U.S. patent application number 10/379956 was filed with the patent office on 2004-06-10 for enhanced exhaust flow control feature.
Invention is credited to Herbst, Robert J., Ho, Thanh.
Application Number | 20040107990 10/379956 |
Document ID | / |
Family ID | 32474204 |
Filed Date | 2004-06-10 |
United States Patent
Application |
20040107990 |
Kind Code |
A1 |
Ho, Thanh ; et al. |
June 10, 2004 |
Enhanced exhaust flow control feature
Abstract
A valve for use in a pneumatic fluid system, such as an air
brake system, is disclosed. The valve provides for fast release of
pneumatic fluid from the delivery cavity through the exhaust port
upon cessation of flow from the pneumatic fluid reservoir through
the supply cavity. The valve includes a flow diverter that
restricts fluid flow from the delivery cavity to the supply cavity
when pneumatic fluid pressure in the supply cavity is less than
that in the delivery cavity with minimal restriction of flow from
the supply cavity to the delivery cavity when pressure in the
supply cavity is greater than in the delivery cavity.
Inventors: |
Ho, Thanh; (Brunswick,
OH) ; Herbst, Robert J.; (Avon, OH) |
Correspondence
Address: |
CALFEE HALTER & GRISWOLD, LLP
800 SUPERIOR AVENUE
SUITE 1400
CLEVELAND
OH
44114
US
|
Family ID: |
32474204 |
Appl. No.: |
10/379956 |
Filed: |
March 5, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60431305 |
Dec 6, 2002 |
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Current U.S.
Class: |
137/102 |
Current CPC
Class: |
B60T 15/02 20130101;
Y10T 137/2544 20150401; Y10T 137/8667 20150401 |
Class at
Publication: |
137/102 |
International
Class: |
F15B 013/04 |
Goverment Interests
[0002] This invention was not made by an agency of the United
States Government nor under contract with an agency of the United
States Government.
Claims
We claim:
1. A valve for use in a pneumatic fluid system comprising: a. a
supply cavity for supplying pneumatic fluid; b. a delivery cavity;
c. an exhaust port; and d. a flow diverter disposed between the
supply cavity and the delivery cavity; wherein the flow diverter is
in an open position when the fluid is communicated from the supply
cavity to the delivery cavity and is in a closed position when the
fluid is communicated from the delivery cavity to the supply cavity
restricting pneumatic fluid flow such that the majority of
pneumatic fluid in the delivery cavity is communicated to the
exhaust port.
2. The valve of claim 1, wherein the flow diverter does not
significantly restrict flow of the pneumatic fluid from the supply
cavity to the delivery cavity.
3. The valve of claim 2, wherein the flow diverter reduces the flow
area by no more than about 25%.
4. The valve of claim 1, wherein the pneumatic fluid is air.
5. The valve of claim 1, wherein the pneumatic fluid system
comprises a vehicle air brake system.
6. The valve of claim 1, further comprising: a. a housing wall
disposed between the delivery cavity and the exhaust port; and b.
an exhaust diaphragm capable of seating against the housing
wall.
7. The valve of claim 6, wherein when the pneumatic fluid is at a
higher pressure in the delivery cavity than in the supply cavity,
the flow diverter restricts flow of the pneumatic fluid from the
delivery cavity to the supply cavity and the diaphragm is unseated
from the housing wall, enabling communication of the pneumatic
fluid from the delivery cavity to the exhaust port.
8. A valve for use in a pneumatic fluid system, comprising: a. a
supply cavity for supplying pneumatic fluid; b. a delivery cavity
in fluid communication with the supply cavity; c. an exhaust port
in fluid communication with the delivery cavity; d. a housing wall
disposed between the delivery cavity and the exhaust port; e. an
exhaust diaphragm capable of seating against the housing wall
between the delivery cavity and the exhaust port; and f. a flow
diverter disposed between the supply cavity and the delivery
cavity; wherein the flow diverter allows the pneumatic fluid to be
communicated to the delivery cavity from the supply cavity with
minimal restriction by the flow diverter, and wherein when the
pneumatic fluid is at a higher pressure in the delivery cavity than
in the supply cavity, the flow diverter restricts flow of the
pneumatic fluid from the delivery cavity to the supply cavity, and
the diaphragm is unseated from the housing wall, enabling
communication of the pneumatic fluid from the delivery cavity to
the exhaust port.
