Control valve for pneumatic conduits

A control valve for controlling a routing of a pressure medium in pneumatic conduits, especially those in motor vehicles, wherein the control valve includes a housing provided with a cylindrical recess and a control slide guided in the cylindrical recess in a longitudinally-displaceable fashion. A gasket or sealing arrangement is provided by means of which a central pneumatic conduit is alternatingly connected, after an operating stroke of the control slide, to a pneumatic conduit lying to the left and to the right of the central pneumatic conduit. The control valve further includes an operating sleeve longitudinally displaceable between two compression springs supported on the control slide and between two detent locations. The operating sleeve is arranged on the control slide in such a way that, upon operation of the operating sleeve, the control slide is braked as soon as sealing elements of the sealing arrangement abut against respective opposite valve seat surfaces. The operating sleeve during a further stroke, upon exceeding a specific resistance, is disengaged from one detent location and, upon further axial displacement, engages into the other detent location against the force or strength of one of the compression springs.

The present invention relates to a control arrangement, and, more 
particularly, to a control valve for controlling the path or routing of a 
pressure medium in a pneumatic conduit, especially pneumatic conduits of 
motor vehicles, which valve includes a housing provided with a cylindrical 
recess and a control slide longitudinally displaceably guided in the 
recess, with a sealing means being provided at the control slide for 
alternatingly connecting a central pneumatic conduit to a pneumatic 
conduit lying to the left and to the right of the central conduit after an 
execution of an operating stroke by the control slide. 
In German Pat. No. 2,444,357 a control valve for pneumatic conduits is 
proposed wherein radially-acting sealing lips slide along a wall of a 
cylindrical recess of the control valve. A disadvantage of this proposed 
construction resides in the fact that lubrication is required to ensure an 
operation of the control valve; however, by virtue of the use of 
lubrication, dirt particles are attracted and deposited between the 
housing and the sealing lips causing leaks. 
The aim underlying the present invention essentially resides in providing a 
control valve for pneumatically-operated devices wherein longitudinal 
changes in an operating linkage of the control valve have no effect on the 
sealing function of the control valve, and wherein short response times 
for the control valve can be maintained. 
In accordance with advantageous features of the present invention, an 
operating sleeve, displaceable longitudinally between two detent locations 
and between two compression springs, is supported on the control slide. 
The operating sleeve is arranged on the control slide in such a way that, 
upon operation of the operating sleeve by a control linkage, the control 
slide is braked as soon as the sealing elements abut against their 
respective opposite valve seat surfaces, and the operating sleeve, during 
its further stroke, upon exceeding a specific resistance, is disengaged 
from one detent location and, upon further axial displacement, engages 
into the other detent location against the force or strength of one of the 
compression springs. 
In accordance with further advantageous features of the present invention, 
a sealing or gasket arrangement includes two axially-acting sealing 
elements fixedly placed on the control slide with the sealing elements 
being displaceably arranged respectively between two mutually-opposed 
valve seat surfaces provided at a side of the housing of the control 
valve. 
Advantageously, in accordance with further features of the present 
invention, the housing is provided with a collar which projects into a 
cylindrical recess, which collar includes a central pneumatic conduit. A 
bore connected to the central pneumatic conduit and terminating in the 
recess is arranged in the collar. The valve seat surfaces for the 
respective sealing elements are located at the collar and opposed valve 
seat surfaces are formed by inserts attached within the recess of the 
housing of the control valve. 
In accordance with still further features of the present invention, each 
sealing element is composed of a firm elastic annular member and of a soft 
elastic sealing lip which projects from the annular member on both sides 
thereof. 
In accordance with still further features of the present invention, the 
control slide is provided with detent grooves and a spring is mounted in 
the operating sleeve, which spring is adapted to lockingly engage in one 
of the detent grooves in such a manner that the detent mechanism 
withstands the force of the compressed compression springs between the 
which the operating sleeve is disposed. 
Advantageously, according to the present invention, one of the ends of the 
compression spring is supported in recesses of the operating sleeve and 
the other ends are supported on supporting rings firmly connected to the 
control slide. 
Accordingly, it is an object of the present invention to provide a control 
valve arrangement for controlling the path or routing of a pressure medium 
in pneumatic conduits which avoids, by simple means, shortcomings and 
disadvantages encountered in the prior art. 
Another object of the present invention resides in providing a control 
valve arrangement for controlling a path or routing of a pressure medium 
in pneumatic conduits which does not require a lubrication of the sealing 
elements thereof. 
Yet another object of the present invention resides in providing a control 
valve arrangement for controlling a path or routing of the pressure medium 
in pnuematic conduits which is insensitive to dirt and almost relatively 
free of wear and tear. 
A further object of the present invention resides in providing a control 
valve arrangement for controlling a path or routing of a pressure medium 
in pneumatic conduits which utilizes long operating strokes but provides 
short switching paths thereby enabling brief response times of the control 
valve. 
A still further object of the present invention resides in providing a 
control valve arrangement for controlling a path or routing of a pressure 
medium in pneumatic conduits wherein a safe and reliable seal is ensured 
under all operating conditions. 
Yet another object of the present invention resides in providing a control 
valve arrangement for controlling a path or routing of a pressure medium 
in pneumatic conduits which is simple in construction and therefore 
relatively inexpensive to manufacture.

