Description: DOUBLE DIAPHRAGM SPRING BRAKE ACTUATOR WITH
INTERNAL BREATHER UNIT AND OPERATION METHOD THEREOF
FIELD OF INVENTION
The present invention relates to the field of mechanics. Specifically, the present
5 invention relates to spring brake actuator. Particularly, the present invention relates
the Double Diaphragm spring brake actuator for the braking system for a vehicle.
More particularly, the present invention relates to a double diaphragm spring brake
actuator with internal breather unit for automobiles.
BACKGROUND OF THE INVENTION
10 In particular, trucks, trailers and other vehicles often have pneumatically operated
Double Diaphragm spring brake actuators, which provide the braking force
necessary to stop the vehicle. A brake pedal is positioned on the floor of the
vehicle's cab and, upon activation, causes pressurized air from a reservoir to enter
the Double Diaphragm spring brake actuator, which in turn causes a push rod to
15 extend out of the Double Diaphragm spring brake actuator and activate a wheel
brake. The wheel brake typically has brake shoes/brake pad with a brake lining
material that is pressed against a brake drum/disc at the vehicle wheel-end to
thereby brake the vehicle. The wheel brake often includes a slack adjustor which
turns a cam roller via a camshaft so as to force the brake shoes/brake pad to engage
20 the brake drum/disc and brake the vehicle, also it is applicable for both drum &
Disc brake actuator. Releasing the pressurized air from the air chamber allows a
spring within the air chamber to retract the push rod back to its original position.
In general, it is well known to employ so-called “spring brake” actuators to provide
service, parking and emergency brake operation on vehicles such as commercial
25 trucks, tractors and trailers equipped with lever-operated drum or disc brakes.
Spring-type brake actuators are typically pneumatically operated and are supplied
with operating air from a compressed air source on the vehicle. These actuators also
3
typically are arranged in a “fail-safe” manner, i.e., where the actuator defaults to a
brake function state upon loss of operating air pressure.
There are few reports available in the literature about the existence of various types
of double diaphragm spring brake actuator.
5 US11209058B2 discloses a spring brake actuator for braking a wheel of a vehicle.
The spring brake actuator has an axially elongated housing having a parking brake
chamber and a service brake chamber; a main compression spring in the parking
brake chamber; a flexible diaphragm in the parking brake chamber; and a pressure
plate in the parking brake chamber, the pressure plate located axially between the
10 main compression spring and the flexible diaphragm. The flexible diaphragm has a
contoured portion that inhibits radial shifting of the pressure plate with respect to
the flexible diaphragm.
US9592813B2 discloses an actuator assembly for a parking brake system. The
present invention also includes is an assembly that includes a spindle; a brake cable
15 in communication with the spindle; and a spring in communication with the spindle.
Movement of the spindle in a first direction causes the brake cable to move so that
a clamping force is created. Movement of the spindle in a second direction causes
the brake cable to move in a second direction so that the clamping force is released.
Movement of the spindle in both the first direction and the second direction causes
20 the spring to compress so that a controller can determine when the clamping force
is created and released.
EP4015323A2 discloses a spring brake actuator (2) for use in a commercial vehicle,
said actuator (2) comprising a service brake portion (4) and a spring brake portion
(6), said spring brake portion (6) having a housing (8, 108) comprising: - a first end
25 (10, 110) being proximal to the service brake portion (4), - a wall section (12, 112)
extending from the first end (10, 110), - a second end (14,114) being distal to the
service brake portion (4), and - a locking mechanism (16, 116) for locking the ends
(10, 110, 14,114) to the wall section (12, 112), characterized in that the locking
4
mechanism (16, 116) is arranged between the wall section (12, 112) and the second
end (14, 114) of said housing (8, 108).
Moreover, from the above cited literature it is clearly evident that the commercially
available spring brake actuator with internal breather in the market have their own
5 advantages.
Furthermore, the above-mentioned prior arts don’t provide sufficient details about
the functioning and construction of the double diaphragm spring brake actuator and
key components which lead to lack of potential, lack of combination of dual
mechanism, also few of the prior arts are provided with an inefficient and
10 inconvenient designs which is not user-friendly, inefficient and leads to
cumbersome in usage.
