Valve arrangement for operator actuated delivery of a pressure medium

A valve arrangement includes a pressure medium inlet chamber, a pressure medium outlet chamber connected to a consumer, for example, a brake cylinder, and a pressure medium exhaust leading to a pressure medium sink. The pressure medium inlet chamber is connected to a pressure medium source. The pressure medium outlet chamber can be connected by operation of a controllable inlet valve to the pressure medium inlet chamber and by a controllable exhaust valve to a pressure medium sink. The actuating force requirement is small because the pressure force on the active surface of the graduating piston is absorbed by the regulating spring. As a result, the actuating force requirement of such arrangement is very low by comparison with the actuating force requirement of heretofore known arrangements. This feature permits facilitated selection of an actuating force requirement by placement of a spring which acts in opposition to an operating element of the arrangement. The invention finds particular significance in applications directed to vehicle braking systems.

BACKGROUND OF THE INVENTION 
The present invention relates to a valve arrangement for use with a valve 
system regulating delivery of a pressure medium, and more particularly, an 
arrangement for controlling operator-actuated delivery of a compressed 
medium to one or more consumers. 
A known pressure medium regulating valve arrangement, in which a pedal 
serves as an operating element, is disclosed, for example, in the WABCO 
Westinghouse publication "Motorwagen-Bremsventil (motor car brake valve) 
461 106 Page 1," August 1973 edition. In the arrangement described 
therein, a regulating spring in the form of an elastomer spring is located 
between a graduating piston and a ram. An outlet valve seat in this valve 
system is installed on the graduating piston and an inlet valve seat on 
the housing of the valve system. As a result, the pressure supplied by the 
valve system produces a force, hereinafter referred to as the "pressure 
force", which is exerted via the ram upon the operating element when the 
arrangement is actuated. In order to maintain actuation of the system, the 
operator must exert an actuating force in opposition to the pressure force 
(and negligible spring return forces), the magnitude of which depends on 
lever ratios between the operating element and the valve system, in 
addition to the pressure force. This means that for a given lever ratio, 
the actuating force is a function of the delivered pressure. The evolution 
of the actuating force as a function of the delivered pressure is referred 
to herein as the "actuating force requirement." 
Often, an application requires a change in the above mentioned lever 
ratios, for example due to a change of the length of the operating 
element, while nevertheless requiring that a value of the actuation force 
requirement be maintained. Conversely, there are applications requiring a 
change in the actuation force requirement while the lever ratios remain 
unchanged. Such applications occur, in particular, when the installed 
actuating element is separated from the valve system, as is provided, for 
example, in the WABCO Westinghouse publication "Motorwagen-Bremsventil 
(Motor Car Brake Valve) 461 295," August 1973 edition. A comparable system 
is also disclosed in FIG. 4 on page 6 of the Clayton Dewandre Air Pressure 
Equipment Brochure "E, E-1, E-2, & DUAL E BRAKE VALVES." In such cases it, 
is not possible to properly adapt the system without changing the diameter 
of the graduating piston, and therefore not without requiring associated 
additional changes in the valve system. These changes, which require a 
redesign of the valve system, result in high development costs. 
Furthermore, the increased number of versions necessitated by such changes 
contribute to increased manufacturing, material and storage costs, among 
others drawbacks. 
It is therefore the object of the present invention to develop an 
arrangement of the type mentioned above which permits the actuation force 
requirement thereof to be adapted to various applications with little or 
no changes in the valve system. 
SUMMARY OF THE INVENTION 
Briefly stated, a valve arrangement is provided for delivery of pressure 
from a pressure supply and which includes a valve system actuated by 
actuating force applied to a movable operating element. The valve system 
of such arrangement includes a housing containing a supply chamber 
connected to the pressure supply, an operating chamber connected to at 
least one consumer, such as a brake cylinder, and a pressure relief 
outlet. A graduating piston which is subjected to a pressure in the 
operating chamber is provided. An inlet valve seat is carried on the 
graduating piston, which together with a sliding valve element forms an 
inlet valve, the inlet valve being operative to control communication 
between the supply chamber and the operating chamber. An outlet valve seat 
is carried on a ram, which together with the sliding valve element forms 
an outlet valve, the outlet valve being operative to control communication 
between the operating chamber and the pressure relief outlet. The ram is 
responsive to actuating movement of the operating element for controlling 
displacement of the sliding valve element, the ram being movable at least 
into a closing direction of the outlet valve and into an opening direction 
of the inlet valve. A regulating spring is held between the graduating 
piston and the housing for biasing the graduating piston against the 
pressure force. 
