AU2005202780A1 - Rotary engine for lawn and garden products, pumps, compressors, and tillers - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): TechTronic Industries Co., Ltd Invention Title: ROTARY ENGINE FOR LAWN AND GARDEN PRODUCTS, PUMPS, COMPRESSORS, AND TILLERS The following statement is a full description of this invention, including the best method of performing it known to me/us: ROTARY ENGINE FOR LAWN AND GARDEN PRODUCTS, PUMPS, COMPRESSORS, AND TILLERS 00 0 TECHNICAL

FIELD

[0001] The present invention relates to portable power tools, and more I particularly to portable power tools using a rotary engine, such as lawn and Sgarden products including line trimmers, lawn edgers, lawn mowers, brush C-i cutters, tillers, hedge trimmers, power hacksaws, chain saws, water pumps, generators, air compressors, blowers, vacuums, etc.

BACKGROUND

[0002] It is known in the prior art to provide a two-stroke or four-stroke internal combustion engine that provides a rotary output for driving portable power machinery such as line trimmers, lawn edgers, lawn mowers, brush cutters, tillers, hedge trimmers, power hacksaws, chain saws, water pumps, generators, air compressors, blowers, and vacuums U.S. Pat. No. 4,189,008, U.S. Pat. No. 4,286,675, U.S. Pat. No.

5,233,946, U.s. Pat. No. 5,327,710, U.S. Pat. No. 6,155,035, and U.S. Pat.

No. 6,305,909). However, for these portable power tool applications, the use of a conventional two-stroke or four-stroke engine has many disadvantages. First, conventional two-stroke or four-stroke engines have many moving parts, including pistons, connecting rods, camshaft, valves, valve springs, rockers, a timing belt, timing gears, and a crankshaft. All of these moving parts lead to reliability concerns. Second, due to the reciprocating masses within conventional two-stroke or four-stroke engines, there are vibration and noise issues. For hand held applications such as line trimmers, chain saws, blowers, vacuums, etc., vibration is fatiguing to the operator, while noise poses both a nuisance and a safety concern. Third, the specific displacement for unit power is relatively large for conventional two-stroke or four-stroke engines, with one power stroke for every rotation of the crankshaft in two-stroke engines and one power stroke for every two rotations in four-stroke engines. This leads to a relatively large engine size and weight. For portable applications where an operator must frequently move or carry the engine, this is undesired.

00 0[0003] For the foregoing reasons, there is a need for a portable power Stool with an engine that has fewer moving parts, reduced vibration and noise, and a more lightweight and compact design than existing designs using conventional two and four-stroke engines.

BRIEF SUMMARY [0004] Accordingly, embodiments of the present invention provide a new and improved engine for portable power tools such as line trimmers, lawn edgers, lawn mowers, brush cutters, tillers, hedge trimmers, power hacksaws, chain saws, water pumps, generators, air compressors, blowers, vacuums, etc. In one embodiment, a small displacement rotary engine is used in portable power tools. This rotary engine design uses fewer parts with a smoother power delivery and a slower rotation, resulting in decreased noise and vibration. By running the rotary engine at higher speeds, which is possible due to a balanced rotor design and fewer moving parts, the design can be very compact for a given power output.

This allows for a compact, lightweight design.

[0005] According to a first aspect of the invention, a portable power tool has a housing, a rotary engine, and a rotary output head. The rotary engine is disposed within the housing and has an output shaft. The rotary output head Is coupled with the output shaft.

[0006] According to a second aspect of the invention, a portable power tool comprises a housing, a rotary engine, and a rotary output head. The housing has a handle. The rotary engine is disposed within the housing, and has an oval chamber with at least one triangular rotor disposed within the chamber. The rotary engine also has an output shaft. A rotary output head is coupled with the output shaft.

[0007] A third aspect of the invention is a portable power tool comprising a housing, a rotary engine, and a rotary output head, The housing has a handle, and the rotary engineis disposed within the housing. The rotary engine has an oval chamber with at least one triangular rotor disposed 00 0 within the chamber. The rotary engine also has an output shaft driven by Sthe rotor. A rotary output head is coupled with the output shaft.

SBRIEF DESCRIPTION OF THE DRAWINGS [0008] FIG. 1 shows a cross section view of one embodiment of the rotary engine of the present invention, oriented vertically.

[0009] FIG. 2 shows a cross section view of one embodiment of the rotary engine of the present invention, oriented horizontally.

[0010] FIG. 3 shows a cross section view of an exemplary full crank rotary engine blower that incorporates the rotary engine of FIG. 2.

[0011] FIG. 4 shows a cross section view of an exemplary full crank rotary engine trimmer that incorporates the rotary engine of FIG. 2.

[0012] FIG. 5 shows a detail cross section view of an exemplary full crank rotary engine trimmer of FIG. 4.