To overcome the existing drawbacks and issues one solution is the introduction of
double diaphragm spring brake actuator. This invention relates to the traditional
knowledge of mechanical engineering, compliant mechanisms, and structural
15 engineering. However, the present invention mainly focuses on designing and
developing a method of operation of double diaphragm spring brake actuator with
internal breather Unit (500) for automobiles. Hence, there exists an urgent need in
the state of art to develop and design a novel a double diaphragm spring brake
actuator with internal breather Unit (500).
20 OBJECTIVES OF THE INVENTION
The major objective of the present invention is to provide a novel spring brake
actuator.
Another objective of the present invention is to provide a novel double diaphragm
spring brake actuator with internal breather Unit (500) for automobiles.
25 Another objective of the present invention is to provide a method of operation of
double diaphragm spring brake actuator with internal breather Unit (500).
5
Further another objective of the present invention is to utilize the developed double
diaphragm spring brake actuator with internal breather Unit (500) for automobiles.
SUMMARY OF THE INVENTION
Accordingly, major aspect of a double diaphragm spring brake actuator with
5 internal breather unit of the present invention discloses a novel double diaphragm
spring brake actuator, comprising a service brake (1), a parking brake (2), and
internal breather Unit (500) a service brake (1) comprising a diaphragm - A (3), a
push rod with clevis assembly (4), a non-pressure plate assembly (5), and a return
spring (6); a parking brake (2) comprising a rear shell (7), a power spring (8), a
10 spring guide (9), an adaptor (10), a diaphragm - B (11), a pusher rod assembly (12),
a flange (13), a spring room (14), a seal (19) & Guide ring (20) assembled in a
groove of the flange (13), and an internal breather Unit (500) ; comprising a spring
(15) assembled in a rod groove of the pusher rod assembly (12), a plug (16), a cap
(17), and O-rings (18) assembled in the rod of the pusher rod assembly (12); thereby
15 allowing atmospheric air from a port to flow to the spring room (14) during parking
brake function, depleting vacuum pressure in the spring room (14) during parking
brake apply & depleting over pressure in the spring room (14) during parking brake
release condition , an Unit (500) O-ring (18b) assembled in a cap groove (17a), a
cap (17b) interference / Threaded lock assembled in the pusher rod assembly (12c),
20 a cap emboss (17c) guiding the plug (16b), and an O-ring (18a) axially inserted
inside the pusher rod assembly (12d) for radial sealing; thereby Unit (500) allowing
air flow through the radial clearance between the rod ID (12b) and plug OD (16c)
during parking brake apply/release; internal breather Unit (500) aids in sealing
between the rod face (12f) and plug sealing bead (16d) during compounding brake
25 function.
Also, the present invention discloses the double diaphragm spring brake actuator
comprising a spring lock arrangement for a pusher rod assembly characterized in
that an internal breather valve assembly positioned within the pusher rod assembly,
30 in which rod with a machining profile arrangement, plug with a profile
6
arrangement, a spring member guide and interference lock arrangement, radial
clearance or radial flow area defined by the internal breather valve, rod hole
diameter providing four equal effective flow passages, ventilation arrangements for
both the rod and plug, an adaptor and spring guide ventilation arrangement, a spring
5 guide hole and slot configuration, ensuring two equal effective flow passages,
sealing arrangement between the rod and plug.
BRIEF DESCRIPTION OF DRAWINGS
10 Figure 1 depicts the Double Diaphragm Spring brake actuator of the present
invention.
Figure 2 depicts the Internal Breather Unit (500) of the present invention.
Figure 3 depicts the Parking brake apply condition of the present invention.
Figure 4 depicts the Parking brake release condition of the present invention.
15 Figure 5 depicts the compounding brake apply condition of the present invention.
Figure 6 depicts the Parking brake apply condition in Internal Breather Unit (500)
of the present invention.
Figure 7 depicts the Parking brake release condition in Internal Breather Unit (500)
of the present invention.
20 Figure 8 depicts the Compounding brake application in Internal Breather Unit (500)
of the present invention.
Figure 9 depicts the Internal Breather Units Push Rod Machining profile
arrangement in Internal Breather Unit (500) of the present invention.
Figure 10 depicts the Internal Breather valve Plug profile arrangement in Internal
25 Breather Unit (500) of the present invention.
Figure 11 depicts the Radial sealings of the present invention.
Figure 12 depicts the internal breather units spring guide casting/machined profile
arrangement in internal breather unit (500) of the present invention.
