DESC:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
EMERGENCY BRAKING SYSTEM USING STORED HYDRAULIC ENERGY IN THE ACCUMULATOR

Applicant:
BEML Limited
A company Incorporated in India under the Companies Act, 1956
Having address:
BEML Soudha, 23/1, 4th Main,
Sampangirama Nagar, Bengaluru - 560 027,
Karnataka, India

The following specification particularly describes the invention and the manner in which it is to be performed.
CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY

[001] The present invention claims priority from Indian patent Provisional Application 202041012002 filed on 19 March 2020.
TECHNICAL FIELD
[002] The present subject matter described herein, in general, relates to an emergency braking system. More particularly, the emergency braking system using stored hydraulic energy in the accumulator.
BACKGROUND
[003] The emergency brakes are a secondary braking control system installed in vehicles. Emergency brakes are also known as e-brakes, hand brakes and parking brakes. The emergency brakes use independent power source to apply the service brakes used to slow and stop vehicles.
[004] During a normal working condition of vehicle, a dozer with hydrostatic steering system the operator stops the equipment by pressing the brake pedal by foot. This pedal is connected to a series of linkages, which in turn connected to the brake booster lever, which is assisted by hydraulic system in which the pressure fluid is supplied from the gear pump, which is coupled to the engine through power take off system. The steering brake is a fluid bath, anchor-type, contracting band brake, which can tighten the outer circumference of the brake drum. The service brake can also be used as a parking brake by depressing the brake pedal and applying the parking brake lock to keep the pedal depressed.
[005] When the engine is in shut down state due to various technical issues, the application of the brakes will becomes very difficult, because the hydraulic assistance is not available during engine off condition or pump failure condition. Because of the failure of braking function at emergency condition, high risk of accident arises.
[006] The Spring Applied Hydraulically Released (SAHR) technology in which mechanical actuator supplies the energy to apply the parking brake. If the spring fails in the SAHR design then the replacement of components are very difficult. Therefore, SAHR is time consuming, critical to design and costly.
[007] Hence, there is necessity of an emergency braking system, which allows the operator to perform the braking function even during the engine off condition.
SUMMARY
[008] Before the present system and method are described, it is to be understood that this application is not limited to the particular machine or an apparatus, and methodologies described, as there can be multiple possible embodiments that are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to emergency braking system using stored hydraulic energy in the accumulator and the aspects are further elaborated below in the detailed description. This summary is not intended to identify essential features of the proposed subject matter nor is it intended for use in determining or limiting the scope of the proposed subject matter.
[009] The present subject matter described herein, in general, relates to the emergency braking system and its purpose is to utilize available stored hydraulic energy in the accumulator for performing braking operations.
[0010] In order to reach above-mentioned purpose of the present invention, the invention is to provide the pressurized fluid to the brake booster at engine off condition; the pressurized fluid is stored in the accumulator as a backup system, which is provided, in the steering hydraulic circuit. During normal operation, the inside of the piston accumulator contains nitrogen gas in compressed form in order to store the hydraulic fluid at the required pressure. During the sudden engine switch off condition or at emergency, the pressurized fluid in the accumulator will be available at the brake booster for braking operation and there by stops the machine to avoid fatal accidents.
[0011] The emergency braking system is applicable to dozers with band brake with hydraulic steering system as well as pipe layers with band brake with hydraulic steering system.
STATEMENT OF INVENTION
[0012] According to the present subject matters discloses an emergency braking system comprises. The system comprise a steering pump configured to assist steering activity and a hydraulic braking circuit, at least one an accumulator configured for storing pressurized fluid, at least one check valve configured for suppling for pressurized fluid to the accumulator through tapped line from the hydraulic braking circuit. At least one shuttle valve configured for actuating a brake booster by optionally switching the supply between the steering pump and the accumulator based on normal working system and emergency braking system respectively.
