BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to machinery having multiple hydraulically actuated functions and, more particularly, to a control system for using a single proportional valve to control multiple hydraulically actuated functions on a piece of machinery such as a tractor or front-end wheel loader.
Construction machinery such as road graders and front-end wheel loaders as well as farm machinery such as farm tractors typically include a plurality of hydraulically actuated features or functions such as a front end loader, grading blade, backhoe assembly, etc. These features may include multiple hydraulically actuated movements. For example, a road grader may include a blade lift, blade tilt, and ripper lift, which all may require separate hydraulic cylinders for operation. In addition, these vehicles, particularly farm tractors may be hydraulically coupled to an implement such as a planter, cultivator, or other farm implement. Some implements may include hydraulic systems that articulate or operate particular features of the implement such as lifting or extending wheels. Generally, an input such as a joystick and/or a plurality of selector switches is mounted in the cab or on a panel of the machinery. The input allows an operator to control the hydraulically actuated functions of the construction machinery or implement.
According to an illustrative embodiment of the present invention, a control system for a construction apparatus includes a hydraulic pump adapted to supply hydraulic fluid to a plurality of hydraulically actuated functions, the control system comprising a proportional valve adapted to selectively control a flow of hydraulic fluid from the hydraulic pump, a plurality of direction valves in communication with the proportional valve and the plurality of hydraulically actuated functions, the directional valves configured to selectively direct hydraulic fluid from the proportional valve to at least one of the hydraulically actuated functions, a first input adapted to actuate the proportional valve to control the flow of hydraulic fluid from the pump to the plurality of directional valves, and a second input adapted to actuate at least one of the plurality of directional valves to supply hydraulic fluid to a corresponding hydraulically actuated function.
According to a further illustrative embodiment of the present invention, a construction apparatus comprises a hydraulic pump adapted to produce pressurized hydraulic fluid, a proportional valve adapted to control a flow rate of hydraulic fluid supplied by the hydraulic pump, a plurality of hydraulically actuated implements, a plurality of inputs, at least one of the inputs corresponding to the proportional valve, at least one of the inputs corresponding to one of the hydraulically actuated implements, and a plurality of directional valves in communication with the proportional valve and the plurality of hydraulically actuated implements, the plurality of directional valves adapted to receive input from the plurality of inputs and direct hydraulic fluid from the proportional valve to the corresponding hydraulically actuated implement.
Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived.
BRIEF DESCRIPTION OF THE DRAWINGS
The detailed description of the drawings particularly refers to the accompanying figures in which:
FIG. 1 is a side view of an illustrative embodiment of a front-end wheel loader;
FIG. 2 is an elevated, profile view of one embodiment of an input that may be used in a the front-end wheel loader shown in FIG. 1;
FIG. 3 is a block diagram of the illustrative embodiment control system of the present invention;
FIG. 4 is a schematic view of one embodiment of the hydraulic control system of FIG. 3 for controlling hydraulically actuated implements of a construction apparatus such as the front-end wheel loader shown in FIG. 1.; and
FIG. 5 is a schematic view of a prior art hydraulic control system for controlling hydraulically actuated implements of a construction apparatus such as the front-end wheel loader shown in FIG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring initially to FIG. 1, one embodiment of a wheel loader 10 is shown. Wheel loader 10 includes a motor 34, a cab 14, a frame 18, and a boom assembly 20. Boom assembly 20 includes a boom 26, a boom cylinder 28, a bucket 30, and a bucket cylinder 32. Boom 26 is pivotally coupled to frame 18 and may be raised and lowered by extending or retracting boom cylinder 28. Bucket 30 is pivotally coupled to boom 26 and may be articulated by extending or retracting bucket cylinder 32. Wheel loader 10 and specifically boom assembly 20 are controlled by an operator and a plurality of controls (not shown) located in cab 14. An example of operator controls is discussed below.
Referring now to FIG. 2, one embodiment of an operator input or control 36 is shown. Input 36 may be located in cab 14 of wheel loader 10 or any other suitable location. In this embodiment, input 36 includes a joystick 38 and a selector 40. Joystick 38 is movable in four directions (A, B, C, D). Selector 40 may be a push button or any other suitable input that may be used by the operator to switch between or select one of the hydraulically actuated functions of wheel loader 10. As described in more detail below, the operator may select any one of a plurality of hydraulically actuated functions of wheel loader 10 that will then be controlled by joystick 38.