Arrangements of the general type mentioned above are employed in all 
technical areas in which pressure-actuated controls are used, in 
particular, controls operated with pressurized gas. Where compressed air 
is the pressurized gas, the pressure relief output for the operated system 
generally exhausts to the atmosphere. When other gases are used, the 
pressure relief output is generally connected to a collection container 
under atmospheric pressure. Vehicle braking systems actuated by compressed 
air represent a significant area of application for embodiment of the 
invention. 
The above, and other objects, features and advantages of the present 
invention will become apparent from the following description read in 
conjunction with the accompanying drawings, in which like reference 
numerals designate the same elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the figures, and in particular FIG. 1, a valve arrangement 
in accordance with an embodiment of the invention is shown, the valve 
arrangement including a valve system 25 and an operating element 10, each 
mounted in a suitable and conventional manner on a bearing element 5, 6. 
Although conveniently depicted in the form of a pedal, operating element 
10 may alternatively be provided in various other suitable forms providing 
analogous function without departure from the invention. Valve system 25 
is mounted in a fixed position, while operating element 10 is mounted for 
pivotable rotation about a bearing shaft 7. Alternative to use of bearing 
shaft 7, a bearing axle may be instead provided. Bearing element 5, 6 
includes a bearing block 6 on which bearing shaft 7 is rotatably received. 
In a non-actuated state, operating element 10 is biased in a rest position 
against a stop carried on bearing block 6. In automotive applications, 
bearing element 5, 6 is generally comprised of a part of the floor of a 
driver's cab or a front wall thereof. 
Valve system 25 is provided with a housing 26 which includes a supply port 
19, a delivery port 2 and a pressure relief outlet 28. Supply port 19 is 
connected to a pressure supply 20, and delivery port 2 is connected to a 
consumer 1, such as for example, a brake cylinder. Consumer 1, depicted as 
one cylinder, may also represent several consumers. In the depicted 
embodiment, pressure relief outlet 28 exhausts to the atmosphere, an 
indication that the depicted embodiment of the example of FIG. 1 is thus 
designed for operation with compressed air as the pressure medium. 
A longitudinally displaceable graduating piston 30 is movably received in 
housing 26. Graduating piston 30 is provided on its longitudinal extension 
with two sealing elements 17, 23 spaced apart a distance from each other 
and disposed circumferentially about graduating piston 30. Sealing 
elements 17, 23 are placed in such manner, and their distance from each 
other is selected such that the outlet of supply port 19 within housing 26 
is inevitably located between sealing elements 17, 23 for any possible 
position of graduating piston 30 when actuated. As a result, a region 
bounded by sealing elements 17, 23, the outer circumferential wall of 
graduating piston 30 and the inner walls of housing 26 defines a first 
supply sub-chamber 22. 
Graduating piston 30 is comprised of hollow structure, and includes a 
cavity, a portion of which constitutes a second supply sub-chamber 32 
connected to first supply sub-chamber 22 via a passage 18. Although shown 
as a single passage, passage 18 may instead take the form of several 
passages. The two supply sub-chambers 22 and 32 together constitute a 
supply chamber 22, 32. 
An operating chamber 16 within housing 26 is connected to delivery port 2, 
and separated from supply chamber 22, 32, in particular, first supply 
sub-chamber 22, by sealing element 17 of graduating piston 30 located 
closest to operating element 10. A face of graduating piston 30 directed 
towards operating chamber 16 is always subjected to the pressure in 
operating chamber 16 and is an active surface 3 of graduating piston 30. A 
passage formed in graduating piston 30 extends from active surface 3 to 
second supply sub-chamber 32. An inlet valve seat 33 is formed on 
graduating piston 30 around this passage, within second supply sub-chamber 
32. 
The other sealing element 23 of graduating piston 30 separates supply 
chamber 22, 32, in particular, the first supply sub-chamber (22), from a 
pressure relief chamber 29 connected to the pressure relief outlet 28. 
Graduating piston 30 is biased by a regulating spring 24 in a direction 
opposite to the direction of the pressure acting upon active surface 3. In 
the depicted example, regulating spring 24 is located within the pressure 
relief chamber 29 between an area of the graduating piston 30 away from 
the active surface 3 and wall of housing 26 delimiting pressure relief 
chamber 29. It is noted, however, that regulating spring 24 may also be 
installed in any other suitable manner providing analogous function. 
