Agricultural mixer with hydraulic drive system including jam detection and resolution features and method of using same

An agricultural mixer includes a hydraulic drive system. The mixer includes an automatic jam-resolving feature, whereby if an auger becomes jammed, the drive system will cause the auger to rotate in a reverse direction for a period of time to resolve the jam. The hydraulic drive system will maintain a speed of rotation of the auger at a relatively constant rate during mixing while choosing an efficient displacement setting for the hydraulic motor. The auger is maintained at a constant speed during a discharge mode by maintaining the motor in a maximum displacement setting. A clean-out mode is provided wherein the auger is rotated at a maximum speed to aid in cleaning out the last remaining feed mixture in the mixer.

FIELD OF THE INVENTION

The present invention relates generally to agricultural mixers of the type that utilize an auger or augers within a mixing tub. More particularly the invention relates to structures and methods for controlling rotation of the auger or augers.

BACKGROUND OF THE INVENTION

Various types of agricultural feed mixers are known. One type of mixer, known as a vertical axis mixer, utilizes a mixing tub having an open upper end and including at least one rotatable auger mounted about a vertical axis within the tub. The rotation of the auger causes feed within the tub to be agitated, chopped, and mixed.

Many of these mixers are mounted upon trailers that can be drawn behind a conventional agricultural tractor. They include drive systems that can be powered by the power take off of the tractor. Other types of mixers are mounted directly on a self-propelled vehicle and are driven by the internal combustion engine that also propels the vehicle. Alternatively, such mixers may be mounted in a stationary position and be provided with their own power source, or include a connection for a power take off.

One of the issues faced by such mixers is providing appropriate rotational force to the auger or augers. The amount of force required to rotate the augers can vary depending upon a number of factors, including the amount of feed in the tub, the stage of the mixing process, whether the augers are already rotating, and the type and condition of the feed. The difficulties in maintaining an appropriate input force to the augers can be exacerbated by variations in the amount of available power provided by the power take off from an agricultural vehicle, and by changing conditions within the material being mixed.

It is typically desirable to maintain a generally constant rate at which feed is discharged from the tub wherein the mixer is discharging the feed. This can be difficult to maintain as the amount of resistance provided by the feed against the augers decreases as the amount of feed in the tub decreases.

Another difficulty associated with this type of agricultural feed mixer is that it can be difficult to completely discharge and clean out all of the feed from the tub as some of the feed may tend to cling to the augers and remain within the tub.

Yet another difficulty faced in operating these vertical auger mixers is that one or more of the augers can stall or jam due to feed wedging between the walls on especially the floor of the tub and the augers. Furthermore, the augers can become stalled due to the feed being packed tightly around the augers during transportation.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an agricultural mixer of the type that utilizes a vertical auger or augers in a tub that overcomes one or more of the above-identified difficulties.

According to one embodiment, the present invention is directed to an agricultural mixer with at least one vertical auger wherein a hydraulic drive system automatically adjusts the auger speed to allow full usage of available power input.

According to another embodiment, the present invention is directed to an agricultural mixer with at least one vertical auger that maintains a generally constant auger speed while discharging feed regardless of power take off input speed variations and variations in resistance against the auger.

According to another embodiment, the present invention is directed to an agricultural feed mixer with at least one vertical auger that includes a clean out mode whereby the auger is caused to rotate significantly faster than during mixing and feeding modes.

According to another embodiment, the present invention is directed to an agricultural feed mixer with at least one vertical auger that includes a jam resolving mode whereby the auger is rotated in a reverse direction and then rotated in a forward rotation to resolve a stalled condition of the auger.

According to one embodiment, the present invention is directed to an agricultural feed mixer that includes a tub and an auger extending into the tub. The auger is rotatable about a vertical axis. A hydraulic drive is operably connected to the auger to rotate the auger about the axis. A jam detection mechanism detects when the auger is jammed such that the auger will not rotate freely in a first direction around the axis. A controller causes the hydraulic drive to rotate the auger in a reverse direction around the axis when the jam detector detects that the auger is jammed.

