Hydraulic system providing energy recovery by double- spool direction valves during lowering in lifting-lowering cylinder in backhoe-loader, wheel loader and excavator work machines

Description

The Field of the Invention

[0001] Invention relates to hydraulic system developed in order to reduce energy consumption during lowering double spool valves in lifting-lowering cylinder in backhoe loader, wheel loader, wheel and crawler excavator work machines.

[0002] The invention particularly relates to hydraulic system that minimizes excessive energy losses during operation, providing travel to zero cavitation levels, preventing oil leakage during long time waiting, eliminating power losses in lowering by the steering wheel or only lowering period, enabling machine to work without vibration in soft and hard ground excavations and providing less fuel-oil consumption and increasing efficiency.Background of the Invention

[0003] Backhoe-Loader is a work machine used for channel excavating and loading works. These machines are defined as Backhoe - Loader in foreign sources. Wheel loader are work machines used in loading works. These machines are defined as Wheel Loader in foreign sources. Rubber and palette excavators are work machines used in excavation and loading works. These machines are described as Wheel Excavator and Crawler Excavator in foreign sources.

[0004] These work machines are used for loading material from excavation works or stocked before, onto trucks for carrying, for conduct of excavations at soft and hard grounds or for carrying work materials from short-distance one place to another. Depending on shovel features they can also be used in ground levelling or simple purpose shovelling. Different purpose loading and unloading functions can also be performed by means of adding different attachments on / into shovel.

[0005] Today fixed capacity gear pump or varying capacity piston pump at existing backhoe loader are used single spool capacity flow-sharing direction control valves. In varying and fixed flow rate pump applications, variance in pump flow rate is provided by means of pilot oil taken from user outlet of single spool valve subject to joystick motion at user inlet. Also, in order to avoid cavitation in low diesel speed for users of valve designs, a regenerative function is also included in the hydraulic system via valve spool in applications. Since flow rate quantity at cylinder output is designed according to single spool parameter based on bucket loaded and diesel engine idle speed via a spool, pressure losses are encountered during flow rate passing returning from pump to cylinder and from cylinder to tank via direction control valve, it is discovered by measurements that power losses occur during lowering motion of lifting-lowering cylinder during high diesel revolution. In addition, while working at low diesel revolution at lifting-lowering cylinder on loader and backhoe side, cavitation occurs in cylinders and during long waiting, if cylinders do not have locking valve, level losses are observed. Also lowering operation is frequently used in the lifting-lowering cylinder by steering wheel on loader side and when steering wheel and lowering movement are made together, pump consumes more power from system than intended quantity. Document EP 2 955 389 A1 discloses for example a hydraulic system with hydraulic energy recovery.

[0006] As a result, the need for a new hydraulic system developed for use in backhoe-loader machines eliminating the disadvantages available in the related art and inadequacy of existing solutions has necessitated development in the related art.Brief Description of the Invention

[0007] Present invention relates to a new hydraulic system developed during lowering operation of lifting-lowering cylinder for use in both backhoe and loader work machines, meeting the needs mentioned above, eliminating all disadvantages and also providing some additional advantages.

[0008] Based on state of the art, purpose of the invention is provide to reduce in pressure losses occurring in the system and energy withdrawn by means of providing proportional flow rate and pressure control, control of external proportional flow rate and regeneration arising from pressure by help of using double spool direction valve instead of single spool direction valve in developed hydraulic system.

[0009] The purpose of invention is to provide achievement of zero cavitation levels with help of proportional regeneration conducted externally from outside of sliding at lowering motion of cylinders working at various diesel revolution and different weights at hydraulic system. Another purpose of the invention is to provide working at lower pressure losses during operation and transition to excavation automatically based on pressure during excavation by help of proportional flow control valve, compensator and regeneration check valve selected independent of direction valve based on cylinder lowering speed at user output in the hydraulic system.

[0010] A further purpose of the invention is to provide prevention of power losses in the system by help of supply of oil as needed by steering wheel in case of steering wheel and boom lowering motions are made at the same time at joystick pulled position.

[0011] Another purpose of the invention is to provide elimination of pressure losses on hydraulic installation by minimizing length of pipe and hose laid on machine by help of carrying designed control block onto cylinder.

[0012] A further purpose of the invention is to provide achievement of lower fuel oil consumption values and achievement of efficiency by help of continued reading of pressure sensors used in A, B user lines and P pump lines and smart software algorithms on hydraulic system design.

[0013] A further purpose of the invention is to provide a lifting / lowering cylinder hydraulic control block as indicated in Claim 1.