Graduating piston 30 is also provided with a further passage at an end 
thereof directed towards pressure relief chamber 29, and thereby also 
towards pressure relief outlet 28. A valve element 21, starting at inlet 
valve seat 33, extends the distance of second supply sub-chamber 32, 
located in the cavity of graduating piston 30 and the further passage. 
Valve element 21 is provided with a passage, designated as a pressure 
relief channel 27, having an opening on one side thereof within inlet 
valve seat 33 of graduating piston 30, and on a remaining side towards 
pressure relief chamber 29. Valve element 21 is slidable relative to 
graduating piston 30 and the passage formed therein in a sealed manner. 
Valve element 21 thereby separates pressure relief chamber 29 from second 
supply sub-chamber 32 and, hence, also from supply chamber 22, 32. 
The ability of the valve element 21 to slide relative to graduating piston 
30 in the direction of operating chamber 16 is limited by the impact of 
valve element 21 upon the surrounding inlet valve seat 33 formed on the 
graduating piston 30. Inlet valve seat 33, together with a surface or edge 
of valve element 21 having a form complementary thereto, constitute an 
inlet valve 21, 33 which controls the connection between supply chamber 
22, 32, in particular, second supply sub-chamber 32, and operating chamber 
16. 
A closing spring 31 is held between valve element 21 and an inner wall of 
second supply sub-chamber 32, biasing valve element 21 in the direction of 
inlet valve seat 33, and thereby in the closing direction of inlet valve 
21, 33. Closing spring 31 assists in the secure closing of inlet valve 21, 
33, in particular, in the presence of low supply pressure. 
A ram 14 extending from an end of housing 26 proximal to operating element 
10 extends into operating chamber 16. Ram 14 is movably displaceable in a 
sealed manner in housing 26 towards valve element 21 and in a direction 
opposite thereto. An end of ram 14 directed towards graduating piston 30 
is sized to allow it to penetrate the passage of graduating piston 30 
surrounded by inlet valve seat 33 between active surface 3 and the second 
supply sub-chamber 32. A circumferential outlet valve seat 15 is provided 
at this end of ram 14. Outlet valve seat 15 is sized so that it delimits 
the outlet of pressure relief channel 27 extending through valve element 
21 on the end thereof directed towards outlet valve seat 15. Outlet valve 
seat 15, together with a surface or edge of valve element 21 having a form 
complementary thereto, constitutes an outlet valve 15, 21 which controls 
the connection between operating chamber 16 and, pressure relief chamber 
29 via pressure relief channel 27, and also therefore pressure relief 
outlet 28 and atmosphere. 
A transmission element 8 is located between ram 14 and operating element 
10, connected to each in a known manner permitting transmission element 8 
to transmit a stroke caused by a rotation of operating element 10 in the 
direction of valve system 25 to the ram 14. A stroke in this direction is 
in the closing direction of outlet valve 15, 21, and at the same time the 
opening direction of inlet valve 21, 33. A connection for producing 
slidable action in an opposite direction is also possible. 
In accordance with a further development of the basic embodiment described 
above, a spring 11 biases operating element 10 in the direction of its 
rest position, as will be discussed in further detail below. 
FIG. 1 shows the arrangement in accordance with the invention in rest 
position. In this state, ram 14, graduating piston 30 and valve element 21 
assume positions in which outlet valve seat 15 is lifted by an opening 
stroke of outlet valve 15,21 from valve element 21. As a result, outlet 
valve 15, 21 is open, and operating chamber 16, as well as consumer 1, is 
connected via pressure relief channel 27, pressure relief chamber 29 and 
pressure relief outlet 28 to the atmosphere. 
To ensure that outlet valve 15, 21 is normally maintained securely in an 
open position, one or several recuperating springs can optionally be 
installed in a known manner on ram 14 and/or on operating element 10. 
Actuation of the system is achieved by rotating operating element 10 in the 
direction of valve system 25. After covering a clearance distance which 
may exist between operating element 10 and the transmission element 8 
and/or ram 14, transmission element 8 transmits the stroke which 
corresponds to a further rotation of operating element 10 to ram 14. As a 
result of the imparted stroke, outlet valve seat 15 comes to rest on valve 
element 21 and thereby closes outlet valve 15, 21 once the opening stroke 
of outlet valve 15, 21 has been covered. As the stroke continues, ram 14 
lifts valve element 21 from inlet valve seat 33 against the force of 
closing spring 31 and/or against a possible force exerted by the supply 
pressure upon valve element 21, thereby opening inlet valve 21, 33. A 
force exerted by the supply pressure on valve element 21 occurs when the 
surfaces surrounded by inlet valve seat 33 and by the seal of valve 
element 21 in the passage of graduating piston 30 are of different size. 
