Blade speed control logic

A construction vehicle is provided having a manual mode in which an operator provides manual inputs to control the movement of a blade to a location and an automatic mode in which a control moves the blade to a predetermined location. The speed of the movement of the blade in the automatic mode is scaled down from the speed of the blade in the manual mode.

FIELD OF THE INVENTION

The present invention relates to construction vehicles and, more particularly, to a method of controlling the speed of a blade tip of a construction vehicle.

BACKGROUND AND SUMMARY OF THE INVENTION

Construction vehicle nay have a manual mode and an automatic mode. In the manual mode, the location of a blade tip may be controlled by user inputs. In an automatic mode, a controller moves the location of the blade tip to a predetermined location. If the controller moves the blade tip too fast, it may overrun the desired location or cause movement that is not smooth.

According to one aspect of the present invention, a construction vehicle is provided that moves materials. The construction vehicle includes a chassis; a plurality of traction devices operably coupled to the chassis to propel the chassis; a blade supported by the chassis and configured to interact with materials to be moved by the vehicle; and a hydraulic system. The hydraulic system includes a plurality of hydraulic cylinders positioned to move the blade between a plurality of positions; a source of pressurized fluid providing pressurized hydraulic fluid; a plurality of user inputs positioned to receive inputs from an operator of the construction vehicle; and a control system having a manual mode and an automatic mode, a controller, and memory storing a predetermined location of the blade. When in the manual mode, pressurized fluid from the source of pressurized fluid is available to a first hydraulic cylinder of the plurality of hydraulic cylinders at a first maximum pressure and the flow of fluid to the first hydraulic cylinder in controlled through operator input to a first input of the plurality of user inputs. When in the automatic mode, pressurized fluid from the source of pressurized fluid is available to the first hydraulic cylinder at a second maximum pressure that is less than the first maximum pressure and the flow of fluid to the first hydraulic cylinder is controlled by the controller using the predetermined location stored in the memory.

According to another aspect of the present invention, a construction vehicle is provided including a chassis; a plurality of traction devices operably coupled to the chassis to propel the chassis; a blade supported by the chassis and configured to interact with materials to be moved by the vehicle; and a hydraulic system. The hydraulic system includes a plurality of hydraulic cylinders positioned to move the blade between a plurality of positions; a source of pressurized fluid providing pressurized hydraulic fluid; a plurality of user inputs positioned to receive inputs from an operator of the construction vehicle; and a control system having a manual mode and an automatic mode, a controller, and memory storing a predetermined location of the blade. When in the automatic mode, the controller controls the flow of fluid to a first hydraulic cylinder of the plurality of hydraulic cylinders to position the blade in the predetermined location and the controller scales down a maximum available pressure from the source of pressurized fluid to the first hydraulic cylinder of the plurality of hydraulic cylinders when compared to a maximum available pressure when in the manual mode.

