Patent Description:
A differential impulse conveyor is a conveyor that moves articles by reciprocating an elongate conveyor tray on which the articles are placed. The conveyor tray moves in a first direction at a first rate of acceleration, then reverses the direction of movement and moves in the second, opposite direction at a second rate of acceleration that is greater than the first rate of acceleration. The first rate of acceleration is selected to prevent slippage of the articles on the conveyor tray so that the articles move along with the conveyor tray in the first direction. The second rate of acceleration, which is greater than the first rate of acceleration in absolute terms (i.e., it is in the opposite direction), is selected to cause the articles on the conveyor tray to slip or slide on the conveyor tray as the conveyor tray returns to its original position. Repeating this cycle of movement causes the articles to move along the conveyor tray in the first direction. The first rate of acceleration, the second rate of acceleration, and the stroke, or distance through which the conveyor tray reciprocates, may be optimized to produce a desired rate of travel of the articles being conveyed.

Some differential impulse conveyors use a motor that operates as a constant speed and an eccentrically mounted pulley or an angled universal joint connection to cyclically vary the speed of the mechanical (shaft) output to the conveyor tray.

<CIT>, which comprises the features mentioned in the preamble of claim <NUM>, discloses a differential motion conveyor comprising a trough and a conveyor drive. The conveyor drive comprises a clutch/brake assembly which is selectively activated for moving the trough at a first speed in a first direction and selectively deactivated when moving the trough at a second speed in an opposite direction. There is further provided a method of conveying material comprising sensing a position of a trough, activating a clutch/brake assembly when the trough is at a first position for moving the trough at a first speed in a first direction, and deactivating a clutch/brake assembly when the trough is at a second position for moving the trough at a second faster speed in a second opposite direction to the first direction.

<CIT> discloses an oscillating conveyor with a conveyor device which can be excited to vibrate by at least one drive device and the vibration of the conveyor device causes the conveyor device stored objects to be conveyed along a conveying path. The conveying surface is spaced apart by elevations of the conveying device and/or by carrying sections between openings of the conveyor device.

<CIT> discloses an inertial-type conveyor system for the moving of articles from one position to another, in which during a forward stroke of a tray of the system, the tray moves at a first acceleration whereby the frictional contact between the articles and the tray moves the articles in the same direction as the tray. Then during a return stroke, of an equal distance, the tray moves at a second acceleration generally greater than the first acceleration such that the articles continue to move by inertia on the tray while the tray is moving backward. The system may be provided with a counterweight system having a counterweight element that moves in an opposite direction to the direction of motion of the tray to offset the reaction force produced by the moving tray. Elimination of undesirable vibrations is achieved through the use of the counterweight system and by having the tray system and the counterweight system to be substantially the same mass and have centers of mass that move along substantially the same line of action. In the preferred embodiment, the simultaneous movement of the tray system and counterweight system is achieved by cam followers in contact with cam surfaces of selected contours on a single rotatable cam member.

<CIT> discloses a rotary to linearly reciprocating motion converter which includes a case and a closure member engaging an opening of the case to dispose a pinion gear rotatably coupled to the closure member. The pinion gear has half the diameter as an interior ring gear of the case and further includes a pinion shaft connected to the pinion gear on a first side of the closure member and to an inboard end of a crank arm on a second side of the closure member. The outboard end of the crank arm has a force transfer member aligned with a point on the periphery of the pinion gear. Rotation of the closure member relative to the case results in the force transfer member moving in a linearly reciprocating mode. The force transfer member may be coupled to a conveyor to reciprocate the conveyor as the closure member rotates.

The present invention proposes a differential impulse conveyor according to claim <NUM>.

Preferred embodiments are defined in claims <NUM>-<NUM>.

As discussed in more detail below, the movement of the conveyor tray in embodiments of the differential impulse conveyor of the present invention is advantageously controlled in a manner that enables increased efficiency, reduced manufacturing cost, and reduced maintenance cost as compared to conventional differential impulse conveyors. In addition, embodiments of the differential impulse conveyor of the present invention enable access to floorspace underneath the conveyor for better cleaning and sanitation.