[0013] In the system, the steering filter is configured to supply the filtered fluid flow towards a shuttle valve and a check valve. The tapped line is configured to connect with the accumulator to generate back up energy for emergency braking. The accumulator is configured to actuate the brake booster on failure of normal working system and to act as emergency braking system. The brake booster is configured for actuating a brake band. The accumulator is configured with nitrogen gas in compressed form to store the pressurized hydraulic fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The foregoing summary, as well as the following detailed description of embodiments, is better understood when read in conjunction with the appended drawing. For illustrating the disclosure, there is shown in the present document example constructions of the disclosure, however, the disclosure is not limited to the specific methods and apparatus disclosed in the document and the drawing.
[0015] The detailed description is described with reference to the accompanying figure. In the figure, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawing to refer like features and components.
[0016] Figure 1 illustrates an emergency braking system.
[0017] Figure 2 illustrates the braking mechanism while engine is in on condition.
[0018] Figure 3 illustrates the flow chart for emergency braking system for dozers.
[0019] The figure depicts various embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion 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
[0020] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising", “having”, and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary, systems and methods are now described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.
[0021] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated, but is to be accorded the widest scope consistent with the principles and features described herein.
[0022] The present subject matter relates to utilizing the stored energy in the accumulator (6) provided in the dozer steering hydraulic circuit in order perform braking operation at emergency condition or at engine off condition.
[0023] Referring now to figure 1, in one aspect of present invention that a steering case sump (1) is configured with a magnetic strainer (2), which further connected to a steering pump (3) and a steering filter (4). The filtered fluid flows from the steering filter (4) towards a shuttle valve (5) and a check valve (11). The fluid may be any type of oil. The check valve (11) further connected with an accumulator (6) and the shuttle valve (5) is connected to a brake booster (9) along with spool (8). The pressurized fluid is applied on the brake booster (9). Therefore, force gets exerted on brake band in order to execute braking operation.
[0024] Now referring to figure 2, in one aspect of present invention the figure 2 relates to the braking operation when the engine is in on condition.
[0025] Further referring to figure 3, The flowchart elaborates the braking operations for two conditions. The method to apply braking is as mentioned below:
[0026] Step 1 - At normal condition, as a vehicle’s engine is started the steering pump (3) gets coupled with the engine in order to deliver pressurized fluid to steering and brake booster.
[0027] Step 2 - This pressure fluid is tapped from the steering pump (3) line. Also, the pressured fluid is tapped by the accumulator (6) line to generate back up energy for emergency braking purpose. The accumulator (6) contains nitrogen gas in compressed form in order to store the hydraulic fluid at the required pressure. The accumulator (6) may be a piston type accumulator.
[0028] Step 3 - At emergency condition, when the vehicle or equipment is working on a gradient or when the equipment or vehicle needs to be stopped then the brake pedal needs to be engaged to apply the brakes.
[0029] Step 4 - At engine on condition, when brake pedal is depressed (brake applied) as shown in Figure 2 a lever (14) pushes a spool (8) to the left, and the flow of fluid at a port C and a port D is connected. Therefore, the fluid from the steering pump (3) flows through the shuttle valve (5) then passes from a port B and flows through an orifice (a) to the port C and D. When the hydraulic pressure at port D rises, it pushes a piston (12) to the left and connects the flow of fluid at the port D and the port A. The fluid then drains from the port A to the steering case. The brake pedal travels the same distance that piston (12) moves by slight depressing force, this movement of the piston (12), pedal and the fluid flow is repeated over a short period (follow-up movement). The spool (8) moves further to the left and connects the flow of fluid at the port B and the port D, which results into smooth contradiction in the volume of fluid band and the brake gets applied. In this way, the hydraulic pressure rises in two stages. Firstly, when the fluid pushes piston (12) lightly and secondly when the flow of fluid at port D and port B is connected, fluid gets pushed strongly. This prevents the brake from being applied suddenly.
[0030] In an exemplary embodiment for the engine on condition, when brake pedal is depressed fully (brake applied) then the brake pedal reaches the end of its travel and leads the flow of fluid at port D and port A remains shut off, therefore the hydraulic pressure rises further. Once the pressure reaches 28 kg/cm², the main relief valve (7) functions and the fluid flows into the lubrication circuit.
