EP-3997276-B1 - 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

EP3997276B1EP 3997276 B1EP3997276 B1EP 3997276B1EP-3997276-B1

Inventors

ÖKMEN, Iskender Atilla

Dates

Publication Date: 20260506
Application Date: 20210531

Claims (3)

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.
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.
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.

Description

The Field of the Invention 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. 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 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. 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. 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. 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 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. 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. 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. 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