Patent Application
20100205953
The present invention relates generally to hydraulic systems for agricultural and construction implements and, more particularly, to a case drain circuit having a pressure switch that shuts down a fan drive motor, from which the case drain circuit receives leakage fluid, during undesirable pressure levels in the case drain circuit.
To improve efficiency many planters are equipped with a bulk fill subassembly. Commonly, a bulk fan drive will include two large tanks or hoppers that are mounted to the planter frame. The tanks are typically loaded with seed and metering systems deliver the seed from the tanks in a controlled manner to the individual seed units carried by the seeder. The metering systems commonly include, or are operable with, a fan assembly that produces an air stream in which product from the tanks is delivered to the individual seed units. In many setups, the bulk fill fan assembly is driven by a solenoid controlled hydraulic motor. Electronic signals are sent to the solenoid, which varies the position of a corresponding valve to control the flow of hydraulic fluid or oil to the motor.
The hydraulic system generally consists of a hydraulic fluid supply line, a hydraulic fluid return line, and a case drain line that delivers leakage fluid from the hydraulic motor to a fluid reservoir, which is generally carried by the tractor rather than the seeder. For most bulk fill subassemblies, the subassembly will include corresponding hydraulic hoses for the aforementioned hydraulic lines that are fitted with suitable couplers for coupling the hoses to the hydraulic system of the tractor that is towing the seeder. In one exemplary configuration, the hose for the case drain line of the bulk fill subassembly will have a male quick connect coupler that interfaces with a female quick connect coupler of the tractor's case drain hose. The case drain line is typically a low pressure line with a pressure generally less than 25 psi. If the connection between the male and female couplers is not made properly or if the connection is broken while the hydraulic motor is turning, the pressure in the case drain line can buildup, and quickly, resulting in motor failure. The likelihood of damage to the motor is particularly acute since most bulk fill assemblies do not provide any audio or visual warning that the connection between the tractor and the bulk fill case drain lines is disconnected or has otherwise become broken.
In addition, a planter will also typically include one or more vacuum fans that are driven by hydraulic motors. Through various connections, such as a T-connection, the case drain lines for these additional hydraulic motors will be connected to the case drain line for the bulk fill fan motor, with a single case drain line being connected to the tractor.
One proposed solution is to dump fluid in the case drain line to atmosphere, but this is not environmentally preferred and can lead to a complete draining of hydraulic fluid of the tractor.
The present invention is directed to a case drain circuit particularly well suited for use with a bulk fill subassembly or other fan driver assembly of an agricultural implement towed by a tractor or similar vehicle and that includes a pressure switch that may cause illumination of an in-cab warning light and/or sounding of an in-cab alarm when pressure in the case drain circuit exceeds a predetermined threshold. The bulk fill subassembly, as well as vacuum fan assemblies, each include a fan that is driven by a respective solenoid controlled hydraulic motor. Hydraulic fluid is supplied under pressure from solenoid controlled flow valves to the motors in accordance with electrical signals that are supplied to the solenoid by a controller. The case drain circuit provides a pathway along which leakage fluids from the motor may be delivered to a fluid reservoir, preferably carried by the tractor or other vehicle towing the agricultural implement. During undesirable high pressure conditions in the case drain circuit, the pressure switch provides a corresponding high pressure signal to the controller that in turn cuts electrical current to the solenoid that controls the flow of hydraulic fluid to the motor to effectively shut down the hydraulic motor.
The case drain circuit may also include an auxiliary fluid dump into which hydraulic fluid may be delivered during high pressure conditions in the case drain circuit. The fluid dump may include a float switch that is activated when the fluid level in the dump reaches a predetermined level. Activation of the float switch may also cause illumination of the in-cab light and/or sounding of the in-cab alarm. Moreover, the float switch may provide a corresponding signal to the controller for the solenoid that responsive thereto cuts current to the solenoid to effectively shutdown the hydraulic motor.
It will thus be appreciated that it is an object of the invention to provide a warning system that signals undesirable pressure conditions in the case drain circuit of a planter.
It will also be appreciated that it is an object of the invention to cause automatic shutdown of a fan driven motor during undesirable pressure conditions in the case drain line for the hydraulic motor.
It is another object of the invention to provide a fluid dump into which hydraulic fluid may be delivered from the case drain line during high pressure conditions in the case drain line.
Other objects, features, and advantages of the invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.
Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout.