One embodiment of the differential impulse conveyor of the present invention includes a variable frequency motor that changes between a first mode that produces a first rate of acceleration of the conveyor tray and a second mode that produces a second rate of acceleration of the conveyor tray in the opposite direction, the first rate of acceleration being less than the second rate of acceleration, in absolute terms. The first rate of acceleration causes the conveyor tray to move from an original conveyor tray position in a forward direction as the counterweight assembly moves from an original counterweight assembly position in the backward direction, opposite to the forward direction, and the second rate of acceleration, which is greater than the first rate of acceleration, causes the conveyor tray to move in the backward direction to return to the original conveyor tray position as the counterweight assembly moves in the forward direction to the original counterweight assembly position. The switching of the motor between the first mode and the second mode is converted into a linearly reciprocating motion of the conveyor tray and of the counterweight assembly, is the result of a change in the electrical current supplied to the motor. The change in the electrical current to the motor that produces the first and second modes of operation is a change in the frequency of the electrical current.

In embodiments of a differential impulse conveyor, which is not part of the invention, a current conditioning device may be used to condition electrical current to the motor to cause the motor to rotate at a first angular velocity for moving the conveyor tray at a first rate of acceleration in the first direction. The current conditioning device then conditions the current to cause the electric motor to rotate at a second angular velocity that is greater than the first angular velocity for moving the conveyor tray at a second rate of acceleration (in absolute terms) that is faster than the first rate of acceleration and in a second direction that is opposite to the first direction until the conveyor tray is restored to its original conveyor tray position. The current conditioning device must be synchronized with the differential impulse movement cycle of the conveyor tray and the counterweight assembly. That is, the current conditioning device must implement the change in the conditioning of the electrical current supplied to the drive motor at the exact moment that the conveyor tray is at its forwardmost position, which is at the end of the first mode of operation of the motor in which the conveyor tray is moved in the forward direction as the counterweight assembly is moved in the opposite direction. The current conditioning device then shifts to the second mode to produce a conditioned current that produces acceleration of the conveyor tray in the opposite direction. In one embodiment of the differential impulse conveyor, the current conditioning device must switch between the first mode and the second mode at the exact moment that the conveyor tray is at forwardmost position, and from the second mode back to the first mode when the conveyor tray is at its rearwardmost position. In other embodiments of the differential impulse conveyor of the present invention, the current conditioning device may switch between the first mode and the second mode at a moment that is in advance of the conveyor tray reaching its forwardmost position, and from the second mode back to the first mode at a moment that is in advance of the conveyor tray reaching its rearwardmost position. This is a mechanical adjustment that is analogous to the spark advance that can be used to optimize the performance of an internal combustion engine having spark ignition of the combustible mixture received into a cylinder. Just as the spark advance, which may vary depending on the speed of the motor, optimizes the performance of the internal combustion engine at a given speed, the advance applied to the time at which the current conditioning device that conditions and feeds electrical current to an embodiment of the differential impulse conveyor switches from the first mode to the second mode, or from the second mode back to the first mode, can be optimized to produce favorable performance and efficient movement of articles moved on the differential impulse conveyor for a given speed setting. The advance can be optimized to accommodate the lag or delay between the moment of change of the current to the electric motor that powers the movement of the conveyor tray and the counterweight assembly of an embodiment of the differential impulse conveyor and the time at which such change begins to impact the characteristics of the movement of the conveyor tray and the counterweight assembly.

While the embodiment of the differential impulse conveyor of the present invention illustrated in the appended drawings shows the detectable markers disposed on the exterior surface of the first rotary to linear reciprocating motion converter, the markers could be disposed on another moving component of the differential impulse conveyor such as, for example, the second rotary to linear motion converter, the counterweight assembly or the conveyor tray. The movement of the differential impulse conveyor system of the present invention is controlled by a sensor that detects the position of the conveyor tray by use of detectable markers disposed on a moving component of the conveyor system. The detectable markers are disposed on a moving component and detected by the sensor when, for example, the conveyor tray reaches the optimal position, at which time the sensor detects a detectable marker, and it generates and sends a signal that shifts the current conditioning device to the second mode, and conditioned current to produce a greater rate of acceleration (in absolute terms) of the conveyor tray in the opposite direction. A row or series of detectable markers can be used to cause the sensor to continue generating and sending a signal to the current conditioning device to cause the current conditioning device to remain in the second mode. When the end of the row or series of detectable markers passes the sensor, the sensor will no longer detect a detectable marker and will cease generating and sending the signal to the current conditioning device, thereby causing the current conditioning device to return to the first mode, so that the conveyor tray will begin to slow and then to reverse direction and move again in the first direction at the first rate of acceleration.