According to another embodiment, the present invention is an agricultural mixer that has an auger extending into a tub, the auger being rotatable in a first direction about a vertical axis to mix material within the tub. A hydraulic motor is operably connected to the auger to rotate the auger about the vertical axis. A hydraulic pump is operably connected to the hydraulic motor to supply pressurized hydraulic fluid to the hydraulic motor. A controller controls the pump and motor. A pressure sensor senses a pressure of the hydraulic fluid and provides a pressure signal to the controller. A rotation sensor senses a rotation speed of the auger and provides a rotation speed signal to the controller. The controller has a jam resolving mode such that when the controller receives a pressure signal above a maximum threshold and a rotation speed signal indicating that the auger is not rotating, the controller causes the auger to rotate in a reverse direction opposite from the first direction for a period of time.

According to another embodiment the present invention is a method of operating an agricultural feed mixer of the type having a generally vertical auger in a tub. The method includes the steps of: detecting that the auger is jammed such that it is not rotating in a forward mixing direction; rotating the auger in a reverse direction after detecting that it is jammed; and rotating the auger in the forward mixing direction after rotating it in the reverse direction.

According to yet another embodiment, the present invention is a method of efficiently operating an agricultural feed mixer of the type having a generally vertical auger in a tub wherein the vertical auger is operably attached to a variable displacement hydraulic motor having a maximum displacement setting and a minimum displacement setting such that the variable displacement auger will rotate the vertical auger within the tub. The auger is rotated in a forward mixing direction using the hydraulic motor at the maximum displacement. A pressure is periodically sensed of hydraulic fluid in communication with the hydraulic motor while the auger is rotating with the hydraulic motor at the maximum displacement setting. The hydraulic motor is shifted to the minimum displacement setting if the sensed pressure of the hydraulic fluid is below a minimum pressure for a first predetermined period of time. the pressure of hydraulic fluid in communication with the hydraulic motor is periodically sensed while the auger is rotating with the hydraulic motor at the minimum displacement setting. The hydraulic motor is shifted back to the maximum displacement setting if the sensed pressure of the hydraulic fluid is above a maximum pressure for a second predetermined period of time.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows a trailer10that includes mixer100according to one embodiment of the present invention. The trailer10includes a hitching tongue12for attachment to a towing vehicle (not shown) such as a tractor. A power take off connection14is provided to attach to the towing vehicle's power take off in order to provide power to the mixer100. A ladder16is provided near a front end of the mixer100. Mixer100includes a tub102that opens upwardly and provides a vessel for containing and mixing livestock feed, or other materials. The mixer100includes at least one vertical auger (not shown) for rotation about a vertical axis to mix material added to the tub100into a desired mixture. Hydraulic motors104transmit power to the augers. A unique hydraulic drive system for operating the hydraulic motors104is described and shown in more detail below. A gate106is provided at a lower portion of the tub102to permit off loading of the mixture. The gate106may be selectively raised or lowered by a user. As an alternative to the gate106provided on the side of the tub102as shown inFIG. 1, a front or rear gate may be provided. Conveyors or the like may be utilized in association with the gate to help in off loading and distributing the mixture. The ladder16includes an upper platform18and railing20. The ladder16and platform18permit a user to view over the top edge of the tub102into the interior of the tub102. The ladder16may also be useful in loading materials into the tub102for mixing.

FIG. 2shows an embodiment of a truck22that includes a mixer100according to one embodiment of the present invention. The truck22has a cab24and a frame26. The tub102of the mixer100is mounted on the truck frame26. A drive line28provides power from an engine (not shown) within the truck cab24to provide power to the pumps (not shown) that ultimately provide pressurized hydraulic fluid to the hydraulic motors104. The hydraulic motors104transmit rotational power to the augers (not shown inFIG. 2) within the mixer100. It should be appreciated that certain features and advantages of the present invention may be used in association with other types of motors and transmissions, in addition to hydraulic motors, including for example variable shifting devices.