Referring now to FIG. 3, a flow chart illustrating one embodiment of a control system of the present invention is shown. Control system 42 may be used to control a plurality of hydraulically actuated functions using only a single proportion valve. In the embodiment of control system 42 shown in FIG. 3, input 44 is coupled to a proportional valve 46 and input 48 is coupled to a plurality of directional valves 50, 52, and 54. Proportional valve 46 receives pressurized hydraulic fluid from a hydraulic pump (not shown) and varies the output or flowrate of pressurized hydraulic fluid based on input 44. Input 44 may be actuated by an operator or other device such as a computer processor to control the flowrate of pressurized hydraulic fluid passing through proportional valve 46. In this embodiment, proportional valve 46 selectively supplies pressurized hydraulic fluid to directional valves 50, 52, and 54. Input 42 is coupled to directional valves 50, 52, and 54 and may be used to select at least one of hydraulically actuated functions 56, 58, and 60 to receive pressurized hydraulic fluid from proportional valve 46. When an operator selects a function with input 48, for example function 58, directional valve 52 is opened to allow fluid communication between proportional valve 46 and function 58. The operator may then use input 44 to open and close proportional valve 44 to operate hydraulically actuated function 58.
Applying control system 42 to wheel loader 10 and input 36, as shown in FIGS. 1 and 2, joystick 38 may be input 44 and selector 40 may be input 48 of control system 42. Hydraulically actuated functions 56, 58, and 60 may be boom cylinder 28, bucket cylinder 32, and an accessory port used with any suitable hydraulic attachment. For this example, the operator may desire to lift boom 26 as shown in phantom in FIG. 1. The operator first selects to control boom cylinder 26 using selector 40 which powers directional valve 54 to open allowing fluid to flow between proportional valve 46 and boom cylinder 56. The operator then uses joystick 38 to actuate proportional valve 38 to allow pressurized hydraulic fluid to pass through directional valve 54 to boom cylinder 28 to lift boom 26.
In another embodiment of control system 42, multiple inputs may be used to control directional valves 50, 52, and 54. For example, in addition to selector 40 of input 36 shown in FIG. 2, movement of joystick 38 in the side-to-side (C to D, D to C) direction or the back and forth (A to B, B to A) direction may automatically select one of the directional valves to open to control a predetermined function. It should be understood by one having ordinary skill in the art that control system 42 may used on any suitable construction apparatus or agricultural tractor. Additionally, any suitable number of inputs and directional valves may be used to direct hydraulic fluid flow from a single proportional valve to a plurality of hydraulically actuated functions.
Referring now to FIG. 4, a schematic 62 for one embodiment of control system 42 is shown. Schematic 62 includes hydraulic pump 43, proportional valve 46, and pairs of directional valves 50, 52, and 54. In this embodiment, a pair of directional valves is used of each for each hydraulically actuated function 56, 58, 60. One directional valve of the pair is positioned in the fluid supply line supplying pressurized hydraulic fluid to the function while the other directional valve of the pair is positioned in the return line that allows displaced hydraulic fluid to flow back into the system. In this embodiment, the pairs of directional valves 50, 52, and 54 are solenoid actuated, spring return electro-hydraulic valves, however any suitable directional valves may be used. As discussed above, when the operator selects one of the hydraulically actuated functions 56, 58, and 60, the corresponding pair of directional valves 50, 52, and 54 is powered to open to allow hydraulic fluid low from proportional valve 46 to the selected hydraulically actuated function.
A schematic of a prior art control system 70 is shown in FIG. 5. Control system 70 includes a hydraulic pump 72, three proportional valves 80, 82, and 84, and three corresponding hydraulically actuated functions 74, 76, and 78. In this embodiment, each hydraulically actuated function requires a corresponding proportional valve. Each proportional valve 80, 82, and 84 is coupled to an input configured to open or close the corresponding proportional valve. Each of the proportional valves directly controls the corresponding hydraulically actuated function after receiving input from an operator or computer control system.
Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the spirit and scope of the invention as described and defined in the following claims.
Patent Application
20070253840