In an embodiment of a differential impulse conveyor, which is not part of the invention, the detectable markers are disposed in a row on the conveyor tray and the sensor is disposed proximal to the conveyor tray to detect the row of detectable markers (or the absence thereof) when they are near (or remote from) the sensor. In one embodiment of the differential impulse conveyor, the detectable markers are disposed in a row on the counterweight assembly and the sensor is disposed proximal to the counterweight assembly to detect the row of detectable markers (or the absence thereof) when they are near (or remote from) the sensor. In one embodiment of the differential impulse conveyor, the detectable markers are disposed in a series on an exterior surface of the first rotary to linear reciprocating motion converter and the sensor is disposed proximal to the first rotary to linear reciprocating motion converter to detect the series of detectable markers on the first rotary to linear reciprocating motion converter (or the absence thereof) when they are near (or remote from) the sensor. In one embodiment of the differential impulse conveyor, the detectable markers are disposed in a series on an exterior surface of the second rotary to linear reciprocating motion converter and the sensor is disposed proximal to the second rotary to linear reciprocating motion converter to detect the series of detectable markers on the second rotary to linear reciprocating motion converter (or the absence thereof) when they are near (or remote from) the sensor. The detectable markers can be placed in a row or in a series on any moving component of the embodiment of the differential impulse conveyor because the position of any movable component can serve as an indicator of the positions of other movable components that are mechanically linked thereto, and can therefore be strategically placed on any movable component to indicate to the sensor the optimal moment for shifting of the current conditioning device from the first mode to the second mode, or from the second mode to the first mode. A row of detectable markers can be placed on, for example, but not by way of limitation, the conveyor tray, the counterweight assembly (if any), or a belt, and a series of detectable markers can be placed on, for example, but not by way of limitation, a rotating component on one of the first rotary to linear reciprocating motion converter or.

One advantage of the differential impulse conveyor of the present invention having a sensor and detectable markers is that the electrical current that is supplied to the electric motor can be "toggled" between a first mode in which the electrical current to the motor has a first frequency that disposes the motor and the conveyor driven thereby in the first mode and a second mode in which the electrical current to the motor has a second frequency that disposes the motor and the conveyor driven thereby in the second mode. The sensor (for example, an optical sensor, a magnetic sensor or an electronic sensor) has parts and components that do not wear and are less likely to fail or require maintenance.

The sensor detects the row or a series of detectable markers, the sensor then generates a signal to the current conditioning device that causes the current supplied to the motor to be conditioned in a manner that shifts the operation of the conveyor from the first mode to the second mode. These types of drives can use a current conditioning device to change the speed of the output shaft rotation of the motor. Alternately, a servo-type motor can be used to control the change in speed from the first mode to the second mode, and back from the second mode to the first mode. Servo-type motors may be less efficient and more expensive than, for example, an alternating current motor or a permanent magnet motor used to create the change in rotational velocity with just the sensor / markers being used to toggle a simple inverter. In an embodiment of a differential impulse conveyor, which is not part of the invention, an Allen Bradley <NUM> model or Yaskawa may be used as the motor.