9. A valve for use in a pneumatic fluid system, comprising: a. a
supply cavity for supplying pneumatic fluid; b. a delivery cavity
in fluid communication with the supply cavity; c. an exhaust port
in fluid communication with the delivery cavity; d. means for
restricting the flow of pneumatic fluid from the delivery cavity to
the supply cavity with minimal restriction of the flow of pneumatic
fluid from the supply cavity to the delivery cavity; and e. means
for directing the flow of the majority of the pneumatic fluid in
the delivery cavity from the delivery cavity to the exhaust port
when pressure of the pneumatic fluid in the delivery cavity exceeds
pressure of the pneumatic fluid in the supply cavity.
10. The valve of claim 9, wherein the means for restricting the
flow of pneumatic fluid comprises a flow diverter between the
supply cavity and the delivery cavity.
11. The valve of claim 9, wherein the means for restricting the
flow of pneumatic fluid reduces the flow area for flow of pneumatic
fluid from the supply cavity to the delivery cavity by no more than
about 25%.
12. The valve of claim 9, wherein means for directing the flow of
the majority of the pneumatic fluid comprises an exhaust diaphragm
capable of seating against and unseating from a housing such that
when pressure of the pneumatic fluid in the delivery cavity exceeds
pressure of the pneumatic fluid in the supply cavity, the exhaust
diaphragm unseats from the housing, providing a flow path for the
pneumatic fluid between the delivery cavity and the exhaust
port.
13. A quick release valve for use in a vehicle air brake system,
comprising: a. a supply cavity; b. a delivery cavity; c. an exhaust
port; and d. a flow diverter that has first and second positions;
wherein the supply cavity is in fluid communication with the
delivery cavity when the flow diverter is in the first position and
the delivery cavity is in fluid communication with the exhaust port
when the flow diverter is in the second position.
14. A flow diverter for use in a valve in a pneumatic fluid system,
comprising: a. a restrictor portion; and b. a spacing portion
having at least one leg; c. wherein the flow diverter is configured
for placement in a bore between a supply cavity in fluid
communication with a delivery cavity such that the flow diverter
minimally restricts flow of pneumatic fluid when the fluid is being
communicated to the delivery cavity from the supply cavity, but
will significantly restrict flow of the pneumatic fluid from the
delivery cavity to the supply cavity.
15. A method of rapidly exhausting air, with minimal restriction of
air inlet flow, from an air brake valve having a supply cavity, a
delivery cavity, an exhaust port, a housing, and an exhaust
diaphragm seated against the housing, comprising: a. restricting
communication of the air from the delivery cavity to the supply
cavity when pressure of the air in the delivery cavity is greater
than pressure of the air in the supply cavity with minimal
restriction of communication of the air from the supply cavity to
the delivery cavity when pressure of the air in the supply cavity
is greater than pressure of the air in the delivery cavity; b.
unseating the exhaust diaphragm from the housing when pressure of
the air in the delivery cavity is greater than pressure of the air
in the supply cavity; and c. causing communication of the air from
the delivery cavity to the exhaust port upon unseating the
diaphragm from the housing.
16. The method of claim 15, wherein restricting communication of
air is accomplished by a flow diverter that is in an open position
when pressure of the air in the supply cavity is equal or greater
than pressure of the air in the delivery cavity and in a closed
position when pressure of the air in the delivery cavity is greater
than pressure of the air in the supply cavity.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from Provisional
Application 60/431,305, filed Dec. 6, 2002, entitled Enhanced
Exhaust Flow Control Feature, the entire disclosure of which is
hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0003] The present invention relates to a valve for quick release
of pneumatic pressure in a pneumatic fluid system. It finds
particular application with air brakes used in conjunction with
heavy or commercial vehicles and will be described with particular
reference thereto. The invention may be used in other applications
without departing from the spirit and scope of the invention.
