DESC:FORM 2

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

COMPLETESPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
A HYDRAULIC SYSTEM FOR DOZER APPLICATION

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 application numbered 202041008688 filed on 28 February 2020.

TECHNICAL FIELD
[002] The present invention relates toa dozer vehicle application and more particularly it relates to a hydraulic system for dozer application

BACKGROUND
[003] The existing hydraulic system is of an open centre type and consists a gear pump driven through power take off (PTO). Hydraulic fluid passes from the pump to a directional control valve. The hydraulic fluid is then directed to reservoir tank during no actuation of cylinders or to a working cylinder when cylinders are actuated.

[004] However, considerable amount of hydraulic power during neutral is converted in to heat and raises the hydraulic oil temperature, which further reduces the shelf life of the hydraulic components and leads to power loss. There is a need to reduce heat losses, which further reduces load on engine and increases fuel economy.

OBJECT OF THE INVENTION
[005] The object of the invention is to provide a hydraulic system for dozer application.

[006] Another object of the invention to provide a hydraulic system for dozer application that has reduced heat losses, thereby reduced power loss and minimizing the risk of overheating of hydraulic oil.

[007] Yet another object of the invention is to provide a hydraulic system for dozer application that reduces load on engine, thereby increases the fuel economy of engine.

[008] Yet another object of the invention is to provide a hydraulic system for dozer application that enhances the shelf life of the hydraulic components.

SUMMARY
[009] Before the present system is 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 embodiment that are not expressly illustrated in the present disclosure. It is also to be understood that the terminology used in the description is for the purpose of describing the particular version or embodiment only and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to a hydraulic system for dozer and the aspects are further elaborated below in 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.

[0010] The present invention discloses a hydraulic system for dozer application comprising a piston pump and a control valve, both of which communicate with a Load sensing (LS) line in the hydraulic system. A manifold block circuit is configured to remove the pilot pump from the circuit and utilize available oilflow of the piston pump for pilot operations. The system monitors the pressure of all the hydraulic cylinders and controls the angle of the swash plate to meet the demands of the cylinders, which ever has the highest-pressure level.

BRIEF DESCRIPTION OF DRAWINGS
[0011] The foregoing summary, as well as the following detailed description of embodiment, is better understood when read in conjunction with the appended drawing. For the purpose of illustrating the disclosure, however, the disclosure is not limited to the specific methods and apparatus disclosed in the document and the drawing.

[0012] 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.
[0013] Figure 1 illustrates block diagram of the hydraulic system for dozer application, in accordance to the present disclosure.
[0014] Figure 2 illustrates the circuit diagram of the hydraulic system for dozer application.

[0015] Figure depicts various embodiments of the present disclosure for purpose of illustration only. Only 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
[0016] 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 similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary, hydraulic system for dozer application are now described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.

[0017] Various modification to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to another embodiment. 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.

[0018] The disclosure herein provides a hydraulic system for dozer applications; wherein the hydraulic system has reduced heat losses, thereby reduced power loss and minimizing the risk of overheating of hydraulic oil. It reduces load on engine, thereby increases the fuel economy of engine. The shelf life of the hydraulic components is enhanced as the load on the engine decreases. It is to be noted that the heat losses in an existing hydraulic systems may be reduced by reducing the hydraulic oil flow to control valve during idle time of 60~65 % of work cycle, wherein the hydraulic system in turn reduces load on engine and increases fuel economy. By using a variable-displacement piston pump, the flow of oil in a particular cycle may be varied keeping the operating speed constant.

[0019] Figure 1 shows the block diagram of the present hydraulic system for dozer application. Figure 2 shows the circuit diagram of the hydraulic system. Referring to Fig, 1 and 2, the hydraulic system may comprises of piston pump (1), a hydraulic tank (6),and a control valve (2); wherein the piston pump (1) is connected to the hydraulic tank (6) and the control valve (2) and wherein the control valve (2) comprises a closed centre load sensing system(CLSS system). The piston pump (1) is also connected to a manifold block (5) through a filter. The piston pump (1) is configured to draw oil from the hydraulic tank (6) and deliver minimum flow at a pressure of 16 bar in the neutral condition. The pilot manifold (5) once charged to 30bar and no joystick (3) is operated, the pilot manifold does not receive oil from piston pump (1) and no relief loss in pilot system in neutral condition. The LS system in the control valve (2) is configured to monitor the load pressures on the system’s cylinders in order to control oil flow from the pump (1).