In an embodiment of a differential impulse conveyor, which is not part of the invention, the center of gravity of the counterweight assembly can be adjusted and can be thereby made to coincide with the center of gravity of the conveyor tray. The center of gravity of the conveyor tray or of the counterweight assembly is the point from which the weight of the conveyor tray or counterweight assembly may be considered to act. The center of gravity may also be referred to as the center of mass. This alignment of the centers of gravity of these two counter-moving objects (the conveyor tray and the counterweight assembly) reduces or eliminates the impulse moment that would otherwise be generated each time that the counterweight assembly and the conveyor tray are accelerated or decelerated in opposite directions by operation of the electric motor acting through the rotating output shaft. In one embodiment of the differential impulse conveyor, the center of gravity of the conveyor tray and/or of the counterweight assembly may be modified by adding or removing, and by positioning and securing removable weights thereon, to make the center of gravity and/or the mass of the conveyor tray and/or counterweight assembly coincide with the to the center of gravity and/or mass of the conveyor tray. This arrangement reduces the strength and durability requirements for the support structure on which the first rotary to linear reciprocating motion converter, the second rotary to linear differential motion converter and the motor of the differential impulse conveyor are supported, and it reduces the wear and tear on structural components of the differential impulse conveyor which may result in lower maintenance. Another advantage of using the first rotary to linear reciprocating motion converter to move the conveyor tray and the second rotary to linear reciprocating motion converter to move the counterweight assembly, if any, is that there is no rise and fall of either of the converter tray or the counterweight assembly because there are no pivoting support legs disposed intermediate the conveyor tray or the counterweight assembly and the floor of the facility (or other support structure).

One advantage of the differential impulse conveyor of the present invention is that the reduced or eliminated impulse moment obtained by adjusting the center of gravity and/or the mass of the conveyor tray and/or the counterweight assembly allows the components of the differential impulse conveyor to be supported with less robust structures that cost less to manufacture and assemble. In addition, the less robust structures that are required enables more thorough cleaning around and underneath components of the conveyor because the less robust structures require less of a footprint and less mechanical bulk.

Another advantage of the differential impulse conveyor of the present invention is that a conventional motor that is powered by a standard alternating electrical current (AC) can be used. This is advantageous because it lowers the cost of the conveyor as compared to conveyors that might use more expensive servo motors. In some embodiments, a permanent magnet motors have also been used which improve on the efficiency and size compared to standard alternating current motors and greatly reduce the cost and complexity of servo motors.

<FIG> is an elevation view of a prior art differential impulse conveyor system <NUM> with a conventional floor-supported conveyor drive system <NUM>. The prior art differential impulse system <NUM> of <FIG> further includes a conveyor tray <NUM> having a first end <NUM>, a second end <NUM> and a trough <NUM> within the conveyor tray <NUM> for receiving and conveying articles (not shown) from the first end <NUM> to the second end <NUM> where the articles are discharged to a downstream station <NUM> such as, for example, a flavoring station at which seasoning or other flavoring agents are added in a predetermined weight percentage amount. The conveyor <NUM> is reciprocated horizontally as indicated by the double-headed arrow <NUM> by the floor-supported conveyor drive system <NUM>.

The floor-supported conveyor drive system <NUM> of the prior art differential impulse conveyor system <NUM> of <FIG> creates an amount of floor space 110A that is, like the adjacent floor space 110B underneath the downstream station <NUM>, very difficult to access and, therefore, very difficult to clean and sanitize. The limited accessibility caused by conventional floor-supported conveyor drive systems presents a problem where the conveyor system <NUM> is used to convey edible goods. Also, the prior art differential impulse system <NUM> includes a pivoting support <NUM> that causes the conveyor tray <NUM> to rise and fall with each cycle as the pivoting support <NUM> moves as indicated by the arrows <NUM>.

