Seed Tube Diffuser for a Pneumatic Seed Planter

This invention relates to a seed tube air diffuser which is installed in the row unit seed tubes of a pneumatic planter. The air diffuser aids in relieving the buildup of back pressure within the seed tube and provides for continuous air flow through the seed tube in the event the air flow is supressed at the lower discharge end of the seed tube due to soil flow along the furrow or ground opener. When the air flow through the seed tube is restricted, seed spacing accuracy of the seed deposited in the ground is effected. The air diffuser by allowing continuous and uniform air flow permits a more uniform seed spacing and prevents clogging of the seed tube by a buildup of seeds within the seed tube due to back pressure.

The air diffuser is a short cylindrical duct member which is spliced into or installed in the seed delivery tube, at a predetermined length from the discharge end. In the body of the member there is provided a plurality of holes; the effective open area of which being approximately fifty-percent greater than the open area within the duct taken on a cross-section of the duct at the location of the holes. These holes permit the discharge of a slight amount of air as a normal minimal back pressure is created in the lower discharge end of the seed delivery tube by the flow of soil around the furrow or ground opener. If the air flow is seriously restricted as a result of blockage around the discharge end and furrow opener, the diffuser will permit a larger amount of air to be discharged through the holes reducing the back pressure and thus maintaining a substantially uniform spacing of seed downstream of the diffuser.

FIG. 1 is an illustration of a pneumatic seed planter with an air diffuser installed in each row unit seed delivery tube;

FIG. 2 is a partial side view showing a seed furrow opener at the discharge end of a delivery tube with an air diffuser spliced into the tube at a determinant length above the discharge end and furrow opener;

FIG. 3 is a partial cross-sectional side view of the air diffuser shown in FIGS. 1 and 2; and

FIG. 4 is a representation of the seed intake end of a seed delivery tube.

FIGS. 1 and 2 show an air diffuser 10 spliced into a cut seed delivery tube 11 upstream of a furrow opener 12 of a pneumatic planter 100. A pair of clamps 13 or other suitable clamping means secure the diffuser to two sections or upper and lower portions 21 and 22 of the delivery tube 11. It has been determined that the air diffuser can be installed in the lower portion 22 of the delivery tube between 25 to 50 inches from the discharge end 14 at the furrow opener 12. As shown in FIG. 4 and described in the related U.S. patent application Ser. No. 377,478 to Bauman et al filed on July 9, 1973, now U.S. Pat. No. 3,860,146, dated Jan. 14, 1975, seed 23 is uniformly deposited by drum 88 and rollers 104 into the intake end 103 of the seed tube 11 and is propelled or accelerated along the length of the tube by the force P of air. The furrow opener 12 (FIG. 2) creates a ditch for depositing each seed 23a as it drops from the seed discharge end 14 of the delivery tube. Should there be a blockage at the discharge end 14, the air in the delivery tube will buildup and create a back pressure P.sub.B which will act upon the seeds 23a traveling through tube. The back pressure P.sub.B will change the velocity of the seeds 23a so that the initial uniform spacing at the intake end 103 will vary as the seeds travel toward the bottom of the tube and are deposited into the ground. To prevent the buildup of back pressure, an air diffuser 10 is provided in the seed delivery tube 11 for venting the discharge end 14 of the tube 11 at the furrow opener 12.

The air diffuser 10, shown in FIG. 3, comprises a cylindrical duct member 101 such as a pipe, tube or conduit. It is manufactured from any suitable material which may be used for transmitting air and solids. The body portion 15 is perforated with a plurality of holes 16 which are arranged in axially spaced-apart rows extending a predetermined distance axially along the body 15. The effective open area of the holes being approximately 50% greater than the open area within the duct member 101 taken on a cross section of the member at the location of the holes. In the preferred embodiment the holes are each approximately 1/8th inch in diameter and extend transversely through two quarter-round portions 17 and 18 of the body 15. The axes of the holes are on parallel planes forming a plurality of parallel axially spaced-apart rows of holes over an axial span from 1 to 11/2 inches. The inside diameter along the span of holes is in the vicinity of 7/8ths of an inch. Also, in the preferred embodiment, there are an even number of rows of even numbered holes spaced between an odd number of rows of odd numbered holes on each quarter-round portion 17, 18. For example four rows of four holes each and five rows of three holes each for a total of 31 holes on each portion. Thus, the two quarters or quarter-round arcuate portions 17, 18 equal one-half of the circumference of the body portion 15 vented for a determinate axial length or span between 1 to 11/2 inches which provides an effective vented area approximately 50% greater than the open area inside the body 15 taken on a cross-section within the span of rows of holes.

The body portion 15 has an air-seed inlet end 19 and an air-seed outlet end 20. Any suitable marking, such as arrow 24, is marked on the body portion 15 to indicate the direction of air-seed flow. Downstream of the last row of holes 25 there is a venturi portion 26 within the duct member 101 which increases the velocity of the air stream and aids in guiding the traveling seed 23a into the lower portion 22 of the seed delivery tube 11. Each end of the duct member 101 is provided with axially extending slots 27 and 28, annular external rings 29 and 30 at the edges of the ends and annular internal rings or shoulder portions 31 and 32 within the duct member 101 at the start or first row 31 of holes and at the downstream end of the venturi portion 26.

A pair of clamps 13 are placed over the slotted ends 19, 20 of the air diffuser 10 against the external rings 29, 30, the seed delivery tube 11 is cut at the distance previously specified, and the upper and lower cut portions 21, 22 are inserted into the duct member 101 up to the shoulder portions 31, 33. An adhesive or sealant may be applied to the cut ends 21, 22 prior to insertion into the duct member 101. The clamps 13 are then drawn tight against the slotted ends 19, 20 securing the cut ends 21 and 22 of the seed delivery tube 11 within the pipe 10. Should back pressure develop downstream of the diffuser 10, the back pressure will vent through the openings 15 and 16 and the seed 23a traveling in the lower portion 22 of the seed delivery tube downstream of the diffuser 10 will drop at a substantially uniform spacing proportional to the spacing at the time the seed was initially deposited into the intake end 103 of the tube.