TECHNICAL FIELD
The present disclosure, in general, relates to a brake booster assembly
for a vehicle and, more particularly, to structure and position of vacuum switch of
the brake booster assembly.
BACKGROUND
Background description includes information that may be useful in
understanding the present invention. It is not an admission that any of the
information provided herein is prior art or relevant to the presently claimed
10 invention, or that any publication specifically or implicitly referenced is prior art.
[0003] A brake booster provides power assist to the brake system and reduces
manual efforts of driver. The brake booster assembly includes variable pressure
chamber, vacuum chamber, tandem master cylinder, and a brake fluid reservoir.
The variable pressure chamber and the vacuum chamber are separated by a
15 diaphragm and valve body that isolates entry of atmospheric pressure into the
vacuum chamber. Upon pressing of brake pedal, air flows into variable pressure
chamber. The atmospheric pressure pushes the diaphragm forward towards the
vacuum chamber which moves the push rod resulting into brake fluid
pressurization inside the master cylinder attached to the front of the vacuum
20 chamber which finally leads into application of hydraulic brakes. The master
cylinder receives fluid from the fluid reservoir to apply hydraulic brakes. Upon
release of the brake pedal, the diaphragm regains its original position and
maintains the vacuum in the vacuum chamber and the variable pressure chamber.
[0004] Referring to figure 1 that illustrates existing block diagram of a brake
25 booster assembly (100) in connection with an electronic control unit (ECU) and
an engine to supply engine vacuum. In a diesel engine, a separate vacuum pump is
installed to supply vacuum in the vacuum chamber. The brake booster 101 has
3
variable pressure chamber and a vacuum chamber 102 that are separated by a
diaphragm (which is not shown in the figure). The vacuum chamber 102 has a
vacuum switch 104 that is fixedly connected with the vacuum chamber 102. The
vacuum switch 104 is bolted to front shell of booster, i.e., vacuum chamber 102
and routed to ECU 109 via main harness 107. Refer figure 1 for schemati5 c
diagram. The vacuum switch 104 is a combination of diaphragm, spring and
switch component which are serially placed. Pressure rise in vacuum chamber 102
or low level of vacuum in the vacuum chamber 102 causes the diaphragm and
spring combination to deform and actuate the vacuum switch 104, resulting in
10 current flow in the circuit connecting switch and the ECU 109. Since the vacuum
switch 104 in current use is complex in construction, it proves to be highly
expensive.
[0005] Further, the vacuum chamber is coupled with tandem master cylinder
(TMC) 103 that receives fluid from fluid reservoir 105. The fluid reservoir 105
15 has a level indicator switch 106 attached to detect level of fluid and send
corresponding signal to the body control module (BCM) 108 that indicates the
same on the instrument panel of the vehicle. As seen from the figure 1, the level
indicator switch 106 and the vacuum switch 104 send signal to the main harness
107 through different routes which increases the requirement of wiring and
20 resultantly increase cost.
[0006] The vacuum switch 104 is bolted and fixed with front shell or vacuum
chamber of the brake booster 101. In case of any failure in the vacuum switch
104, the entire brake booster 101 has to be replaced with new one as the vacuum
switch 104 is permanently fixed with the vacuum chamber. Therefore, there is a
25 high replacement cost in the existing brake booster.
[0007] Based on the above mentioned technical problems, there is need for a
brake booster that can provide serviceability of the vacuum switch, reduces
requirement of the wiring harness, and reduces cost of vacuum switch damage.
4
OBJECTS OF THE DISCLOSURE
[0008] Some of the objects of the present disclosure, which at least one
embodiment herein satisfy, are listed hereinbelow.
[0009] The principal object of the present invention is to provide a brake
booster assembly having separate provision for vacuum 5 switch.
[0010] Another object of the present invention is to provide a brake booster
assembly having integrated fluid reservoir and vacuum chamber.
[0011] Another object of the present invention is to provide a brake booster
assembly having vacuum switch integrated with fluid level indicator switch.
10 [0012] Another object of the present invention is to provide a brake booster
assembly with reed switch to indicate level of vacuum in the vacuum chamber.
