Claims:1. An improved hydraulic control system for an earthmoving or construction machine to conserve energy comprising :
? At least one primary pump unit for pumping hydraulic fluid from a hydraulic reservoir and deliver it to a hydraulic fluid pressure line 1;
? At least one auxiliary or secondary pump unit for pumping hydraulic fluid from a hydraulic reservoir and deliver it to a hydraulic fluid pressure line 2;
? At least one hydraulic fluid pressure sensing unit mounted on either hydraulic fluid pressure line 1 or hydraulic fluid pressure line 2 or both;
? At least one hydraulic fluid reservoir through which hydraulic fluid may be circulated to the hydraulic fluid pressure line 1 or the hydraulic fluid pressure line 2 or both and also connected to a return port; and
? At least one hydraulic fluid pressure relief valve or control valve for controlling fluid circulation across the hydraulic fluid pressure line 1 or the hydraulic fluid pressure line 2 or both.

2. The improved hydraulic control system claimed in claim 1, wherein the primary pump unit for pumping hydraulic fluid from the hydraulic reservoir driven by either machine engine, external engine, battery, external or internal power source, combination of either mentioned sources or any other means.

3. The improved hydraulic control system claimed in claim 1, wherein
the auxiliary or secondary pump unit for pumping hydraulic fluid from the hydraulic reservoir driven by either machine engine, external engine, battery, external or internal power source, combination of either mentioned sources or any other means.

4. The improved hydraulic control system claimed in claim 1, wherein the hydraulic fluid pressure sensing unit mounted either on the hydraulic fluid pressure line 1 or on the hydraulic fluid pressure line 2 or both to measure hydraulic fluid pressure across the respective pressure lines or both.

5. The improved hydraulic control system claimed in claim 1, wherein the hydraulic fluid pressure relief valve or control valve receive signal from the said pressure sensing unit mechanically, electronically, hydraulically or by any other means or combination of thereof.

6. The improved hydraulic control system claimed in claim 1, wherein the hydraulic fluid pressure relief valve or control valve either close or open hydraulic fluid flow across the hydraulic fluid pressure line 2 in accordance with the input data received through the said pressure sensing unit.

7. The improved hydraulic control system claimed in claim 1, wherein the hydraulic fluid pressure relief valve or control valve bypass the hydraulic fluid flow across the hydraulic fluid pressure line 2 to the hydraulic fluid pressure line 1 in accordance with the input data received through the said pressure sensing unit.

8. The improved hydraulic control system claimed in claim 1, wherein the hydraulic fluid reservoir contain hydraulic fluid and connected with the return port of the hydraulic fluid pressure line 1 and the hydraulic fluid pressure line 2.

9. The improved hydraulic control system claimed in claim 1, wherein the hydraulic fluid pressure sensing unit mounted either on the hydraulic fluid pressure line 1 or on the hydraulic fluid pressure line 2 or both to measure pressure differential between the hydraulic fluid pressure line 1 and the hydraulic fluid pressure line 2

10. The improved hydraulic control system claimed in claim 1, wherein the hydraulic fluid pressure sensing unit detect stalling of hydraulically controlled operation due to overloading.

11. A improved hydraulic control system for a earthmoving or construction machine to conserve energy comprising :
? At least one primary pump unit for pumping hydraulic fluid from the hydraulic reservoir and deliver it to the hydraulic fluid pressure line 1;
? At least one auxiliary pump unit for pumping hydraulic fluid from the hydraulic reservoir and deliver it to the hydraulic fluid pressure line 2;
? At least one hydraulic fluid pressure sensing unit mounted on either hydraulic fluid pressure line 1 or hydraulic fluid pressure line 1 or both;
? At least one hydraulic fluid reservoir through which the hydraulic fluid may be circulated to the hydraulic fluid pressure line 1 or the hydraulic fluid pressure line 2 or both and also connected with the return port;
? At least one hydraulic fluid pressure relief valve or control valve for controlling fluid circulation across the hydraulic fluid pressure line 1 or the hydraulic fluid pressure line 2 or both; and
? At least one electronic control unit for processing input data received through the said hydraulic fluid pressure sensing unit and for controlling functioning of the said hydraulic fluid pressure relief valve or control valve.