[0013] FIG. 6 shows a cross section view of an exemplary half crank rotary engine trimmer that incorporates the rotary engine of FIG. 2.

[00141 FIG. 7 shows a detail cross section view of an exemplary half crank rotary engine trimmer of FIG. 6.

[0015] FIG. 8 shows a cross section view of an exemplary full crank rotary engine compressor that incorporates the rotary engine of FIG. 2.

[0016] FIG. 9 shows a cross section view of an exemplary full crank rotary engine pump that incorporates the rotary engine of FIG. 2.

[0017] FIG. 10 shows a cross section view of an exemplary full crank rotary engine tiller that incorporates the rotary engine of FIG. 2.

[0018] FIG. 11 is a sketch of an exemplary rotary engine blower.

[0019] FIG. 12 is a sketch of another exemplary rotary engine blower.

[0020] FIG. 13 is a sketch of an exemplary rotary engine trimmer.

[0021] FIG. 14 is a sketch of an exemplary rotary engine trimmer using a transmission.

[0022] FIG. 15 is a sketch of an exemplary rotary engine trimmer that 0 shows the ignition coils.

00 00[0023] FIG. 16 is a sketch of the rear view of the rotary engine trimmer of FIG. 15 illustrating the ignition coils.

Vin DETAILED DESCRIPTION OF THE DRAWINGS AND THE SPRESENTLY PREFERRED EMBODIMENTS c [0024] Referring now to FIG. 1, a cross section of an internal combustion rotary engine 10 is shown. The rotary engine 10 has a triangular rotor 20 that rotates within a housing 12 having an oval-shaped (epitrochoidal) chamber 14. The pressure of combustion is contained in a combustion space 25 formed by part of the housing 12 and sealed by a plurality of seals 26 (FIG. 5) on one face of a triangular rotor 20, which the rotary engine 10 uses instead of the pistons and cylinders found in two or four stroke engines. In the center of the rotor is a large internal rotor gear that rides around a smaller gear 40 that is fixed to the housing 12 of the rotary engine 10. The rotor 20 is also fitted onto a lobe (not shown) mounted eccentrically on an output shaft 50. A carburetor 70 supplies a fuel-air mixture through an intake port 16 into the housing 12. A spark plug ignites the fuel-air mixture after it is compressed by one face of the rotor The combustion cycle drives the rotor 20, releasing the combustion products through an exhaust port 18, which is located in the housing 12, into an exhaust muffler 80. A fuel tank 90 with a cap 92 (seen in FIG. 3), located underneath the rotary engine 10, supplies fuel to the carburetor for the fuel-air mixture.

[0025] The rotary engine 10 shown in FIG. 1 has a vertically aligned chamber 14. FIG. 2 illustrates an alternate embodiment of a rotary engine 110, where the chamber 114 is aligned horizontally. It should be noted that the rotary engine 10, 110 of the present invention incorporates components that are similar in design and/or function as those described in U.S. Patent No. 2,988,065, issued June 13, 1961, and entitled Rotary Internal Combustion Engine. The contents of this patent are hereby incorporated by reference to avoid the unnecessary duplication of the 00 description of these similar components. The engine displacement and C' power ratings of the rotary engine 10, 110 are between 10-50 cc (cubic ri centimeters) and 0.8 to 5.0 HP (horsepower), respectively.

[0026] In the portable power tool embodiments using a rotary engine C' described below and illustrated in FIGS. 3-10, the rotary engine 10, 110 is mounted in a housing 310, 410, 510, 610, 710, and 810. Rotary engine 110 may be completely housed within housing 310, 410, 510, 610, 710, and 810, taking advantage of the compact size of rotary engine The output shaft 50 of rotary engine 10, 110 is journaled at both ends by a front engine bearing 352 and a rear engine bearing 354. Front engine bearing 352 and rear engine bearing 354 may be conventional ball or roller bearings, available, for example, from NTN BEARING CORPORATION OF

AMERICA.

[0027] A magneto-flywheel 372 is rotationally coupled to the output shaft The flywheel 372 is magnetically coupled to a solid state ignition module 370 for developing ignition current to spark plug 60 through a spark plug wire 64 (FIG. which is electrically coupled to spark plug through a spark plug boot 62. A plurality of vanes 374 are circumferentially located on the magneto-flywheel 372. As the rotary engine 10 undergoes combustion and causes the output shaft 50 to rotate, the flywheel 372 is rotated. As the flywheel 372 rotates, the plurality of vanes 374 forces air from an air intake (not shown) over a plurality of cooling fins 320 that radially extend from rotary engine housing 10 to an exhaust (not shown), thereby cooling the rotary engine 10, 110.

