TECHNICAL FIELD

The invention relates to a suspension control valve arrangement for use in a pneumatic suspension system of a commercial vehicle. Furthermore, the invention relates to a pneumatic suspension system of a commercial vehicle and a commercial vehicle comprising such a pneumatic suspension system.

BACKGROUND

Pneumatic suspension systems in commercial vehicles in general comprise air bellows at the vehicle axles, in particular one air bellows at each wheel, in order to adjust the axle height and the damping characteristics, in particularly in dependence of a load measurement or height measurement. The suspension system in general comprises a suspension valve arrangement with three valve positions for enabling the following operation modes: A supply mode for supplying the air bellows with air for lifting the axle, an exhaust mode for exhausting or venting the air bellows for lowering the axle and a blocking mode for blocking the air in the bellows for keeping the stored air volume constant. Thus a suspension valve arrangement or levelling valve arrangement for a height control of an axle can be realised with a 3/3-way valve comprising a supply position, an exhaust position and a blocking position.

EP 556 086 B1 and EP 1 310 388 B1 disclose suspension valve systems with plate-like valve elements, which can be realised by ceramic plates. Two plate-like elements comprise conduits, grooves and holes and can be rotatably displaced with respect to one another for forming different air passages in different rotation positions. The ceramic plates are biased against each other by a spring and can be in contact without further sealing elements, thereby enabling a displacement via a manually operable handle, e.g. a lever, by the operator with low resistance.

However, the air flow realisable by such a valve design is limited. Such a limitation of the flow is helpful for adjusting specific height levels; however, in some situations a quick venting or quick exhausting of the air bellows is desired.

DE 37 16 436 C2 and DE 43 29 432 C1 disclose levelling valves with height limitation and an additional pneumatic valve for a quick release or quick venting of the air bellows. However, the additional hardware needed leads to higher costs and additional plumbing.

SUMMARY

A goal of the invention is to realise a suspension control valve arrangement which can be made with little effort and high reliability.

The present disclosure introduces a suspension control valve arrangement, a pneumatic suspension system comprising this suspension control valve arrangement and a commercial vehicle with such a pneumatic suspension system.

According to the invention a service valve arrangement is provided for realising a normal operation status configured for selecting one the three normal operation modes of air supply, air blocking and exhausting; further a dump-control device is provided to allow switching between the normal operation status and a quick-dump mode, in which the service valve arrangement is bypassed, thereby enabling a quick exhaust or a quick dump with a higher exhaust volume rate.

The service valve arrangement is switchable into three valve positions, i.e. a supply position, a blocking position and a normal exhaust position, in which valve positions the ports of the housing—the supply port, delivery port and exhaust port—are interconnectable with each other in order to realise the three normal operation modes. In the quick-dump mode, however, the delivery port is connected with the exhaust port without limitation by the valve channels or valve conduits, thereby allowing higher exhaust volume rates.

According to a preferred embodiment, the dump-control device is realised by a displaceable control piston, which is in particular linearly displaceable between two positions. In this case, the control piston is employed in connection with an “ordinary” service valve, that is, a service valve without a dump-control device, to provide the service valve arrangement. Especially, the displaceable control piston may be employed in connection with a standard, prior-art, possibly readily available service valve. The piston can be slidably provided in e.g. a sleeve inserted into the housing, wherein a space between a circumferential piston surface and the housing or the sleeve is separated into two or more piston chambers. This separation can be realised by e.g. a sealing means provided in an axial direction between the piston chambers. The piston chambers connect the valve ports of the ordinary service valve; thus the displacement of the control piston results in a displacement of the piston chambers with respect to the valve ports of the service valve, thereby blocking the service valve in the quick-dump mode. Furthermore, in the quick-dump mode an exhaust air passage between the exhaust port and the delivery port of the housing is unblocked or released, thereby bypassing the blocked service valve. The exhaust air passage in the housing for this quick-dump mode is preferably designed with a higher cross-section than the internal valve passages.