12. The improved hydraulic control system claimed in claim 11, wherein the said hydraulic fluid pressure sensing unit measure the hydraulic fluid pressure across the hydraulic fluid pressure line 1 or the hydraulic fluid pressure line 2 or both and further input signals send to the electronic control unit.

13. The improved hydraulic control system claimed in claim 11, wherein the electronic control unit process the input signals received through the said hydraulic fluid pressure sensing unit and give further control signals to the said hydraulic fluid pressure
, Description:FIELD OF THE INVENTION
The present invention relates to off-road vehicle and/or construction, earthmoving equipment and particularly to hydraulic system in off-road vehicle and/or construction, earthmoving equipment and more particularly to method to conserve energy by discontinuing hydraulic flow of auxiliary equipment or implements.

BACKGROUND OF THE INVENTION
Due to the huge size and weight of off-road or construction machine and functions need to perform while in the field and hence all off-road or construction machine generally well equipped with hydraulics system to control various operation of machine such as digging, excavating, loading, hammering, compaction etc. as well to provide power to various auxiliary or additional equipment used in such machine.
Hydraulic system further utilized in earthmoving or construction machine to convenience to operator to control various functions and also to provide better safety to operator and people working around the machine.

Various operations such as digging, excavating, loading, hammering, compaction etc. including operation of hydraulic powered auxiliary or additional equipment used in such machine, requires a source of hydraulic fluid to perform these abovementioned operations. Hydraulic fluid is generally circulated by a pump and/or motor driven by the machine engine.
Primary pump is used for circulating pressurised hydraulic fluid across various fluid circulation lines to perform various mentioned operations. The standard corresponding fluid pressure is required throughout these lines to perform such operation. However, if there has been least little pressure drop across the pressure line causes operation get stop or stall. There has been high probability that primary pump become disabled or is not operating.
Primary pump suck hydraulic fluid from hydraulic reservoir and send it further to fluid pressure lines to perform various operation on the machine. Primary hydraulic pump is driven by prime mover, machine engine or any other means.
Secondary/Auxiliary pump is also installed on hydraulic reservoir. Secondary/Auxiliary pump is also driven by prime mover, machine engine or any other means or combination thereof. Secondary/Auxiliary pump suck hydraulic fluid from hydraulic reservoir and push it further to any other secondary operations such as cooling fan motor to reduce temperature of hydraulic fluid used for transmission, engine or fluid used for any other means in the machine.
In order to overcome a stalling effect which might result if primary hydraulic pumping system is disabled or not operating because of overloading, a secondary or an auxiliary pump is incorporated on such earthmoving or construction equipment.
A typical earthmoving or construction equipment includes hydraulic system having one or more hydraulic pump. Various hydraulically operated services are linked with hydraulic pump. One or more pressure relief valve or control valves are used to control supply of hydraulic fluid from hydraulic pump to fluid pressure lines used for various operations. These pressure relief valve or control valves are controlled by operator via joystick or dashboard or any other actuating means. Thus machine operation may use control interface to control operation of the one or more control valves to cause actuation of one or more of the actuators. The actuators are used for controlling various operation and parts of machine.
Conventionally earthmoving or construction machine equipped with above mentioned hydraulic system. However, pressure of hydraulic fluid is controlled by operator through joystick or any other manual means. It is often observed that machine operator has to perform two or more tasks simultaneously while working on a machine. A machine operator has always needs to control the pressure of primary pump and secondary/auxiliary pump at a real time. Whenever primary pump get stalled, disabled or not operating because of overloading or lack of hydraulic fluid in pressure line, machine operator has to regulate control valve or relief valve through joystick or any other manual means such a way that flow of hydraulic fluid to secondary/auxiliary pump will be stopped and/or diverted to hydraulic fluid reservoir.
Now when an earthmoving or construction equipment moved to other hydraulic operation where required hydraulic fluid pressure is less than predetermined hydraulic fluid pressure valve then operator has to switch on a secondary/auxiliary pump through joystick or any other manual means. Whenever again primary pump get stalled, disabled or not operating because of overloading or lack of hydraulic fluid in pressure line or because of certain operation requires more hydraulic pressure than predetermine value of hydraulic pressure then operation has to ‘switch off’ secondary/auxiliary pump through joystick or any other manual means. The process of ‘switch on’ and ‘switch off’ of secondary/auxiliary pump through joystick may be cyclic and hence more attention is requiring while performing various operations. It became cumbersome and difficult to operator to control hydraulic fluid pressure during various operations while focusing on other tasks.
In a conventional hydraulic system, the fixed displacement hydraulic pumps are used as a power source for the hydraulic actuators. The fixed displacement hydraulic pump delivers a constant flow at particular pump shaft speed irrespective of the energy demand of the system. There is substantial loss of energy in such systems due to non-demanded energy supply.
In addition to similar hydraulic system, gear pump is used to deliver flow which drives the hydraulic driven fan motor to cool the oil of the machinery. In such systems, the energy demand remains same at a particular input shaft seal.
Yet in another known system, to meet and optimize the flow demand of the hydraulic system, fixed displacement or variable displacement hydraulic pumps are used as power source with known pressure compensation methods. Such hydraulic systems requires high degree of complexity and very precise contamination control is required, again which is relatively difficult to maintain for many off-road machines working in extreme conditions of environment and put a significant cost impact and complexion in the whole system.
To overcome abovementioned shortcoming and problems associated with conventional system, it is more desirable to achieve a control method that is more simple, fast and energy-efficient than previously known methods and solves or at least relieves some of the problems discussed above.
It is therefore an object of the present invention is to overcome one or more problems associated with the prior art.
One another object of the present invention is to develop simple and electronically controlled relief valve or control valve management system.
Yet another object of the present invention is to develop mechanically and automatically controlled relief valve or control valve management system.
One more object of present invention is to develop a hydraulic fluid pressure control system which is user friendly and cost effective.
Yet another object of present invention is to supply required hydraulic fluid according to requirement and at pre-determined pressure.
A method according to an aspect of the present invention is also disclosed.
Further advantageous embodiments and further advantages of the invention emerge from the detailed description below.