<FIG> is an elevation view of an embodiment of a differential impulse conveyor system <NUM> of the present invention. The embodiment of the differential impulse conveyor <NUM> of <FIG> includes an elongate conveyor tray <NUM> having a first end <NUM>, a second end <NUM>, a trough <NUM> (not shown) therein to support goods or articles (not shown) moved using the differential impulse conveyor <NUM>, the conveyor tray <NUM> being linearly reciprocatable forward (towards the second end <NUM>) and backward (towards the first end <NUM><NUM>) as indicated by the double-headed arrow <NUM> shown on the conveyor tray <NUM>. The embodiment of the differential impulse conveyor <NUM> of <FIG> further includes a counterweight assembly <NUM> that is linearly reciprocatable backward (towards the second end <NUM>) and forward (towards the first end <NUM>) as indicated by the double-headed arrow <NUM> shown on the counterweight assembly <NUM>. The counterweight assembly <NUM> of <FIG> includes weights <NUM> that are removably securable to the counterweight assembly <NUM>. Adding or removing removably securable weights <NUM> enables the user of the embodiment of the differential impulse conveyor <NUM> to adjust the center of gravity (not shown) and the mass of the counterweight assembly <NUM>. Adjusting the center of gravity and the mass of the counterweight assembly <NUM> by removing or adding weights <NUM> allows the user to minimize or eliminate impulse moments cyclically developed as a result of the acceleration of the conveyor tray <NUM> and the counterweight assembly <NUM> in opposite directions during operation of the differential impulse conveyor <NUM>, as will be discussed further below. The removably securable weights <NUM> may be secured to the counterweight assembly <NUM> using fasteners (not shown) such as conventional screws, bolts, nuts or clips, or by having prefabricated receptacles or pockets disposed on the counterweight assembly <NUM>.

The embodiment of the differential impulse conveyor <NUM> of <FIG> further includes an electric motor <NUM> having a conductive cable <NUM> for conducting electrical current to the motor <NUM>, the motor <NUM> being secured to a support structure <NUM> and intercoupled through a first belt <NUM> with a first rotary to linear reciprocating motion converter <NUM> that converts the rotary motion of the output shaft <NUM> to a linearly reciprocating motion that moves the conveyor tray <NUM>. The motor <NUM> also drives and is intercoupled through the second belt <NUM> with a second rotary to linear reciprocating motion converter <NUM> that converts the rotary motion of the output shaft <NUM> to linearly reciprocating motion that moves the counterweight assembly <NUM> in opposition to the conveyor tray <NUM>. In the embodiment of the differential impulse conveyor <NUM> of <FIG>, the motor <NUM> is intercoupled with the first rotary to linear reciprocating motion converter <NUM> through the first belt <NUM> and the second belt <NUM>, and the motor <NUM> is intercoupled with the second rotary to linear reciprocating motion converter <NUM> through the first belt <NUM> and the second belt <NUM>. However, in other embodiments, the motor <NUM> may be intercoupled with the first rotary to linear reciprocating motion converter <NUM> and also to the second rotary to linear reciprocating motion converter <NUM> directly, or the motor <NUM> nay be intercoupled to the first rotary to linear reciprocating motion converter <NUM> and the second rotary to linear motion converter <NUM> through other arrangements of belts, chains or gears, etc..

The first rotary to linear reciprocating motion converter <NUM> of <FIG> has an exterior surface <NUM> to which a plurality of detectable markers <NUM> have been secured in a row or a series. The row or series of detectable markers <NUM> are shown disposed on the exterior surface <NUM> of the first rotary to linear reciprocating motion converter <NUM> to extend about one-half of the circumference of the exterior surface <NUM> of the first rotary to linear motion converter <NUM>. A sensor <NUM> is disposed proximal to the exterior surface <NUM> of the first rotary to linear reciprocating motion converter <NUM> to detect the detectable markers <NUM> as the motor <NUM> operates to rotate the first rotary to linear reciprocating motion converter <NUM> relative to the sensor <NUM>. The sensor <NUM> generates a signal <NUM> to a current conditioning device (not shown in <FIG>) to be discussed in more detail herein below. The signal <NUM> generated by the sensor <NUM> is delivered to a current conditioning device (not shown) by way of, for example, but not by way of limitation, a conductive wire, a fiber optic cable, or wirelessly.

The first rotary to linear reciprocating motion converter <NUM> is intercoupled intermediate the motor <NUM> and the conveyor tray <NUM> and the second rotary to linear reciprocating motion converter <NUM> is intercoupled intermediate the motor <NUM> and the counterweight assembly <NUM>. The conveyor tray <NUM> includes a conveyor tray coupling <NUM> having a receptacle <NUM> through which the first rotary to linear reciprocating motion converter <NUM> is coupled to the conveyor tray <NUM>. The counterweight assembly <NUM> includes a counterweight assembly coupling <NUM> having a receptacle <NUM> through which the second rotary to linear reciprocating motion converter <NUM> is coupled to the counterweight assembly <NUM>.