[0013] These and other objects and advantages will become more apparent
when reference is made to the following description and accompanying drawings.
SUMMARY
15 [0014] This summary is provided to introduce concepts related to a structure
of brake booster assembly. The concepts are further described below in the
detailed description. This summary is not intended to identify key features or
essential features of the claimed subject matter, nor is it intended to be used to
limit the scope of the claimed subject matter.
20 [0015] In an embodiment, the present disclosure relates to a brake booster
assembly for assisting brakes in automobile. The brake booster assembly includes
a booster having a vacuum chamber and a variable pressure chamber separated by
a diaphragm. The vacuum chamber is coupled with tandem master cylinder
(TMC) which is coupled with a fluid reservoir to receive brake fluid. The fluid
25 reservoir has a fluid level indicator switch that indicates level of brake fluid in the
fluid reservoir and transmits corresponding signal of fluid level to body control
5
module (BCM). The brake booster assembly has an additional vacuum chamber
that is integrated with the fluid reservoir and coupled with the main vacuum
chamber by a vacuum line to maintain same vacuum level in the additional
vacuum chamber. The additional vacuum chamber has a vacuum switch that is
provided to measure vacuum level in the vacuum chamber and send th5 e
corresponding signals to the ECU.
[0016] In an aspect, the vacuum switch includes a diaphragm that is
positioned inside the additional vacuum chamber and a magnet that is attached to
the diaphragm facing wall of the additional vacuum chamber. Further, a reed
10 switch is positioned externally to the additional vacuum chamber below the
magnet to close circuit when the magnet moves closer to the switch. Upon low
level of vacuum in the additional vacuum chamber, the diaphragm is deflected
which causes the magnet to move closer to the reed switch to close the circuit and
send signal to the ECU.
15 [0017] In an aspect, the reed switch of the vacuum switch is coupled with
engine control unit (ECU) via main harness.
[0018] In an aspect, the vacuum switch is integrated with the fluid level
indicator switch by a single switch housing connector with four pins in which
each pair of pins connects to the two integrated reed switches which
20 independently correspond to fluid level indicator switch and vacuum switch
respectively. The switch housing connector is positioned such that one reed switch
lies beneath the magnet inside fluid reservoir and another reed switch is placed
below the magnet inside the additional vacuum chamber.
[0019] In an aspect, the vacuum switch and the fluid level indicator switch use
25 single harness as route to their respective control modules.
[0020] Various objects, features, aspects, and advantages of the inventive
subject matter will become more apparent from the following detailed description
6
of preferred embodiments, along with the accompanying drawing figures in which
like numerals represent like components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The illustrated embodiments of the subject matter will be best
understood by reference to the drawings, wherein like parts are designated by 5 like
numerals throughout. The following description is intended only by way of
example, and simply illustrates certain selected embodiments of devices, systems,
and methods that are consistent with the subject matter as claimed herein,
wherein:
10 [0022] Fig. 1 illustrates schematic diagram of existing brake booster assembly
in connection with peripheral system;
[0023] Fig. 2 illustrates schematic diagram of brake booster assembly in
connection with peripheral system, in accordance with an embodiment of the
present disclosure; and
15 [0024] Fig. 3 illustrates structure of vacuum switch in the vacuum chamber
integrated with the brake fluid reservoir as shown in the fig. 2, in accordance with
an embodiment of the present disclosure.
[0025] The figures depict embodiments of the present subject matter for the
purposes of illustration only. A person skilled in the art will easily recognize from
20 the following description that alternative embodiments of the structures and
methods illustrated herein may be employed without departing from the principles
of the disclosure described herein
DETAILED DESCRIPTION
[0026] The detailed description of various exemplary embodiments of the
25 disclosure is described herein with reference to the accompanying drawings. It
should be noted that the embodiments are described herein in such details as to
7
clearly communicate the disclosure. However, the amount of details provided
herein is not intended to limit the anticipated variations of embodiments; on the
contrary, the intention is to cover all modifications, equivalents, and alternatives
falling within the scope of the present disclosure as defined by the appended
claims5 .