[0020] Further, the piston pump (1) and the control valve (2) are linked with a Load sensing (LS) line in the hydraulic system; wherein the LS system is configured to sense a load-induced pressure in control valve (2) is sensed by and the oil flow is adjusted to maintain the demand by the actuator. The LS system is provided to monitor pressures of all the hydraulic cylinders and to control the angle of a swash plate of the piston pump (1) to meet the demands of the cylinders that has the highest pressure level.

[0021] In an embodiment, the piston pump (1) may be a variable piston pump, an axial piston pump or alike. The control valve (2) may be a pilot actuated type, proportional direction control valve; wherein the control valve (2) controls the direction of flow inside the hydraulic system.

[0022] In an embodiment of the disclosure, a LS port of the control valve (2) is connected to a load-signal port (X) of the piston pump (1) controller through a hose; wherein the load-signal port in the control valve (2) connects ports A and B of each section of the control valve (2) through a series of shuttle valves. This connection ensures that the actual pressure at the cylinder is fed to the pump (1) and the pump (1) accordingly strokes to meet flow demand by the cylinder.

[0023] Further said manifold block (5) comprises an accumulator; wherein the accumulator facilitates storage of pressurized oil and to utilise the pressurised oil in order to bring down a Blade of the dozer, if it is in lifted condition and the engine is turned off. The manifold block (5) also comprises a built-in additional emergency blade lowering system; wherein the blade lowering system lowers down the blade to the ground to act as brake in case the accumulator is completely discharged. A blade lift cylinder rod connected to the manifold block by button filter (8) and connected to 'C" port of manifold is configured to assist the emergency lowering system to lower the blade.

[0024] Further, the system comprises of an additional safety hydraulic cut-off switch (cut off switch); wherein the cut-off switch is configured to cut off the supply to joystick (3) thereby preventing the danger of unintended fall down of blade, during maintenance or service of work attachment.

[0025] Further the operations of the hydraulic system are controlled by actuating a joystick (3), wherein the joystick (3) may be a proportional pressure reducing valve is used to control implement operations of hydraulic dozer. It is a light weighted touch control system device wherein an operator can control all the operations of the hydraulic system such as blade up/lower, blade tilt etc., from a cabin. The joystick (3) controls the operations of the control valve for all the implement operation. The pressure energy source for operating the joystick (3) is received from the piston pump (1) system, accumulator backup and also from Blade lift cylinder line stored energy for hazard free equipment operations.

[0026] Further the hydraulic system comprises a flow and pressure compensator, wherein the flow and pressure compensator match pump output flow and pressure to system demand. Thereby the flow and pressure compensator may automatically regulate pump displacement to deliver the oil flow required to maintain a constant pressure drop across a valve spool or other flow limiting device. The pressure compensator section of the controller is configured to automatically de-stroke when the pre–adjusted maximum system pressure is reached to protect the system from infinite load pressures.

[0027] In an embodiment a return line filter is connected to the hydraulic tank (6) and a main junction block; wherein the return line filter (4) cleans the oil from the main junction block.

[0028] Further, the invention can be used, but not limited to, in the following applications.

[0029] A hydraulic system for dozer application comprises of a control valve (2) configured with a centre load sensing system (CLSS) to monitor the load pressures on the system’s cylinders to control oil flow from the piston pump (1). A piston pump (1) configured to draw oil from the hydraulic tank (6) and deliver at least pressure of 16 bar in the neutral condition. A manifold block (5) configured to be charged at 30 bar without joystick (3) operation, to prevent relief loss in pilot system in neutral condition. The CLSS is configured to monitor pressures of all the hydraulic cylinders and to control the angle of a swash plate of the piston pump (1) to supply required oil to cylinders. The control valve (2) is configured to control the direction of flow inside the hydraulic system. The CLSS port of the control valve (2) is configured to be connected to a load-signal port (X) of the piston pump (1) through a hose and the load-signal port of the control valve (2) is adapted to connect ports A and B through a series of shuttle valves to ensure the required pressure at the piston pump (1) for meeting flow demand of the cylinder. The manifold block (5) is configured with an accumulator to facilitate storage of pressurized oil to bring down a lifted blade of the dozer in engine off condition. The system is provided with a built-in additional emergency blade lowering system configured with a blade lift cylinder rod connected to the manifold block by button filter (8), through 'C" port to assist the emergency lowering system by lowering the blade to the ground to act as brake in accumulator discharged condition. The system is configured with a cut-off switch to cut off the supply to joystick (3) to prevent unintended fall down of blade, during maintenance or service of work attachment. The joystick (3) controls the operation of hydraulic system such as blade up/lower, blade tilt etc. The system is configured with a flow and pressure compensator to automatically regulate pump displacement and deliver the required oil flow to maintain a constant pressure drop across a valve spool or other flow limiting device. The piston pump (1) is a variable piston pump or an axial piston pump. The control valve (2) is a pilot actuated type or proportional direction control valve.

