DESC:CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY
[001] The present application does not claim priority from any patent application.
TECHNICAL FIELD
[002] The present disclosure in general relates to the field of earth moving machinery, and more particularly, the present subject matter relates an unloading of Hydraulic system in dozers to minimise the hydraulic loss (optimal use of hyd. system)
BACKGROUND
[003] Generally, the dozer hydraulic system consists of hydraulic oil reservoir (tank), gear pumps to discharge oil flow, direction control valve for oil flow path control, hydraulic cylinders for movement of blade, pilot oil control system for actuation of control valve spools and pipes & hoses for conducting of oil flow path connections.
[004] The power train system of dozer consists of Engine, PTO, Torque converter, Transmission and final drive with brake system. Hydraulic cylinders for lift, lower and tilt of dozer blade attachment. Currently the Hydraulic system consists of Main control valve, joystick, pilot oil supply block & accumulator for emergency operation when engine is switched off. The hydraulic system operates at higher pressure drop during the neutral as well as during operation. Predominantly dozer operates through a power train during dozing operation. During this period hydraulics being used only 5~8% compared to dozing. Large amount of energy is losses noticed (approx 10% of rated hydraulic load) in neutral condition in the main hydraulic system and also during the entire operation the pilot pump is relieving continuously in the rated pressure without doing any work. this will add and additional power loss.
[005] Generally, pressure drop in the hydraulic system & oil relieving in the circuit is nothing but wasting of power and adding heat to the system. Continuous operation in this condition leads to failure of seals of hydraulic aggregates and reduces the life span. This also leads to accelerate degradation of the oil. In the process of reduce the hydraulic losses and designing the optimum hydraulic circuit, unloading the hydraulic system was found necessary. Designed the hydraulic circuit with unloading feature and engineered on Dozer. Whenever the hydraulic work attachment operates thorough pilot valve, the un loader valve closes and oil is directed towards control valve for the actuation of dozer blade. After the work being operated & pilot valve moves back to neutral then the un loader opens and the oil drained into the tank at lower pressure around 1.5 bar. The pressure loss is as much as 12 bar in the conventional circuit.
SUMMARY
[006] This particular hydraulic system unloading methodologies is understood that this application is not limited to the particular methodologies described, as there can be multiple possible embodiments, which 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 implementations, 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 unloading of hydraulic. This summary is not intended to identify essential features of the claimed subject matter nor it is intended for use in determining or limiting the scope of the claimed subject matter.
[007] In this embodiment, unloading of hydraulic system of dozer and its method is disclosed. In the embodiment, whenever there is no hydraulic aggregates operations, hydraulic oil flow unloading to the tank with very less pressure drop, so with this embodiment keeping the hydraulic system and its aggregates healthy and low maintenance cost. With conventional system there is cooler to dissipate the heat generated within the hydraulic circuit. Its mounted in front of the engine radiator but the pressure drop within the cooler connection pipes and pressure drop across the cooler will again generate the heat. Originally Dozers are not being engineered with Hydraulic oil cooler engineering of in efficient hydraulic system leads to raise in oil temperature and forced to engineer hydraulic oil cooler in front of radiator. This affects the performance of engine due to insufficient fresh air flow around the engine compartment and the LAT of the engine is reduced. Therefore to overcome all these under performance issues finally concluded to minimize the Hydraulic losses. Unloading the hydraulic system is one method to reduce the losses and to keep the complete system trouble free.