[0027] It is also to be understood that various arrangements may be devised
that, although not explicitly described or shown herein, embody the principles of
the present disclosure. Moreover, all statements herein reciting principles, aspects,
and embodiments of the present disclosure, as well as specific examples, are
10 intended to encompass equivalents thereof.
[0028] The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of example embodiments. As
used herein, the singular forms “a",” “an” and “the” are intended to include the
plural forms as well, unless the context clearly indicates otherwise. It will be
15 further understood that the tennis “comprises,” “comprising,” “includes” and/or
“including,” when used herein, specify the presence of stated features, integers,
steps, operations, elements and/or components, but do not preclude the presence
or addition of one or more other features, integers, steps, operations, elements,
components and/or groups thereof.
20 [0029] It should also be noted that in some alternative implementations, the
functions/acts noted may occur out of the order noted in the figures. For example,
two figures shown in succession may, in fact, be executed concurrently or may
sometimes be executed in the reverse order, depending upon the functionality/acts
involved.
25 [0030] Unless otherwise defined, all terms (including technical and scientific
terms) used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which example embodiments belong. It will be further
8
understood that terms, e.g., those defined in commonly used dictionaries, should
be interpreted as having a meaning that is consistent with their meaning in the
context of the relevant art and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0031] These and other advantages of the present subject matter would 5 be
described in greater detail with reference to the following figures. It should be
noted that the description merely illustrates the principles of the present subject
matter. It will thus be appreciated that those skilled in the art will be able to devise
various arrangements that, although not explicitly described herein, embody the
10 principles of the present subject matter and are included within its scope.
[0032] As known, the brake booster amplifies the driver’s braking effort by
utilizing vacuum generated in intake manifold. Braking effort of driver is
inversely related to amount of vacuum available in brake booster. Hence, vacuum
switch is added in brake booster to monitor vacuum level available inside brake
15 booster and send signal to ECU whenever vacuum inside the booster chamber
drops to a threshold limit below which driver effort to stop the vehicle increases
significantly. Subsequently, ECU cuts off engine-power to auxiliary systems like
heating, ventilation, and air conditioning (HVAC) system such that certain level
of vacuum in booster is maintained above threshold limit. In existing designs,
20 vacuum switch assembled on front shell of the booster is expensive and its wiring
route requires a separate connection.
[0033] In the present invention, a float type switch is integrated with level
indicator switch in brake fluid reservoir which replaces the current vacuum switch
and thereby provides a cheaper and more convenient alternative.
25 [0034] Figure 2 illustrates schematic diagram of brake booster assembly, in
accordance with an embodiment of the present subject matter. The brake booster
assembly 300 has a booster chamber 301 having variable pressure chamber and a
9
vacuum chamber 302 that are separated by a diaphragm (which is not shown in
the figure). The vacuum chamber 302 is coupled with tandem master cylinder
(TMC) 303. The tandem master cylinder 303 is coupled with the fluid reservoir
304 that pressurizes brake fluid upon application of atmospheric pressure to the
variable pressure cham5 ber.
[0035] In the present invention, an additional vacuum chamber 307 integrated
with the fluid reservoir 304 is provided to represent replica of the main vacuum
chamber 302. The additional vacuum chamber 307 is coupled with the main
vacuum chamber 302 via vacuum line 308 that maintains same vacuum level in
10 both the chambers. The vacuum line 308 creates vacuum in the vacuum chamber
302 and the additional vacuum chamber 307. The vacuum line 308 is coupled
with air intake manifold 401 in gasoline engines and with vacuum pump 401 in
the diesel engines.
[0036] The fluid reservoir 304 is provided with a level indicator switch 305
15 which is float type switch that works on the magnet connection with the reed
switch. Similarly, in the additional vacuum chamber 307 integrated with the fluid
reservoir 304, a vacuum switch 309 is provided to measure vacuum level in the
vacuum chamber 307 which is replica of the main vacuum chamber 302.
Therefore, by measuring the vacuum level of the additional vacuum chamber 307,
20 the vacuum switch 309 measures the vacuum level of the main vacuum chamber
302.
