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FORM 2
THE PATENT ACT 1970
[39 OF 1970]
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
[See Section 10 and Rule 13]
TITLE: “SOLENOID ASSISTED HYDRAULIC BRAKE SYSTEM TO IMPROVE
BRAKE PEDAL FEEL”
Name and address of the Applicant:
TATA MOTORS LIMITED, an Indian company having its registered office at
Bombay house, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra,
INDIA.
Nationality: INDIAN
The following specification particularly describes the invention and the manner in which
it is to be performed.
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TECHNICAL FIELD
Embodiments of the present disclosure relate to a brake system of a vehicle, more
particularly embodiments relate to a hydraulic brake system of the vehicle.
BACKGROUND OF DISCLOSURE
Hydraulic brake systems are used in automobiles to control or slow down the vehicle
when needed. A typical hydraulic brake system consists of brake booster which is
coupled with tandem master cylinder, when driver presses brake pedal, hydraulic
pressure will be generated in the tandem master cylinder with the assistance of brake
booster. The hydraulic pressure generated in the tandem master cylinder is applied on
disc brake caliper or wheel cylinder assembly in drum brake which is connected in the
wheel end. The disc brake caliper or wheel cylinder assembly converts the hydraulic
pressure into brake force, which in turn used to slow down or stop the vehicle. The
human machine interfaces of hydraulic braking system of a vehicle should be laid out in
such a way that they are not only safe in objective terms but can also be used intuitively
with ease.
Brake pedal feel plays vital role in generating the confidence level the driver perceives
while applying brake in any given condition. Based on the perception or confidence level
of driver, the brake system itself can be termed as spongy, sharp, hard brakes.
Manufacturers often insist on “typical” brake pedal feel for a brand to raise recognition of
the vehicle type through the haptic features “felt” by the customer. The desired brake
pedal feel can be achieved by choosing or designing appropriate brake system. Even
though brake system components have gone through lot of modifications to improve
brake pedal feel, due to limitations in production aspect, all the modification cannot be
perceived on brake pedal feel. Also, due to unconventional dimensioning and weight
distribution of vehicles between front and rear axles, currently it is observed that only by
sizing of brake system, desired brake pedal feel cannot be achieved.
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In light of foregoing discussion, it is necessary to implement a secondary electro
hydraulic assistance system integrated with conventional hydraulic braking system to
achieve desired brake pedal feel, and to reduce brake system response time.
SUMMARY OF THE DISCLOSURE
The shortcomings of the prior art are overcome and additional advantages are provided
through the provision of system as claimed in the present disclosure.
Additional features and advantages are realized through the techniques of the present
disclosure. Other embodiments and aspects of the disclosure are described in detail herein
and are considered a part of the claimed disclosure.
One embodiment of the present disclosure relates to a hydraulic brake system of a
vehicle. The system comprises a pedal arm mounted on firewall of the vehicle, a vacuum
booster connected to an upper end of the pedal arm and a tandem master cylinder coupled
to the vacuum booster for supplying hydraulic fluid to a plurality of valves when pressure
of hydraulic fluid in the tandem master cylinder is above predetermined limit. The system
further comprises a sensing means mounted on the pedal arm for detecting movement of
said pedal arm, a solenoid actuated cylinder electrically connected to the sensing means
and fluidly connected to the plurality of valves for supplying hydraulic fluid to said
valves when pressure of hydraulic fluid in the tandem master cylinder is below the
predetermined limit. The sensing means activates the solenoid actuated cylinder when the
pedal arm is actuated. The plurality of valves each comprising plurality of inlet ports and
at least one outlet port. The inlet ports of the valves are fluidly connected to the tandem
master cylinder and the solenoid actuated cylinder respectively, and outlet ports of the
valves are fluidly connected to a wheel cylinders for applying brake.
In an embodiment of the present disclosure, a timer is interfaced with the solenoid
actuated cylinder for deactivating the solenoid actuated cylinder after preset time lapse.
In an embodiment of the present disclosure, the plurality of valves is atleast one of spool
valves and solenoid valves.
