The present invention is broadly concerned with improved pumping units of the type specifically designed for handling of food products, in order to accurately pump such products with a minimum of product disruption, such as smearing or tearing of meat products. More particularly, the invention is concerned with such pumping units, and the pumping assemblies forming a part thereof, which include features assuring minimal product disruptions with high pumping speeds and accurate pumping rates.
U.S. Pat. No. 5,479,847 describes a highly successful commercial food pump manufactured and sold by Marlen International, Inc. The pump described in the '847 patent includes an upright hopper which receives incoming food materials to be pumped. The materials pass from the hopper into a common internal chamber. A pair of shiftable sleeves within the chamber reciprocate in an alternating, fore-and-aft manner to form respective charges of food materials within each sleeve. As each sleeve is filled, an associated piston is used to force the food charge out of the pump and into an outlet assembly having a central rotatable valve. This pump can thus be operated in a batch-continuous fashion to deliver food products to downstream processing devices.
In some instances, it has been found that the pump of the '847 patent can lead to tearing or smearing of food products, particularly in the case of meats. This is believed to result from the use of the reciprocating sleeves and pistons, which present relatively sharp edges that can cut or pierce food products during operation. Similarly, the pistons and central outlet valve can create similar issues. It would therefore be desirable to provide an improved food pump which has all of the desirable characteristics of the prior pump, while minimizing product disruptions.
References describing food pumps include US and foreign Patents and Publications Nos. U.S. Pat. Nos. 3,456,285, 3,887,964, 4,167,374, 4,431,384, 4,863,317, 4,884,594, 5,464,338, 5,474,101, 5,553,985, 5,688,534, 6,467,403, 7,182,224, 7,225,554, 2013/0248026, and GB 1547407, and Busch Machinery product brochure.
The present invention overcomes the problems outlined above and provides pumping assemblies for use in food or related pumps, which largely resolve food disruption issues. Broadly speaking, such pumping assemblies include an elongated, normally upright, stationary, tubular valve body presenting a material inlet end configured to be coupled with a source of material to be pumped (e.g., a hopper), a material outlet end for directing pumped material to an outlet device, and a pump opening. An elongated, stationary, tubular pumping chamber is operatively connected with the pump opening of the tubular body. A four-port valve spool is located within the tubular body and presents an arcuate outer surface; the spool has a material inlet port, a pumped material outlet port, first and second operating ports, a first passageway interconnecting the first operating port and the material inlet port, and a second passageway interconnecting the second operating port and the material outlet port. A piston is located within the pumping chamber and is shiftable between a fill position, a compression position, and a discharge position. Importantly, the piston has an arcuate face closely complemental with the arcuate outer surface of the spool, which creates a piston cleaning action as the spool rotates; moreover, this eliminates the possibility of product collection between the piston face and spool.
A drive is operably coupled with the spool for selective shifting of the spool between a pumping chamber fill position where the spool first operating port is in communication with the pumping chamber, and a material discharge position where the second operating port is in communication with the pumping chamber. The piston is operable to shift within the pumping chamber when the spool is in the pumping chamber fill position in order to introduce material into the pumping chamber from the source through the first passageway, and to discharge the material within the pumping chamber through the second passageway when the spool is in the discharge position.
Additionally, the spool of the preferred pumping assembly has an imperforate surface between the first and second operating ports. This surface is of a size to completely block the pump opening of the tubular body. Accordingly, the spool is shifted to an intermediate position between the fill and discharge positions, in order to allow the piston to recompress a charge of material within the pumping chamber prior to discharge thereof. such pre-compression serves to increase the accuracy of the weight or volume of material to be delivered.
Turning now to the drawings, a pumping unit 20 is depicted in
The housing assembly 22 is itself conventional, and has leveling feet 32 with internal space to house drives and electrical control circuitry for the overall unit. The hopper assembly 24 includes a pair of identical, upright, conical material hoppers 34 and 36 mounted on a carriage 38. The latter is supported on side rails 40 and rollers 42, thereby permitting fore-and-aft shifting of the entire hopper assembly. Each hopper 34, 36 has an openable lid 44, as well as an augur drive assembly 46 for selective rotation of an internal augur 48 within the hopper (
The valve 54 is a four-port, three-position directional or spool valve, and includes an upright, tubular valve casing or body 62 secured to block 60, as well as an internal spool assembly 64 within the body 62. The body 62 includes a lower connection flange 66 supporting an upright tubular sidewall 68 and an uppermost flange 70, thereby defining an upper material inlet end 72 and a lower output end 74. The sidewall 68 also has a pump opening 75 between the input and output ends 72, 74.
The spool assembly 64 is best understood from a consideration of
The spool assembly 64 is selectively rotated by means of a drive assembly 94. The assembly 94 includes a dished, annular drive plate 96 having locking lugs 98 designed to mate with the lugs 82, and a sealing ring 100 between the plate 96 and the lower periphery of spool 76. A secondary sealing ring 102 is located below the marginal edge of plate 96. An annular bearing 104 is located within a mounting hole 106 formed in block 60 and supports a drive gear 108. An apertured outlet plate 110, having an upstanding tubular connector 112, is disposed below gear 108 and supports a generally Y-shaped output tube 114, which couples with the unit output 30. An electric drive motor 116 depends from the plate 110 and includes a drive gear 118 located above the plate 110 and in meshed engagement with drive gear 118. Accordingly, upon actuation of motor 116, the spool 76 is rotated between the operational positions thereof, as will be described.
The pumping chamber 56 is in the form of an elongated, tubular, laterally extending component 120, which is secured to sidewall 68 in communication with the opening 75. The piston assembly 58 has a material-engaging piston 122 slidably received within the component 120, together with an elongated piston rod 124 extending rearwardly from the piston 122. The rod 124 is housed with a tubular chamber 126, and is coupled with a conventional drive (not shown) located within box 128. An electric screw drive motor 130 is connected to the drive within box 128. Actuation of the motor 130 serves to advance or retract the piston 122 within the tubular component 120. It will also be observed that the piston 122 includes an innermost face plate 132 (
The operation of pumping assembly 26 will next be described, in sequential order wherein material is first withdrawn from the associated hopper 34 and introduced into the pumping chamber 56, followed by compression of the material within the chamber 56, and ultimate delivery of the compressed material to outlet tube 114. Referring first to the initial step (
In the next step (
In the final step (
It will also be appreciated that the pumping assembly 28 operates in conjunction with the assembly 26 in a preselected relationship so that successive charges of material are delivered to the outlet 30 during operation of the pumping unit 20. This operation may be in an asynchronous or synchronous mode, to deliver either a continuous output or successive double loads to outlet 30.
Additionally, the fact that the hoppers 34, 36 are mounted on carriage 38 allows the hoppers to be bodily moved in a fore-and-aft direction relative to the valves 54. Thus, as illustrated in