[0028] The rotary engine 10 is also equipped with a conventional recoil starter 360. Starter 360 consists of a starter housing 362, a starter pull handle 364, a starter rope (not shown), and a starter cup 366. An operator pulls on handle 364 to start the rotary engine 10, 110. Alternately, other starter systems may also be used, such as an electric starter.

[0029] A standard centrifugal clutch 480 (FIG. 4) may be mounted directly to the flywheel 372. As flywheel 372 increases its angular velocity, 00 0 centrifugal clutch 480 is forced radially outward and engages a clutch drum 482, transmitting torque from output shaft 50 to clutch drum 482. Clutch drum 482 is coupled with a drive shaft 452 and rotationally supported by a clutch bearing 450. Clutch bearing 450 may be a conventional ball or roller bearing.

[0030] In general, rotary engines run at very high speeds up to 20,000 RPM. These high speeds may not be ideal for driving the clutch and shaft in various lawn and garden power tool applications. Therefore, a transmission (not shown) may be used to couple the clutch 482 and the drive shaft 452. The transmission provides a gear reduction or increase to reduce or increase the output torque available to drive shaft 452 from output shaft 50. The transmission may also be used to move the axis of the drive shaft 452 with respect to housing 310, 410, 510, 610, 710, and 810. The transmission may help to improve the life and design of the clutch 480 and drive shaft 452.

[0031] Referring now to FIG. 3, a cross section of a full crank blower 300 using the rotary engine 10, 110 is illustrated. Blower 300 has a housing 310 with an ergonomically positioned handle 318. Handle 318 is aligned near the center of gravity so that an operator is not subjected to undue torque as the blower 300 is carried. Starter 360, described above, is coupled with and starts rotary engine 10, 110. Housing 310 defines a volute chamber (not shown) where a rotary impeller 380 is rotationally coupled with the output shaft 50 of the rotary engine 10, 110. Rotary impeller 380 draws air from an air intake (not shown) in housing 310. Air flows through the intake, into the volute chamber, and is blown out by the rotary impeller 380 through a blower pipe (not shown). Rotary impeller 380 and the blower pipe are centrally located for better balancing and packaging.

[0032] FIGS. 4 and 5 illustrate a full crank rotary engine trimmer 400 using the rotary engine 10, 110. Trimmer 400 has a housing 410 00 00 containing the rotary engine 10, 110. The driveshaft 452 is rotationally coupled with a trimmer head 420 having a string 424 and a string guard C 422. Driveshaft 452 is positioned within an outer tube 426. Outer tube 426 extends from the housing 410 to the trimmer head 420 and protects driveshaft 452. An operator starts the trimmer 400 by pulling on the starter handle 364, rotating the engine shaft 50. Once the engine 10, 110 starts the combustion cycle, the rotary engine 10, 110 drives the engine shaft and flywheel 372, which in turn drives the drive shaft 452 through the centrifugal clutch 480. The drive shaft 452 drives the trimmer head 420, rotating the string 424 perpendicularly to the drive shaft 452.

[0033] FIGS. 6 and 7 illustrate a half crank rotary engine trimmer 500 using the rotary engine 10, 110. Trimmer 500 operates similarly to trimmer 400, where a trimmer head 420 is rotationally coupled to driveshaft 452.

However, trimmer 500 mounts the rotary engine 10, 110 directly to housing 500, with rear engine plate 520 of rotary engine 50 exposed. The output shaft 50 of rotary engine 10, 110 extends only from the front end of rotary engine 10, 110, and is supported by the front engine bearing 352, although the half crank shaft may be supported by at least a pair of bearings. The flywheel 372, the starter 360, and the clutch 480 are all mounted on the front end of output shaft 50. This leads to a more compact design, requiring fewer parts than the full crank rotary engine trimmer 400 described above.

[0034] A full crank rotary engine compressor is illustrated in FIG. 8. As with the blower 300 and trimmers 400, 500 described above, compressor 600 uses rotary engine 10, 110, which is positioned within a housing 610 and mounted on a base 620. The compressor 600 couples a crankshaft 630 within a crankcase 632 to output shaft 50. Crankshaft 630 is coupled to a connecting rod 634, which drives a reciprocating piston 636 and cylinder 638 arrangement. Compressor 600 also has an inlet 640 and an outlet 650. each with valves 642, 652. Compressor 600 may be pneumatically coupled with a storage tank (not shown) to operate 00 0 pneumatic tools, clean equipment and work areas, or quickly inflate tires, Ssports equipment, pools, etc. Wheels (not shown) may be mounted to Sbase 620 for easy mobility. Additionally, a handle 612 is ergonomically positioned on housing 610 and aligned near the center of gravity so that San operator is not subjected to undue torque as the compressor 600 is carried.