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In an embodiment of the present disclosure, the solenoid valves are actuated by atleast
one of pressure sensor and pressure switch based on pressure of hydraulic fluid flowing
into the solenoid valves.
In an embodiment of the present disclosure, the spool valves comprises at least one
spring loaded plunger disposed inside a housing of each spool valve, and the spring
loaded plunger opens and closes inlet ports of the spool valves based on pressure of
hydraulic fluid flowing into the spool valves. The spring loaded plunger opens the inlet
ports of each spool valve which are connected to the solenoid actuated cylinder for
supplying hydraulic fluid to the spool valves when pressure of hydraulic fluid flowing
into the spool valves from the tandem master cylinder is below predetermined limit.
And the spring loaded plunger closes the inlet ports of each spool valve which are
connected to the solenoid actuated cylinder when pressure of hydraulic fluid flowing into
the spool valves from the tandem master cylinder is above predetermined limit.
In an embodiment of the present disclosure, the predetermined limit of pressure of the
hydraulic fluid ranges from about 1bar to about 3bar.
In an embodiment of the present disclosure, a reservoir fluidly connected to the tandem
master cylinder and the solenoid actuated cylinder for supplying hydraulic fluid to said
cylinders.
In an embodiment of the present disclosure, the tandem master cylinder, the solenoid
actuated cylinder, the spool valves and a reservoir are connected to each other using
atleast one of hoses and tubes.
The foregoing summary is illustrative only and is not intended to be in any way limiting.
In addition to the illustrative aspects, embodiments, and features described above, further
aspects, embodiments, and features will become apparent by reference to the drawings
and the following detailed description.
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OBJECTIVES OF THE DISCLOSURE
One object of the present disclosure is to provide the hydraulic braking system of the
vehicle which has secondary electro hydraulic assistance system for reducing the initial
brake pedal feel.
One object of the present disclosure is to provide the hydraulic system of the vehicle
which has secondary electro hydraulic assistance system to reduce response time and
reaction time of the brake system.
One object of the present disclosure is to provide the hydraulic system of the vehicle
which has secondary electro hydraulic assistance system to reduce stopping distance for
the given input.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
The novel features and characteristic of the disclosure are set forth in the appended
claims. The disclosure itself, however, as well as a preferred mode of use, further
objectives and advantages thereof, will best be understood by reference to the following
detailed description of an illustrative embodiment when read in conjunction with the
accompanying figures. One or more embodiments are now described, by way of example
only, with reference to the accompanying figures wherein like reference numerals
represent like elements and in which:
FIG. 1 illustrates a layout of hydraulic brake system of the present disclosure.
FIGS. 2a and 2b illustrates sectional views of spool valves of the hydraulic brake system
of the present disclosure.
The figures depict embodiments of the disclosure for purposes of illustration only. One
skilled in the art will readily recognize from 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.
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DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present
disclosure in order that the detailed description of the disclosure that follows may be
better understood. Additional features and advantages of the disclosure will be described
hereinafter which form the subject of the claims of the disclosure. It should be
appreciated by those skilled in the art that the conception and specific embodiment
disclosed may be readily utilized as a basis for modifying or designing other structures
for carrying out the same purposes of the present disclosure. It should also be realized by
those skilled in the art that such equivalent constructions do not depart from the spirit and
scope of the disclosure as set forth in the appended claims. The novel features which are
believed to be characteristic of the disclosure, both as to its organization and method of
operation, together with further objects and advantages will be better understood from the
following description when considered in connection with the accompanying figures. It is
to be expressly understood, however, that each of the figures is provided for the purpose
of illustration and description only and is not intended as a definition of the limits of the
present disclosure.
To overcome the drawbacks mentioned in the background the hydraulic brake system is
provided with a secondary electro hydraulic assistance system which reduces the brake
pedal feel, brake system response time and braking distance.