In the drawings:
A planter 10 is shown in
The frame 12 also supports a pair of tanks 24, 26 that carry seed, fertilizer or other planting material to be deposited onto the planting surface. Planting material is fed from the tanks 24, 26 in a conventional manner using a metering subassembly (not shown) to two sets of row or dispensing units 28, 30, respectively. The row units 28, 30 are spaced linearly along the frame 12 and include a material dispensing port associated with a material hopper, furrow opener, and a packer wheel, as known in the art. One skilled in the art will appreciate that material is fed from the tanks 24, 26 to the individual material hoppers of each row unit. The material metering system controls the dispensing of material from the individual hoppers. A platform 32 is mounted to a rearward portion of the frame proximate the tanks 24, 26 to enable a loader to fill the tanks 24, 26 with seed when desired.
The frame 12 and its components are supported above the planting surface by four center carrying wheels 34 (only one of which is visible in the figure) and four outer carrying wheels (all of which are designated by reference numeral 37) that support the wings 12a, 12b, of the frame 12. The frame 12 includes a pair of foldable markers 38, 40 with each including a marker wheel 42, 44, respectively, as is also known in the art, that are supported by the wings 12a, 12b when retracted (as shown in
As known in the art, the metering system referenced above meters product from tanks 24, 26 and preferably into an air stream. Referring now to
A case drain line 68 is provided to pass leakage fluid from the motor 48 to the case drain circuit of the tractor. Preferably, the supply line 56 is connected to the supply circuit of the tractor using a quick connect coupler 70. Similarly, the return line 62 and the case drain are connected to corresponding circuits of the tractor using quick connect couplers 72 and 74, respectively.
In accordance with one embodiment of the present invention, a pressure switch 76 is plumbed in the case drain line 68. The pressure switch 76 is switched between a LOW pressure position and a HIGH pressure position based on the pressure in the case drain line 68. More particularly, the pressure switch 76 provides an electrical output to the controller for the solenoid 54 when pressure in the case drain line 68 exceeds a predetermined threshold. In a preferred embodiment, the threshold is below a maximum pressure that may be tolerated by the motor 48 without structural failure. When the motor 48 is running and the connection of the case drain line 68 to the case drain circuit of the tractor is broken, the pressure in the case drain line 68 will increase. When the pressure has reached the predetermined threshold, the pressure switch 76 will switch from a LOW pressure position to a HIGH pressure position and provide a corresponding signal 78 to the controller for the solenoid 54. The controller will, in turn, cut power to the solenoid 54 effectively cutting the supply of hydraulic fluid to the motor 48. The motor 48 will then coast to a stop as permitted by the coast check valve 66. Continued operation of the motor 48 will not be possible until pressure in the case drain line 68 drops below the threshold and the pressure switch resets.
In addition to shutting down the motor 48, when the pressure in the case drain line 68 exceeds the desirable working pressure, a warning light 80 in the operator cab (not shown) of the tractor is illuminated. It is contemplated that the warning light may be activated directly by the output signal of the pressure switch 76 or by a separate signal that is provided by a controller, such as the controller that controls operation of the solenoid 54. Alternately, or in addition, an alarm may be sounded when pressure in the case drain line 68 has reached the predetermined threshold. Thus, an operator sitting in the operator cab is notified that an undesirable condition is present in the case drain line 68 and that attention thereto is needed. It is further contemplated that a separate light or audible alarm may be activated by stopping of the motor 48 or the fan 46 thus signaling to the operator that operation thereof has been stopped. It is also contemplated that an air flow (sensor) may also be used to signal that the air stream is not being properly generated.
In a further embodiment, a float switch 86 is provided in the collector reservoir 82 that is activated when the fill level in the collector reservoir 82 reaches a predetermined level. In a preferred embodiment, the float switch 86 outputs a signal to the controller for the solenoid 54 similar to the output signal provided by the pressure switch 76. Thus, when the level of fluid in the collector reservoir reaches a predetermined level, the motor 48 will be shutdown.
In addition, in a preferred embodiment, when the float switch 86 is triggered, a warning light, e.g., light 80, and/or audible alarm in the operator cab of the tractor is activated signaling the operator that an undesirable condition is present in the case drain line 68 and that the float switch has been activated. It is recognized that the pressure switch 76 and the float switch 86 can cause illumination or sounding of the same lights and alarms or different lights and alarms to provide the operator with some specificity as to what is being signaled.
It will be appreciated that the float switch 86 is not reset until the hydraulic fluid is drained from the collector reservoir 82. Thus, the motor cannot be restarted when the float switch has been triggered until after the fluid level in the collector reservoir 82 has been lowered below the predetermined trigger level.
It will also be appreciated that the case drain of other hydraulic motors, such as those to drive vacuum fans, may be connected with a suitable connection to case drain line 68 and thus, if an undesirable pressure is present in the case drain line, all of the motors associated with the case drain line may be shutdown in a manner as described above.
Many changes and modifications could be made to the invention without departing from the spirit thereof. The scope of these changes will become apparent from the appended claims.