According to another aspect of the present invention, a method of moving material is provided. The method includes the steps of providing a construction vehicle including a chassis, a plurality of traction devices operably coupled to the chassis to propel the chassis, a blade supported by the chassis and configured to interact with materials to be moved by the vehicle, and a hydraulic system. The hydraulic system includes a plurality of hydraulic cylinders positioned to move the blade between a plurality of positions; a source of pressurized fluid providing pressurized hydraulic fluid; a plurality of user inputs positioned to receive inputs from an operator of the construction vehicle; and a control system having a manual mode and an automatic mode, a controller, and memory. The method further includes the steps of storing a predetermined location of the blade into the memory; moving the blade to a location in response to manual user input to a first input of the plurality of user inputs; switching the control system from the manual mode to the automatic mode; scaling down the supply of pressurized fluid available to a first hydraulic cylinder of the at least one of the plurality of hydraulic cylinders in response to switching step; moving the blade to the predetermined location after the switching step; switching the control system from the automatic mode to the manual mode; scaling up the supply of pressurized fluid available to the first hydraulic cylinder in response to the step of switching the control system from the automatic mode to the manual mode, and moving the blade to a location in response to manual user input to the first input after the step of switching the control system from the automatic mode to the manual mode.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1illustrates a construction vehicle, such as a backhoe loader10, having a chassis/frame12to which are mounted ground engaging wheels14for supporting and propelling frame12. Although the current disclosure is illustrated as a wheeled work vehicle, it can also be mounted on a crawler work vehicle having tracks or other suitable work vehicles having traction devices other than wheels for supporting and propelling a frame. In addition, the blade tip logic of the present disclosure could be used other construction vehicles, such as excavators, motor graders, crawlers, bull dozers, etc. Backhoe loader10is provided with a loader bucket16having a suitable loader bucket linkage for manipulating loader bucket16relative to frame12. The rear of vehicle frame12is provided with a swing frame18. A boom20is pivotally coupled to swing frame18, a dipperstick22is pivotally connected to boom20at pivot24, and a blade/bucket26is pivotally connected to dipperstick22. Vehicle10includes several cylinders for manipulating the position and orientation of bucket26including one or more swing cylinders28that move boom20side-to-side relative to frame12, one or more boom cylinders30that rotate boom20relative to frame12; one or more crowd cylinders32that rotates dipperstick22relative to boom20; and one or more bucket cylinders34that rotate bucket26relative to dipperstick. Backhoe loader10is also provided with two stabilizers36.

The operation of vehicle10is controlled from either an open or closed operator's station38. The operator may operator bucket26in manual mode or an automatic mode. In the manual mode, the operator manipulates a plurality of operator controls or levers40positioned in operator's station38. In the automatic mode, the operator presses a mode button (or moves a switch)41, as shown inFIG. 2, and a controller42automatically moves the tip of bucket26to a predetermined location and orientation. The predetermined location and orientation may be provided by a grade control system that attempts to match to the location and/or orientation of the tip of bucket26to a programmed position and/or orientation. Additional details of a suitable grade control system are provided in U.S. Pat. No. 6,253,160 to Hanseder, the entire disclosure of which is expressly incorporated by reference herein. Other grade control systems may also be used with the present disclosure including laser guided systems and sonic system.

As shown inFIG. 2, vehicle10includes a pump44that provides pressurized fluid, a boom valve46that controls the flow of hydraulic fluid from pump44to boom cylinder30; a crowd valve48that controls the flow of hydraulic fluid from pump44to crowd cylinder32, and a bucket valve50that controls the flow of hydraulic fluid from pump44to bucket cylinder32. A hydraulic line52(shown in phantom) provides hydraulic fluid to valves46,48,50.

The position of cylinders30,32,34controls the location of the tip of bucket26. Controller42may provide hydraulic, electric, or other signals to valves46,48,50to provide control thereof. Similarly, controller42may receive hydraulic, electric, or other signals from levers40or the other control inputs.

Cylinders30,32,34may be dual acting cylinders that allow for extension and retraction. Although single hydraulic lines54are shown extending from valves46,48,50to cylinders30,32,34, multiple lines may be provided to supply pressurized fluid to either side of pistons (not shown) within cylinders30,32,34. Similarly, although not shown, a tank, accumulator, or other reservoir is provided to receive fluid flowing out of cylinders30,32,34. Valves46,48,50are provided with multiple ports to receive fluid from pump44, direct fluid from valve46,48,50to a reservoir, and direct pressurized fluid to valves46,48,50as necessary. Additional details of suitable valves46,48,50are provided in U.S. Pat. No. 7,415,822, titled “Load sense boost device,” to Harber et al., filed Jul. 21, 2005, the entire disclosure of which is incorporated by reference herein.

In the manual mode, an operator provides manual inputs to levers40. In response to inputs from levers40, controller42controls the position of valves46,48,50to control the flow of fluid to and from cylinders30,32,34. Thus, an operator manually moves levers40to position the tip of bucket26in the desired location to scoop up or otherwise move material, such as dirt.