FIG. 3is a schematic representation of a mixer100according to one embodiment of the present invention. According to the embodiment ofFIG. 3, the mixer100includes a single vertical auger106that rotates about a generally vertical axis107. The auger106extends into tub102in order to mix and ultimately dispense a mixture112provided within tub102. The mixture112may include ingredients such as hay, grain, silage, feed additives, molasses, animal fat, and other ingredients may be added into the tub102through the open top end. The auger106can then be rotated to mix the ingredients. The auger106includes a shaft108from which auger flights110extend generally radially outwardly. Rotation of the shaft106causes the auger flights110to move through the mixture112in order to chop and blend the mixture112. As used herein, the term auger is meant to refer to any structure that can be rotated about a vertical axis within a tub in order to chop and/or blend a feed mixture. The auger106is mounted to a hydraulic drive system101that controls the rotational force applied to the auger106.

The hydraulic drive system101includes a hydraulic motor104that has an output shaft114that engages the auger106to provide rotational force to cause the auger106to rotate about axis107. According to one embodiment, the hydraulic motor104is a variable displacement motor that includes at least two speeds, a high speed when the motor is adjusted to a minimum displacement, and a low speed when the motor is adjusted to a maximum displacement setting. According to one embodiment, the hydraulic motor104may be a two-speed hydraulic motor sold under the brand and model designation Poclain MS50. Pressurized hydraulic fluid is provided to the motor104by pump116. According to one embodiment, the pump116is a variable output two direction pump. According to one embodiment, the variable output two direction pump is a pump sold under the brand and model designation Linde HPV 75CC. The pump116provides pressurized hydraulic fluid to the motor104through hydraulic lines118and120. When the motor104is operated to drive the auger106in a forward direction that chops and mixes the mixture102, line118acts as a supply line, and line120acts as a return line for the hydraulic fluid to the pump116. When the motor104is operated to drive the auger106in a reverse direction, line120acts as a supply line, and line118acts as a return line for the hydraulic fluid to the pump116. While omitted from the drawings for ease of understanding, those of skill in the art will appreciate that additional components such as pressure relief valves, temperature sensors, cooling fans, and the like should be include in the hydraulic system.

The pump116is driven by a power supply122that rotates an output shaft124engaged by the pump116. The output shaft124may be a power take off from a tractor, in the case where the mixer100is mounted on a trailer10as shown inFIG. 1. Alternatively, the output shaft124may be an output shaft from a self-propelled vehicle, such as the truck22ofFIG. 2. An electronic controller126is provided as part of the hydraulic drive system101in order to automatically control the components of the mixer100. According to one embodiment, the controller126is a programmable 30-pin digital controller. According to one embodiment, the controller126maybe programmed to act as a partial integral derivative (PID) controller. In the embodiment shown inFIG. 3, the controller126receives input signals from a motor output speed sensor128, a power take off sensor130, and a line pressure sensor132. The motor output speed sensor128may be a pulse pickup that senses the rate of rotation of the output shaft114of the motor104, and provides a signal to the controller126indicating that rotation rate. The motor speed sensor128is an indirect sensor for the rate or rotation of the auger106. The power takeoff sensor130may also be a pulse pickup sensor that senses the rate of rotation of the power takeoff shaft124and provides a signal to the controller126that indicates that rotation rate. The line pressure sensor132is a pressure sensor that senses the pressure within the hydraulic line connecting the pump116with the motor104and provides a signal to the controller indicating that pressure level. The line pressure sensor132may be located at a variety of locations within the hydraulic circuit as will be known to those of skill in the art.

The controller126also includes output lines to provide control signals to the pump116and the motor104. Output signal line134permits the controller126to provide a control signal to the pump116. The control signal may adjust the rate at which the pump116provides hydraulic fluid to the motor104. Additionally, the output signal line134permits the controller to provide a signal that controls the direction of flow out of the pump116, such that the pump116can rotate the motor104in either a forward or reverse direction about the axis107. The output signal line136permits the controller126to provide a control signal to motor104in order to shift the motor104between the low speed maximum displacement setting and the high speed minimum displacement setting.

The controller126should be in connection with a user interface (not shown) that permits a user to provide input to and receive feedback from the controller126. The controller126should be programmed with logic that causes the hydraulic drive system101to operate as desired based on control settings provided by a user through the user interface and on the feedback received from the various components by the controller126during operation.