Thus a first piston chamber around the control piston is preferably part of the internal valve passages of the service valve arrangement, in particular part of an internal valve delivery channel, and a displacement of the control piston and its sealing means thus blocks a connection between the valve delivery port and either the valve supply port or the valve exhaust port.

The design with an ordinary service valve and the control piston for switching between a normal operation status and a quick-dump mode offers several advantages, in particular a compact design, wherein the additional hardware for the control piston is relatively small. Furthermore, such a control piston enables a high reliability and an easy operability, in particular a manual operability. In particular, the integration of a piston chamber into the internal valve passages is advantageous.

The service valve arrangement can, in particular, be realised by plate-like valve parts, in particular ceramic plates, being pressed against each other and comprising channels, grooves and/or through-holes, thereby forming the internal valve passages. By rotating the valve parts with respect to each other, these through-holes, grooves and/or channels are brought into different connection positions, thereby realising the different valve positions or valve functions of the ordinary service valve. Valve arrangements with rotatable plate-like valve parts, which form internal valve passages for different valve positions of e.g. a 3/3-way valve, are in general known from e.g. EP 1 310 388 B1 and EP 556 086 B1; however, according to the invention the internal valve passages preferably include a piston chamber formed by the displaceable control piston, in order to realise a blocking of the service valve in the quick-dump mode.

In particular, the inventive combination of piston chambers formed by a control piston with a plate-valve arrangement of two plate-like elements comprising through-holes and conduits enables a compact and reliable design in a common housing. Preferably, the housing comprises an elongated part for the control piston arrangement, e.g. with the control piston, the sleeve for guiding the control piston and a biasing spring. The service valve preferably comprises a rotation axis which is perpendicular to the symmetry axis and displacement axis of the control piston. The plate-like elements are preferably provided adjacent to the piston chamber surrounding the control piston. Thus, a compact design with a common housing is provided. Advantageously, a lid for covering the service valve and bearing the valve shaft is fixed to the housing.

The actuation of the service valve arrangement can preferably be realised by a manually operable device, i.e. a handle, in particular a lever, for rotating an operation shaft provided between the lever and the rotatable valve plate. Thus, the operator can turn the lever with little effort. The dump control can be realised either manually, in particular with a push button or another manually operable actuation means, or with an auxiliary force. As an auxiliary force, a pneumatic port for receiving a pneumatic control signal can be implemented, in particular for displacing the control piston against its bias spring.

The suspension control valve arrangement is in particular provided for a dumping function of both air bellows of a vehicle axle, in particular a rear axle of the vehicle. Thus the axle can be lowered very quickly, for example for releasing a trailer, which is fixed to the coupling heads provided at the rear side of the commercial vehicle.

According to a preferred embodiment, the two delivery ports for the two air bellows are connected with each other within the housing. In order to avoid an asymmetric filling of the air bellows, a throttle can be provided between the supply port and the delivery connection of the delivery ports. Such a throttle is preferably provided in the first piston chamber, which realises the air passage or air connection between the supply valve port and the delivery valve port. Thus an asymmetric hardware design is possible, in which the valve supply port, e.g. a passage or through-hole in the ceramic plates facing the piston chamber, is provided at e.g. a top side of the piston chamber and the delivery ports in the housing are positioned with different distances to this valve supply port. The provision of a throttle helps to equalise the supply air stream and pressure from the supply valve port before it reaches the delivery ports; furthermore, the normal exhaust stream from the delivery ports to the common exhaust can be equalized by this throttle or another throttle.

The throttle can in particular be provided in the first piston chamber connecting the valve ports or at the valve plates; hereby the exhaust air passage of the dump function is not affected by this throttle function, since the aim of the dump function is to realise a quick dump or quick release, in particular for a complete air release of the air bellows, wherein an asymmetric release is not problematic for such a quick-dump function.

Thus, the invention enables a compact design, in particular with a housing which can be made as a metal diecast, with additional equipment like a lid, for covering and bearing the lever arrangement, and a cap or end cover for securing the piston arrangement.

The invention is hereinafter described in detail with reference to the appended drawings. The drawings are provided herewith for purely illustrative purposes and are not intended to limit the scope of the present invention.

