Fluid handling – Convertible
Reexamination Certificate
1998-03-16
2001-08-07
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Convertible
C137S596170, C137S625650, C137S884000, C251S129160
Reexamination Certificate
active
06269834
ABSTRACT:
PRIOR ART
The invention is based on an electromagnetically actuatable pneumatic directional control valve.
Directional control valves of this kind are used in utility vehicles for actuating pneumatic auxiliary units, such as differential locks, actuation of the engine brake, transmission control, luggage compartment flap actuation in busses, etc. from the driver's cab. The directional control valves are most often combined into a so-called valve block which is connected to a compressed air supply line. The number of valves in a valve block is determined by the number of pneumatic auxiliary units to be connected.
The directional control valves are embodied as both electromagnetically, directly actuated valves and electromagnetically pilot-controlled valves. In the latter, a pneumatically actuated main valve is switched by an electromagnetically actuated pilot-control valve. It is standard to use both types of valve in the same vehicle.
In a known directional control valve of the type mentioned at the beginning (U.S. Pat. No. 4,524,797), the supply conduit leading to the compressed air network connection and the ventilation conduit leading to the vent are disposed flush with each other in a valve housing and at right angles to the working conduit leading from the working connection. The magnet coil of the electromagnet rests coaxially on a cylindrical housing part of the valve housing, which housing part contains the supply conduit. The cylindrical armature of the electromagnet is guided so that it can move axially on the inside of the housing and constitutes the valve member, which rests alternatingly on one of the two valve seats, which are embodied at the conduit mouths of the supply conduit and the ventilation conduit. Depending on the position of the valve member, the working conduit is connected to the ventilation conduit or the supply conduit. For the purpose of fastening the directional control valve to a carrier plate in the motor vehicle, pins protrude from the valve housing, which extend at right angles to the supply conduit. When combining a number of valves into a valve block, the valves are attached to the carrier plate next to one another in a parallel alignment of the supply conduits and the compressed air network connections of the individual valves are connected to one another by means of individual plug adapters. The plug adapters are plugged into one another and are respectively slid onto the compressed air network connection on the valve housing. The first plug adapter carries a connection fitting for the compressed air supply line; the last plug adapter is closed off at the end by means of a stopper.
ADVANTAGES OF THE INVENTION
The directional control valve according to the invention, has the advantage that by means of the division into the valve housing and the connecting plate with the corresponding arrangement of the connection fittings and connecting conduits as well as the embodiment of the connecting means on the connecting plate, not only is a modular building-block system achieved for constituting the two necessary types of valves out of largely equivalent elements, but it is also possible to combine the valves into a valve block in an essentially simpler and more efficient manner. The connecting plates of a number of valves connected to the valve housing are simply placed against one another, wherein the connection fitting of the compressed air network connection of the one valve is plugged into the connecting bore of the compressed air connection of the neighboring valve, and they are then connected to each other with positive engagement via the connecting elements. The assembly process takes place without tools in an extremely short time. Separate connecting means, such as the plug adapters in the known directional control valve are no longer necessary. Tolerance problems do not occur due to the radially sealing O-rings between the connection fitting and connecting bore. The O-rings are pre-installed and lie protected in the connecting bores of the compressed air network connection. The disassembly of the valve block is carried out by means of a flat object, with the aid of which the connecting means are released, which are preferably embodied as detent mechanisms. As a result of the extremely low assembly and disassembly time, a considerable cost reduction is produced both in manufacturing and in servicing procedures.
The modular building-block system that can be constituted with the directional control valve according to the invention includes a uniform valve housing and two different embodiments of connecting plates as well as a closure element for closing the connecting bores of the compressed air network connection. The two connecting plate variants are embodied identically on the outside, i.e. they have the same connection fittings and connection bores of the compressed air network connection as well as the same connection means. Only the inside of the connecting plate is changed in so far as a purely conduit device is integrated into the connecting plate for directly connected valves, and in addition to the conduit embodiment, a pneumatically actuated seat valve is integrated into the connecting plate for pilot-controlled valves. As a result of the thus far equivalent embodiment of the connecting plates, different valve types can be combined into one valve block as needed without causing problems.
Advantageous embodiments and improvements of the electromagnetically actuatable directional control valve are possible by means of the measures taken in the remaining claims.
According to a preferred embodiment of the invention, a stepped plug-in fitting with two coaxial fitting sections of different diameters is embodied on the bottom of the valve housing and a stepped plug-in bore with two coaxial bore sections of different diameters is embodied on the top of the connecting plate. The plug-in fitting can be plugged into the plug-in bore in a sealed fashion with the interposition of a radially sealing O-ring between each fitting and bore section. The supply conduit feeds into the circular end face of the smaller diameter fitting section and the working conduit feeds into the annular end face of the larger diameter fitting section. The smaller diameter bore section of the plug-in bore is connected to a connecting conduit which joins the connection fitting to the connecting bore of the compressed air network connection in the connecting plate. The connecting plate is embodied for a directional control valve that is directly actuated by the electromagnet, so that the larger diameter bore section of the plug-in bore communicates with the working connection and is embodied for a pneumatically actuated valve that is pilot-controlled by the electromagnet, so that the larger diameter bore section of the plug-in bore feeds into a connecting conduit which can communicate via a control conduit with a work chamber of a seat valve, which chamber is defined by an advancing piston. Via a valve tappet, the advancing piston actuates a valve plate which opens or closes a valve opening. The valve opening joins the working connection on the connecting plate to the connecting conduit between the connection fitting and the connecting bore of the compressed air network connection in the connecting plate.
According to a preferred embodiment of the invention, the housing and the connecting plate can be connected to each other in detent fashion, for which purpose detent openings are provided, along with detent projections that can snap into them. The detent projections are preferably disposed protruding radially on the circumference of the valve housing and the detent openings are disposed on the connecting plate. By means of this detent connection, it is very simple to mount the individual valve, wherein there are no tolerance problems thanks to the radially sealing O-rings between the plug-in fitting of the valve housing and the plug-in bore in the connecting plate. The O-rings are pre-installed in a protected fashion and do not require any special handling durin
Bastianelli John
Greigg Edwin E.
Greigg Ronald E.
Hepperle Stephen M.
Knorr-Bremse
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