FIG. 1 is an exemplary embodiment of the present disclosure which illustrates a layout of
hydraulic brake system (100). The hydraulic brake system comprises a pedal arm (101)
mounted on firewall of vehicle. The pedal arm (101) comprises a pedal pad mounted on
its lower end for actuating the pedal arm (101) by the driver. A vacuum booster (102) is
connected to upper end (101a) of the pedal arm (101) and said vacuum booster (102) is
coupled to a tandem master cylinder (103) through a clevis pin arrangement. The vacuum
booster (102) creates greater braking force from a minimum pedal effort, based on
difference between atmospheric pressure and engine manifolds vacuum. The vacuum
booster (102) can increase the pedal force about 2 to about 4 times depending on size of
diaphragm of the vacuum booster (102). The tandem master cylinder (103) is fluidly
connected with plurality of valves (104 and 105) using at least one of hoses or tubes
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(110) for supplying hydraulic fluid to the valves (104 and 105) when pressure of the
hydraulic fluid in the tandem master cylinder (103) is above predetermined limit to apply
the brake.
The hydraulic brake system (100) further comprises a secondary electro hydraulic
assistance system for reducing the brake pedal feel, brake system response time and
braking distance. The secondary electro hydraulic assistance mechanism comprises a
sensing means (106) mounted on pedal arm (101) for detecting movement of said pedal
arm (101). A solenoid actuated cylinder (107) is electrically connected to the sensing
means (106) and fluidly connected to the plurality of valves (104 and 105) using at least
one of tubes or hoses (110) for supplying hydraulic fluid to said valves (104 and 105)
when pressure of hydraulic fluid in the tandem master cylinder (103) is below the
predetermined limit. The sensing means (106) activates the solenoid actuated cylinder
(107) as soon as the pedal arm (101) is actuated by the driver to supply the hydraulic
fluid to the valves (104 and 105) for applying brakes. This reduces the initial brake pedal
effort and thereby reduces brake system response time and braking distance. Further, a
timer (108) is interfaced with the solenoid actuated cylinder (107) for deactivating the
solenoid actuated cylinder (107) after lapse of preset time.
The solenoid actuated cylinder (107) will supply the hydraulic fluid to the valves (104
and 105) only when pressure of the hydraulic fluid flowing from tandem master cylinder
(103) to the valves is less than predetermined limit, and the same will be deactivated by
timer (107) after present time.
In one aspect of the present disclosure, the sensing means (106) is selected from at least
one of brake light switch and pressure sensor mounted on pedal arm (101). The sensing
means (103) activates the solenoid actuated cylinder (107) when the pedal arm is
actuated.
The valves (104 and 105) comprises plurality of inlet ports (104a, 105a and 104b, 105b)
and at least one outlet port (104c and 105c). The inlet ports (104a, 105a and 104b, 105b)
of the valves (104 and 105) are fluidly connected to the tandem master cylinder (103) and
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the solenoid actuated cylinder (107) respectively using atleast one of tubes and hoses
(110) for supplying hydraulic fluid to the valves (104 and 105). And outlet ports (104c
and 105c) of the valves (104 and 105) are fluidly connected to wheel cylinders using
atleast one of tubes and hoses (110) for applying brake. In one aspect of the present
disclosure the valves (104 and 105) are atleast one of solenoid valves and spool valves.
The system (100) further comprises at least one of pressure sensor and pressure switch
placed in brake circuit to monitor brake line pressure. The solenoid valves (104 and 105)
are interfaced with the pressure sensor or pressure switch, and said pressure sensor or
pressure switch actuates the solenoid valves (104 and 105) based on pressure of hydraulic
fluid flowing into the solenoid valves (104 and 105). The solenoid valves (104 and 105)
open the inlet ports (104b and 105b) connected to the solenoid activated cylinder (107)
for supplying hydraulic fluid to the solenoid valves (104 and 105) when pressure of the
hydraulic fluid sensed by the pressure sensor or pressure switch is less than
predetermined limit to apply brakes. And the solenoid valves (104 and 105) open the inlet
ports (104a and 105a) connected to the tandem master cylinder (103) for supplying
hydraulic fluid to the solenoid valves (104 and 105) when pressure of the hydraulic fluid
sensed by the pressure sensor or pressure switch is more than predetermined limit to
apply brakes.
In one aspect of the present disclosure, the predetermined pressure value of the hydraulic
fluid ranges from about 1 bar to about 3 bar depending on the dimensions of the brake
system (100).