SUMMARY OF THE INVENTION
The present invention is directed to improved energy management and hydraulic control system in an earthmoving or construction equipment. In one as aspect of the present invention, the improved hydraulic fluid management system comprises a hydraulic fluid reservoir, primary hydraulic pump, secondary/auxiliary pump, pressure relief valve or hydraulic fluid control valve, hydraulic fluid pressure sensing unit, ECU (electronic control unit), hydraulic fluid return line etc. Hydraulic fluid from hydraulic reservoir is pumped by said primary hydraulic pump and further said hydraulic fluid is transferred to hydraulic pressure line which further may be used for performing various operations like digging, excavating, loading, hammering, compaction etc, but not restricting to thereof. A secondary/ auxiliary pump is also installed on hydraulic fluid reservoir and it pumps hydraulic fluid from hydraulic reservoir and further it transferred to other hydraulic pressure lines which further may be used for other applications such as cooling fan motor to cool transmission, engine or hydraulic fluid in the machine, steering, braking or any other purpose which is not mentioned thereof.
A hydraulic fluid pressure relief valve or control valve is installed on hydraulic fluid pressure line 2 and it further control hydraulic fluid flowing through hydraulic fluid pressure line 2.
A hydraulic pressure sensing unit is installed on hydraulic fluid pressure line 1 and which detect pressure flowing through hydraulic fluid pressure line 1. A hydraulic pressure sensing unit may be used for calculating pressure differential between hydraulic fluid pressure line 1 and hydraulic fluid pressure line 2. If pressure in hydraulic fluid pressure line 1 is greater than predetermined pressure or predetermined pressure differential across hydraulic fluid pressure line 1 and hydraulic fluid pressure line 2, then a hydraulic fluid pressure relief valve or control valve get block/close automatically and hence hydraulic fluid flow to additional service area such as steering, braking will get stopped or slowed down and hence hydraulic fluid circulated to hydraulic reservoir. Hence all hydraulic fluid will be circulated only through primary pump, which leads to reduce load on hydraulic fluid pressure line 1. If pressure in hydraulic fluid pressure line 1 is greater than predetermined pressure or predetermined pressure differential across hydraulic fluid pressure line 1 and hydraulic fluid pressure line 2 and/or overloading condition amounting on hydraulic fluid pressure line 1, then hydraulic fluid flowing via secondary/ auxiliary pump may be bypassed to hydraulic fluid pressure line 1 instead of passing it through hydraulic fluid pressure line 2.
Another aspect of present invention, a hydraulic fluid pressure relief valve or control valve can be controlled mechanically or electronically or combination of both.
When hydraulic fluid pressure across hydraulic fluid pressure line 1 is equal or lesser than pre-determined pressure limit or pressure differential between hydraulic fluid pressure line 1 and hydraulic fluid pressure line 2 is equal or lesser than pre-determined pressure differential then hydraulic fluid pressure sensing unit gives signal to hydraulic fluid pressure relief valve or control valve.
Further a hydraulic fluid pressure relief valve or control valve stop dumping/circulation of hydraulic fluid to reservoir or bypass of hydraulic fluid from hydraulic fluid pressure line 2 to hydraulic fluid pressure line 1 and hence additional hydraulic applications such as steering, braking start operating at its fullest level.
This kind of hydraulic fluid management system gives significant energy saving without affecting much on the performance and efficiency. Further energy saved by non-operation of auxiliary services can be used for other primary operations such as digging, excavating, loading, hammering, compaction etc. but not restricting to thereof. If saved energy is not used in other primary operations then also it reduces the energy load on the prime mover.