[0030] Exemplary 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.
[0031] Some embodiment heat may reduce heat losses by reducing the hydraulic oil flow to control valve during idle time of 60~65 % of work cycle, which in turn reduces load on engine and increases fuel economy.

[0032] Some embodiment mayhave lesser power losses, increase life of hydraulic components and increased fuel economy and also eliminate use of pilot pump and hydraulic oil cooler and its piping.

[0033] Some embodiment may eliminate additional cooler and corresponding piping to reduce the hydraulic oil temperature as the risk of overheating is reduced and heat losses are reduced.

[0034] REFERENCE NUMERALS:

Element Description Reference Numeral
Piston Pump 1
Control valve 2
Joystick 3
Return line filter 4
Manifold block 5
Hydraulic tank 6
Pilot filter 7
Button filter 8

,CLAIMS:
1.A hydraulic system for dozer application comprising:
at least one hydraulic tank (6) configured to supply hydraulic oil;
at least one piston pump (1) configured to be connected to hydraulic tank to deliver oil to the system;
at least one control valve (2) configured to be connected to the piston pump (1) to control the direction of flow of oil inside the system;
at least one joystick (3) configured to control the operations of a blade of hydraulic dozer;
at least one return line (4) filter configured to filter the oil returning to the system; and
at least one manifold block (5) configured to supply oil to the hydraulic dozer for emergency lowering of the blade.

2. The hydraulic system for dozer application as claimed in claim 1, wherein the said control valve (2) is configured with a centre load sensing system (CLSS) to monitor the load pressures on the system’s cylinders to control oil flow from the piston pump (1).

3. The hydraulic system for dozer application as claimed in claim 1, wherein the said piston pump (1) is configured to draw oil from the hydraulic tank (6) and deliver at least pressure of 16 bar in the neutral condition.

4. The hydraulic system for dozer application as claimed in claim 1, wherein the said manifold block (5) is configured to be charged at 30bar without joystick (3) operation, to prevent relief loss in pilot system in neutral condition.

5. The hydraulic system for dozer application as claimed in claim 1, wherein the said CLSS is configured to monitor pressures of all the hydraulic cylinders and to control the angle of a swash plate of the piston pump (1) to supply required oil to cylinders.

6. The hydraulic system for dozer application as claimed in claim 1, wherein the said control valve (2) is configured to control the direction of flow inside the hydraulic system.

7. The hydraulic system for dozer application as claimed in claim 1, wherein the said CLSS port of the control valve (2) is configured to be connected to a load-signal port (X) of the piston pump (1) through a hose and the load-signal port of the control valve (2) is adapted to connect ports A and B through a series of shuttle valves to ensure the required pressure at the piston pump (1) for meeting flow demand of the cylinder.

8. The hydraulic system for dozer application as claimed in claim 1, wherein the said manifold block (5) is configured with an accumulator to facilitate storage of pressurized oil to bring down a lifted blade of the dozerin engine off condition.

9. The hydraulic system for dozer application as claimed in claim 1, wherein the said system is provided with a built-in additional emergency blade lowering systemconfigured with a blade lift cylinder rod connected to the manifold block by button filter (8), through 'C" port to assist the emergency lowering system by lowering the bladeto the ground to act as brake in accumulator discharged condition.

10. The hydraulic system for dozer application as claimed in claim 1, wherein the said system is configured with a cut-off switch to cut off the supply to joystick (3) to prevent unintended fall down of blade, during maintenance or service of work attachment.

11. The hydraulic system for dozer application as claimed in claim 1, wherein the said joystick (3) controls the operation of hydraulic system such as blade up/lower, blade tilt etc.

12. The hydraulic system for dozer application as claimed in claim 1, wherein the said system is configured with a flow and pressure compensator to automatically regulate pump displacement and deliver the required oil flow to maintain a constant pressure drop across a valve spool or other flow limiting device.

13. The hydraulic system for dozer application as claimed in claim 1, wherein the said piston pump (1) is a variable piston pump or an axial piston pump.

14. The hydraulic system for dozer application as claimed in claim 1, wherein the said control valve (2) is a pilot actuated type or proportional direction control valve.