REFERENCE NUMERALS:
7
Table 1: Reference numerals for “A DOUBLE DIAPHRAGM SPRING BRAKE
ACTUATOR WITH INTERNAL BREATHER UNIT (500) AND
OPERATION METHOD THEREOF” of the present invention:
S.NO PART NAME PART NUMBER
1 Service Brake (1)
2 Parking Brake (2)
3 Diaphragm - A (3)
4 A Push Rod with Clevis Assembly (4)
5 A Non-Pressure Plate Assembly (5)
6 A Return Spring (6)
7 Rear Shell (7)
8 Power Spring (8)
9 Spring Guide (9)
10 an adaptor (10)
11 Diaphragm-B (11)
12 pusher rod assembly (12)
13 Components of Internal Breather Unit
Push Rod with multiple contours
(12a) (12b) (12c) (12d)
(12e) (12f) & (12g)
14 Flange (13)
15 Spring room (14)
16 Spring with front end and rear end (15) (15a & 15b)
17 Plug having multiple contours (16), (16a,16b,16c & 16d)
18 Cap with contours (17), (17a, 17b, 17c)
19 O-rings with ends (18), (18a & 18b)
20 Lip Seal (19)
21 Guide ring (20)
22 Internal breather Unit (500)
5
8
DETAILED DESCRIPTION OF THE INVENTION
The present invention as embodied by “A DOUBLE DIAPHRAGM SPRING
BRAKE ACTUATOR WITH INTERNAL BREATHER UNIT AND
OPERATION METHOD THEREOF”, succinctly fulfils the abovementioned
5 need(s) in the art. The present invention has objective(s) arising as a result of the
above-mentioned need(s), said objective(s) being enumerated below. In as much as
the objective(s) of the present invention are enumerated, it will be obvious to a
person skilled in the art that the enumerated objective(s) are not exhaustive of the
present invention in its entirety, and are enclosed solely for the purpose of
10 illustration. Further, the present invention encloses within its scope and purview,
any structural alternative(s) and/or any functional equivalent(s) even though such
structural alternative(s) and/or any functional equivalent(s) are not mentioned
explicitly herein or elsewhere, in the present disclosure. The present invention
therefore encompasses also, any improvisation(s)/modification(s) applied to the
15 structural alternative(s)/functional alternative(s) within its scope and purview. The
present invention may be embodied in other specific form(s) without departing
from the spirit or essential attributes thereof.
Throughout this specification, the use of the word "comprise" and variations such
as "comprises" and "comprising" may imply the inclusion of an element or elements
20 not specifically recited.
The present invention relates to internal Breather Unit (500) in Double Diaphragm
Spring Brake Actuator for vehicles. The Double Diaphragm Spring Brake Actuator
is a device used to convert pneumatic pressure energy into mechanical output force.
It consists of both Service brake and Parking brake components.
25 Service Brake:
The Service brake portion of the actuator includes a Diaphragm, Push rod with
Clevis assembly, non-pressure plate assembly, and a return spring.
Parking Brake:
9
The Parking brake section of the actuator consists of a Rear shell, power spring,
spring guide, Adaptor, Diaphragm, Pusher rod assembly, flange, Spring room, and
internal breather Unit (500).
In reference to Figure 1 and Figure 2, is illustrated an Internal Breather Unit (500)
5 consist of spring (15) Assembled in the rod groove of Pusher rod Assembly (12),
Plug (16), Cap (17), & O-rings (18) assembled in the Rod of Pusher rod assembly
(12). Seal (19) & Guide ring (20) is assembled in flange (13) Groove. The internal
breather valve fitted inside the Pusher Rod assembly (12) of the Double Diaphragm
Spring Brake Actuator.
10 Reference is drawn to Figure 10 and 11, Spring (15a) is assembled in Pusher rod
Assembly Groove (12a). Plug (16a) insert with spring (15b), the elastic member
(15) helps to open the valve in vacuum condition. Spring (15a) Top end is placed
in rod of Pusher rod assembly (12a) & another end (15b) on plug (16a). Plug (16)
& Spring (15) properly displaced inside the Rod of Pusher rod assembly (12b).
15 Spring aids in the valve open and closing condition. O-ring (18b) is assembled in
Cap Groove (17a). Cap (17b) interference lock/ threaded lock assembled in Pusher
rod assembly (12c).
In reference to Figure 11, Cap emboss (17c) is configured to guide the plug (16b).