[0014] A further purpose of the invention is to provide a lifting / lowering cylinder hydraulic control block as indicated in Claim 2.

[0015] A further purpose of the invention is to provide a lifting / lowering cylinder hydraulic control block as indicated in Claim 3.

[0016] The structural and characteristic features and all advantages of the invention will be understood better in the figures given below and the detailed description by reference to the figures. Therefore, the assessment should be made based on the figures and taking into account the detailed descriptions.Brief Description of Figures

[0017] In order to make the embodiment and additional members being subject of the present invention as well as the advantages clearer for better understanding, it should be assessed with reference to the fallowing described figures. Figure 1 is a general view of hydraulic circuit of hydraulic control block with double spool direction valve lifting-lowering cylinder. Figure 2 is a general view of hydraulic system circuit chart of hydraulic system of double spool direction valve lifting-lowering cylinder on wheel loader, wheel excavator, backhoe loaders in preferred embodiment of the invention. Figure 3 is a general view of hydraulic circuit of hydraulic control block with double spool direction valve lifting-lowering cylinder at preferred embodiment for excavator of the invention. Reference Numbers

[0018] QPump output flow rate 1.0.Multi-purpose security block 2.0.Lifting / lowering cylinder hydraulic control block 2.1.Pressure compensator lifting proportional direction valve (OR1) 2.2.Pressure compensator lowering proportional direction valve (OR2) 2.3.Primary check valve 2.4.Secondary check valve 2.5.Counterbalance valve 2.6.Normally closed proportional relief valve (OR4) 2.7.Third check valve 2.8.Fourth check valve 2.9.Pressure compensator proportional flow control valve (OR3) 2.10.Compensator 2.11.Balance compensator orifice 2.12.MA Pressure sensor 2.13.MB Pressure sensor 2.14.MP Pressure sensor 3.0Hydraulic pumps (pump types according to different application types) 4.0Hose boost valves 5.0Lifting-lowering cylinders Detailed Description of the Invention

[0019] In this detailed description, hydraulic system developed to provide energy recovery during lowering at lifting-lowering cylinder hydraulic control block (2.0) developed for use in work machines such as backhoe-loader, wheel loader and wheel and crawler excavator disclosed under this invention has been disclosed only as example for the purpose of better understanding of the subject and described in a manner not causing any restrictive effect.

[0020] As shown in figure 1, the lifting-lowering cylinder hydraulic control block (2.0) hydraulic system of the invention prevents level losses of cylinder at the lifting-lowering cylinder hydraulic control block (2.0) during waiting in idle status. The hydraulic system comprises pressure compensator lifting proportional direction valve (OR1) (2.1) and pressure compensator lowering proportional direction valve (OR2) (2.2) providing waiting at minimum pump outlet flow rate (Q) and pressure in cases when joystick does not move, providing flow rate control at user input in joystick movements, pressure compensator proportional flow control valve (OR3) (2.9) conducting flow rate control at user output, compensator (2.10) for regeneration at idle motions via forth check valve (2.8), cancelling regeneration and starting automatic excavation start period during excavation, also proportional relief valve (2.6) normally in close status providing non-vibrated working of work machine on hard ground under effect of other attachments by conducting selective pressure control at user input also during lowering.

[0021] MA pressure sensor (2.12), MB pressure sensor (2.13) and MP pressure sensor (2.14) added to the hydraulic system are constantly read and based on various application types, different type of hydraulic pump (3.0) selections and smart software algorithms provide control of pump output flow rate (Q) and / or pressure compensator lifting proportional direction valve (OR1) (2.1) and pressure compensator lowering proportional direction valve (OR2) (2.2) control to provide fuel oil consumption advantage. The pressure compensator lifting proportional direction valve (OR1) (2.1) and pressure compensator lowering proportional direction valve (OR2) (2.2) check pump output flow rate (Q) based on system need and in case more than one user working, flow sharing can be provided. When steering wheel is also used during lowering period in the hydraulic system at the same time, hydraulic pump (3.0) provides operation only as needed by steering wheel at pump flow rate and pressure. The pressure compensator lifting proportional direction valve (OR1 (2.1) and the pressure compensator lowering proportional direction valve (OR2) (2.2) of the hydraulic system provide hydraulic pump (3.0) to perform operation at minimum power consumption as left without energy. Production of pump output flow rate (Q) needed by system is provided from hydraulic pump (3.0) subject to LS load pressure at joystick motion rate at all pump applications. When floating mode selection switch is pressed, the pressure compensator proportional flow control valve (OR3) (2.9) is stimulated together with normally close proportional relief valve (OR4) (2.6) and lifting-lowering cylinder (5.0) is brought into floating position and levelling conditions are provided. Selections of the pressure compensator lifting proportional direction valve (OR1) (2.1), the pressure compensator lowering proportional direction valve (OR2) (2.2), the pressure compensator proportional flow control valve (OR3) (2.9) and the normally close proportional relief valve (OR4) (2.6) can be made as hydraulic pilot operated or electro-hydraulic operated valve. At variable pumps (3,0), minimum pump pressure is provided according minimum operating pressure given by pump manufacturer and working conditions at the machine.