[0004] Some air brake valves used in the industry today (e.g., in
Europe) do not meet release timing requirements of Federal Motor
Vehicle Safety Standard (FMVSS) 121, Air Brake Systems. The release
timing requirements relate to how quickly the brakes release after
the brake pedal is allowed to return to its normal position. In
order to use these valves in the worldwide market, the release
timing must be improved to meet the requirements of this market. As
shown in FIG. 1, current brake system valves utilize a fixed inlet
orifice 1 to generate a pressure differential across an exhaust
diaphragm 2 to enhance the release timing.
[0005] When the actuator 3 for the brake valve is released (e.g.,
foot lifted from a brake pedal), the air flows from the brake
chamber 4 to the actuator 3 through a fixed inlet orifice 1. While
the fixed inlet orifice does provide some pressure differential
across the exhaust diaphragm, relatively little air, less than 50%,
actually is exhausted through the exhaust port, and only slight
improvements are realized for the release timing. Moreover, this
method restricts the inlet capacity of the valve. Furthermore, this
method does not sufficiently improve the release timing to meet the
FMVSS 121 requirements.
[0006] Patent disclosure DE3938101A1 discusses reducing the vent
time of a pressure control valve for improved release timing. In
this disclosure a "reflux" valve is placed directly in the inlet
flow path, thus restricting the inlet flow. Inclusion of a reflux
valve that restricts inlet flow doesn't, however, provide both
apply and release timing sufficient to meet, for example the
requirements of FMVSS 121. Apply timing relates to how quickly the
brakes are applied after pressing the brake pedal. The enhancement
for the release timing in disclosure DE3938101A1 degrades the
performance of the valve for the apply timing. With the current
sizing requirements of the antilock brake system (ABS) valve, it is
not capable to meet both apply and release timing of FMVSS 121
using the "reflux" valve design.
[0007] The present invention provides a new and improved apparatus
and method which addresses the above-referenced problems.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] In the accompanying drawings which are incorporated in and
constitute a part of the specification, embodiments of the
invention are illustrated, which, together with a general
description of the invention given above, and the detailed
description given below, serve to exemplify the embodiments of this
invention.
[0009] FIG. 1 illustrates a prior art valve;
[0010] FIG. 2 illustrates a flow diverter as positioned during a
brake application in accordance with one embodiment of the present
invention; and
[0011] FIG. 3 illustrates a flow diverter as positioned during a
brake release in accordance with one embodiment of the present
invention;
[0012] FIG. 4 illustrates a perspective view of the flow diverter
in accordance with one embodiment of the present invention; and
[0013] FIG. 5 illustrates a graph showing test data.
DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENT
[0014] In order to provide decreased release timing, such as to
meet the FMVSS 121 release timing requirements, the delivery air of
the air brake system valve is diverted to the exhaust port in order
to limit the amount of air returning through the inlet port of the
valve. In this manner, the release timing is improved without
significantly increasing the apply timing. The feature described
below meets the required release timing of FMVSS 121 without
significantly restricting the inlet capacity of the valve (see
FIGS. 2 and 3) such that the required apply timing of FMVSS 121 is
met. The invention is not limited to features requiring compliance
with FMVSS 121 release and apply timing requirements, but is
discussed below in relation to features that will meet these
requirements.
[0015] As used herein, "apply timing" means the time from the first
movement of the brake valve actuator (brake pedal) for the brake
chamber to reach 60 psi with an initial service reservoir pressure
of 100 psi. As used herein, "release timing" means the time from
initial brake pedal movement (release) for a set of brake chambers
initially at 95 psi to reach 5 psi. Unless otherwise specified, use
of the term "or" herein is the inclusive, and not the exclusive,
use. See BRYAN A. GARNER, A DICTIONARY OF MODERN LEGAL USAGE 624
(2d Ed. 1995).
[0016] The release timing of a brake valve correlates to how
quickly the pressure of the pneumatic fluid therein, often air, is
released from the brake chamber 4 (see FIG. 1). The more quickly
the pneumatic fluid pressure applied to the brake chamber 4 is
released, the more quickly the brake will release. The present
invention provides for a restriction in the fluid flow from the
brake chamber 4 to more quickly begin fluid communication with an
exhaust port and to redirect more of the fluid to the exhaust port
after the actuator 3 is released. This creates a pressure
differential across the exhaust diaphragm 2 to unseat the exhaust
diaphragm 2 and exhaust fluid. The greater the pressure
differential, the more quickly the exhaust diaphragm 2 is unseated
and the greater is the quantity and speed of the fluid exhausted.
