BACKGROUND

FIELD OF THE INVENTION

The present invention generally relates to a liquid extraction machine. More specifically, the present invention relates to an internal bleeding roller for the liquid extraction machine.

BACKGROUND OF THE INVENTION

A liquid extraction machine has two or more rollers for extracting a liquid, such as sugar cane juice from sugar cane or bagasse. A conventional liquid extraction machine has a top roller and at least one bottom roller to extract the liquid. In case of sugar cane juice extraction machine, the top and bottom rollers rotate in opposite directions to extract the juice by squeezing the sugar cane or bagasse. Traditionally, top and bottom rollers include a shaft and a shell tightly fitted over the shaft. The outer peripheral surface of the shell is formed with circumferential V-shaped grooves which are equidistantly spaced axially. Moreover, the bottom rollers are provided with grooves formed radially along bottom of the V-shaped grooves such that the extracted liquid flows out of the roller through the grooves. The extracted liquid is collected into a receptacle underneath the liquid extraction machine and the collected liquid is pumped out for further process, continuously.

During operation of the liquid extraction machine, the top and bottom rollers squeeze the sugar cane or bagasse and a substantial amount of the extracted liquid tends to be trapped above the sugar cane or in bagasse blanket. In order to reach the bottom roller, the liquid has to trickle down through the sugar cane or bagasse. However, a significant amount of the extracted liquid is re-absorbed by the sugar cane or bagasse during the process. The accumulated liquid on surface

l of the top and bottom rollers results in slippage between the rollers and the bagasse blanket. Hence, the capacity and efficiency of the liquid extraction machine is adversely affected.

As a partial solution to above listed drawbacks, U.S. Pat. No. 3,969,802 discloses an internal bleeding roller for squeezing juice from sugar cane or bagasse. The internal bleeding roller has a shaft and a shell mounted over the shaft. Multiple bores are formed radially at the bottom of circumferentially extending V-shaped grooves of the shell. The bores open into corresponding axial channels within the shell of the internal bleeding roller. The juice squeezed from the sugar cane or bagasse flows through the bores and then axially out through the axial channels. The major drawback of such an internal bleeding roller is that the shell is a single unit having both the bores and the axial channels. The outer diameter of the shell is the outer diameter of the internal bleeding roller and the inner diameter of the shell is the outer diameter of the shaft. When a re-shelling (i.e. replacement of the shell because of wear on the outer diameter) process needs to be carried out, the shell has to be replaced, including shell part of the axial channels, which are usually intact. Also, the passage of juice through the axial channels weakens the shell thereby causing a possibility of breakage to the internal bleeding roller. The parallel nature of the axial channels gives rise to hoop stresses which may result in premature failure of the shell.

Another major drawback of the traditional internal bleeding roller is re-absorption of extracted juice by sugar cane blanket. Although, the internal bleeding roller is invented to overcome the re-absorption problem, it fails to avoid complete re-absorption of the juice by the sugar cane blanket. The extracted juice is re-absorbed in the cane blanket if the juice passages are flooded due to limitations of the design of the juice passages. The re-absorption also takes place due to insufficient emptying time of the juice passages. Therefore, there exists a need for an internal bleeding roller that minimizes the hoop stresses, prevents re-absorption, and prevents breakage of the shell. An embodiment of the present invention provides an improved internal bleeding roller for a liquid extraction machine. The improved internal bleeding roller (referred to as "roller" hereinafter) includes a cylindrical shaft, a cylindrical sleeve mounted tightly over the cylindrical shaft, and a cylindrical shell mounted onto peripheral surface of the mounting sleeve. The cylindrical shaft provides rotation to the roller through a power drive. The cylindrical sleeve is provided with a_pluraljty of longitudinal flow channels equally spaced around the peripheral surface thereof. The longitudinal flow channels have increasing cross-sectional area from center of the cylindrical sleeve to edges of the cylindrical sleeve. The design of the longitudinal flow channels allows liquid to flow easily out of the roller by avoiding flooding of the liquid. An outer surface of the cylindrical shell has a plurality of circumferential V-shaped grooves. The outer surface along with the plurality of circumferential V-shaped grooves forms a rolling surface to crush the sugar cane or bagasse. A plurality of bores are formed radially to the cylindrical shell at bottom of each circumferential V-shaped groove. The plurality of bores allow the liquid to flow towards the longitudinal flow channels. A plurality of tapered nozzles are fitted in the respective bores of the cylindrical shell. The ends of the nozzles open at the corresponding longitudinal flow channels. Each nozzle has increasing cross-sectional area axially along its length to prevent clogging of the nozzles by bagasse particles. The design of flow channels and nozzles allow the internal bleeding roller to efficiently overcome the re-adsorption of the liquid by sugar cane or bagasse.