[0022] Figure 2 shows hydraulic system circuit chart of invention for wheel loader, backhoe-loader, wheel excavator applications and figure 3 shows hydraulic system circuit chart for crawler excavator applications. Hydraulic pump (3.0) may select fixed flow rate or variable flow rate (load sensing or electronic flow controlled), while the hydraulic pump (3.0) driving can be made by diesel engine or electrical motor.

[0023] At all hydraulic pump (3.0) applications signal is transmitted via LS line to pump subject to LS load pressure at joystick motion rate and thus flow rate needed by system is produced from the pump. MA pressure sensor (2.12), MB pressure sensor (2.13) and MP pressure sensor (2.14) are continuously read by software and controls pump output flow rate (Q) by help of smart algorithms and serious advantages are achieved by help of smart algorithm software. At different working periods different ΔP values can be adjusted from software. Since at fixed flow rate pump (3.0) application hydraulic pump (3.0) pumps fixed flow rate by variable revolution electrical motor, pump output flow rate (Q) quantity is adjusted by electrical motor revolution in a manner MP-MA=ΔP or MP-MB=ΔP subject to motion of cylinders from software. At electronic flow rate controlled pump application with diesel driving engine, electronic pump output flow rate (Q) is adjusted from software in a manner pressure difference is MP-MA=ΔP, MP-MB=ΔP subject to motion speed of cylinder. At variable load sensing hydraulic pump (3.0) with diesel driving engine, pump output flow rate (Q) is adjusted by hydraulic LS signal transmitted to hydraulic pump (3.0) in a manner P-LS=ΔP is constant subject to motion speed of cylinders. At fixed flow rate hydraulic pump (3.0) (with load sensing) with diesel driving engine, user can control flow rate she / he needs by sending hydraulic pump (3.0) flow rate over need of user via hydraulic LS signal transmitted by fixed pressure adjusted compensator at multi-purpose security block (1.0) in pressure to tank in + spring strength. While hydraulic lifting / lowering cylinder hydraulic control block (2.0) works without energy, as long as joystick does not move, pressure compensator lifting proportional direction valve (OR1) (2.1), pressure compensator lowering proportional direction valve (OR2) (2.2), pressure compensator proportional flow control valve (OR3) (2.9) and normally close proportional relief valve (OR4) (2.6) are in close position. In figure 1 pressure compensator lifting proportional direction valve (OR1) (2.1) and pressure compensator lowering proportional direction valve (OR2) (2.2) do not transmit flow from hydraulic pump (3.0) to cylinder when joystick is not used and also LS lines are kept open to tank. At hydraulic pumps (3.0) if P line is close and LS signal pressure is 0, hydraulic pump (3.0) produces minimum pump output flow date (Q) value. In this case hydraulic pump (3.0) remains at minimum pressure and energy consumed from system is kept at minimum level. When hydraulic lifting / lowering cylinder hydraulic control block (2.0) works without energy, pressure compensator lifting proportional direction valve (OR1) (2.1), pressure compensator lowering proportional direction valve (OR2) (2.2), pressure compensator proportional flow control valve (OR3) (2.9) and normally close proportional relief valve (OR4) (2.6) have close zero leakage structure at non-operated position and also other primary check valve (2.3), secondary check valve (2.4), third check valve (2.7), forth check valve (2.8), counterbalance check valve (2.5) have zero leakage structure. When joystick is not used at lifting-lowering cylinder (during waiting), a level loss is not experienced in the cylinder.

[0024] When lifting-lowering cylinder is at lowering period, pressure compensator proportional flow control valve (OR3) (2.9) is operated and lowering can be made, regeneration is provided at cylinder by help of fixed pressure adjusted compensator (2.10) and forth check valve (2.8). Lowering speed of lifting-lowering cylinder is calibrated via pressure compensator proportional flow control valve (OR3) (2.9) at joystick motion. At lowering position, at variable diesel revolution , pressure compensator lowering proportional direction valve (OR2) (2.2) can provide operation of minimum hydraulic pump (3.0) to operate with zero cavitation at cylinder and low-pressure losses. Also, at variable diesel revolution pressure compensator lowering proportional direction control valve (OR2) (2.2) allows flow sharing when other users are activated thanks to its compensator structure.