BRIEF DESCRIPTION OF THE DRAWINGS
With reference to the following drawings, a more detailed description of different exemplary embodiments of the invention will follow below.
In the drawings:
Figure 1 Illustrates side view of a construction or earthmoving machine incorporating a hydraulic control system according to the present invention;
Figure 2 Illustrates a schematic representation showing a hydraulic control system according to the present invention;
Figure 3 Illustrates a schematic representation showing a hydraulic control system incorporating electronic control unit according to the present invention;
Figure 4 Illustrates a schematic representation showing a hydraulic control system with bypass mechanism according to the present invention; and
Figure 5 Illustrates a schematic representation showing a hydraulic control system with bypass mechanism connected after main orifice according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION
An improved hydraulic control system for an earthmoving or construction machine to conserve energy according to an embodiment of the present invention will be described hereinunder with reference to FIGS. 1 to 5.
As shown in FIG. 1, a construction or earthmoving machine (10).
The construction or earthmoving machine (10) may be machine incorporating an improved hydraulic control system; however embodiments of present invention are not restricted to machine depicted in FIG.1. The concept and other embodiments of the present invention may be used in other types of machine and machine illustrated in FIG.1 is merely shown as example.
The construction or earthmoving machine (10) consisting of a main body (12), cab structure (14), actuating means (24), wheels (18), working element or working implement (22), arm or boom structure (20), and an engine (16).
The said can structure (14) is mounted on said wheels (18). There may be multiple numbers of wheels mounted on single or multiple axles. The said wheels (18) are driven by said engine (16). The said working element or working implement (22) is attached to arm or boom structure (20) through pivot joint. The said actuating means (24) are working on hydraulic mechanism and there may be multiple actuating means located at multiple locations. The said actuating means (24) are critical part of machine and it may be used for performing various hydraulic operations through the construction or earthmoving machine (10). There may be multiple said working elements or working implement (22) attached to the construction or earthmoving machine (10).
As shown in FIG. 2, the improved control system (20) for an earthmoving or construction machine to conserve energy is provided with primary hydraulic pump (111) and an auxiliary /secondary pump unit (112) which are mounted on hydraulic fluid reservoir (110).
The primary pump unit (111) and auxiliary /secondary pump unit (112) for pumping hydraulic fluid from hydraulic reservoir driven by either machine engine, external engine, battery, external or internal power source, combination of either mentioned sources or any other means (which is not shown in fig.). The said primary pump unit (111) pumps hydraulic fluid from the hydraulic reservoir (110) and deliver it to hydraulic fluid pressure line 1 as shown in FIG.1 whereas the said auxiliary / secondary pump unit (112) pumps hydraulic fluid from the hydraulic reservoir (110) and deliver it to hydraulic fluid pressure line 2. The construction and functioning of hydraulic pump units (111 & 112) may be same or different depending upon the requirements.
The hydraulic fluid pressure line 1 delivers hydraulic fluid to main actuator to perform various functions such as digging, lifting, hammering, compacting, steering, braking, engine cooling system or any other purposes.
The hydraulic fluid pressure line 2 delivers hydraulic fluid to auxiliary actuator or auxiliary hydraulic circuit to perform various functions such as steering, braking, cooling system or any other purpose. In FIG. 2 the hydraulic fluid pressure line 2 delivers hydraulic fluid to drive auxiliary motor (113); however it may be used for other applications depending on requirements.