As a rule, such a force is intentionally avoided by appropriate sizing of 
these surfaces. 
When inlet valve 21, 33 is open, compressed air is permitted to flow from 
supply chamber 22, 32 into operating chamber 16, and from operating 
chamber 16 through the delivery port 2 into consumer 1. The pressure which 
then builds up in operating chamber 16 and in consumer 1 also acts upon 
active surface 3 of graduating piston 30, exerting a force thereupon. As a 
result, graduating piston 30 moves into the pressure relief chamber 29, 
compressing regulating spring 24. If the compression of regulating spring 
24, and thereby the distance covered by graduating piston 30, is as great 
as the previously applied stroke of valve element 21, the inlet valve seat 
33 comes again into resting contact with valve element 21 and thereby 
again closes inlet valve 21, 33. In this position now reached, termed 
herein the "end position," outlet valve 15, 21, as well as inlet valve 21, 
33 are closed, so that no flow from pressure supply 20 to consumer 1 may 
occur. 
A reverse actuation of the arrangement is effected by a corresponding back 
stroke of ram 14. Outlet valve seat 15 is then lifted from valve element 
21, and opens outlet valve 15, 21. Compressed air from operating chamber 
16 and consumer 1 can now be exhausted through pressure relief channel 27, 
pressure relief chamber 29 and pressure relief outlet 28 to the 
atmosphere. Due to the resultant pressure drop in operating chamber 16, 
regulating spring 24 is released, urging graduating piston 30 back towards 
its initial position. If the back stroke of ram 14 were to consist of only 
a partial back stroke, the back shift of graduating piston 30 ends again 
in an end position when valve element 21 is again seated on outlet valve 
seat 15 to close outlet valve 15, 21. If the back stroke of ram 14 were to 
consist of a complete back stroke, outlet valve 15, 21 remains open even 
after graduating piston 30 has been pushed back into its initial starting 
position, so that a complete pressure relief of operating chamber 16 and 
of the consumer 1 takes place. 
During the functions described above, the force of the pressure in 
operating chamber 16 exerted on active surface 3 of graduating piston 30 
is always absorbed by regulating spring 24. In the end positions, the 
force exerted on active surface 3 and the force of regulating spring 24 
are balanced. During the entire procedure, ram 14 need only overcome the 
force of closing spring 31 and/or possibly the force of the supply 
pressure on valve element 21. 
A back stroke of ram 14 is triggered either by turning back or releasing 
operating element 10, depending on the design of the particular 
arrangement. Where operating element 10 is turned back, ram 14 can be 
retracted with a suitable design of the angular connections between ram 
14, transmission element 8, and operating element 10, and/or can follow 
the return rotation under the influence of a return setting force. In case 
of release of operating element 10, the return setting force exerted upon 
the ram 14 can also cause the return rotation of the operating element 10 
and/or assist a return spring of operating element 10. Such return setting 
force can be produced, for example, by a return spring acting upon ram 14 
or by making the surfaces surrounded by seal 13 of ram 14 in housing 26 
larger than the surface surrounded by outlet valve seat 15. 
The actuating force which the operator must apply on operating element 10 
during the described functions depends, in addition to one or more 
possibly present return springs, on the negligible forces of closing 
spring 31 and of the supply pressure exerted upon valve element 21 and on 
the possible return setting force exerted upon ram 14. 
Whatever means are ultimately used to effect a return stroke or a return 
rotation of ram 14 and of operating element 10, the necessary actuating 
force applied to operating element 10 to overcome these influences is very 
low by comparison with the actuating force requirement of the heretofore 
known arrangement mentioned initially. Therefore, the arrangement 
according to the invention can be actuated practically without any 
actuating force, operating purely as a function of the actuating distance. 
For this reason the arrangement in accordance with any of various 
embodiments of the invention has few requirements with regard to its 
installation, and is therefore well suited for virtually all applications. 
Notwithstanding the above advantages, an actuating force with a measurable 
value is often required, for example, when applying the arrangement to use 
in a vehicle braking system. In such applications, an actuating force 
requirement can be produced without changing valve system 25, by providing 
a spring which exerts a spring force on operating element 10 in a 
direction opposite to the direction of movement for the closing of outlet 
valve 15, 21 and the opening of inlet valve 21, 33. Spring 11, mentioned 
previously, is an example of such a spring. 
Spring 11 is held between bearing element 5, 6 and operating element 10, 
retained on operating element 10 via a spring plate 9 which is urged by 
spring 11 against a shoulder of transmission element 8. 