[0025] During excavation when maximum breaking force (vehicle lifting from ground position) is established, user's lifting-lowering from hydraulic pump (3.0) subject to joystick motion is provided by means of achievement of flow rate needed for lifting from ground speed of the machine subject to cylinder diameter. During lowering, hydraulic pump (3.0) minimum flow rate is needed normally due to potential energy in cylinder. For that reason, operation is provided with low pressure losses at variable diesel revolution. Due to weight effect of piston side of cylinder MA pressure sensor (2.12) used in MA line remains at 50 bars and above pressure, when lifting - lowering cylinder touches ground level, MA line pressure goes under 50 bars, pressure compensator lowering proportional direction control valve (OR2) (2.2) is operated and hydraulic pump (3.0) flow rate is transmitted to system at lowering rate upon joystick motion. Hydraulic pump (3.0) generates pressure and pump output flow rate (Q) in minimum value during cylinder lowering process, if joystick is still in pulled position and MA pressure sensor (2.12) is under 50 bars, pressure compensator lowering proportional direction valve (OR2) (2.2) is operated and machine is forced to lift from ground at the joystick motion rate. When machine is at excavation position, oil returning from cylinder returns to tank via compensator (2.10) and counterbalance valve (2.5) at low pressure. Thus since hydraulic pump (3.0) remains at minimum flow rate and pressure until passing into breaking / lifting force in lowering period, energy consumption from the system is also minimized. Excavation pressure may vary proportionally according to soft and hard ground conditions from normally closed proportional relief valve (OR4) (2.6). Operator can make cylinder's lowering pressure value selection by selective button from normally close proportional relief valve (OR4) (2.6).

[0026] When vehicle moves in lifting-lowering cylinder, it is desired to conduct levelling operation. When button for selection of lifting-lowering cylinder to floating period is pressed, stimulation is given to pressure compensator proportional flow control valve (OR3) (2.9) and normally close proportional relief valve (OR4) (2.6). Boom cylinder at floating mode is in free motion in up and down direction. Since said flow rate shared double- spool pressure compensator lifting proportional direction valve (OR1) (2.1) and pressure compensator lowering proportional direction valve (OR2) (2.2) are not operated, hydraulic pump (3.0) does not pump output flow rate (Q), hydraulic pump (3.0) output remains at minimum pressure and minimum flow rate value. In floating period piston side of cylinder can make oil absorption from counterbalance valve check valve (2.5) and rod side from tank line via third check valve (2.7).

[0027] After loading, lifting-lowering cylinder with steering wheel, lowering position is a period mostly used by operator. After vehicle loading operation, machine is departed from vehicle while boom lowering operation with steering wheel is conducted by operator. A hydraulic pump (3.0) flow rate is not needed due to the potential energy of attachment weight during lowering. Oil need corresponding to steering wheel need of hydraulic pump (3.0) is adequate. During lowering only pressure compensator proportional flow control valve (2.9) stimulation is adequate.

[0028] Lifting-lowering cylinder lifting period is performed by transmitting stimulation to normally closed proportional relief valve (OR4) (2.6) by pressure compensator proportional lifting direction valve (OR1) (2.1). Calibration of minimum and maximum speeds of lifting cylinder in lifting period is made by operating pressure compensator proportional lifting direction valve (OR1) (2.1) at joystick motion rate and flow rate needed is pumped to the system by hydraulic pump (3.0). Flow rate at rod side of cylinder is submitted to tank via normally closed proportional relief valve (OR4) (2.6) without pressure.