Unlike conventional valves that have some restriction, however, the
present invention provides a restriction that does not
significantly reduce the incoming fluid flow upon application of
the actuator 3 to engage the brake. Therefore, there is minimal
reduction of the apply timing due to the restriction.
[0017] Generally, the restriction device, herein called a flow
diverter, has at least two positions-a first or open position when
the pneumatic fluid flows to actuate the brake and a second or
closed position when the brake is released. When in the first
position, the flow diverter does not significantly restrict fluid
flow to actuate the brake. When in the second position, the flow
diverter diverts fluid flow to the exhaust by restricting the flow
back in the direction of the actuator 3. The flow diverter may
divert all or a portion of the fluid to the exhaust. Thus, the flow
diverter does not significantly reduce the apply timing, as does a
conventional fixed inlet orifice 1.
[0018] FIG. 2 illustrates a flow diverter 20 as positioned during a
brake application, in accordance with one embodiment of the present
invention. FIG. 3 illustrates the flow diverter 20 as positioned
during a brake release operation, in accordance with the embodiment
illustrated in FIG. 2. Air flow paths of the delivery air during
brake application and release are shown by arrows in FIGS. 2 and 3,
respectively. Flow diverter 20 moves freely within a bore 22
according to relative air pressures in a supply (inlet) cavity 24
and a delivery cavity 26.
[0019] As shown in FIG. 2, air from a service reservoir (not shown)
enters the supply (inlet) cavity 24 via an inlet/outlet port 30
when a brake valve 32 is actuated via, for example, a foot pedal
34. The air creates pressure in the supply cavity 24 and passes to
a control side 36 of an exhaust diaphragm 40. The pressure created
by the air at the control side 36 creates a stronger force on the
exhaust diaphragm 40 than the pressure on the other side of the
exhaust diaphragm 40 and urges the exhaust diaphragm 40 to seat
against a housing wall 42 at a point 44. Typically, the exhaust
diaphragm 40 will be biased to seat against the housing wall 42 at
point 44. A portion of the other side of the exhaust diaphragm 40
is exposed to the pressure of delivery cavity 26 and a portion is
exposed to the pressure of an exhaust port 46. The pressure of the
exhaust port 46 is generally atmospheric pressure. As will be
discussed in more detail below, the seating of the exhaust
diaphragm 40 at the point 44 creates a seal between the delivery
cavity 26 and the exhaust port 46. At the same time, the air
creating pressure in the supply cavity 24 also passes through a
passage 48 between a supply (hold) diaphragm 50 and a housing wall
52.
[0020] After passing through the passage 48, the air passes into
the bore 22. A flow diverter 20, which is described in more detail
below, is positioned within the bore 22. The air exits the bore 22
via a passage (not shown) into the delivery cavity 26. Because of
the seal created between the delivery cavity 26 and the wall 42 at
point 44, the air entering the delivery cavity 26 from the bore 22
does not pass to the exhaust port 46; instead, the air passes from
the delivery cavity 26 to a delivery port 56 and then to a brake
chamber 60.
[0021] As shown in FIGS. 2 and 4, the flow diverter 20 includes a
restrictor portion 100 and a spacer portion 102. In the illustrated
embodiment, the restrictor portion 100 is flat; furthermore, the
spacer portion includes a plurality (e.g., four) of legs 102a,
102b, 102c, 102d. Additionally, an outer diameter of the restrictor
portion 100 is sized to be smaller than an inner diameter of the
bore 22. In one embodiment, the outer diameter of the restrictor
portion 100 is about 0.475 inches while the inner diameter of the
bore 22 is about 0.490 inches. The flow diverter 20 illustrated in
FIGS. 2 and 4 represents only one embodiment and other embodiments
including other designs, shapes, and/or dimensions of the flow
diverter 20 relative to the bore 22 are contemplated.