BRIEF DESCRIPTION OF DRAWINGS
[008] The foregoing detailed description of embodiments is better understood when read in conjunction with the appended drawings. For the purpose of illustrating of the present subject matter, an example of construction of the present subject matter is provided as figures; however, the present subject matter is not limited to the specific method disclosed in the document and the figures.
[009] The present subject matter is described detail with reference to the accompanying figures. In the figures, 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 drawings to refer various features of the present subject matter.
[010] Figure 1 illustrates the conventional method of hydraulic circuit,
[011] Figure-2 illustrates hydraulic system of dozer with Unloading methodology, in accordance with an embodiment of the present subject matter.
[012] Figure-3 illustrates the unloader of main control valve block and FIG-4 illustrates pilot un loader block, in accordance with an embodiment of the present subject matter.
[013] FIG-5 illustrates the process Flowchart diagram of the invention, in accordance with an embodiment of the present subject matter.
DETAILED DESCRIPTION
[014] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to 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. It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although any an Unloading of hydraulic system of dozer , similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary, Unloading of hydraulic system of dozer and method are now described.
[015] 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 for an Unloading of hydraulic system of dozer. However, one of ordinary skill in the art will readily recognize that the present disclosure for an Unloading of hydraulic system of dozer is not intended to be limited to the embodiments described, but is to be accorded the widest scope consistent with the principles and features described herein.
[016] In one embodiment, Unloading of hydraulic system of dozer is disclosed. Referring to Figure 1, conventional hydraulic system illustrated.. In the figure 1 The principle components of the system are 1.Control Valve 2. Joy stick for blade, 3. Accumulator 4. Manifold block, 5. Pilot pump, 6. Pilot filter, 7. Main hydraulic pump, 8. Hydraulic oil cooler,
[017] Referring to figure 2, the circuit diagram shown represents the Unloading hydraulic system of dozer is illustrated in Fig-2. In the figure 2 the principle components of the system are 1.Control Valve 2. Joy stick for blade, 3. Accumulator 4. manifold block, 5. Pilot pump 6. Pilot filter 7. Main hydraulic pump, 8. Pilot unloader 9. Main unloader. 10. Pilot shut off valve
[018] Referring now to Figure 2 a method for Unloading of hydraulic system of dozer is disclosed. In the Fig -2 schematic shows the unloading of main pump and pilot pump during neutral. In the main un-loader circuit Fig3, Dozer travels through power train system which consists of Engine, Torque converter, transmission and final drive during this period Dozer blade is not being operated. This period is hydraulically neutral since dozer blade attachment is not being operated. During this period it is necessary to unload the hydraulic system rather passing through main control valve because the percentage of usage will be very minimum compared to dozer travel (5 to 8%). In the Unloading hydraulic oil from the pump flows through un loader valve(9) to hydraulic tank directly. The pressure drop is low during this period around 1.5 bar.
When it is required to operate the work attachment it is necessary to close the unloader valve to direct the oil from the pump to the direction control valve (1) and then to the actuators cylinders. Whenever operate the Dozer blade through joy stick(2) a pilot signal from Y of joy stick closes the unloader and opens when joy stick is in neutral when there is no pilot signal from port Y. The oil drained into the tank at lower pressure around 1.5 bar against 12 bar in the conventional circuit hence the hydraulic losses are minimum.
In the process of further refining the hydraulic circuit after introducing the main unloader, it has been found that pilot pump is dumping oil with higher pressure without doing any work. Modified circuit to use the pilot pump only for initial charging of accumulator and then start unloading at lower pressure. To achieve the same introduced the pilot un loader (8) to unload the pilot pump at lower pressure when it is not being used.
An hydraulic line is branched out from the main hydraulic pressure line connected to P2 port of pilot manifold block (4) of fig 4. The pressure reducing valve in the manifold block regulates pressure to 30 bar and this pressure is being used for pilot operation, simultaneously the same pressure will operate the pilot unloader to dump the pilot pump flow to tank at lower pressure. The operation Pilot unloader regulates the pilot pressure to 20 bar in the accumulator circuit and starts unloading charge pump flow to tank at 7 bar.
In the event of fall in pressure in the pilot circuit to 85% of set value(20bar) the pilot un loader stops unloading to tank and allows reach pilot pressure up to 20 bar. The pilot pressure of 20 bar is sufficient to operate the main hydraulics of the dozer. During the operation of work attachment the pilot pump starts unloading full flow at 7 bar.
Features achieved with the new unloader Hydraulic circuit.
? Initial charging of accumulator by pilot pump
? Unloading of both Main and pilot pump at low pressure this avoided continuous loss of energy.
? Operation of pilot hydraulics through main hydraulic circuit
ADVANTAGES
? Factory set no further fine tuning.
? In the event of pilot pump failure the main pump charges the accumulator till pilot operational pressure reaches and continues the charging during the regular operation.
? The variation of pilot pressure during low and high rpm is absent.
? Reduced fuel consumption Problem of engine getting switched off is absent.
? Service life of hydraulic components is enhanced due to low working temperature.
? Feature works with conventional circuit.
? Enhancing the change over period of hydraulic element and Hydraulic oil.