O-Ring (18a) is axially inserted in the inside of the Pusher rod assembly (12d). It is
20 Radially sealing (18b), (17a) & (18a), (12d) the pressure of the service side. During
parking brake (2) function, spring (8) start to expand & moves the spring guide (9),
Diaphragm (11) and Pusher rod assembly (12), so volume increase happens in
spring room (14). This volume increase causes vacuum pressure in spring room
(14). Atmospheric air from the port (Via DBV/ Relay valve/modulator valve/Quick
25 Release valve) flows to the spring room (14) through the hole provided in the rod
of Pusher rod Assembly (12e), Rod ID (12b), plug OD (16c), rod vented hole (12g),
Adaptor (10), Spring Guide slot (9a) & Spring Guide vented hole (9b). This vacuum
in spring room (14) is depleted (Figure 6 & 3).
10
From Figure 7 & 4 it is clearly inferred that during Parking brake (2) release, air
load will be Applied over Diaphragm (11), Spring guide (9), so spring (8) get
compressed, volume reduction takes place in spring room (14). This causes over
pressure built in the spring room (14). This over pressure will be depleted through
5 port (Via DBV/ Relay valve/ modulator valve/ Quick Release valve) through the
hole provided in the Rod of Pusher rod Assembly (12e), Rod ID (12b), plug OD
(16c), Rod vented hole (12g), Adaptor (10), Spring Guide slot (9a) & Spring Guide
vented hole (9b). This Over Pressure in spring room (14) is depleted.
From Figure 2 & 11, it is clearly inferred that in both Parking brake apply/ release
10 IBV valve will be in normally open condition, Air flows through the Radial
clearance between Rod ID (12b) & Plug od (16c). Moreover, figure 2 is in open
condition and figure 11 is in closed condition.
From Figure 5 & 8, it is clearly inferred that during compounding brake function,
both parking brake (2) and service brake (1) are applied. Air pressure in service
15 chamber flows through the Pusher rod Assembly hole (12e) Internal Breather parts
like Rod (12) and plug (16). Due to the air load acts on plug top side (16b), by
compressing spring (15) sealing happens between Rod face (12f) and plug sealing
bead (16d) also explained in Figure11.
SERVICE BRAKE WORKING:
20 During normal vehicle condition, parking brake power spring (8) is
compressed/caged by means of air pressure applied in port is clearly explained in
Figure 1. During service brake (1) function, pressurized air is supplied from
reservoir to port, which acts on the diaphragm (3), the pressure energy is converted
into linear mechanical force and transferred to ‘S’ cam through push rod with Clevis
25 assembly (4), & Slack Adjuster. Hence brake is applied.
PARKING BRAKE FUNCTION:
11
During Parking brake (2) function, air pressure from the port will be depleted to
atmosphere. This air pressure release allows power spring (8), Spring Guide (9),
Diaphragm (11) & Pusher rod Assembly (12) start to expand and spring force is
transferred to slack adjuster via push rod with Clevis assembly (4). Slack Adjuster
5 convert liner motion to rotary motion & Transfer output force to ‘S’ cam Shaft and
brake is applied.
During parking brake (2) function, air pressure from port is exhausted through
graduated hand control valve. so heavy coil spring (8) starts to expand and applies
the parking brake. Due to the spring (8), Spring guide (9), Diaphragm (11) and
10 Pusher rod assembly (12) movement, volume increase happens in spring room (14).
This causes vacuum pressure in spring room (14). Atmospheric air from the port
(Via DBV/ Relay valve/Modulator valve/Quick Release valve) flows to the spring
room (14) through the hole provided in the rod of Pusher rod Assembly (12),
annular clearance between Plug (16) & pusher rod (12), Adaptor (10) and Spring
15 Guide (9). This vacuum in spring room (14) is depleted.
PARKING BRAKE RELEASE:
Parking brake (2) release of the present invention involves the air pressure, which
is applied through port through graduated hand control valve. So Heavy coil spring
(8) start to be compressed, and parking brake (2) is released. Due to the Spring (8),
20 Spring Guide (9), Diaphragm (11), and Pusher rod assembly (12) movement,
volume reduction happened in spring room (14). This causes over pressure built in
the spring room (14). Over pressure in the spring room (14) will be depleted through
port via, Spring Guide (9), Adaptor (10), annular clearance between plug (16) &
Rod hole in Pusher rod assembly (12) and seal (19).