A reservoir (109) is provided in the hydraulic brake system (100) for storing hydraulic
fluid. The reservoir (109) is fluidly connected to the tandem master cylinder (103) and
the solenoid actuated cylinder (107) for supplying hydraulic fluid to the tandem master
cylinder (103) and the solenoid actuated cylinder (107) for applying brake.
FIGS. 2a and 2b are exemplary embodiments of the present disclosure which illustrating
sectional views of spool valves (104 and 105) of the hydraulic brake system (100). The
spool valves (104 and 105) comprises a steel or aluminium cylinder acting as housing of
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the valves (104 and 105). The housing is sealed at one end and provided with lock nut at
the other end. A spring loaded plunger (A) is disposed inside the housing of each spool
valve (104 and 105). The spring loaded plunger (A) opens and closes inlet ports (104a,
105a and 104b, 105b) of the spool valves (104 and 105) based on pressure of hydraulic
fluid flowing into the spool valves (104 and 105). The plunger (A) opens the inlet ports
(104b and 105b) of each spool valve (104 and 105) which are connected to the solenoid
actuated cylinder (107) for supplying hydraulic fluid to the spool valves (104 and 105)
when pressure of hydraulic fluid flowing into the spool valves (104 and 105) from the
tandem master cylinder (103) is below predetermined limit to apply brake. And the spring
loaded plunger (A) closes the inlet ports (104b and 105b) of each spool valve (104 and
105) which are connected to the solenoid actuated cylinder (107) and opens the inlet ports
(104a and 105a) of each spool valve (104 and 105) which are connected to the tandem
master cylinder (107) when pressure of hydraulic fluid flowing into the spool valves (104
and 105) from the tandem master cylinder (103) is above predetermined limit to apply
brake.
The working of hydraulic brake system (100) is explained in conjunction with FIG. 1.
When pedal arm (101) is depressed slightly, brake light switch (103) gives electrical
signal to solenoid actuated cylinder (107) and solenoid of the solenoid actuator cylinder
(107) gets operated. This generates pressure in hydraulic fluid, and the hydraulic fluid is
supplied to the spool valves (104 and 105), since the spring loaded plunger (A) is in first
position, the generated pressure directly actuates wheel cylinders which in turn apply
limited braking to vehicle. When brake pedal (101) is further depressed to the level from
which pressure starts getting developed at tandem master cylinder (103), this pressure
starts acting on the spring loaded plunger (A) face, once designed pressure is reached at
tandem master cylinder (103), the spring loaded plunger (A) will be moved to second
position. At second position, tandem master cylinder (103) pressure starts operating the
wheel cylinders to apply the brake. The solenoid actuated cylinder (107) output will be
blocked and the timer (108) will deactivates the solenoid actuated cylinder (107). Now
the brake system is operating as a conventional brake system.
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In the hydraulic brake system (100) of the instant invention, brakes are getting applied at
as soon as brake pedal (101) is depressed by assisting arrangement, reaction time of brake
system will be reduced which in turn reduces the stopping distance. Also, before
conventional brake system comes into action, due to solenoid assistance, threshold
volume of brake system is already filled; this in turn reduced the spongy brake pedal feel.
Further, the initial brake pedal feel of the vehicle is improved with the provision of
solenoid assisted brake system
Equivalents
With respect to the use of substantially any plural and/or singular terms herein, those
having skill in the art can translate from the plural to the singular and/or from the singular
to the plural as is appropriate to the context and/or application. The various
singular/plural permutations may be expressly set forth herein for sake of clarity.
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 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 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 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
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introduced claim recitation is explicitly recited, 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 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.). 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, 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 both terms. For example, the phrase "A or B" will be understood to
include the possibilities of "A" or "B" or "A and B."
While various aspects and embodiments have been disclosed herein, other aspects and
embodiments will be apparent to those skilled in the art. The various aspects and
embodiments disclosed herein are for purposes of illustration and are not intended to be
limiting, with the true scope and spirit being indicated by the following claims.