The first rotary to linear reciprocating motion converter <NUM> and the second rotary to linear reciprocating motion converter <NUM> operate <NUM> degrees (<NUM> radians) out of phase one with the other so that the linear reciprocation of the conveyor tray <NUM> and the opposed linear reciprocation of the counterweight assembly <NUM> are maintained in an opposing relationship to balance the impulse moments generated when these components are accelerated by operation of the motor <NUM>. Stated another way, as the conveyor tray <NUM> is accelerated by the motor <NUM> towards the second end <NUM> of the conveyor tray <NUM>, the counterweight assembly <NUM> is accelerated towards the first end <NUM> of the conveyor tray <NUM>, and as the conveyor tray <NUM> is accelerated by the motor <NUM> towards the first end <NUM> of the conveyor tray <NUM> to return to its original position, the counterweight assembly <NUM> is accelerated towards the second end <NUM> of the conveyor tray <NUM> to return to its original position. This arrangement balances the forces applied by the motor <NUM>, the first rotary to linear reciprocating motion converter <NUM> and the second rotary to linear reciprocating motion converter <NUM> to the conveyor tray <NUM> and the counterweight assembly <NUM>, respectively. The removably securable weights <NUM> on the counterweight assembly <NUM> may be added or removed to fine tune the balancing impulse moment balancing between these reciprocating components of the differential impulse conveyor <NUM>. Alternately, removably securable weights <NUM> may be disposed on the conveyor tray <NUM>, or removably securable weights <NUM> may be disposed on the conveyor tray <NUM> in addition to the counterweight assembly <NUM>.

The motor <NUM>, the first rotary to linear reciprocating motion converter <NUM> and the second rotary to linear reciprocating motion converter <NUM>, and the components of the differential impulse conveyor <NUM> that are supported by the first rotary to linear motion converter <NUM> and/or the second rotary to linear motion converter <NUM>, are supported by a structural support <NUM> which is, in turn, supported above a support surface or floor <NUM> by a proximal support <NUM> and a distal support <NUM>. The proximal support <NUM> may be secured to the floor <NUM> at a proximal flange <NUM> and the distal support <NUM> may be secured to the floor <NUM> at a distal flange <NUM>. The balancing of the center of gravity and/or the masses of the conveyor tray <NUM> and the counterweight assembly <NUM> can dramatically reduce or eliminate the amount of the forces cyclically applied to the proximal support <NUM> and the proximal flange <NUM> and to the distal support <NUM> and the distal flange <NUM> during operation of the differential impulse conveyor <NUM>, and also reduces or eliminates torque cyclically applied to the connection <NUM> between the proximal support <NUM> and the support structure <NUM> and the connection <NUM> between the distal support <NUM> and the support structure <NUM>.

As can be seen in <FIG>, the differential impulse conveyor <NUM> can be used to receive a stream of goods <NUM> discharged from a distal end <NUM> of a supply conveyor <NUM> to the first end <NUM> of the conveyor tray <NUM>, to convey that stream of goods <NUM> to the second end <NUM> of the conveyor tray <NUM>, and to discharge that stream of goods <NUM> to a discharge conveyor <NUM>. The differential impulse conveyor <NUM> may be used to convey a stream of goods <NUM> to a process or a station such as, for example, but not by way of limitation, a flavoring station at which flavoring agents are added to the goods <NUM>, a bagging machine where the goods <NUM> are bagged or packaged, a weighing apparatus, or to any of a number of other processes or stations within a facility that houses the differential impulse conveyor <NUM>.

