US3515258A

US3515258A - Pawl for centrifugal thrower

Info

Publication number: US3515258A
Application number: US710956A
Authority: US
Inventors: Walter W Wolfe; Herbert A Holten; Jack D Messner; Ivan E Olson
Original assignee: VAN DUSEN AND CO Inc
Current assignee: DYNAMATIC FEEDING SYSTEMS INC A MN CORP; VAN DUSEN AND CO Inc
Priority date: 1968-03-06
Filing date: 1968-03-06
Publication date: 1970-06-02
Anticipated expiration: 1987-06-02

Description

June 2, 1970 w. WPWOLFE ETAL 3,515,258

PAWL FOR CENTRIFUGAL THROWER 2 Sheets-Sheet 2 Filed March 6, 1968 MQE 9 lrrokusys United States Patent U.S. Cl. 198-128 8 Claims ABSTRACT OF THE DISCLOSURE A pawl or paddle used in connection with a centrifugal thrower for throwing material. The pawl is pivoted to the outer end of an arm on a spider and freely swings. The pawl is made up of two plate like members formed into a V-shape with a narrow web (the plates are substantially wider than the web) holding the plates together. The pivot for the pawl is at the closed end of the V. The pawl thus has a symmetrical configuration when the pawl is rotating. It has a leading face which slopes forwardl at an angle from a radial plane passing through the axis of the spider and the pivot axis of the pawl. This gives greater capacity for the same horsepower.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to pawls or paddles used on the impellers of centrifugal throwers.

Background of the invention The ability to obtain a high output of a centrifugal type material thrower at low horsepower has been sought for a long time. A straight sided swinging paddle or pawl used with impellers has not given the maximum output, and various different designs have been advanced. Included are scooping type impellers which theoretically are supposed to give additional capacity by providing a scoop type action as they rotate and engage the material to be thrown. However, these pawls or paddles are expensive to manufacture and also require a substantial amount of horsepower for the amount of capacity. The problem has been to keep the cost of manufacture down and still increase output without increasing horsepower requirements.

SUMMARY OF THE INVENTION The present invention relates to a pawl or paddle for the impeller of a centrifugal thrower having at least one forwardly inclined face which will engage material as the impeller rotates and throw the material outwardly under centrifugal force. The weight of the material tends to move the pawl rearwardly about its pivot and the centrifugal force on the pawl tends to hold it in its normal radial position. The leading face then assumes a natural angle where maximum throwing capacity is achieved. As shown, when a V-shaped pawl is used the pawl is made using two blades shaped in a V and held together with a narrow web at right angles to the planes of the blades. The rearward slanting blade of the pawl has a leading face on either side of the web and this leading face will tend to create an outward rush of air immediately following the material being thrown outwardly and tends to give an extra boost to the material.

The symmetrical design of the pawl permits the pawl to be reversed in direction as wear occurs to increase the effective life of a single pawl thereby reducing operating and maintenance costs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view showing a centrifugal thrower of the type using a pawl made according to the present invention;

FIG. 2 is a sectional view taken on line 22 of FIG. 1;

FIG. 3 is a sectional view taken on line 3-3 in FIG. 2; and

FIG. 4 is a sectional view taken on line 4-4 in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, first, a centrifugal thrower 10' is shown to illustrate the environment in which the pawl operates. The thrower is moving material 11, such as chopped corn or grass or other material. The thrower assembly includes a frame 13 mounting a rotor drive motor 14 which obtains electric power through suitable connections and which is used to drive the rotor of the thrower. An auger trough 15 which, in turn, rotatably mounts an auger 16, extends laterally from a thrower housing 17. The terminology used in this specification will be thrower for the assembly but it can also be termed a blower of the centrifugal type. However, the action here is more of a scooping and throwing action rather than blowing. A separate motor 18 is mounted to the outer end of the trough 15 and a drive assembly, such as a chain and sprocket is attached from the output shaft of the motor to the shaft for auger 16. The motor 18 is also powered from an electrical source. Material to be lifted by the thrower is placed in the auger housing and conveyed by the anger (with motor 18 running) toward housing 17. When the material reaches the housing 17 it is engaged by the thrower and the material will be thrown up through a guide chute 22 and out of the machine into the desired location. The guide chute 22 has a gooseneck portion at its upper end which can be rotated to any desired position.

The motor 14 drives an exial shaft 24 mounted in the housing 17 with suitable bearings 25 mounted on the side walls of the housing. A rotor assembly 26 is mounted on the shaft 24 and has a hub which is pinned to the shaft so that it will turn with the shaft. The rotor assembly includes a spider 27 which, as shown, has 3 arms. On the outer end of the arms of the spider there are hubs 28.

A pair of swinging pawls or paddles 30 are mounted onto the opposite sides of each of the hubs 28 with a pin 31 that is held in place in a convenient manner such as with the use of a spring pin. These pawls are free to swing around the axis of the pins 31, and are placed in a side by side position. As can be seen, the outer ends of the pawls provide a small clearance with the periphery of the housing 17 and there is a small bit of side clearance along the pawls.