25 In both Parking brake apply/ release IBV valve will be in normally open condition.
During compounding brake function, both parking brake (2) and service brake (1)
will be applied, Air pressure will be depleted in Port and air applied in port. The
12
flow of air from service port to spring room is prevented by closure of hole in pusher
rod assembly (12) by plug (16), due to air pressure load acting on top side.
The present invention prevents dust & mud water entry to the spring room, which
helps to improve the life of the spring room parts.
5 In reference to Figure 11 it is clearly inferred that the internal breather valve is fitted
inside the Pusher Rod assembly (12) of the Double Diaphragm Spring Brake
Actuator. Spring (15a) is assembled in Pusher rod Assembly Groove (12a). Plug
(16a) insert with spring (15b). The elastic member (15) helps to open the valve in
vacuum condition. Spring (15a) top end placed in rod of Pusher rod assembly (12a)
10 Fig (9) & (11) & another end (15b) on plug (16a) (Figure 10 & 11). Plug (16) &
Spring (15) properly displacement inside the Rod of Pusher rod assembly (12b).
Spring aid is provided for the valve open and closing condition. O-ring (18b) is
assembled in Cap Groove (17a). Cap (17b) interference / Threaded lock assembled
in Pusher rod assembly (12c). Cap emboss (17c) help to guide the plug (16b). O15 Ring (18a) axially insert in the inside of the Pusher rod assembly (12d). It is
Radially sealing (18b), (17a) & (18a), (12d) the pressure of the service side.
From figure (3) & (6), it is clearly inferred that during parking brake (2) function,
spring start to expand & moves the spring guide (9), Diaphragm (11) and Pusher
rod assembly (12), so volume increase happens in spring room (14). This causes
20 vacuum pressure in spring room (14). Atmospheric air from the port (Via DBV/
Relay valve/modulator valve/Quick Release valve) flows to the spring room (14)
through the hole provided in the rod of Pusher rod Assembly (12e), Rod ID (12b),
plug OD (16c), rod vented hole (12g), Adaptor (10), Spring Guide slot (9a) &
Spring Guide vented hole (9b). This vacuum in spring room (14) is depleted.
25 During Parking brake (2) release, air load will be Applied over Diaphragm (11),
Spring guide (9), so spring (8) get compressed, volume reduction happened in
spring room (14). This causes over pressure built in the spring room (14). This over
pressure will be depleted through port (Via DBV/ Relay valve/ modulator valve/
Quick Release valve) through the hole provided in the Rod of Pusher rod Assembly
13
(12e), Rod ID (12b), plug OD (16c), Rod vented hole (12g), Adaptor (10), Spring
Guide slot (9a), Spring Guide vented hole (9b) & lip seal (19). This Over Pressure
in spring room (14) is depleted.
In both Parking brake apply/ release IBV valve will be in normally open condition,
5 Air flows through the Radial clearance between Rod ID (12b) & Plug od (16c).
From figure (5) & (8), it is clearly inferred that during compounding brake function
(Figure 8), both parking brake (2) and service brake (1) are applied. Air pressure in
service chamber flows through the Pusher rod Assembly hole (12e), internal
breather parts like rod (12) and plug (16). Due to the air load acting on plug top side
10 (16b), by compressing spring (15) sealing happens between Rod face (12f) and plug
sealing bead (16d).
Furthermore, from the figure 11, it is clearly inferred that Spring lock arrangement
on pusher rod assembly and internal breather valve assembly inside the pusher rod
assembly arrangements, Plug & spring member guide & interference lock
15 arrangement, Radial clearance or radial flow area of the internal breather valve, Rod
hole diameter & 2/4 equal effective flow passage, Rod & Plug ventilation
arrangement, Rod & Plug sealing arrangement, Cap & O- ring radial sealing
arrangement, Plug & spring Travel inside the rod arrangement, Cap emboss & plug
guide profile arrangement. Also, from the figure 9 Internal breather valve Assembly
20 inside the Pusher rod Assembly arrangements. Also, figure 12 spring guide air
ventilation, Figure 10 Plug sealing & profile arrangement.