Referral Numerals:
Reference Number Description
100 Hydraulic brake system
101 Pedal arm
101a Upper end of the pedal arm
102 Vacuum booster
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103 Tandem master cylinder
104 and 105 Valves
104a, 105a and 14b
and 105b
Inlet ports of the valves
104c and 105c Outlet ports
106 Sensing means
107 Solenoid actuated cylinder
108 Timer
109 Reservoir
110 Tubes or hoses
A Spring loaded plunger
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We claim
1. A hydraulic brake system (100) of a vehicle comprising:
a pedal arm (101) mounted on firewall of the vehicle;
a vacuum booster (102) connected to an upper end of the pedal arm (101a)
using suitable means;
a tandem master cylinder (103) coupled to the vacuum booster (101) for
supplying hydraulic fluid to a plurality of valves (104 and 105) when pressure of
hydraulic fluid in the tandem master cylinder (103) is above predetermined limit;
a sensing means (106) mounted on the pedal arm (101) for detecting
movement of said pedal arm (101);
a solenoid actuated cylinder (107) electrically connected to the sensing
means and fluidly connected to the plurality of valves (104 and 105) for supplying
hydraulic fluid to said valves (104 and 105) when pressure of hydraulic fluid in
the tandem master cylinder is below the predetermined limit, wherein the sensing
means (106) activates the solenoid actuated cylinder (107) when the pedal arm
(101) is actuated;
the plurality of valves (104 and 105) each comprising plurality of inlet
ports (104a, 105a and 104b, 105b) and at least one outlet port (104c and 105c),
wherein inlet ports (104a, 105a and 104b, 105b) of the valves (104 and 105) are
fluidly connected to the tandem master cylinder (103) and the solenoid actuated
cylinder (107) respectively, and outlet ports (104c and 105c) of the valves (104
and 105) are fluidly connected to a wheel cylinders for applying brake.
2. The system as claimed in claim 1, wherein a timer (108) is interfaced with the
solenoid actuated cylinder (107) for deactivating the solenoid actuated cylinder
(107) after preset time lapse.
3. The system as claimed in claim 1, wherein the plurality of valves (104 and 105) is
atleast one of spool valves and solenoid valves.
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4. The system as claimed in claim 3, wherein the solenoid valves are actuated by
atleast one of pressure sensor and pressure switch based on pressure of hydraulic
fluid flowing into the solenoid valves (104 and 105).
5. The system as claimed in claim 3, wherein the spool valves comprises at least one
spring loaded plunger (A) disposed inside a housing of each spool valve (104 and
105), and the spring loaded plunger (A) opens and closes inlet ports (104a, 105a
and 104b, 105b) of the spool valves (104 and 105) based on pressure of hydraulic
fluid flowing into the spool valves (104 and 105).
6. The system as claimed in claim 3, wherein the spring loaded plunger (A) opens
the inlet ports (104b and 105b) of each spool valve (104 and 105) which are
connected to the solenoid actuated cylinder (107) for supplying hydraulic fluid to
the spool valves (104 and 105) when pressure of hydraulic fluid flowing into the
spool valves (104 and 105) from the tandem master cylinder (103) is below
predetermined limit.
7. The system as claimed in claim 6, wherein the spring loaded plunger (A) closes
the inlet ports (104b and 105b) of each spool valve (104 and 105) which are
connected to the solenoid actuated cylinder (107) when pressure of hydraulic fluid
flowing into the spool valves (104 and 105) from the tandem master cylinder
(103) is above predetermined limit.
8. The system as claimed in claim 1, wherein the predetermined limit of pressure of
the hydraulic fluid ranges from about 1bar to about 3bar.
9. The system as claimed in claim 1 further comprises a reservoir (109) fluidly
connected to the tandem master cylinder (103) and the solenoid actuated cylinder
(107) for supplying hydraulic fluid to said cylinders (103 and 107).
10. The system as claimed in claim 1, wherein the tandem master cylinder (103), the
solenoid actuated cylinder (107), the spool valves (104 and 105) and a reservoir
(109) are connected to each other using atleast one of hoses and tubes (110).
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11. A vehicle comprising a hydraulic brake system as claimed in claim 1.