable valve parts of the slide valves 101 , 102 as "valve bodies" 132 , 148 and the movable valve parts of the magnet valves 213 , 214 referred to as "control members" 154 , 156 . The pressure for adjusting the valve members 122 , 124 , 124 ', 124 ''is called "control pressure" and the pressure for adjusting the valve body 132 , 148 is called "signal pressure". The different designation of the valve parts and the pressures is only for easier reading and for a better understanding of the present application.

Claims (8)

1. Air suspension system for vehicles, with at least one air bellows ( 15 , 16 ) arranged between an axle ( 3 ) and a vehicle body of the vehicle, with a compressed air supply device, with at least one, at least one variable valve cross-section ( 136 , 138) connected to the at least one air bellows , 138 ′, 138 ′ ′) monitoring valve device ( 12 , 13 , 51 , 53 , 312 , 313 ), as well as with a control unit controlling the valve device, the valve device at least one valve member ( 122 , 124 , 124 ′, which can be actuated against a valve seat) 124 ''), the position of which determines the valve cross-section, and the position of the valve member being controllable by means of a control pressure, characterized in that an adjustable valve body ( 132 , 148 ) is provided, the position of which is set by means of electrical means ( 48 , 49 , 112 , 113 , 114 , 212 , 213 , 214 ) can be adjusted by supplying electrical energy d whose control position determines the control pressure, the control position of the valve body ( 132 , 148 ) being retained when the supply of electrical energy is ended. 2. Air suspension system according to claim 1, characterized in that the electrical means ( 48 , 49 , 112 , 113 , 114 , 212 , 213 , 214 ) at least comprise an electromagnetically actuated control member ( 154 , 156 ), with the aid of which one for setting the actuating pressure serving to control the position of the valve body ( 132 , 148 ). 3. Air suspension system according to claim 1 or 2, characterized in that at least one holding element ( 134 ) holding the valve body ( 132 , 148 ) is provided. 4. Air suspension system according to one of the preceding claims, characterized in that a locking ( 56 ) is provided which holds the valve body ( 132 , 148 ) in a specific setting position. 5. Air suspension system according to claim 4, characterized in that the lock ( 56 ) with the help of the electrical means ( 49 ) can be locked ent. 6. Air suspension system according to one of the preceding claims, characterized in that the vehicle comprises, in addition to said axis ( 3 ), at least one further axis ( 2 ), wherein said axis ( 3 ) can be lifted off a surface. 7. Air suspension system according to one of the preceding claims, characterized in that ventilation of the at least one air bellows ( 15 , 16 ) causes an increase in a distance between said axis ( 3 ) and the vehicle body. 8. Air suspension system according to claim 6, characterized in that said axis ( 3 ) can be lifted off the ground by venting the at least one air bellows ( 17 ).