The differential impulse conveyor <NUM> of <FIG> further includes a counterweight assembly linear bearing <NUM> that supports and allows linear reciprocation of the counterweight assembly <NUM> as it is reciprocated by operation of the motor <NUM>. The differential impulse conveyor <NUM> of <FIG> further includes a conveyor tray linear bearing <NUM> that supports and allows linear reciprocation of the conveyor tray <NUM> as it is reciprocated in opposition to the counterweight assembly <NUM> by operation of the same motor <NUM>. The linear bearing <NUM> appears in <FIG> to be very similar to the first rotary to linear reciprocating motion converter <NUM> and to the second rotary to linear reciprocating motion converter <NUM>. This similarity is because the first rotary to linear reciprocating motion converter <NUM> and to the second rotary to linear reciprocating motion converter <NUM> are similar in structure to the linear bearing <NUM>, the difference being that the dimensions of the components of the linear bearing <NUM> are such that the range of movement of the counterweight assembly <NUM> is insufficient to cause the linear bearing <NUM> to reach its extreme range of movement in either direction of reciprocation, thereby preventing the linear bearing <NUM> from binding or becoming bound at its extreme range of movement. This adaptation of what would otherwise be structured as a rotary to linear reciprocating motion converter of <CIT>, and can be understood further by review of <CIT>. In an embodiment, a single electric motor <NUM> is connected and timed to the first rotary to linear reciprocating motion converter <NUM> and the second rotary to linear reciprocating motion converter <NUM> using a timing belt. However, an embodiment is known that includes two separate motors <NUM>, one for driving the first rotary to linear reciprocating motion converter <NUM> which, in turn, drives the conveyor tray <NUM>, and the other for driving the second rotary to linear reciprocating motion converter <NUM> which, in turn, drives the counterweight assembly <NUM> (if any). Using a common current conditioner to drive the two motors provides for timing of one motor <NUM> with the other motor <NUM> which, in turn, times the conveyor tray <NUM> with the counterweight assembly <NUM>. Although the counterweight assembly <NUM> reduces stresses on components of an embodiment of the conveyor system <NUM> of the present invention, some embodiments do not include a counterweight assembly <NUM>.

<FIG> is a perspective view of the counterweight assembly <NUM> of the embodiment of the differential impulse conveyor <NUM> of <FIG>. The floor <NUM> of the counterweight assembly <NUM> is disposed intermediate a first side panel 30A and a second side panel 30B of the counterweight assembly <NUM>. The floor <NUM>, the first side panel 30A and the second side panel 30B together form a trough within the counterweight assembly <NUM> to movably receive at least a portion of the conveyor tray <NUM> therein. The opening <NUM> in the floor <NUM> of the counterweight assembly <NUM> accommodates the first rotary to linear reciprocating motion converter <NUM> disposed intermediate the motor <NUM> and the conveyor tray <NUM> (not shown in <FIG> - see <FIG>), and is elongated in the direction of reciprocation of the counterweight assembly <NUM> to accommodate the reciprocating movement of the counterweight assembly <NUM> relative to the stationary (but rotating) first rotary to linear reciprocating motion converter <NUM> that reciprocates the conveyor tray <NUM>.

<FIG> is an elevation view of the counterweight assembly <NUM> of <FIG>, and shows a counterweight coupling <NUM> on the counterweight assembly <NUM>, the counterweight coupling <NUM> having a receptacle <NUM> therein for engaging the first rotary to linear reciprocating motion converter <NUM> (not shown in <FIG> - see <FIG>). The optional removably securable weights <NUM> (see <FIG>) are removed from the counterweight assembly <NUM> in <FIG> for clarity. The span <NUM> of the opening <NUM> in the floor <NUM> shown in <FIG> is shown by the double-headed arrow on the second side panel 30B of <FIG>.