In a preferred embodiment, the present invention discloses a novel double
diaphragm spring brake actuator, comprising:
25 a) a service brake (1),
b) a parking brake (2), and
c) internal breather Unit (500)
14
a service brake (1) comprising a diaphragm - A (3), a push rod with
clevis assembly (4), a non-pressure plate assembly (5), and a return
spring (6);
a parking brake (2) comprising a rear shell (7), a power spring (8), a
5 spring guide (9), an adaptor (10), a diaphragm - B (11), a pusher rod
assembly (12), a flange (13), a spring room (14),
a seal (19) & Guide ring (20) assembled in a groove of the flange (13),
and an internal breather Unit (500) ; comprising a spring (15) assembled
in a rod groove of the pusher rod assembly (12), a plug (16), a cap (17),
10 and O-rings (18) assembled in the rod of the pusher rod assembly (12);
thereby allowing atmospheric air from a port to flow to the spring room
(14) during parking brake function, depleting vacuum pressure in the
spring room (14) during parking brake apply & depleting over pressure
in the spring room (14) during parking brake release condition , an Unit
15 (500) O-ring (18b) assembled in a cap groove (17a), a cap (17b)
interference / Threaded lock assembled in the pusher rod assembly
(12c), a cap emboss (17c) guiding the plug (16b), and an O-ring (18a)
axially inserted inside the pusher rod assembly (12d) for radial sealing;
thereby Unit (500) allowing air flow through the radial clearance
20 between the rod ID (12b) and plug OD (16c) during parking brake
apply/release; internal breather Unit (500) aids in sealing between the
rod face (12f) and plug sealing bead (16d) during compounding brake
function.
25 In accordance with the present invention, the internal breather Unit (500)
comprises an elastic member aid to open the valve in vacuum conditions,
and O-rings to provide radial sealing and pressure sealing.
As per the present invention, the pusher rod assembly (12) further comprises
30 a rod vented hole (12g) for air flow.
15
In another embodiment the present invention comprising a spring lock
arrangement for a pusher rod assembly characterized in that
an internal breather valve assembly positioned within the pusher rod
assembly,
5 wherein rod with a machining profile arrangement, plug with a
profile arrangement, a spring member guide and interference lock
arrangement, radial clearance or radial flow area defined by the
internal breather valve, rod hole diameter providing four equal
effective flow passages, ventilation arrangements for both the rod
10 and plug, an adaptor and spring guide ventilation arrangement, a
spring guide hole and slot configuration, ensuring two equal
effective flow passages, sealing arrangement between the rod and
plug.
15 As per the present invention, the closing pressure of the internal breather
valve is less than 2.5 bar.
As per the present invention, the overpressure generated in the spring room
(14) ranges from 1.0 to 2.5 bar due to the internal breather valve.
20
In accordance with the present invention, the vacuum pressure generated in
the spring room (14) is less than 1.0 bar due to the internal breather valve.
In yet another embodiment the present invention discloses a method of
25 operation of double diaphragm spring brake actuator as described above,
a) supplying pressurized air from a reservoir to a port, which acts
on a diaphragm, converting the pressure energy into linear
mechanical force, and transferring the force to an 'S' cam through
a push rod with clevis assembly and a slack adjuster,
30 b) depleting air pressure from a port to atmosphere, allowing a
power spring, a spring guide, a diaphragm, and a pusher rod
16
assembly to expand, and transferring spring force to a slack
adjuster via a push rod with clevis assembly,
c) applying air pressure through a port, compressing a heavy coil
spring, and releasing the parking brake,
5 d) allowing atmospheric air from a port to flow to the spring room
through a hole provided in the rod of the pusher rod assembly,
an annular clearance between a plug and the pusher rod, an
adaptor, and a spring guide,
e) allowing over pressure to be depleted through a port via a spring
10 guide, an adaptor, an annular clearance between a plug and the
rod hole in the pusher rod assembly, and a seal,
f) depleting air pressure in a port and applying air pressure in
another port, preventing the flow of air from the service port to
the spring room by closing a hole in the pusher rod assembly
15 with a plug due to air pressure load acting on the top side.
In further embodiment the present invention discloses the step of venting
atmospheric air as described above from a port to a spring room (14) through the
rod vented hole (12g) in a parking brake function.
20
It will be apparent to a person skilled in the art that the above description is for
illustrative purposes only and should not be considered as limiting. Various
modifications, additions, alterations, and improvements without deviating from the
spirit and the scope of the invention may be made by a person skilled in the art.