According to one feature of the present invention, the hydraulic drive system101will drive the auger106at an appropriate speed to allow full usage of available horse power to efficiently mix the mixture112without stalling. According to this feature, a user will enter a setting of a mixing mode into the user interface (not shown). The controller126may be programmed with a minimum power takeoff speed, for example, 2000 rpm. If the PTO sensor130senses that the power takeoff shaft124is not rotating at or above the minimum setting, the controller126will provide an output to the user interface indicating that the power takeoff shaft is not rotating at a sufficient speed, and the system will not attempt to shift into a mixing mode. If the power takeoff shaft124is rotating at a sufficient speed above the programmed minimum, the controller126will send appropriate signals to cause the auger106to rotate at a preset maximum displacement mixing rotation speed. For example, during mixing while the motor is in the maximum displacement setting it may be desirable to have the auger106rotate at about 23 rpm. When in the mixing mode, the controller126first controls the pump116and motor104to maintain the rotation of the auger106at the predefined maximum displacement mixing rotation speed (e.g., 23 rpm). The controller126will adjust the output of the pump116in order to maintain the speed of rotation of the auger106at the desired setting. The controller126will also monitor the hydraulic pressure at the motor104by way of receiving a signal from the line pressure sensor132.

At the start of a mix mode cycle, the motor104will be set at maximum displacement. If the motor hydraulic pressure drops below a specified minimum for a set period of time, the controller126will shift the motor104to the minimum displacement setting. For example, if the line pressure at the motor104drops below 2000 psi for more than five seconds, the controller126will cause the motor104to shift to the minimum displacement setting. This increases the efficiency of the operation of the system by operating in the minimum displacement mode when feasible. The controller126then seeks to maintain the auger106at a minimum displacement mixing rotation rate that is higher than the rotation rate associated with the maximum displacement setting. Typically the minimum displacement mixing rotation rate will be set at about 35 rpm. If, after shifting to the minimum displacement setting, the hydraulic pressure at the motor104rises above a specified maximum for a set period of time, the controller126will cause the motor104to shift back to the maximum displacement setting. This prevents the auger106from stalling. For example, if the hydraulic pressure sensed by the line pressure sensor132is above 4000 psi for more than five seconds, the controller126will shift the motor104back to the maximum displacement setting, and again seek to maintain the rotation of the auger at the slower maximum displacement mixing rotation rate of 23 rpm. In this fashion, the hydraulic drive system101automatically adjusts the motor104to operate at an efficient setting and speed.

Occasionally during a mixing operation, the auger106may become jammed by mixture material112being wedged between the auger106and the bottom or side walls of the tub102. According to one feature of the present invention, the hydraulic drive system101will recognize the jammed condition and attempt to automatically resolve it. If the auger106becomes jammed, the pressure at sensor132will be at a maximum line pressure, for example equal to a relief valve setting. Furthermore, the motor output speed sensor128will be sending a signal to the controller126that the rotation rate is at or near zero. If both of these conditions persist over a set period of time, the controller126will shift to a jam-resolving mode. In the jam-resolving mode, the controller126causes the pump116to operate in a reverse direction such that the motor104rotates in a reverse orientation, consequently causing the auger106to be rotated in a reverse direction. The auger106is rotated in a reverse direction for a short period of time in order to relieve the pressure and reposition the content of the feed mixture112that caused the jam. After rotating in a reverse direction for a short period of time, the auger106is again rotated in the forward direction, which should hopefully now be able to proceed freely without being jammed. The controller126may attempt to free the jam by performing the reverse rotation function a few times, if the initial operation of the reverse function is not sufficient to clear the jam.

For example, if the sensor128senses that the motor output shaft114is not rotating, and the pressure sensor132senses that the hydraulic pressure in the line is a above a specified minimum pressure, and these two conditions persist for a period of time, for example 12 seconds, the controller126will shift into the jam-resolving mode and will cause the auger106to rotate in reverse orientation for a set period of time, for example five seconds. The controller126will then cause the pump to again flow in the forward direction to cause forward rotation of the auger106. If the auger106again is jammed, as indicated by a maximum pressure at the pressure sensor132and lack of rotation at the sensor128, the controller126will again try the reversing operation. If three of the reversing operations in a row are not sufficient to free the jam, then a fault condition is indicated, and a user will be required to turn off the power and manually resolve the jam.