<FIG> is a plan view of an arrangement of a sensor <NUM> such as, for example, one of an optically detectable, a magnetically detectable and an electronically detectable set of detectable markers <NUM> coupled to the exterior surface <NUM> of the first rotary to linearly reciprocating motion converter <NUM>. The sensor <NUM> is disposed adjacent to the first rotary to linearly reciprocating motion converter <NUM> to detect the presence of the markers <NUM> as the first rotary to linearly reciprocating motion converter <NUM> rotates in the direction of the arrow <NUM>. The sensor <NUM> generates a signal <NUM> to the current conditioning device <NUM> that varies the frequency of the current <NUM> supplied to the motor <NUM>. The current <NUM> supplied to the motor <NUM> by the current conditioning device <NUM> is provided to operate the motor <NUM> in a first mode when a marker <NUM> is in close proximity to the sensor <NUM> and the signal <NUM> (as illustrated in <FIG>) is being generated by the sensor <NUM> and delivered to the current conditioning device <NUM> and the current <NUM> (see <FIG>) supplied to the motor <NUM> by the current conditioning device <NUM> is provided to operate the motor <NUM> in a second mode when a detectable marker <NUM> is not in close proximity (as will occur upon continued rotation of the first rotary to linear reciprocating motion converter <NUM> in the direction of the arrow <NUM>) and the signal <NUM> is no longer being generated and delivered to the current conditioning device <NUM>. In the embodiment of the current frequency control system illustrated in <FIG>, the detectable markers <NUM> are disposed on about one-half (<NUM> degrees or <NUM> radians) of the circumference of the exterior surface <NUM> of the first rotary to linear reciprocating motion converter <NUM> to thereby produce a current having a frequency switching between the first mode and the second mode to produce the "slow forward, fast back" motion of the conveyor tray <NUM> that moves goods along the conveyor tray <NUM> (not shown in <FIG>).

<FIG> is an illustration of a current conditioning control system that can be used to control the adjustments made to the electrical current that is provided to the electric motor <NUM>. For the current frequency control system illustrated in <FIG>, it may be said that the absence of a signal <NUM> being generated by the sensor <NUM> and delivered to the current conditioning device <NUM> (when no detectable marker <NUM> is in close proximity to the sensor <NUM>) is itself, in effect, a second signal which is, in this case, a non-signal that causes the current conditioning device <NUM> to switch to the second mode. Alternately, in other embodiments of the differential impulse conveyor <NUM>, a current frequency control system may sense two different rows or series of detectable markers <NUM>, each row or series being of a different type of detectable markers <NUM> and each resulting in a different signal generated by the sensor <NUM>. The (those) signal(s) <NUM> are delivered to the current conditioning device <NUM>, a first signal <NUM> corresponding to operation of the motor <NUM> in the first mode and a second signal (not shown) corresponding the operation of the motor <NUM> in the second mode.

Claim 1:
A differential impulse conveyor (<NUM>), comprising:
an elongate conveyor tray (<NUM>) movable in a forward direction at a first rate of acceleration and in a backward direction, opposite to the forward direction, at a second rate of acceleration that is greater than the first rate of acceleration, thereby cyclically moving goods along the tray in the forward direction, the tray having a first end (<NUM>), a second end (<NUM>), a trough (<NUM>) therein for conveying goods, and a conveyor drive coupling (<NUM>);
an electrically powered motor (<NUM>) having a rotating output shaft (<NUM>);
a first rotary to linear reciprocating motion converter (<NUM>) coupled intermediate the rotating output shaft (<NUM>) of the motor (<NUM>) and the conveyor drive coupling (<NUM>); and
wherein operation of the motor (<NUM>) causes the conveyor tray (<NUM>) to move in the forward direction; and
wherein continuing operation of the motor (<NUM>) causes the conveyor tray (<NUM>) to reverse direction and to move in the backward direction,
characterized in that the differential impulse conveyor further comprises:
a current conditioning device (<NUM>) electrically coupled to the motor (<NUM>) to condition a source of input electrical current, the current conditioning device having a first mode in which an output electrical current to the motor causes the motor operate at a first speed to move the conveyor tray in the forward direction and a second mode in which an output electrical current to the motor causes the motor to operate at a second speed that is greater than the first speed to move the conveyor tray in the backward direction;
a plurality of markers (<NUM>) secured to a moving component of the differential impulse conveyor; and
a sensor (<NUM>) disposed proximal to the moving component sensing movement of the plurality of markers (<NUM>), wherein the sensor is configured to generate a signal to the current conditioning device (<NUM>) to switch between the first mode and the second mode when the sensor detects one or more of the plurality of markers in close proximity to the sensor.