The hydraulic fluid pressure sensing unit (214) is mounted on either hydraulic fluid pressure line 1 or hydraulic fluid pressure line 2 or both to measure hydraulic fluid pressure across corresponding lines. The hydraulic fluid pressure relief valve or control valve (114) for controlling fluid circulation across hydraulic fluid pressure line 1 or hydraulic fluid pressure line 2 or both is located between hydraulic fluid pressure line 1 and hydraulic fluid pressure line 2. The hydraulic fluid pump (110) supplies pressurised hydraulic fluid to one or many hydraulic actuators (not shown in FIG.) via main orifice (115) to perform various hydraulic operations.
The hydraulic fluid reservoir (110) through which hydraulic fluid may be circulated to hydraulic fluid pressure line 1 or hydraulic fluid pressure line 2 or both and it is again connected to return port.
The hydraulic fluid pressure sensing unit (214) measure real time pressure across pressure line 1 and/or pressure line 2 and gives signals to pressure relief valve or control valve (114) for controlling fluid circulation across hydraulic fluid pressure line 1 or hydraulic fluid pressure line 2 or both. If pressure in hydraulic fluid pressure line 1 is greater than predetermined pressure or predetermined pressure differential across hydraulic fluid pressure line 1 and hydraulic fluid pressure line 2, then a hydraulic fluid pressure relief valve or control valve (114) get block/close automatically and hence hydraulic fluid flow to additional service area (113) such as steering, braking, cooling system or any other purpose will get stopped and hence hydraulic fluid circulated to hydraulic reservoir (110). Hence all hydraulic fluid will be circulated only through primary pump (111), which leads to reduce load on hydraulic fluid pressure line 1.
According to FIG. 3, the improved control system (20) for an earthmoving or construction machine to conserve energy is provided with primary hydraulic pump (111) and an auxiliary /secondary pump unit (112) which are mounted on hydraulic fluid reservoir (110). In additional to abovementioned embodiment electronic control unit hereafter called as ECU (116) is installed in between hydraulic pressure line 1 and hydraulic pressure line 2.
The primary pump unit (111) and auxiliary /secondary pump unit (112) for pumping hydraulic fluid from hydraulic reservoir driven by either machine engine, external engine, battery, external or internal power source, combination of either mentioned sources or any other means (which is not shown in fig.). The said primary pump unit (111) pumps hydraulic fluid from the hydraulic reservoir (110) and deliver it to hydraulic fluid pressure line 1 as shown in FIG.1 whereas the said auxiliary / secondary pump unit (112) pumps hydraulic fluid from the hydraulic reservoir (110) and deliver it to hydraulic fluid pressure line 2. The construction and functioning of hydraulic pump units (111 & 112) may be same or different depending upon the requirements.
The hydraulic fluid pressure line 1 delivers hydraulic fluid to main actuator to perform various functions such as digging, lifting, hammering, compacting, steering, braking, engine cooling system or any other purposes.
The hydraulic fluid pressure line 2 delivers hydraulic fluid to auxiliary actuator or auxiliary hydraulic circuit to perform various functions such as steering, braking, cooling system or any other purpose. In FIG. 3 the improved control system (30) includes the hydraulic fluid pressure line 2 delivers hydraulic fluid to drive auxiliary motor (113); however it may be used for other applications depending on requirements.
The hydraulic fluid pressure sensing unit (214) is mounted on either hydraulic fluid pressure line 1 or hydraulic fluid pressure line 2 or both to measure hydraulic fluid pressure across corresponding lines.
The hydraulic fluid pressure sensing unit (214) gives input signals to ECU (116) in form of digital or analog or combination of both or by any other means. The said ECU (116) process the input signals and give appropriate output signals to the hydraulic fluid pressure relief valve or control valve (114) for controlling fluid circulation across hydraulic fluid pressure line 1 or hydraulic fluid pressure line 2 or both is located between hydraulic fluid pressure line 1 and hydraulic fluid pressure line 2.