[0031] Step 5 – At engine off condition, when the engine is in off condition and emergency situation arises, then after the brake pedal is depressed the pressurized fluid stored in the accumulator is used for braking. Now referring to the Figure 2. during the sudden engine switch off and at emergency situation, when the brake pedal is depressed slightly the lever (2) pushes spool (8) to the left, and the flow of this pressurized fluid in the accumulator at the port C and the port D gets connected. Therefore, the fluid from the accumulator flows through the shuttle valve (5) then passes from the port B and flows through the orifice (a) to the port C and D.
[0032] Once the hydraulic pressure at the port D rises, it pushes piston (12) to the left and connects the flow of fluid at the port D and the port A. The fluid then drains from the port A to the steering case. The brake pedal travels the same distance that piston (12) moves by slight depressing force, this movement of the piston (12), pedal and the fluid flow is repeated over a short period (follow-up movement).The spool (8) moves further to the left and connects the flow of fluid at the port B and the port D. The volume of fluid flowing to the port D increases and the piston (12) moves faster. The piston (12) continues to push lever (13) leads to smooth contradiction of brake band (10) and the brake gets applied.
[0033] In another embodiment, an emergency braking system comprises, a steering pump (3) configured to assist steering activity and a hydraulic braking circuit, at least one an accumulator (6) configured for storing pressurized fluid, at least one check valve (11) configured for suppling for pressurized fluid to the accumulator (6) through tapped line from the hydraulic braking circuit. At least one shuttle valve (5) configured for actuating a brake booster (9) by optionally switching the supply between the steering pump (3) and the accumulator (6) based on normal working system and emergency braking system respectively.
[0034] In the system, the steering filter (4) is configured to supply the filtered fluid flow towards a shuttle valve (5) and a check valve (11). The tapped line is configured to be connect with the accumulator (6) to generate back up energy for emergency braking. The accumulator (6) is configured to actuate the brake booster (9) on failure of normal working system and to act as emergency braking system. The brake booster (9) is configured for actuating a brake band. The accumulator (6) is configured with nitrogen gas in compressed form to store the pressurized hydraulic fluid.
[0035] Exemplary system embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include those provided by the following features.
[0036] Some object of the invention is to provide emergency braking during the engine off condition.
[0037] Some object of the invention is to use the hydraulic pressure to braking system.
[0038] Part List
Part No. Part Name
1 Steering case sump
2 Magnet strainer
3 Steering pump (gear pump)
4 Steering filter
5 Shuttle valve
6 Accumulator
7 Relief valve
8 Spool
9 Brake booster (piston)
10 Brake Band
11 Check valve
12 Piston
13 Push lever
14 Lever
,CLAIMS:
1. An emergency braking system comprises;
a steering pump (3) configured to assist steering activity and a hydraulic braking circuit;
at least one an accumulator (6) configured for storing pressurized fluid;
at least one check valve (11) configured for suppling for pressurized fluid to the accumulator (6) through tapped line from the hydraulic braking circuit; and
at least one shuttle valve (5) configured for actuating a brake booster (9) by optionally switching the supply between the steering pump (3) and the accumulator (6) based on normal working system and emergency braking system respectively.
2. The system as claimed in claim 1, wherein the steering filter (4) is configured to supply the filtered fluid flow towards a shuttle valve (5) and a check valve (11).
3. The system as claimed in claim 1, wherein the tapped line is configured to be connect with the accumulator (6) to generate back up energy for emergency braking.
4. The system as claimed in claim 1, wherein the accumulator (6) is configured to actuate the brake booster (9) on failure of normal working system and to act as emergency braking system.
5. The system as claimed in claim 1, wherein the brake booster (9) is configured for actuating a brake band.
6. The system as claimed in claim 1, wherein the accumulator (6) is configured with nitrogen gas in compressed form to store the pressurized hydraulic fluid.