? OBSERVATIONS / PERFORMANCE WITH NEW UNLOADING CIRCUIT

COMPARISION OF RESULTS
OLD Hyd system Power loss in neutral Main Hyd+ Pilot Hyd. 7+1=8kW
NEW Hyd. Power loss in neutral Main Hyd.+ Pilot hyd 0.925 + 0.3 =1.2kW

With this as much as 85% of Hydraulic energy saving is achieved by modifying complete hydraulics system of Dozer, eliminated the hydraulic oil cooler, improved the Engine performance and limiting ambient temperature of engine.

The benefits and advantages which may be provided by the present invention have been described above with regard to specific embodiments. These benefits and advantages, and any elements or limitations that may cause them to occur or to become more pronounced are not to be construed as critical, required, or essential features of any or all of the embodiments.

While the present invention has been described with reference to particular embodiments, it should be understood that the embodiments are illustrative and that the scope of the invention is not limited to these embodiments. Many variations, modifications, additions and improvements to the embodiments described above are possible. It is contemplated that these variations, modifications, additions and improvements fall within the scope of the invention.

,CLAIMS:We Claim:
1. Unloading of hydraulic system of dozer wherein it is having control valve, joystick, accumulator , manifold block, pilot pump, pilot filter, main hydraulic pump, pilot unloader, main unloader and shut off valve in which dozer travels through power train system which consists of Engine, Torque converter, transmission and final drive during this period Dozer blade is not being operated this period is hydraulically neutral since dozer blade attachment is not being operated, it is necessary to unload the hydraulic system rather passing through main control valve because the percentage of usage will be very minimum compared to dozer travel (5 to 8%); in the Unloading hydraulic oil from the pump flows through un loader valve(9) to hydraulic tank directly, the pressure drop is low during this period around 1.5 bar.
2. Unloading of hydraulic system of dozer as claimed in claim 1 when it is required to operate the work attachment it is necessary to close the unloader valve to direct the oil from the pump to the direction control valve (1) and then to the actuators cylinders and whenever it is to operate the dozer blade through joy stick(2) a pilot signal from Y of joy stick closes the unloader and opens when joy stick is in neutral when there is no pilot signal from port Y and the oil drained into the tank at lower pressure around 1.5 bar against 12 bar in the conventional circuit hence the hydraulic losses are minimum.
3. Unloading of hydraulic system of dozer as claimed in claim 2 wherein modified circuit uses pilot pump only for initial charging of accumulator and then start unloading at lower pressure for this pilot un loader (8) is introduced to unload the pilot pump at lower pressure when it is not being used.
4. Unloading of hydraulic system of dozer as claimed in claim 3 wherein hydraulic line is branched out from the main hydraulic pressure line connected to P2 port of pilot manifold block (4) , the pressure reducing valve in the manifold block regulates pressure to 30 bar and this pressure is being used for pilot operation, simultaneously the same pressure will operate the pilot unloader to dump the pilot pump flow to tank at lower pressure, the operation Pilot unloader is regulates the pilot pressure to 20 bar in the accumulator circuit and starts unloading charge pump flow to tank at 7 bar.
5. Unloading of hydraulic system of dozer as claimed in claim 4 wherein in the event of fall in pressure in the pilot circuit to 85% of set value(20bar) the pilot un loader stops unloading to tank and allows reach pilot pressure up to 20 bar, the pilot pressure of 20 bar is sufficient to operate the main hydraulics of the dozer. During the operation of work attachment the pilot pump starts unloading full flow at 7 bar.