In the rest position of the depicted arrangement, i.e. the rest position of 
operating element 10, spring 11 urges the latter against the stop formed 
on bearing block 6, and thus also acts as a return spring. Spring 11 
imposes a spring force which the operator experiences as an actuating 
force required to produce the rotation for the actuation of the 
arrangement. 
Since the output force of a spring can easily be changed by known means, 
this further development offers a simple option for adaptation of 
particular actuating requirements for all applications. 
A change in spring force can be effected by replacing an existing spring 11 
with one having the desired output force. Another option is to install 
spring 11 such that it is adjustable. A variant of the embodiment 
providing such selective variability in spring tension is depicted in FIG. 
1. Bearing element 5, 6 is provided with a threaded neck 4 disposed around 
the passage of transmission element 8. A spring seat 12 with internal 
threads is threadably received on threaded neck 4, and can be displaced 
lengthwise by rotation thereof. By virtue of lengthwise displacement of 
spring seat 12, the compressive tension of spring 11, and thereby its 
output force, can be adjusted. 
Further options for readily permitting adaptation of the arrangement to 
different applications are provided by spring 11 through the selection or 
modification of its characteristic force/deflection line. By employing 
suitable designs, spring 11 may be given a linear or a non-linear 
characteristic force/deflection line, with corresponding evolution of the 
actuating force upon operating element 10. Often a progressive evolution 
of the actuating force is required. This can be achieved, for example, by 
means of a progressive characteristic force/deflection line of spring 11, 
or can be assisted by same, for example when regulating spring 24 already 
has a progressive characteristic line. 
Spring 11, which is depicted as a helical-compression spring, can also be 
provided in a completely different form without departure from the 
contemplated scope of the invention. For example, it may be alternatively 
provided as an elastomer spring similar to the regulating springs in the 
WABCO Westinghouse publications already mentioned, and which are 
incorporated herein by reference. 
Spring 11 can also be assisted or replaced by one or more springs having 
different placement, for example, next to transmission element 8 and/or 
operating element 10, or disposed in a tension spring arrangement. 
Turning now to FIG. 2, another arrangement according to a further 
embodiment of the invention is shown, depicted from the perspective as 
viewed by the operator. 
A valve system 45 is lever-operated in the depicted example, such as 
described in the WABCO Westinghouse publication "Motorwagen-Bremsventil 
461 295," which was already mentioned earlier, and which is incorporated 
herein by reference. 
In the arrangement in accordance with the embodiment of FIG. 2, operating 
element 10 is used for the simultaneous actuation of another device 40, 
which, in the depicted example is an electrical brake signal transmitter 
of an electrically controlled vehicle braking system. Such a brake signal 
transmitter is described, for example, in U.S. Pat. No. 4,818,036, 
entitled "BRAKING POWER TRANSMITTER," issued to Reinecke on Apr. 4, 1989, 
and which is incorporated herein by reference. 
To actuate the other device 40, a cam 39 is installed on bearing shaft 7, 
fixedly connected thereto. 
Depending on the particular application, the other device 40 may be 
different than that of the example shown without departure from the 
contemplated scope of the invention. Furthermore, several additional 
devices could also be provided, in which case bearing shaft 7 would be 
provided with corresponding cams for operation of same. Such arrangement, 
however, does not necessarily require that a special cam for every other 
device be provided on bearing shaft 7. Rather, it is possible for the 
devices to be placed at an angle to each other, and the cam, distributed 
over its circumference, provided with a special cam contour for each of 
these devices. 
Reference numerals 35 and 38 designate rotary bearings of bearing shaft 7. 
When so desired in a particular a system application, an actuating force 
can be provided conveniently, as shown, by a spring system. The spring 
system in the depicted example is located next to operating element 10, 
and contains one spring 44. Bearing shaft 7, which is fixedly connected to 
operating element 10, acts upon spring 44 by intercalation of a cup ram 36 
moved via an additional cam 37. Spring 44 can be adjusted by means of a 
spring seat 43 and an adjustment screw 41, a desired setting of which is 
maintained by a lock nut 42. 
The explanations applicable to one figure also apply generally to the 
remaining figure, directly or in corresponding application, to the extent 
that the above details are not in conflict with one another. 
Having described preferred embodiments of the invention with reference to 
the accompanying drawing, it is to be understood that the invention is not 
limited to those precise embodiments, and that various changes and 
modifications may be effected therein by one skilled in the art without 
departing from the scope or spirit of the invention as defined in the 
appended claims.