The hydraulic fluid pressure sensing unit (214) measure real time pressure across pressure line 1 and/or pressure line 2 and gives signals ECU (116) which further gives signals to pressure relief valve or control valve (114) for controlling fluid circulation across hydraulic fluid pressure line 1 or hydraulic fluid pressure line 2 or both.
Once ECU (116) receive input signals from hydraulic fluid pressure sensing unit (214), ECU (116) process the data and perform logic to confirm whether pressure in hydraulic fluid pressure line 1 is greater than predetermined pressure or predetermined pressure differential across hydraulic fluid pressure line 1 and hydraulic fluid pressure line 2. If pressure in hydraulic fluid pressure line 1 is greater than predetermined pressure or predetermined pressure differential across hydraulic fluid pressure line 1 and hydraulic fluid pressure line 2 then ECU (116) sends output signals to a hydraulic fluid pressure relief valve or control valve (114) to block/close said valve and hence hydraulic fluid flow to additional service area (113) such as steering, braking, cooling system or any other purpose will get stopped and hence hydraulic fluid circulated to hydraulic reservoir (110). Hence all hydraulic fluid will be circulated only through primary pump (111), which leads to reduce load on hydraulic fluid pressure line 1.
The hydraulic fluid pressure relief valve or control valve (114) for controlling fluid circulation across hydraulic fluid pressure line 1 or hydraulic fluid pressure line 2 or both is located between hydraulic fluid pressure line 1 and hydraulic fluid pressure line 2.
The hydraulic fluid pump (110) supplies pressurised hydraulic fluid to one or many hydraulic actuators (not shown in FIG.) via main orifice (115) to perform various hydraulic operations.
The hydraulic fluid reservoir (110) through which hydraulic fluid may be circulated to hydraulic fluid pressure line 1 or hydraulic fluid pressure line 2 or both and it is again connected to return port.
The hydraulic fluid pressure value differential across hydraulic fluid pressure line 1 and hydraulic fluid pressure line 2 may be pre-set or predetermined in ECU unit (116). The overloading condition amounting on hydraulic fluid pressure line 1 may be detected by either ECU (116) or hydraulic fluid pressure sensing unit (214).
As shown in FIG. 4, in the improved control system (40) , if pressure in hydraulic fluid pressure line 1 is greater than predetermined pressure or predetermined pressure differential across hydraulic fluid pressure line 1 and hydraulic fluid pressure line 2 and/or overloading condition amounting on hydraulic fluid pressure line 1, then hydraulic fluid flowing via secondary/ auxiliary pump (112) may be bypassed to hydraulic fluid pressure line 1 instead of passing it through hydraulic fluid pressure line 2. In FIG.4, hydraulic fluid is bypassed and connected to hydraulic pressure line 1 at the connecting point (215) before it passed to main orifice (115) to perform various hydraulic operations. If certain hydraulic operations require more pressurized hydraulic fluid then pressurised fluid across hydraulic fluid pressure line 2 may be directly utilise to reduce load amounted across hydraulic fluid pressure line 1.
In reference to FIG.5, in the improved control system (50), if hydraulic fluid pressure required for perform various operations (not shown in fig.) is lesser than the pressure across the hydraulic fluid pressure line 1 and/or the pressure across the hydraulic fluid pressure line 2 is more than required to perform various auxiliary services then such high pressured hydraulic fluid may be directly supplied to hydraulic fluid pressure line 1 at connecting point (215) after one or more actuator services point (not shown in fig.). It may be also connected to return port line which further connects to reservoir (110).
This kind of hydraulic schematic gives significant energy saving in the system without affecting much on the performance. The energy saved by the unloading the motor (113) can be used in other hydraulic power requirements in hydraulic fluid pressure line 1. If saved energy is not used in other hydraulic power requirement then it reduces the energy load on the prime mover.