[0029] Pressure compensator proportional lifting direction valve (OR1) (2.1) and pressure compensator proportional lowering direction valve (OR2) (2.2) located in hydraulic system gives minimum flow rate and pressure to hydraulic pump (3.0) while without stimulation under normal conditions, during idle waiting in hydraulic system, leakages that might occur in cylinders are prevented, when stimulation is given to pressure compensator proportional flow control valve (OR3) (2.9), zero cavitation is provided in cylinders while hydraulic pump (3.0) is not active in lowering period of cylinders. Reduction in fuel-oil consumption and increase in efficiency can be brought to higher rates by help of reading MA pressure sensor (2.12), MB pressure sensor (2.13) and MP pressure sensor (2.14) installed onto MA, MB, MP lines in lowering cylinder hydraulic control block (2.0) and smart algorithm software. In said hydraulic system flow rate control is made by pressure compensator lowering proportional direction control valve (OR2) (2.2), regeneration by means of pressure control by normally close proportional relief valve (OR4) (2.6), flow rate control in idle movements by pressure compensator proportional flow control valve (OR3) (2.9), fourth check valve (2.8) and compensator (2.10) and flow rate control based on pressure by means of automatically cancelling regeneration during excavation, and thus motions to initiate pressure can be provided. Also on hard ground conditions, lifting cylinder is enabled to work at lower excavation pressure by help of selective stimulation to be given to normally close proportional relief valve (OR4) (2.6) under effect of other attachment and thus excavator can be provided with facility to operate without vibration in working conditions on hard grounds.

Claims

1. A lifting / lowering cylinder hydraulic control block (2.0) developed to provide energy recovery during lowering action of lifting-lowering cylinders in work machines such as backhoe loaders, wheel loaders, wheel and crawler excavators characterized by comprising; - pressure compensator lifting proportional direction valve (OR1) (2.1): ∘ which is configured to provide waiting at minimum pump outlet flow rate (Q) and pressure in cases when joystick does not move, ∘ which is configured to provide flow rate, pressure control at user input in joystick movements ∘ and which is configured to provide flow sharing, in case of working of more than one user, ∘ which has normally close and having zero leakage structure, while lifting-lowering cylinder hydraulic control block (2.0) works without energy, when in no operated position; - pressure compensator lowering proportional direction valve (OR2) (2.2): ∘ which is configured to provide waiting at minimum pump outlet flow rate (Q) and minimum pressure in cases when joystick does not move, ∘ which is configured to provide flow rate control according to system's need at user input at joystick motions, ∘ and which is configured to provide flow sharing in case of more than one user works, ∘ which has normally close and having zero leakage structure, while lifting-lowering cylinder hydraulic control block (2.0) works without energy, when in no operated position, ∘ which is configured to provide working of hydraulic pump (3.0) at only steering wheel pump flow rate and steering wheel pressure value in cycle, when going into lowering period with steering wheel, despite joystick is active or which is configured to provide minimum flow rate and pressure control at hydraulic pump (3.0) during only lowering at lifting-lowering cylinder, without operation of steering wheel, - pressure compensator proportional flow control valve (OR3) (2.9): ∘ which has normally close and zero leakage structure, in non- operated position, o which is configured to conduct control of flow rate and pressure at cylinder output,zero cavitation and regeneration in idle motions at lowering period, and which is configured to provide period to go into automatic excavation by cancelling regeneration during excavation; when lifting-lowering cylinder hydraulic control block (2.0) works without energy, - normally close proportional relief valve (OR4) (2.6): ∘ which has normally close and zero leakage structure in non- operated position, ∘ which is configured to conduct selective pressure control at user input of cylinder and which is configured to provide vibrationless operation of machine at hard ground under effect of other attachments, while lifting-lowering cylinder hydraulic control block (2.0) works without energy, - fourth check valve (2,.8) and compensator (2.10): ∘ which is configured to control flow rate and pressure at cylinder output, zero cavitation and regeneration at idle motions in lowering period and which is configured to provide period to go into automatic excavation by cancelling regeneration during excavation; - MA pressure sensor (2.12) and MB pressure sensor (2.13) installed onto MA and MB ports and MP pressure sensor (2.14) installed onto P line, which are configured to provide advantages in fuel oil consumption by help of smart software algorithms.

2. The lifting / lowering cylinder hydraulic control block (2.0) according to claim 1 characterized by comprising; - pressure compensator proportional flow control valve (OR3) (2.9), - normally close proportional relief valve (OR4) (2.6), - compensator (2.10), - third check valve (2.7) and - counterbalance valve (2.5) which are configured to provide interconnection and connection to tank of A and B lines of cylinder when floating mode selection key is pressed for providing minimum power consumption of levelling conditions at lifting / lowering cylinder.

3. The lifting / lowering cylinder hydraulic block (2.0) according to claim 1 wherein; - pressure compensator lifting proportional direction valve (OR1) (2.1), - pressure compensator lowering proportional direction valve (OR2) (2.2), - normally close proportional relief valve (OR4) (2.6), - pressure compensator proportional flow control valve (OR3) (2.9) which are hydraulic operated-or electro-hydraulic operated valve.

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