[0022] For example, the surface of restrictor portion 100 may be of
any shape suitable for use, including regular or irregular
polygons, such as rectangular, pentagonal, hexagonal, octagonal, or
dodecahedral polygons. Preferably, the restrictor portion 100 is
circular, if the cross-section of the bore 22 is circular. The
diameter of the restrictor portion 100 is dimensioned relative to
the diameter of the bore 22 such that the restrictor portion 100
provides sufficient resistance to the flow of air to divert a
sufficient amount, preferably at least about 50%, of the air in the
delivery cavity 26 to the exhaust port 46. The flow diverter 20
also is dimensioned so that there is minimal restriction in the
flow of air from supply cavity 24 to delivery cavity 26. The
restriction is such that the desired apply timing may still be
obtained. Preferably, the flow diverter 20 provides a restriction
in the flow in this direction of no more than about 25%. Therefore,
one of skill in the art may determine the optimum diameter of the
restrictor portion 100 without undue experimentation.
[0023] Moreover, while the spacer portion 102 is illustrated with
four legs 102a, 102b, 102c, 102d, there may be any number of legs,
including three legs, so long as there is sufficient stability to
enable the flow diverter 20 to divert the requisite air to the
exhaust port 46 without significantly restricting the flow of air
from the supply cavity 24 to the delivery cavity 26 when the brake
valve 32 is actuated. The number of legs may be chosen without
departing from the spirit and scope of the invention.
[0024] The shape of the legs 102a, 102b, 102c, 102d is illustrated
as rectangular prisms, but any suitable shape is contemplated, such
as any suitable regular or irregular polygon, and is within the
spirit and scope of the invention. The shape of the legs 102a,
102b, 102c, 102d is to be selected such that there is minimal
interference with air flow between the supply cavity 24 and the
delivery cavity 26, while providing sufficient support for the
restrictor portion 100. For example, the shape of the legs 102a,
102b, 102c, 102d may be selected to have tapering or curved
portions to reduce the turbulent flow characteristics of the air
and to reduce stress points on the flow diverter 20. In one design,
the legs 102a, 102b, 102c, 102d have a triangular cross section.
There may also be ribs between the legs or otherwise provided, for
example, to provide additional strength for the legs.
[0025] The specific dimensions of the restrictor portion 100 and
the spacer portion 102 may be selected based on the circumstances
and parameters of each particular application without departing
from the spirit and scope of the invention. Suitable dimensions may
be determined without undue experimentation based on the
measurement of the release timing and apply timing of the
brake.
[0026] Also, the flow diverter 20 may be a spherical ball or a
cylindrical slug or other shape dimensioned such that, for example,
the pressure of the air in the supply cavity 24 is sufficient to
move the ball or slug substantially out of the way of the flow of
air from the supply cavity 24 to the delivery cavity 26, but the
ball or slug interposes restriction in the flow of air from the
delivery cavity 26 to the supply cavity 24. Thus, the flow diverter
20 need not have both a restrictor portion 100 and a spacer portion
102, but may be provided as one portion.
[0027] Although the flow diverter 20 has been discussed thus far as
restricting flow of air from the supply cavity 24 to the delivery
cavity 26, but allowing some flow of air in this direction, the
flow diverter 20 may also completely restrict any flow of air from
the supply cavity 24 to the delivery cavity 26. There need not be
any leak by or flow of air back into the supply cavity 24 around or
through the flow diverter 20. For example, a flapper or check valve
may be placed in or near the passage 48 that is in an open position
when air is flowing from the supply cavity 24 to the delivery
cavity 26, but is in a closed position when air is no longer
flowing in that direction.
[0028] The material from which the flow diverter 20 is made may be
any conventional material selected, for example, based on cost,
availability, weight, or any other parameter without departing from
the spirit and scope of the invention. Preferably, the material is
plastic, but metals, such as aluminum, are also suitable. The
specific material chosen may affect the restriction of fluid flow
because of, for example, weight or surface smoothness, but the
appropriate shape and dimensions for the chosen material may be
determined without undue experimentation.
[0029] As illustrated in FIG. 2, the flow diverter 20 is positioned
in the bore 22 upon a brake application such that the flow diverter
20 does not substantially interfere with the flow of air from the
supply cavity 24 to the delivery cavity 26 via the bore 22. For
example, the restrictor portion 100 is above the passage (not
shown) from the bore 22 to the delivery cavity 26. The legs 102a,
102b, 102c, 102d are designed such that they do not substantially
interfere with the flow of air from the bore 22 to the delivery
cavity 26 upon brake application.