In the automatic mode, controller42controls the position of valves46,48,50to control the flow of fluid to and from cylinders30,32,34. Thus, an operator presses mode button41and controller42controls the movement of the tip of bucket26to a predetermined location stored in the memory of controller42or other memory of vehicle10. Unlike the manual mode, less than full pressure and/or the full flow rate available from hydraulic pressure from pump44is used to move the tip of bucket26. For example, if full available pump pressure from pump44to cylinders30,32,34under the manual mode is 2,500 psi, controller42provides less than 2,500 psi to one or more of cylinders30,32,34under the automatic mode. According to one embodiment, controller42scales back the available pressure by 5 or 10%. According to other embodiments, controller42scales back the available pressure by other percentages or amounts, such as 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%. As a result of the scaling back (or down), the tip of bucket26moves at a slower rate. Thus, an operator can move the tip of bucket26faster during the manual mode than controller42can move the tip during the automatic mode. According to one embodiment, a user or programmer can adjust the amount of scaling using an input58or by adjusting the programming of controller42. The adjustments may be discrete or infinite.

As shown inFIG. 2, controller42reduces the available pressure or flow to cylinders30,32,34using flow restrictors56to reduce the pressure and flow. Flow restrictors56are electrically or hydraulically controlled, for example. During the manual mode, flow restrictors56provide little, if any, pressure drop and/or flow restriction. During the automatic mode, flow restrictors56drop the pressure and/or restrict the flow of fluid. Although restrictors56are shown separate from valves46,48,50, restrictors56may be incorporated as part thereof. According to another embodiment, a single restrictor56′ is provided downstream of pump44to reduce the pressure from pump44. Further, controller42may provide the functional equivalents of restrictors56by reducing the available pressure output from pump44. For example, during manual operation, controller42may control pump44to provide a maximum pressure output of 2,500 psi and during automatic operation, controller42may control pump44to provide a maximum pressure output of 2,250 psi (i.e. 10% less than the maximum pressure output).

As a result of providing less pressure to cylinders30,32,34, they move in a slower, smother manner than if full pressure (ex. 2,500 psi) is provided. For example, at full pressure, cylinders30,32,34may over shoot their desired position. This overshooting is reduced by providing less pressure to cylinders30,32,34. According to one embodiment, full pressure is provided to one or more of cylinders30,32,34during the manual mode, and less than full pressure is provided to the other cylinders30,32,34during the automatic mode.

Although vehicle10is shown as a backhoe loader, the principles of the present disclosure may also be applied to other construction vehicles. For example, according to one embodiment of the present disclosure, the principles are applied to the tilt and lift of a mold board/grader blade of a motor grader.

Another example is shown inFIGS. 3 and 4showing a crawler dozer110having a chassis/frame112to which are mounted ground engaging tracks114for supporting and propelling frame112. Crawler dozer110is provided with a dozer blade116that can be raised and lowered (as shown inFIG. 3), titled between multiple positions (as shown inFIG. 4), and angled between multiple positions (as shown inFIG. 3). Cylinders such as hydraulic cylinders30,32,34may be used to perform these raise, tilt, and angle adjustments. When in the automatic mode, such as when a grade control system is activated, controller42moves a lower tip of dozer blade116to a desired height and tilt to obtain a predetermined height and grade of earth as crawler dozer110grades a work site. According to one embodiment, the supply of pressurized fluid to tilt cylinder32is scaled down during movement of dozer blade116to this predetermined location and orientation. While the supply of pressure to tilt cylinder32is scaled down during this automatic mode, the supply of fluid to height cylinder30may remain at full pressure. Thus, the adjustment of the tilt of blade116is slowed down and the adjustment of the height of blade116is not. The supply of fluid to angle cylinder34may remain at full pressure and under manual control while tilt and height cylinders32,30are under the control of the automatic mode.