[0037] In an aspect, the vacuum switch 309 is integrated with level indicator
switch 305 of the fluid reservoir 304. As shown in figure 3, the vacuum switch
309 includes a diaphragm 309a, a magnet 309b and a reed switch 309c. The
25 diaphragm 309a is positioned inside the additional vacuum chamber 307 and the
magnet 309b that is attached to the diaphragm 309a at lower side which faces
opposite wall of the additional vacuum chamber 307 where the reed switch 309c
is placed. The diaphragm 309a is placed inside the additional vacuum chamber
10
307 in proximity to the reed switch 309c. The switch 309c is positioned below the
magnet 309b to close circuit when the magnet 309b moves closer to the switch
309c. The switch 309c is connected with engine control unit 310 via main harness
311. Upon low level of vacuum below a threshold level in the additional vacuum
chamber 307, the diaphragm (309a) is deflected which causes the magnet 5 309b to
move closer to the reed switch 309c to close the circuit and send signal to the
ECU 310. The ECU 310 sends instructions to engine 400. The ECU 310 cuts off
engine-power to auxiliary systems like HVAC such that certain level of vacuum
in vacuum chamber 302 is maintained above the threshold limit. The switch 309c
10 in the vacuum switch 309 is reed switch. Further, switch housing 500 of the
vacuum switch 309 and the level indicator switch 305 may be same.
[0038] Further, the vacuum switch 309 uses the same wiring harness routing
as of the level indicator switch 305 for sending the signals. Accordingly, there is a
requirement of less wiring harness.
15 [0039] Further, in case of vacuum switch failure, only vacuum switch is
replaced which is cheaper in the present invention. If there is any failure in the
vacuum chamber 307, only the additional vacuum chamber and the fluid reservoir
304 have to be replaced which is made of plastic material. Therefore, replacing
the complete integrated part is also cheaper than replacing the complete brake
20 booster.
[0040] In another embodiment of the present invention, the present brake
booster assembly uses a float type switch integrated with level indicator switch in
brake fluid reservoir. A separate vacuum chamber 307 as a part of the fluid
reservoir 304 is constructed in which vacuum is maintained by separate route
25 from vacuum line 308. The integrated switch component is to be placed in
between the two chambers such that circuits inside the switch can individually be
actuated by the respective chamber levels. A diaphragm is placed inside the
additional vacuum chamber in proximity to the integrated switch. A magnet is
11
attached to the diaphragm facing the wall, opposite of which the switch is placed.
The diaphragm and magnet combination is placed in such a way that in case of
pressure rise inside the additional vacuum chamber, the diaphragm is deflected
and the magnet moves closer to the reed switch, closes the circuit and thereby
signals 5 the ECU.
[0041] It will be understood by those within the art that, in general, terms used
herein, and especially in the appended claims (e.g., bodies of the appended
claims) are generally intended as “open” terms (e.g., the term “including” should
be interpreted as “including but not limited to,” the term “having” should be
10 interpreted as “having at least,” the term “includes” should be interpreted as
“includes but is not limited to,” etc.). It will be further understood by those within
the art that if a specific number of an introduced claim recitation is intended, such
an intent will be explicitly recited in the claim, and in the absence of such
recitation no such intent is present. For example, as an aid to understanding, the
15 following appended claims may contain usage of the introductory phrases “at least
one” and “one or more” to introduce claim recitations. However, the use of such
phrases should not be construed to imply that the introduction of a claim recitation
by the indefinite articles “a” or “an” limits any particular claim containing such
introduced claim recitation to inventions containing only one such recitation, even
20 when the same claim includes the introductory phrases “one or more” or “at least
one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should
typically be interpreted to mean “at least one” or “one or more”); the same holds
true for the use of definite articles used to introduce claim recitations. In addition,
even if a specific number of an introduced claim recitation is explicitly recited,
25 those skilled in the art will recognize that such recitation should typically be
interpreted to mean at least the recited number (e.g., the bare recitation of “two
recitations,” without other modifiers, typically means at least two recitations, or
two or more recitations). Furthermore, in those instances where a convention
12
analogous to “at least one of A, B, and C, etc.” is used, in general such a
construction is intended in the sense one having skill in the art would understand
the convention (e.g., “a system having at least one of A, B, and C” would include
but not be limited to systems that have A alone, B alone, C alone, A and B
together, A and C together, B and C together, and/or A, B, and C together, etc.)5 .