, Claims:WE CLAIM:
1. A double diaphragm spring brake actuator, comprising:
5 a) a service brake (1),
b) a parking brake (2), and
c) internal breather Unit (500)
a service brake (1) comprising a diaphragm - A (3), a push rod with
clevis assembly (4), a non-pressure plate assembly (5), and a return
10 spring (6);
a parking brake (2) comprising a rear shell (7), a power spring (8), a
spring guide (9), an adaptor (10), a diaphragm - B (11), a pusher rod
assembly (12), a flange (13), a spring room (14),
a seal (19) & Guide ring (20) assembled in a groove of the flange (13),
15 and an internal breather Unit (500) ; comprising a spring (15) assembled
in a rod groove of the pusher rod assembly (12), a plug (16), a cap (17),
and O-rings (18) assembled in the rod of the pusher rod assembly (12);
thereby allowing atmospheric air from a port to flow to the spring room
(14) during parking brake function, depleting vacuum pressure in the
20 spring room (14) during parking brake apply & depleting over pressure
in the spring room (14) during parking brake release condition , an Unit
(500) O-ring (18b) assembled in a cap groove (17a), a cap (17b)
interference / Threaded lock assembled in the pusher rod assembly
(12c), a cap emboss (17c) guiding the plug (16b), and an O-ring (18a)
25 axially inserted inside the pusher rod assembly (12d) for radial sealing;
thereby Unit (500) allowing air flow through the radial clearance
between the rod ID (12b) and plug OD (16c) during parking brake
apply/release; internal breather Unit (500) aids in sealing between the
rod face (12f) and plug sealing bead (16d) during compounding brake
30 function.
18
2. The double diaphragm spring brake actuator as claimed in claim 1,
wherein the internal breather Unit (500) comprises an elastic member aid to
open the valve in vacuum conditions, and O-rings to provide radial sealing
and pressure sealing.
5
3. The double diaphragm spring brake actuator as claimed in claim 1,
wherein the pusher rod assembly (12) further comprises a rod vented hole
(12g) for air flow.
10 4. The double diaphragm spring brake actuator as claimed in claim 1,
comprising a spring lock arrangement for a pusher rod assembly
characterized in that
an internal breather valve assembly positioned within the pusher rod
assembly,
15 wherein rod with a machining profile arrangement, plug with a
profile arrangement, a spring member guide and interference lock
arrangement, radial clearance or radial flow area defined by the
internal breather valve, rod hole diameter providing four equal
effective flow passages, ventilation arrangements for both the rod
20 and plug, an adaptor and spring guide ventilation arrangement, a
spring guide hole and slot configuration, ensuring two equal
effective flow passages, sealing arrangement between the rod and
plug.
25 5. The double diaphragm spring brake actuator as claimed in claim 1,
wherein the closing pressure of the internal breather valve is less than 2.5
bar.
6. The double diaphragm spring brake actuator as claimed in claim 1,
30 wherein overpressure generated in the spring room (14) ranges from 1.0 to
2.5 bar due to the internal breather valve.
19
7. The double diaphragm spring brake actuator as claimed in claim 1,
wherein vacuum pressure generated in the spring room (14) is less than 1.0
bar due to the internal breather valve.
5 8. A method of operation of double diaphragm spring brake actuator as
claimed in claim 1, comprising:
a) supplying pressurized air from a reservoir to a port, which acts
on a diaphragm, converting the pressure energy into linear
mechanical force, and transferring the force to an 'S' cam through
10 a push rod with clevis assembly and a slack adjuster,
b) depleting air pressure from a port to atmosphere, allowing a
power spring, a spring guide, a diaphragm, and a pusher rod
assembly to expand, and transferring spring force to a slack
adjuster via a push rod with clevis assembly,
15 c) applying air pressure through a port, compressing a heavy coil
spring, and releasing the parking brake,
d) allowing atmospheric air from a port to flow to the spring room
through a hole provided in the rod of the pusher rod assembly,
an annular clearance between a plug and the pusher rod, an
20 adaptor, and a spring guide,
e) allowing over pressure to be depleted through a port via a spring
guide, an adaptor, an annular clearance between a plug and the
rod hole in the pusher rod assembly, and a seal,
f) depleting air pressure in a port and applying air pressure in
25 another port , preventing the flow of air from the service port to
the spring room by closing a hole in the pusher rod assembly
with a plug due to air pressure load acting on the top side.
9. The method of operation of double diaphragm spring brake actuator
30 as claimed in claim 4, wherein the step of venting atmospheric air from a
20
port to a spring room (14) through the rod vented hole (12g) in a parking
brake function.
Dated this 15
th day of May 2024
5 -SDKalyanchand Jhabakh (IN/PA-830)
Agent for Applicant