Another object of the present invention is to allow separation of the cylindrical shell from the cylindrical sleeve thereby facilitating easier replacement of the cylindrical shell when the circumferential V-shaped grooves experience wear and tear.

BRIEF DESCRIPTION OF DRAWINGS

The features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. Embodiments of the present invention will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the scope of the claims, wherein like designations denote like elements, and in which: Figs. 1 and 2 represent a perspective view of an improved internal bleeding top roller of a liquid extraction machine, according to an illustrative embodiment of the present invention;

Fig. 3 represents a perspective view of a cylindrical sleeve of the improved internal bleeding top roller, according to an illustrative embodiment of the present invention;

Fig. 4 represents a perspective view of a longitudinal flow channel formed on the cylindrical sleeve, according to an illustrative embodiment of the present invention;

Fig. 5 represents a perspective view of a cylindrical shell of the improved internal bleeding top roller, according to an illustrative embodiment of the present invention;

Fig. 6 represents a sectional view of a nozzle in the cylindrical shell of the improved internal bleeding top roller, according to an illustrative embodiment of the present invention;

Fig. 7 represents a schematic illustration of working of the liquid extraction machine showing the flow of juice in the improved internal bleeding top roller, according to an illustrative embodiment of the present invention;

Figs. 8 and 9 represent a perspective view of an improved internal bleeding bottom roller of the liquid extraction machine, according to an illustrative embodiment of the present invention; and

Fig. 10 represents a schematic illustration of working of the liquid extraction machine showing the flow of juice in the improved internal bleeding bottom roller, according to an illustrative embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION As used in the specification and claims, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "an article" may include a plurality of articles unless the context clearly dictates otherwise.

Those with ordinary skill in the art will appreciate that the elements in the Figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some of the elements in the Figures may be exaggerated, relative to other elements, in order to improve the understanding of the present invention.

There may be additional components described in the foregoing application that are not depicted on one of the described drawings. In the event such a component is described, but not depicted in a drawing, the absence of such a drawing should not be considered as an omission of such design from the specification.

Before describing the present invention in detail, it should be observed that the present invention utilizes a combination of system components which constitutes an internal bleeding roller for a liquid extraction machine. Accordingly, the components and the method steps have been represented, showing only specific details that are pertinent for an understanding of the present invention so as not to obscure the disclosure with details that will be readily apparent to those with ordinary skill in the art having the benefit of the description herein.

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting but rather to provide an understandable description of the invention. The liquid extraction machine (not shown) may typically include a top roller, a feed roller and a discharge roller to extract liquid from sugar cane or bagasse. The feed roller and the discharge roller together are termed as 'bottom rollers'. The top roller rotates in opposite direction to rotation of the bottom rollers allowing the sugar cane or bagasse to crush by squeezing juice out and into a suitable receptacle. The top roller and the bottom rollers are internal bleeding rollers and have substantially identical structures.

Figs. 1 and 2 represent a perspective view of an improved internal bleeding top roller 100 of the liquid extraction machine. In an embodiment, the improved internal bleeding top roller 100 (referred to as either "top roller" or "roller", hereinafter) includes a cylindrical shaft 102, a cylindrical sleeve 104 mounted over the cylindrical shaft 102, and a cylindrical shell 106 mounted over the cylindrical sleeve 104. The cylindrical shaft 102 provides motion to the top roller 100 and is made of at least one of medium carbon and low alloy steel. The cylindrical shaft 102 is driven by a suitable driving mechanism (not shown), such as gears that mesh together via teeth and are used to transmit rotary motion from one shaft to another, shaft mounted geared motors and the like.

Fig. 3 illustrates the cylindrical sleeve 104 having a through bore axially which allows it to be mounted fixedly on the cylindrical shaft 102. The cylindrical sleeve 104 has inner and outer surfaces 200a and 200b. The cylindrical sleeve 104 rotates along with the cylindrical shaft 102 as the inner surface 200a remains in contact with cylindrical shaft 102. The cylindrical sleeve 104 is provided with a plurality of longitudinal flow channels 108, preferably equally spaced around the peripheral outer surface 200b, as shown in Fig. 3. The plurality of longitudinal flow channels 108 (hereinafter, referred to as "longitudinal flow channels 108") allow the liquid to flow out of the top roller 100. The longitudinal flow channels 108 are slots that are formed on the outer surface 200b of the cylindrical sleeve 104 for allowing the liquid to flow through the slots. The longitudinal flow channels 108 have increasing cross sectional area towards ends of the cylindrical sleeve 104.

Fig. 4 illustrates one of the plurality of longitudinal flow channels 108. As illustrated in Fig. 4, the longitudinal flow channel 108 has a center (mid-point) 110, a first end 112a and a second end 112b. In an example, the width and depth of the longitudinal flow channel 108 at the center 110 of the cylindrical sleeve 104 are w and d, respectively. The width and depth of the longitudinal flow channel 108 at the first end 112a of the cylindrical sleeve 104 are wl and dl, respectively. The width and depth of the longitudinal flow channel 108 at the second end 112b of the cylindrical sleeve 104 are w2 and d2, respectively. The longitudinal flow channel 108 has increasing width and depth towards the first and second ends 112a and 112b of the cylindrical sleeve 104 compared to the center 110_of_the cylindrical sleeve l04. In-other words, it is evident- that wl, w2 > w and dl, d2 > d. Further, wl and w2 may be equal or different; dl and d2 may be equal or different, depending on the design requirements. The liquid that enters the longitudinal flow channel 108 tends to flow towards the first and second ends 112a and 112b due to the increasing cross sectional area from the center 110. The design of the longitudinal flow channel 108 prevents the stagnation of the liquid in the channels thereby avoiding backlash. The shape of cross sectional area of the longitudinal flow channels 108 can be of different shapes such as circular, elliptical, rectangular, and trapezoidal and/or truncated sector-shaped, with an increasing area from the center 110 towards the first and second ends 112a and 112b of the cylindrical sleeve 104. The number of longitudinal flow channels 108 varies based on requirements of the design of the top roller 100.

Further, the longitudinal flow channel 108 from the first and second ends 112a and 112b diverge at an angle 'q' at the center 110 of the cylindrical sleeve 104 as shown in Fig.4. The angle q may be of 140° to 180° (preferably 166°). The angle q is not limited to 140° to 180°, and it may be of any value according to desired requirements of a person. The longitudinal flow channels 108 are skewed on both sides with reference to axial axis at the center of the cylindrical sleeve 104. The design results in reduction of hoop stresses thereby minimizing the possibility of failure of the cylindrical shell 106. The design of the longitudinal flow channels 108 reduces the concentration of stress on the cylindrical shell 106 and also increases the strength of the cylindrical shell 106 and cylindrical shaft 102 combination.

Fig. 5 represents a perspective view of the cylindrical shell 106 of the top roller 100. The cylindrical shell 106 has a through bore axially along its length. The cylindrical shell 106 has inner and outer surfaces 202a and 202b respectively, and the cylindrical shell 106 is mounted over the cylindrical sleeve 104. The cylindrical shell 106 has a plurality of circumferential V- shaped grooves 114 (referred to as "circumferential V-shaped grooves 114" hereinafter) that are formed along the length of the cylindrical shell 106. The circumferential V-shaped grooves 114 are equally spaced around the peripheral outer surface 202b of the cylindrical shell 106. The outer surface 202b along with the circumferential V-shaped grooves 114 forms a rolling surface for the top roller 100. The rolling surface allows the top roller 100 to crush sugar cane or bagasse to extract the liquid therefrom. A plurality of bores 116 (referred to as "bores 116" hereinafter) are formed radially on the cylindrical shell 106. The bores 116 are formed at the bottom of each of the plurality of circumferential V-shaped grooves 114. The bores 116 communicate with the longitudinal flow channels 108 to allow the liquid to flow out of the roller 100. The bores 116 are formed above the longitudinal flow channels 108 thereby guiding the liquid out of the roller 100. The arrangement of the bores 116 varies with the arrangement of the longitudinal flow channels 108 on the cylindrical sleeve 104. The bores 116 allow the liquid on the outer surface 202b of the cylindrical shell 106 to flow towards the longitudinal flow channels 108 of the cylindrical sleeve 104.

A plurality of nozzles 118 (referred to as "nozzles 118" hereinafter) are fitted in the bores 116 on the outer surface 202b of the cylindrical shell 106. Fig. 6 illustrates one of the nozzles 118. As illustrated in the Fig.6, the nozzle 118 is tapered radially along its length. The inner cross-sectional area of the nozzle 118 increases axially along its length. In an example, the inner diameter of the nozzle 118 at opening on the cylindrical shell 106 is pi. The inner diameter of the nozzle 118 at opening on to the cylindrical sleeve 104 is p2. The inner diameter of the nozzle 118 increases axially, hence p2 > pi. Each nozzle 118 is fitted in the respective bore 116 on the cylindrical shell 106 by using a 'Morse taper' and an anaerobic adhesive. The pressure that is created during crushing of the sugar cane or the bagasse forces each nozzle 118 to move inwards. However, the tighter fit between each nozzle 118 and its corresponding bore 116 prevents the inward movement of each nozzle 118. Each nozzle 118 is fitted exactly above the longitudinal flow channels 108 of the cylindrical sleeve 104 to collect the extracted liquid. Each nozzle 118 is tapered with increasing bore size axially thereby ensuring the nozzle 118 to be free from clogging. The cross sectional area of the nozzle 118 increases by allowing the bagasse pieces or any other foreign bodies to flow freely through the nozzle 118. Each nozzle 118 is made of soft brass, bronze, cast iron, nylon, polytetrafluoroethylene (PTFE) or any other polyvinyl chloride (PVC) material. The soft brass or nylon nozzles 118 resist corrosion and are soft enough to wear off as the cylindrical shell 106 wears. The length of the nozzle 118 is pre-determined based on the wear of the cylindrical shell 106. In an example, the nozzle 118 does not need to be changed for the wear of 3 to 4% of outer diameter of the cylindrical shell 106. The nozzles 118 may be arranged in a different pattern such as zigzag rather than arranging in a straight path relatively to the longitudinal flow channels 108 of the cylindrical sleeve 106.

In an embodiment, the design of bores 116 allows arrangement of two nozzles 118 on the cylindrical shell 106 without compromising strength of the roller 100. The two bores 116 formed at a distance on the outer surface 202b converge on the inner surface 202a of the cylindrical shell 106. The two nozzles 118 are fitted in the corresponding bores 116. The double nozzle design increases the liquid extraction, which proved to be beneficial for reducing moisture in the bagasse. In another embodiment, the design of the bores 116 allows arrangement of three nozzles 118 on the cylindrical shell 106 without compromising strength of the roller 100. The three bores 116 formed at a distance on the outer surface 202b converge on the inner surface 202a of the cylindrical shell 106. The three nozzles 118 are fitted in their corresponding bores 116. The triple nozzle design increases the liquid extraction, which proved to be beneficial for reducing moisture in the bagasse.

The circumferential V-shaped grooves 114 of the cylindrical shell 106 might undergo wear and tear after a prolonged use for crushing sugar cane or bagasse. As the cylindrical shell 106 is a separate member from the cylindrical sleeve 104, the cylindrical shell 106 can be handled easily and also be removed for re-shelling without much efforts compared to conventional shell roller.

The cylindrical sleeve 104 is shrink-fitted on to the cylindrical shaft 102. The shrink- fitting creates problems of fretting when mounting the cylindrical sleeve 104 over the cylindrical shaft 102. The fretting problem is avoided by using the cylindrical sleeve 104 made up of SBR special alloy or Ductile Iron grade 500/7 or 600/3 having a modulus of elasticity of roughly 90% of steel on the cylindrical shaft 102. The SBR special alloy reduces the fretting and corrosion to a great extent. The cylindrical sleeve 104 has a life equivalent to the life of the cylindrical shaft 102 and hence only cylindrical shell 106 has to be replaced during subsequent re-shelling process.

In an embodiment, the length of the cylindrical sleeve 104 is more than the length of the cylindrical shell 106. Hence, the cylindrical sleeve 104 provides more strength to the cylindrical shaft 102. The additional strength results in reduction of fatigue stresses in a journal portion thereby decreasing the chances of premature failure of the cylindrical shaft 102 in the journal portion.

As shown in Fig. 7, the internal bleeding top roller 100 has longitudinal flow channels 108 that are skewed towards the first and second ends of the cylindrical sleeve 104. During crushing operation, both skewed ends of the longitudinal flow channels 108 are progressively above the horizontal plane passing through the center of the cylindrical sleeve 108. As the extracted liquid fills the longitudinal flow channels 108, the discharging ends of the longitudinal flow channels 108 being above the horizontal plane of the center allow excess liquid to flow in a liquid ring basin. The longitudinal flow channels 108 remain full for a certain period of time. However, the pressure on the sugar cane or bagasse is high in the indicated areas 'A' and 'B'; hence re-absorption is not possible. Whereas as rotation progresses, the centerline of the top roller 100 comes out of the high pressure area i.e., in 'C. The ends of the longitudinal flow channels 108 are at relatively lower level than the center. The gravity allows the liquid in the liquid ring basin to flow out by preventing re-absorption.

In an embodiment, the internal bleeding roller is a bottom roller 120. Figs. 8 and 9 illustrate the bottom roller 120 which includes a cylindrical shaft 102, a sleeve 122 mounted over the cylindrical shaft 100 and a cylindrical shell 106 mounted over the cylindrical sleeve 122. The cylindrical shells 102 of the bottom and top roller 120 and 100 are identical. The design of the sleeve 120 of the bottom roller 120 is different from the design of the cylindrical sleeve 104 of the top roller 100. The cylindrical sleeve 104 of the bottom roller 120 has different arrangement of flow channels 124 as compared to the top roller 100 as shown in Fig. 9. A plurality of circumferential slots 126 are formed at the peripheral outer surface of the sleeve 122. The circumferential slots 126 intersect with the flow channels 124. The plurality of circumferential slots 126 are like internal Messchaert grooves.

As shown in Fig. 10, as pressure on the sugar cane or bagasse is high in the indicated areas 'A' and 'Β', the extracted liquid through nozzles 118 fills the flow channels 124 and empties into the internal circumferential slots 126 (empty spaces). By virtue of gravity, the liquid trickles down in the circumferential slots 126 to bottom of the roller 120 (indicated by arrows) and out through either the nozzles 118 or end of the flow channels 124 that empty into juice/liquid guards. The design of the flow channels 124 completely eliminates the re-absorption. The design also eliminates need to have circumferential slots 126, thus increasing the strength of the cylindrical shell 106. Especially for the bottom roller 120, the reduction in moisture content in the bagasse blanket is considerably higher than the reduction in conventional rollers.

In another embodiment, the internal bleeding roller 100 includes the cylindrical shaft 102 and the cylindrical shell 106 mounted over the cylindrical shaft 102. A plurality of longitudinal flow channels (not shown) are cast in the cylindrical shell 106 rather than in a separate component such as sleeve. The cylindrical shell 106 is made of steel in order to provide strength which is otherwise compromised due to the bores 116. The longitudinal flow channels have increasing cross-sectional areas towards ends of the cylindrical shell 106. The design allows easy displacement of liquid from the internal bleeding roller 100 without any back flow. The bores 116 of the cylindrical shell 106 are tapered radially to prevent clogging through the pieces of sugar cane or bagasse. Preferably, design of the longitudinal flow channels is circular. The longitudinal flow channels of circular design do not have corners or angles for the bagasse to get lodged. Hence, blockage due to accumulation of the bagasse or fiber is avoided in the internal bleeding roller 100. Further, the circular shaped longitudinal flow channels are also easy to clean, either by cylindrical brush, or pressurized steam.

The benefits of the roller 100 depend upon the amount of liquid that is extracted through the nozzles 118 and the amount of liquid extracted is function of the number of nozzles per groove. The traditional roller has one nozzle per groove per flow channel. The disclosed roller is capable for allowing two or three nozzles per groove per flow channel. The extracted liquid flows through the nozzles 118 and the longitudinal flow channels 108. The extracted liquid eventually flows to the liquid rings/liquid guards and consequently to liquid basin. Therefore, the flow design reduces flooding considerably and hence re-absorption.

The design of the roller 100 reduces the pressure due to the liquid and also reduces the quantity of juice re-absorbed by the bagasse or sugar cane. Moreover, the roller 100 increases the amount of liquid extracted, reduces the power required to run the liquid extraction machine, increases the milling capacity, reduces the slippage of the cane blanket on the roller surface and wear of the cylindrical shell 106 is also reduced considerably. However, most of the above indicated benefits are interdependent. If mill capacity is to be increased by using roller 100, the cylindrical shell 106 wear may not be reduced. If lower power consumption is desired, benefit of increased juice extraction may be lost.

The usage of SBR alloy or Ductile Iron 500/7 or 600/3 material for cylindrical shell 106 increases wear resistance and also has higher life than conventional cast iron material. Further, the cylindrical shell 106 requires lesser re-grooving, with lesser re-shelling frequency. Moreover, the roller 100 reduces cylindrical shell 106 wear and increases mill capacity by increasing gripping area. The SBR alloy cylindrical shell 106 has better welding properties thereby allowing denser arcing which remains firmer during crushing and requires lesser frequent arcing. The SBR alloy cylindrical shell 106 is easily adopted to double/triple nozzles in the rollers entailing higher extraction efficiency due to the high strength. The roller 100 reduces flooding and also reduces reabsorption of the liquid in the bagasse. Also, the roller 100 reduces liquid pressure consequently near nip reducing input power and increasing extraction.

The present invention has been described herein with reference to a particular embodiment for a particular application. Although selected embodiments have been illustrated and described in detail, it may be understood that various substitutions and alterations are possible. Those having ordinary skill in the art and access to the present teachings may recognize additional various substitutions and alterations are also possible without departing from the spirit and scope of the present invention, and as defined by the following claims.