The pawls themselves each have a hub 32 that is bored to receive the pins 31. A pair of blade members 33 and 34 (leading and trailing) are integral with the hubs 32 and are joined together with a web 35. The web 35 has been put in at right angles to the planes of the

blade members

33 and 34 and is relatively narrow and positioned in the center of these blade members. The outer ends of the blade members are cut as shown at 36 on a plane at right angles to a radial plane passing through the axes of spider 26 and pin 31. There is no obstruction for movement of material along the sides of the web 32 outwardly as shown by the arrows 37 in FIG. -4.

The rotor is rotating as indicated by the arrow 40, and material or silage 11 moved into the housing 17 by the auger 15 will be engaged by the leading face 33L of the leading blade 33 of each of the paddles as they rotate. A quantity of material will be carried around by the paddle. The plane of the face 33L will remain advanced from a radial plane passing through the axes of the pin 31 and the shaft 24. This gives a leading face for carrying the material, and centrifugal force on the material will tend to throw it outwardly through the discharge opening 41 of the housing 17. The leading face of each pawl tends to build up the velocity pressure of the material as it discharges. In an ordinary single plane paddle there is a vacuum created at the trailing face of the paddle. However, the trailing blade 34 also has air flowing outwardly along its leading face 34L (on either side of the web) and this tends to overcome any vacuum effect. This additional air coming out along the paddle 34L will give an added boost to the material thrown by the leading blade 33. This design gives an additional capacity to blowers or throwers without increasing the horsepower requirement. If necessary, the housing can be provided with suitable openings along its sides for letting make-up air flow in.

As shown, the blades incline from a bisecting radial line on the paddle approximately in either direction, or in other words, the two

blades

33 and 34 form an included angle of approximately 30. This inclination is sufiicient to make sure that there is a forward incline to the leading face of the leading paddle with respect to a radial line even when it is loaded. Only one blade with a leading face also would be beneficial, but it would have to be balanced with respect to its attachment axis. When the spider is rotating the leading face should be at a leading angle with respect to the radial plane passing through the axis of the spider and the pivot axis of the pawl.

The use of the two blades with only a narrow joined web (in radial direction) and an open end between the blades permits the material to flow off the leading face of the leading blade, and air to flow off the leading face of the trailing blade. There are no obstructions for this air flow at the outer end of the web. The paddles or pawls are free-swinging, and will assume their natural position as they rotate.

What is claimed is:

1. In a device for moving material comprising a housing, a rotor mounted for rotation about a rotor axis inside said housing, said housing has a discharge opening for discharging material, the improvement comprising a pawl pivotally mounted adjacent to the outer periphery of said rotor for free swinging movement about a pawl axis, said pawl comprising a first blade member having a planar rotationally leading surface extending on one side of said pawl axis only and extending substantially the full width of said pawl in the outer end portions thereof and being substantially parallel to said pawl axis, and means fixed to said blade member comprising counterweight means which causes the blade member to move on the opposite side of said pawl axis from the rotor axis and holds the planar leading surface of said blade member inclined at a rotationally leading angle with respect to a radial plane passing through the rotor axis and the pawl axis under centrifugal force when the rotor is rotating, said blade member being substantially unobstructed along the side edges thereof on both the leading and trailing surfaces thereof.

2. The combination as specified in claim 1 wherein said pawl comprises two blade like members formed into a 4 general V-shape, with the closed end of the V adjacent the pawl axis, and means holding said blade like members in position with respect to the axis, so that said pawl is symmetrical about a bisecting line passing through the pivotal axis of said pawl.

3. The combination as specified in claim 2 wherein said means joining said blade like members together comprises a web, said web being a further plate like member of very narrow cross-section dimension positioned at substantially right angles to the planes of said blade like members.

4. The combination as specified in claim 3 wherein the space between said blade like members is substantially unobstructed at the outer end of said pawl.

5. The combination as specified in claim 3 wherein there are two pawl mounted side by side about a common axis on said mounting member, the two pawls together being leading surfaces extending substantially across the width of the housing.

6. The combination specified in claim 3 wherein the blade like members have an included angle of substantially 30.

7. A pawl for a solid material thrower having a rotor rotating about a rotor axis, including a hub having means for pivotally mounting said pawl for free swinging movement about a pawl axis at one end of said pawl to the periphery of said rotor, a pair of blade members fixed to said hub, said blade members being positioned to form a V-shape and being fixed to said hub and spaced apart throughout their length, said blade members having substantialy planar outwardly facing surfaces parallel to said pawl axis and having a width at the outer end portions thereof in direction along said axis substantially equal to the greatest width of the pawl in said direction and each being substantially thinner than said width, said blade members diverging from said hub at substantially equal angles with respect to a bisecting plane passing through said pawl axis, said hub having axial length substantially less than the width of said blade members at the outer portions thereof, said blade members tapering from their maximum width to the width of said hub adjacent said hub, and a web member substantially narrower in direction along said pawl axis than said blade members joining said blade members together, there being no other connecting members between said blade members.

8. The combination as specified in claim 7 wherein each blade member has an inner face surface forming the inner portions of the V-shape extending from opposite sides of said web to the edges of said blade members, said inner surfaces being substantially parallel to the respective outwardly facing surfaces of said blade member.

References Cited UNITED STATES PATENTS 2,587,154 2/1952 Hartz 103-97 2,958,412 11/1960 Buschbom 198-128 FOREIGN PATENTS 88,019 8/1896 Germany.

RICHARD E. AEGERTER, Primary Examiner U.S. Cl. X.R. 239672