Referring now to the drawings wherein like reference numerals are used in 
both views to designate like parts and, more particularly, to FIG. 1, 
according to this figure, a control valve generally designated by the 
reference numeral 1 employed for, for example, controlling 
pneumatically-operated devices of a motor vehicle such as a central 
locking mechanism, includes a cylindrical housing 2 with three 
seriesarrangedconnections 3a, 4a, 5a, as viewed in the longitudinal 
direction, for accommodating pneumatic conduits 3, 4, 5 and a bolt-shaped 
slide 7 longitudinally displaceably guided in a cylindrical recess 6 of 
the housing 2. Annular sealing elements or gaskets generally designated by 
the reference numerals 8,9 are arranged on the control slide 7. 
Advantageously, the housing 2 of the control valve 1 and the connections 
3a, 4a, 5a are made in one piece from a synthetic resinous material. 
The housing 2 of the control valve 1 includes an internally-disposed collar 
12 forming two planar valve seat surfaces 10,11 cooperable with the 
annular sealing elements 8,9. A passage bore 15 is arranged in the collar 
12 and extends from the central connection 4a and serves to communicate 
the central connection 4a with either an annular chamber 13 or an annular 
chamber 14 in dependence upon a position of the control slide 7. Both 
annular chambers 13,14 are defined by an insert generally designated by 
the reference numeral 16 and an insert 17 which form planar valve seats 
18,19, respectively opposed to the valve seats 10,11, and cooperable with 
the annular sealing elements 8,9. The insert 17 is of a disk-shape and is 
sealing arranged in the cylindrical recess 6 by either being clipped into 
a recess in an inner wall of the cylindrical recess 6 or by being welded 
to the wall of the recess 6. The insert 16 is formed of a bushing 20 
provided with a collar portion 21 which serves as an abutment. 
Advantageously, the insert 16 is welded to the inner wall of the recess 6 
and/or to the housing 2 of the control valve 1. 
The annular sealing elements 8,9, constructed as ribs, include a central 
hard elastic ring member or portion 24,25 adapted to lie in grooves 22,23 
of the control slide 7 and soft elastic sealing lips 26,27 and 28,29 which 
respectively project laterally from the ring portions 24,25. The sealing 
lips 26,28 respectively sealingly contact the valve seat surfaces 11,18 
under tension in the manner illustrated in FIG. 1 so that the 
centrally-mounted conduit is connected to the conduit 3 lying to the right 
thereof. 
An operating sleeve 32, lying between two compression springs 30,31, is 
arranged on a part of the control slide 7 projecting from the housing 2 of 
the control valve 1. The operating sleeve 32 is displaceably supported 
between two detent grooves 33,34 on the control slide 7 which grooves 
33,34 serve to define detent locations or end points of the displacement 
path of the operating slide 32. A spring 35 is locked in the detent groove 
34 and is clamped into an annular groove 36 (FIG. 2) of the operating 
sleeve 32. In addition to the groove 36, a trough-shaped indentation 37 is 
provided in the operating sleeve 32 to accommodate a stroke of the spring 
35. 
The compression spring 30 is supported on a supporting ring 38 arranged at 
an end side of the control slide 7 and the compression spring 31 is 
supported on a supporting ring 39 located approximately at a longitudinal 
center of the control slide 7. 
In use, the housing 2 of the control valve 1 is fixedly mounted at a 
portion of the vehicle with an operating linkage (not shown) being adapted 
to engage the operating sleeve 32 at an articulating point 40. 
To eliminate a connection or communication of the pneumatic conduit 4 to 
the conduit 3, and to connect the conduit 4 to the conduit 5, the 
operating sleeve 32 is shifted by the operating linkage. After an 
operating stroke distance x is traversed, the sealing lips 27,29 
respectively come into contact with the valve seat surfaces 10,19. The 
operating sleeve is advanced uniformly by the operating linkage; whereas, 
the control slide 7 is braked by virtue of the cooperation between the 
annular sealing elements 8,9 and the sealing surfaces 10,19. After 
exceeding a certain resistance caused by the sealing elements 8,9, the 
operating sleeve 32 is disengaged and shifted against the force of the 
compression spring 30 until the spring 35 associated with the operating 
sleeve 32 engages the detent groove 33. The strength of the detent 
mechanism, i.e., spring 35 and detent groove 33, is so great that it 
withstands the force of a compressed compression spring 30. 
The compression springs 30,31 serve the task of ensuring the contacting of 
the annular sealing elements 8,9 against the respective valve seat 
surfaces during a displacement of the operating sleeve 32 from one detent 
location to the other, i.e., from the groove 34 to the groove 33. 
The arrangement of the compression springs 30,31 as well as the detent 
locations defined by the grooves 33,34 provides long operating strokes but 
short switching paths thereby enabling brief response times for the 
control valve 1 since, upon an operation of the operating sleeve 32, the 
operating sleeve 32 effects a switching over of the control valve after 
traversing a stroke corresponding to the functional stroke distance x 
which takes places prior to a displacement over the complete operating 
stroke distance y. 
While we have shown and described only one embodiment in accordance with 
the present invention, it is to be understood that the invention is not 
limited thereto but is susceptible of numerous changes and modifications 
as are obvious to those of ordinary skill in the art, and we therefore do 
not wish to be limited to the details shown and described herein but 
intend to cover all such changes and modifications as known to one skilled 
in the art.