According to another feature of the present invention, the hydraulic drive system101may be shifted into a discharge mode by a user through the user interface. In the discharge mode, the auger speed is preferably maintained at a constant rate that is relatively slow as compared to the standard mixing speed. The power input required to maintain the auger106at a desired discharge rotation rate may vary significantly depending upon the amount of feed mixture112remaining in the tub102. Therefore, as a general rule the amount of force required to rotate the auger106will decrease as the feed mixture112is depleted from the tub102. When the hydraulic drive system101is shifted into the discharge mode, the controller126will control the output of the pump116to attempt to maintain the auger106at a rotation rate of about 18 rpm. In order to maintain the auger106at a relatively constant rotation rate, the controller126will maintain the motor104in the maximum displacement setting at all times when the system is in the discharge mode. Therefore, even if the pressure within line132drops to a low level, the motor104will not shift to the minimum displacement setting, and will remain at the maximum displacement setting. This avoids a temporary jump in rotation speed of the auger106that would occur if the motor104shifted to the more efficient minimum displacement setting.

According to another feature of the present invention, the hydraulic drive system101may be shifted into a clean-out mode at the end of a discharge mode in order to fully discharge the feed mixture112and clean off the auger106. Therefore, if during the discharge mode the pressure sensor128senses that the pressure has dropped below a specified minimum for a set period of time, a user will be able to shift into the discharge mode using the user interface to provide a signal to the controller126. In the discharge mode, the controller126shifts the motor104to the minimum displacement setting and attempts to maintain the auger106at a maximum rotation speed. For example, if during the discharge mode the pressure at sensor128remains below 2500 psi during a 3-second interval, the user may shift to the clean-out mode. When that happens, the controller126will shift the motor104to the minimum displacement setting, and will control the output of the pump116to rotate the auger106at a rate of about 48 rpm.

FIGS. 4 and 5illustrate a mixer200according to another embodiment of the present invention. Mixer200is similar to mixer100that has previously described with respect toFIG. 3, except that mixer200includes two augers206A&B. The operation and construction of mixer200should be apparent to those skilled in the art in light of the above detailed discussion related to mixer100shown inFIG. 3. Each of the augers206A and206B are provided with their own corresponding hydraulic motor204A and B. Each of the hydraulic motors204A and B are hydraulically connected with corresponding pumps216A and B. Both of the pumps216A and B are powered by a single power source222, such as a power takeoff. The programmable controller226receives input signals from motor speed sensors228A and B. The controller226also receives pressure input signals from line pressure sensors232A and B. The controller226also receives an input signal from power takeoff sensor230that indicates to the controller226at what speed the power takeoff shaft224is rotating.

The operation of the hydraulic control system201of the mixer200is similar to that of hydraulic drive system101with respect to mixer100shown inFIG. 3. A user may select whether to control the augers206A and B in tandem or individually. If the augers206A and206B are operated in tandem, a single mode is selected for operation of both of the augers206A and206B. For example, both the augers206A and206B may be controller according to the parameters of the mixing mode. In the tandem control setting, the jam mode will only be entered if both of the augers206A and206B satisfy the jam conditions of having a maximum pressure at sensors232A and B and a no-rotation condition sensed by motor sensors228A and B. Similarly, the system will only shift into the cleanout mode when the line pressure is sensed to be below the specified minimum for a set period of time for both augers206A and206B.

According to another feature of the present invention, the augers206A and206B may be operated independently. A primary usage for this feature would be to maintain one of the augers, for example206A in a stationary condition, while discharging the feed in proximity to auger206B.

A preferred embodiment of the present invention has been set forth above and in the drawings. It should be understood by one of ordinary skill in the art that modifications may be made in many of the details discussed above, especially in matters of shape, size, and arrangement of parts. For example, while embodiments showing both one and two-auger mixers have been shown and described, the present invention should not be limited to such embodiments. Mixers employing three or more augers may also beneficially use the present invention. Such modifications are deemed to be within the scope of the present invention, which is to be limited only by the broad general meaning of the terms in which the appended claims are expressed.