Patent Application
20070209356
The present invention relates generally to hydraulic control systems. More particularly, the present invention relates to a hydraulic control system for machines having a steering wheel and a joystick.
Many pieces of construction equipment use hydraulics to control the functions performed by the equipment. For example, many pieces of construction equipment use hydraulics to control the steering. On some pieces of construction equipment, both a steering wheel and a joystick are provided to hydraulically control the direction of the vehicle.
According to one exemplary aspect of the present invention, a vehicle is provided that includes a chassis, a plurality of traction devices configured to propel the chassis on the ground, at least one hydraulic actuator positioned to power a function of the vehicle, and a hydraulic control system. The hydraulic control system includes a pressure source providing pressurized hydraulic fluid, a first user input, a valve control assembly that receives pressurized fluid in response to the first user input to control the flow of fluid from the pressure source to the at least one hydraulic actuator, and a second user input. The valve control assembly receives pressurized fluid in response to the second user input to control the flow of fluid from the pressure source to the at least one hydraulic actuator. The hydraulic control system further includes a diverter that communicates the pressurized fluid provided in response to the second input from the valve control assembly when the first user input receives an input from a user.
According to another exemplary aspect of the present invention, a method of prioritizing inputs to a vehicle is provided. The method includes the steps of providing a vehicle including a chassis, a plurality of traction devices configured to propel the chassis on the ground, at least one hydraulic actuator, and a hydraulic control system. The hydraulic control system includes a pressure source, a first user input, a first control valve that receives input from the first user input to control the flow of fluid from the pressure source to the at least one hydraulic actuator, a second user input, and a second control valve that receives input from the first user input to control the flow of fluid from the pressure source to the at least one hydraulic actuator. The method further includes the step of diverting pressurized fluid from the second control valve in response to user input to the first user input.
Additional features of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the presently perceived best mode of carrying out the invention.
The detailed description of the drawings particularly refers to the accompanying figures in which:
A wheel loader 10 is shown in
To move and power the various components of loader 10, it includes a plurality of hydraulic actuators 24. As shown in
To power and control hydraulic actuators 24, loader 10 includes a hydraulic control system 28 as shown in
As shown in
Steering wheel 34 is coupled to an orbital valve 38 that controls a first spool control valve 40. Depending on the direction and speed of rotation of steering wheel 34, orbital valve 38 controls the position of spool valve 40. The position of spool valve 40 controls the direction and rate of hydraulic fluid provided by pump 30 to steering cylinders 26 and the direction and rate of hydraulic fluid from steering cylinders 26 to tank 32. Spool valve 40 controls the flow of hydraulic fluid to and from steering cylinders 26 so they operate in opposite directions.
Joystick 36 is electronically coupled to an electronic controller 42 that receives input from joystick 36 and controls a plurality of solenoid valves 44. Solenoid valves 44 receive hydraulic fluid from pump 30. According to the exemplary embodiment of the present disclosure, a pressure reduction valve 46 reduces the pressure of the hydraulic fluid received from pump 30 and provided to solenoid valves 44.
Solenoid valves 44 provide pilot fluid to a second spool control valve 48 which controls the supply of hydraulic fluid to and from steering cylinders 26. Depending on the direction and extent of tilt of joystick 36, spool valve 48 controls the direction and rate of hydraulic fluid from pump 30 to steering cylinders 26 and the direction and rate of hydraulic fluid from steering cylinders 26 to tank 32. Spool valve 48 controls the flow of hydraulic fluid to and from steering cylinders 26 so they operate in opposite directions.
As mentioned above, control system 28 is configured to give input to steering wheel 34 priority over input to joystick 36. A priority valve 50 is provided between pressure reduction valve 46 that provides priority to steering wheel 34 over joystick 36. As steering wheel 34 turns, orbital valve 38 provides an output pressure signal to spool valve 40 which also provides pilot pressure to priority valve 50. Thus, when steering valve 40 rotates, orbital valve 38 controls the position of priority valve 50.
As shown in
According to an alternative embodiment of the present disclosure, a valve (not shown) is provided between pressure reducing valve 46 and pump 30 to block the flow of fluid when an input is detected to steering wheel 34. Such a valve may be piloted in a manner similar to priority valve 50. Thus, when steering wheel 34 is rotated, pilot fluid is blocked from solenoids 44 to block input from joystick 36. Alternatively, this valve may also be provided between pressure reducing valve 46 and solenoids 44. In these embodiments, priority valve 50 may or may not be provided.
The control system above has been described in reference to a wheel loader. According to other embodiments of the present disclosure, the control system may be provided on other vehicles such as articulated dump trucks, backhoe loaders, dozers, crawler loaders, excavators, skid steers, scrapers, trucks, cranes, graders, or any other type of vehicles known to those of ordinary skill in the art. In addition to wheels, other types of traction devices may be provided on such vehicles such as tracks or other traction devices known to those of ordinary skill in the art.
According to alternative embodiments of the present disclosure, the priority of other inputs are control by the priority system described above. For example, other dual inputs functions may be provided with a priority system, such as dual bucket controls on a wheel loader, backhoe, or other vehicle having multiple bucket controls; dual boom controls on a backhoe or other vehicle having a boom with multiple boom control inputs; and any other vehicle functions having dual inputs for the particular function. Additionally, the priority system described above may be used on controls for different functions where is it is desirable to give one function priority over another function.
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.