[0035] FIG. 9 illustrates a full crank rotary engine pump assembly 700 using a rotary engine 10, 110. Pump assembly 700 houses rotary engine 110 within a housing 710. Housing 710 and a centrifugal pump 750 are mounted to a base 720. Pump 750 has inlet and outlet ports 754 and 756, and couples a centrifugal impeller 752 to output shaft 50. Fuel tank may be positioned beneath pump 750. Centrifugal impeller 752 may be adapted to pump water, air, or some other fluid. Additionally, a handle 712 is ergonomically positioned on housing 710 and aligned near the center of gravity so that an operator is not subjected to undue torque as the pump assembly 700 is carried.

[0036] A tiller 800 using rotary engine 10, 110 is illustrated in FIG. Tiller 800 has a housing 810 containing the rotary engine 10, 110. The driveshaft (not shown) is rotationally coupled with a tiller head 820. An operator starts the tiller 800 by pulling on the starter handle 364, rotating the engine shaft 50. Once the engine 10, 110 starts the combustion cycle, the rotary engine 10, 110 drives the engine shaft 50 and flywheel 372, which in turn drives the drive shaft 452 through the centrifugal clutch 480.

The drive shaft 452 drives the tiller head 820.

[0037] It will be appreciated that the above illustrated and described rotary engine provides a novel power configuration which may be used to deliver rotary power to a number of different portable power tool applications. The rotary engine is particularly well suited for driving a flexible line trimmer for cutting vegetation, but it may also be used to for a 9 brush cutter having a rigid blade, or a lawn edger. The rotary engine may also be used for driving a hedge trimmer, vacuum, blower, snow blower, power hacksaw, circular saw, chain saw, water pump, lawn mower, or for driving a generator, for example. The small displacement rotary engine design uses few moving parts with a smoother power delivery and a slower rotation, resulting in decreased noise and vibration. By running the rotary engine at higher speeds, which is possible due to a balanced rotor design and 0 fewer moving parts, the design can be very compact for a given power output. This allows for a compact, lightweight design. Further, emission levels are expected to be N equal to or better than emissions produced by two-stroke engines.

[0038] It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.

[0039] It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

[0040] In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e.L to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims (16)

1. A portable power tool comprising: a. a housing; b. a rotary engine disposed within the housing and having an output shaft; and c. a rotary output head coupled with the output shaft.

2. The portable power tool of Claim 1, wherein the rotary engine has an oval chamber and at least one triangular rotor disposed within the chamber.

3. The portable power tool of Claim 2, wherein the rotary output head is an impeller, a line trimmer, or a tiller.

4. The portable power tool of Claim 1, wherein the rotary engine has a half-crank. The portable power tool of Claim 1, wherein the rotary engine has a full-crank.

6. A portable power tool comprising: a. a housing with a handle; b. a rotary engine disposed within the housing, wherein the rotary engine has an oval chamber and at least one triangular rotor disposed within the chamber, and wherein the rotary engine has an output shaft; and c. a rotary output head coupled with the output shaft.

7. The portable power tool of Claim 6, wherein the rotary output head is an impeller, a line trimmer, or a tiller. 00 S8. The portable power tool of Claim 6, wherein the rotary engine ri has an engine displacement of approximately 10 to 50 cubic centimeters. S9. The portable power tool of Claim 6 further comprising a fuel tank and a carburetor coupling the fuel tank with the rotary engine. The portable power tool of Claim 6 further comprising a centrifugal clutch coupling the output shaft to the rotary output head.

11. The portable power tool of Claim 6 further comprising a transmission coupling the output shaft to the rotary output head.

12. The portable power tool of Claim 6, wherein the rotary engine has a half-crank.

13. The portable power tool of Claim 6, wherein the rotary engine has a full-crank.

14. A portable power tool comprising: a. a housing with a handle; b. a rotary engine disposed within the housing, wherein the rotary engine has an oval chamber and at least one triangular rotor disposed within the chamber, and wherein the rotary engine has an output shaft driven by the rotor; and c, a rotary output head coupled with the output shaft. The portable power tool of Claim 14, wherein the rotary output head is an impeller.

16. The portable power tool of Claim 14, wherein the rotary output head is a line trimmer. 00 C 17. The portable power tool of Claim 14, wherein the rotary output C-i head is a tiller.

18. The portable power tool of Claim 14, wherein the rotary engine has an engine displacement of approximately 10 to 50 cubic centimeters.

19. The portable power tool of Claim 14 further comprising a fuel tank and a carburetor coupling the fuel tank with the rotary engine. The portable power tool of Claim 14 further comprising a centrifugal clutch coupling the output shaft to the rotary output head.

21. The portable power tool of Claim 14 further comprising a transmission coupling the output shaft to the rotary output head.

22. The portable power tool of Claim 14, wherein the rotary engine has a half-crank.

23. The portable power tool of Claim 14, wherein the rotary engine has a full-crank. Dated this 24th day of June 2005 TECHTRONIC INDUSTRIES CO., LTD By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia