US2791252A

US2791252A - Means fdr preventing overloads on cane

Info

Publication number: US2791252A
Authority: US
Publication date: 1957-05-07
Anticipated expiration: 1974-05-07

Description

y 7, 1957 M. D. CHURCH v MEANS FOR PREVENTING OVERLOADS on em: CUTTERS, CANE SHREDDERS AND THE LIKE Filed Aug 24, 1955 MAYNARD D. CHURCH IN VEN TOR.

FIG. 2

United States Patent MEANS FOR PREVENTING OVERLOADS ON CANE CUTTERS, CANE SHREDDERS AND THE LIKE Maynard D. Church, Mount Dora, Fla, assignor to Worthington Corporation, Harrison, N. J., a corpora lion of Delaware Application August 24, 1953, Serial No. 376,217

9 Claims. (Cl. 146-1) This invention relates to cane sugar mills and more particularly to speed control means for controlling the speed of operation of the cane conveyor or carrier in accordance with the operation of the cane cutter or shredder to avoid overloading the cutter or shredder and the resulting undesirable conditions among which are loss of production of the mill due to stoppage while the clogged cutter or shredder is being cleaned.

In cane sugar mills, sugar cane is fed to the milling rolls by a cane carrier or conveyor of a suitable type which is driven by a suitable prime mover usually a reciprocating steam engine, although a steam turbine, or other suitable prime mover may be employed.

A rotating multi-bladed cane knife or cane cutter driven by a suitable prime mover such as a steam turbine or steam engine is mounted in such relation to the carrier that it will cut the cane into smaller pieces and also tends to smooth the cut cane into a more uniform layer or blanket as it passes to the milling rolls.

In some mills a cane shredder is used to shred the cane as it passes on the carrier or conveyor to the milling rolls and the present invention is applicable for use in mills employing either a cutter or shredder.

The present invention comprises means actuated by variances in the pressure difference on the upstream and downstream sides of the control valve for motive fluid supplied to the prime mover of the rotary cutter or shredder to control the motive fluid delivered to the prime mover of the cane carrier or conveyor whereby the speed of operation of the carrier or conveyor will be controlled in accordance with the load on the cutter, thus preventing clogging and stoppage of the cutter by an excessively heavy quantity of cane being fed to the cutter by the carrier.

With these and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, showing means for preventing overloads on prime movers for driving cane cutters, cane shredders and the like of a preferred form embodying the invention, and the features forming the invention will be specifically pointed out in the claims.

In the drawings:

Figure l is a diagrammatic view in perspective of a part of a cane sugar mill illustrating the present invention.

Figure 2 is an enlarged sectional view through the improved control means employed in the present invention.

In cane mills wherein the juice is extracted from cane, the sugar cane is fed to the mill by a carrier or conveyor indicated as 1 in Figure 1 of the drawings, which is of any suitable construction but usually an endless belt. This conveyor 1 is driven by a suitable prime mover as indicated at 2 utilizing a motive fluid for its operation, such as steam.

The cane, as it is carried by the carrier 1 is reduced in particle size by a cutter or shredder and, in the present case, a rotary cane cutter or cane knife 3 is illustrated,

which is essentially a plurality of cutting blades 4 radially mounted on a shaft, which engages the cane on the carrier 1 and cuts the cane into pieces. The rotary cutter 3 is operated by a prime mover 5 which in the present instance is a steam turbine. Speed reducing gears 6 are illustrated in the connection between the steam turbine 5 and the cutter 3 but of course the invention is not limited to this specific construction.

The speed of operation of the turbine 5 is controlled by a governor valve 7 of the usual approved type employed in connection with steam turbines which controls the speed of operation of the turbine by admitting more or less steam to the steam chest 8 of the turbine structure 5 as is usual in the operation of turbines.

Steam under pressure is delivered to the turbine 5 through the steam inlet pipe 9 and, the governor valve 7 to the steam chest 8 of the turbine.

When the load on the turbine is light or small, the governor valve 7 will be nearly closed and the pressure in the steam chest 8 will be much lower than the pressure in the steam inlet 9. When the load on the turbine is heavy or large, the governor valve 7 will be open further and the pressure of the steam in the steam chest 8 will be much nearer the pressure of the steam in the steam inlet 9. The present invention utilizes changes in the differential between these two pressures to so control the speed of the cane carrier 1 that cane will not be fed to the cane cutter so fast as to overload the turbine driving the cane cutter. That is, pressure dilierences between the steam pressure in the turbine inlet pipe 9 and the steam pressure admitted by the governor valve 7 to the steam chest 3 is used to control the speed of the prime mover driving the cane-carrier and thereby the rate at which Cane is fed to the cane-cutter.

Operating fluid is fed to the prime mover 2 which drives the cane carrier through a suitable inlet pipe 10 which normally has a manually operated valve 11 therein and which has a second valve 12 in the line it), The valve stem 13 of the valve 12 is connected to a diaphragm 14 sealed in a fluid tight housing 15 and loaded by a spring 16. A pipe 17 opens into the housing 15 on one side of the diaphragm 14 and opens into the steam supply line to the turbine 5 downstream of the governor controlled valve 7 as clearly shown in Figure 2 of the drawings. This pressure tends to close valve 12. A second pipe 18 opens into the housing 15 on the oppQsite side of the diaphragm 14 from the pipe 17. The pipe 1.8 opens into the steam supply pipe 9 that is upstream of the governor controlled valve 7 in the steam supply line to the turbine 5. This pressure tends to open valve 12.

The pressure from pipe 17 is always less than the pressure from pipe 18 but spring 16 is so positioned that it aids the pressure from pipe 17 to move valve 12, towards a closed position. Spring 16 is so compressed that as load on the turbine increases and pressure in pipe 17 becomes closer to that in pipe 18 the combined effect of steam pressure from pipe 17 plus the force of spring 16 will move the valve 12 towards a closed position, thereby slowing the speed of prime mover 2 and cane carrier ,1, 'and reducing the rate at which cane is fed to the cane cutter. As the load on the cane cutter, and therefore the load on the turbine, is reduced the differential between the pressures on the two sides of the governor valve will increase and the valve 12 will be moved towards a more open position thereby permitting the prime mover 2. and the cane carrier 1 to run faster. The net effect is to permit the cane carrier to run at Whatever speed is desired subject only to slowing when cane is fed to the cane knives in such quantity as to seriously overload the turbine 5 which drives the cane cutter 3. This will in turn operate the diaphragm 14 and move the valve 12 in further opening position thus restoring the previous speed of motive fluid to the prime mover 2 and restore the operation of the carrier 1 to its previous speed.

The device as described operates on the difference in steam pressure between the two sides of the governor valve which gives a definite indication of the load being carried by the turbine in relation to the capacity of the turbine to produce power at the pressure existing in inlet pipe 9. As the pressure in pipe 9 is subject to variation with boiler pressure changes and other causes it is necessary to work on the differential pressure rather than on the pressure in steam chest 8 only, if it is to be effective over a range of steam pressure in inlet steam pipe 9.

The device for controlling the speed of prime mover 2 is shown as a simple valve for regulating the admission of steam.

The device consisting of diaphragm 14 and associated parts are shown as acting directly on valve 12.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown, but that they may be widely modified within the invention defined by the claims.

What is claimed is:

1. In a sugar cane mill, a combination of a cane carrier, a prime mover for operating said cane carrier, means for reducing the particle size of the cane delivered thereto by said carrier, a second fluid prime mover for operating said cane particle size reducing means, a governor-controlled valve controlling flow of fluid to said second prime mover, and means connected on the upstream and downstream sides of said governor-controlled valve operated by variances in the pressure difference of the fluid for controlling the speed of said carrier-operating prime mover.

2. The combination as claimed in claim 1 wherein said pressure responsive means includes a spring-loaded diaphragm, a housing enclosing said diaphragm, means for delivering operating pressure fluid from the upstream side of said governor-controlled valve at one side of the diaphragm, and means for delivering operating fluid from the downstream side of said governor-controlled valve to the other side of said diaphragm.

3. In a sugar cane mill, the combination, of a cane carrier, a prime mover for operating said cane carrier, means for reducing the particle size of the cane delivered thereto by said carrier, a steam turbine for driving said cane particle size reducing means, a governor-controlled valve controlling delivery of steam to said steam turbine, and means connected on the upstream and downstream sides of said governor-controlled valve operated by variances in the pressure difference of steam for controlling the flow of fluid to said carrier operating prime mover.

4. In a sugar cane mill, the combination, of a cane carrier, a prime mover for operating said cane carrier, means for reducing the particle size of the cane delivered thereto by said carrier, a steam turbine for driving said cane particle size reducing means, a governor-controlled valve controlling delivery of steam to said steam turbine, a valve for controlling delivery of operating fluid to said carrier operating prime mover, and means connected on the upstream and downstream sides of said governorcontrolled valve for operating said second valve operated by variances in the pressure difference of steam for controlling the delivery of operating fluid to the carrier operating prime mover.

5. In a sugar cane mill, the combination, of a cane carrier, a prime mover for operating said cane carrier, means for reducing the particle size of the cane delivered thereto by said carrier, a steam turbine for driving said cane particle size reducing means, a governor-controlled 4 valve controlling delivery of steam to said steam turbine, a valve for controlling delivery of operating fluid to said carrier operating prime mover, and means connected on the upstream and downstream sides of said governor-controlled valve for operating said second valve operated by variances in the pressure difference of steam for controlling the delivery of operating fluid to the carrier operating prime mover, said pressure operated means including a spring-loaded diaphragm, a housing enclosing said diaphragm, means for delivering operating fluid from the upstream side of said governor-controlled valve at one side of said diaphragm and means for delivering operating fluid from the downstream side of said governorcontrolled valve to the other side of said diaphragm.

6. In a sugar cane mill, the combination of a cane carrier, carrier turbine means connected to said carrier for operating the carrier to convey sugar cane disposed thereon, a cane cutter comprising a plurality of blades positioned adjacent said carrier and adapted to cut sugar cane conveyed thereon, cutter turbine means connected to said cutter for rotating said blades, a first steam supply line connected to said carrier turbine means and having 7 a valve disposed therein for regulating the flow of steam therethrough, a second steam supply line connected to said cutter turbine means, a governor valve disposed in said second steam line for regulating the flow of steam therethrough, actuating means operatively associated with I said first valve to move said first valve into an opened first valve into a closed position when the pressure differential falls below a predetemined value, and to operate said actuating means to move said first valve into an opened position when the pressure differential exceeds a predetermined value.

7. The combination of claim 6 wherein the actuating means comprises a valve stem connected at the upper portion thereof to said first valve and at the lower portion thereof to a resilient diaphragm disposed within a fluid tight casing.

8. The combination of claim 6 wherein the control means comprises a fluid tight casing and a spring-loaded resilient diaphragm disposed therein to form fluid tight compartments.

9. In a sugar cane mill, a combination of a cane carrier, a prime mover for operating said cane carrier, means for reducing the particle size of cane delivered thereto by said carrier, a second fluid prime mover for operating said cane particle size reducing means, a governor-controlled valve controlling flow of fluid to said second prime mover, actuating means for controlling the speed of said carrier operating prime mover, and means connected on the upstream and downstream sides of said governor-controlled valve operated by variances in the pressure difference of the fluid for acting on said actuating means.

References Cited in the file of this patent UNITED STATES PATENTS I 1,580,431 Gassman Apr. 13, 1926 1,735,389 Hall Nov. 12, 1929 2,005,561 Roscoe et al. June 18, 1935 2,059,830 Warner Nov. 3, 1936 2,179,559 Meyer Nov. 14, 1939