[0030] As shown in FIG. 3, when the brake valve 32 is no longer
actuated (e.g., when the brake valve or foot pedal is released),
air begins to flow from the control side 36 of the exhaust
diaphragm 40 into the supply cavity 24. Air in the supply cavity 24
is exhausted via the inlet/outlet port 30, thereby causing a
pressure drop in the supply cavity 24. Once the pressure in the
supply cavity 24 drops, air begins to flow from the delivery cavity
26 to the supply cavity 24 via the bore 22. The flow diverter 20 is
then positioned as shown in FIG. 3. The restrictor portion 100
reduces the amount of air that flows from the delivery cavity 26 to
the supply cavity 24 via the bore 22 and passage 48.
[0031] Because a restricted amount of air is permitted to escape
from the delivery cavity 26 via the bore 22 and, furthermore,
because of the reduced pressure at the control side 36 of the
exhaust diaphragm 40, the pressure of air in the delivery cavity 26
urges the exhaust diaphragm 40 to become unseated from the wall 42
at the point 44. Consequently, air passes from the delivery cavity
26 to the exhaust port 46 via a channel 62 defined between the
exhaust diaphragm 40 and wall 42. More specifically, the higher
pressure in the delivery cavity 26 unseats the exhaust diaphragm
40, directing the major portion of the delivery air flow out the
exhaust port 46. The combination of low pressure on the control
side 36 of the exhaust diaphragm 40 and high pressure on the seat
side speeds the opening of the exhaust valve and the release timing
of the valve.
[0032] As shown in FIGS. 2 and 3, the flow diverter 20 allows
minimally-restricted inlet flow during brake application and meters
back flow during brake release. The metering of back flow quickly
induces a differential pressure across the exhaust diaphragm
triggering the opening of the exhaust seat. This unseating results
in the improved release timing that meets the FMVSS 121 timing
requirements.
[0033] The flow diverter 20 is a flow-activated device having two
positions of operation. During a brake application the flow
diverter is moved by the application air to its minimally
restricted open position. This allows the ABS valve to meet the
FMVSS 121 apply timing requirement. During the brake application
release, the flow of delivered air carries the flow diverter 20 to
its metering position (see FIG. 3). At this position the flow
diverter 20 diverts the majority of the air in the delivery cavity
to the exhaust port 46 and restricts the amount of air returning to
the inlet/outlet 30 of the valve 32 through the clearance between
its outside diameter and the housing bore's inside diameter.
[0034] A valve available from Knorr Bremse with a part number of
BR9164 was fitted with a flow restrictor 20 having three legs with
substantially triangular cross sections. In this embodiment, the
inner diameter of the bore 22 was about 0.490 inches and the outer
diameter of the restrictor portion 100 was about 0.481 inches. FIG.
5 illustrates a graph 200 of test data showing a reduction in the
amount of time for releasing pressure in the delivery cavity 26
(see FIGS. 2 and 3) from 95 psi to 5 psi. A line 202 shows that,
for these dimensions, it took about 0.564 seconds to release the
pressure without the flow diverter according to the present
invention. Furthermore, a line 204 shows that, for the same
embodiment, it took about 0.267 seconds to release the pressure
with the flow diverter according to the present invention. The
reduction in flow area for the air passing from the supply cavity
24 to the delivery cavity 26 imposed by the flow diverter 20 for
three different tests was about 23.3%, about 23.8%, and about
23.9%, with an average of about 23.7%, or less than 25%.
[0035] While the present invention has been illustrated by the
description of embodiments thereof, and while the embodiments have
been described in considerable detail, it is not the intention of
the applicants to restrict or in any way limit the scope of the
appended claims to such detail. Additional advantages and
modifications will readily appear to those skilled in the art.
Therefore, the invention, in its broader aspects, is not limited to
the specific details, the representative apparatus, and
illustrative examples shown and described. Accordingly, departures
may be made from such details without departing from the spirit or
scope of the applicants' general inventive concept.
* * * * *