In those instances where a convention analogous to “at least one of A, B, or C,
etc.” is used, in general such a construction is intended in the sense one having
skill in the art would understand the convention (e.g., “a system having at least
one of A, B, or C” would include but not be limited to systems that have A alone,
10 B alone, C alone, A and B together, A and C together, B and C together, and/or A,
B, and C together, etc.). It will be further understood by those within the art that
virtually any disjunctive word and/or phrase presenting two or more alternative
terms, whether in the description, claims, or drawings, should be understood to
contemplate the possibilities of including one of the terms, either of the terms, or
15 both terms. For example, the phrase “A or B” will be understood to include the
possibilities of “A” or “B” or “A and B.”
[0042] While the foregoing describes various embodiments of the invention,
other and further embodiments of the invention may be devised without departing
from the basic scope thereof. The scope of the invention is determined by the
20 claims that follow. The invention is not limited to the described embodiments,
versions or examples, which are included to enable a person having ordinary skill
in the art to make and use the invention when combined with information and
knowledge available to the person having ordinary skill in the art.

We claim:
1. A brake booster assembly (300) for assisting brakes in automobile, the
brake booster assembly comprising:
a booster (301) having a vacuum chamber (302) and a variable
pressure chamber, the vacuum chamber (302) coupled with tandem mast5 er
cylinder (303);
a fluid reservoir (304) coupled with the tandem master cylinder
(303) to supply brake fluid;
a fluid level indicator switch (305) provided with the fluid reservoir
10 (304) to transmit signal of fluid level to body control module (BCM) (306)
and indicate level of brake fluid in the fluid reservoir (304); and
characterized in that
an additional vacuum chamber (307) integrally provided with the
fluid reservoir (304), the additional vacuum chamber (307) is coupled with
15 the vacuum chamber (302) by a vacuum line (308); and
a vacuum switch (309) provided with the additional vacuum
chamber (307) to measure vacuum level in the additional vacuum chamber
(307).
2. The brake booster assembly (300) as claimed in claim 1, wherein the
20 additional vacuum chamber (307) is integrated with the fluid reservoir
(304).
3. The brake booster assembly (300) as claimed in claim 1, wherein the
vacuum switch (309) comprises:
a diaphragm (309a) positioned inside the additional vacuum
25 chamber (307);
14
a magnet (309b) attached to the diaphragm (309a) facing wall of
the additional vacuum chamber (307); and
a switch (309c) positioned below the magnet (309b) to close circuit
when the magnet (309b) moves closer to the switch (309c).
4. The brake booster assembly (300) as claimed in claim 3, wherein the switc5 h
(309c) is coupled with engine control unit (ECU) (310) via main harness
(311).
5. The brake booster assembly (300) as claimed in claim 3, wherein the switch
(309c) is reed switch.
10 6. The brake booster assembly (300) as claimed in claim 3, wherein upon low
level of vacuum in the additional vacuum chamber (307), the diaphragm
(309a) is deflected which causes the magnet (309b) to move closer to the
switch (309c) to close the circuit and send signal to the ECU (310).
7. The brake booster assembly (300) as claimed in claim 1, wherein the
15 vacuum line (308) maintains same level of vacuum in the vacuum chamber
(302) and the additional vacuum chamber (307).
8. The brake booster assembly (300) as claimed in claim 1, wherein the
vacuum switch (309) is integrated with the fluid level indicator switch
(305).
20 9. The brake booster assembly (300) as claimed in claim 1, wherein the
vacuum switch (309) and the fluid level indicator switch (305) use same
harness routing.
10. The brake booster assembly (300) as claimed in claim 1, wherein the
additional vacuum chamber (307) and the fluid reservoir (304) are made of
25 plastic material.