This invention relates to an engine, and more particularly, a small four-cycle utility engine that is particularly suitable for typical power tools driven by a vertical or horizontal power shaft.
Portable power tools such as line trimmers, blowers/vacuums, and chain saws must be able to run in a very wide range of orientations. However, in most power tools such as generators or tillers/cultivators, power shaft orientation is either substantially horizontal or vertical. Therefore, it is not necessary for these typical power tools to be able to run in a very wide range of orientations having complicated and economically ineffective constructions.
For some tillers/cultivators powered by four-cycle engines with a vertical power shaft, lubrication also becomes a serious problem since it is difficult to use the same lubrication system as engines with a horizontal power shaft.
U.S. Pat. No. 6,250,273 to Ryuu et al. discloses a prior art utility engine for horizontal and vertical shaft orientations, which is incorporated herein by reference. However, constructions are still complicated because special rotating parts having inclined shafts to a crankshaft or a camshaft are necessary for lubrication and speed control.
Further, because the splashing blades 41 adjacent the driven gear 40 are immersed in an oil in the oil reservoir 17 and splash oil in the direction which is composed by the peripheral and centrifugal forces by rotation of rotary board 35, splashed oil is concentrated in the corner of crankcase and does not direct to the center portion of the crankcase to lubricate moving parts effectively and it produces heating of oil by useless churning.
Further, because the side cover has portions to support the intermediate shaft and the inclined governor shaft, size of the side cover is large and machining for the side cover is complicated and requires high level of accuracy.
Therefore, it is an object of the present invention to provide a small four-cycle utility engine having an internal lubrication system, which is especially suitable for both vertical and horizontal power shaft engines having components that are easy to make.
Although U.S. patent application Ser. No. 12/954,945 by Kurihara et al. and U.S. patent application Ser. No. 13/286,323 by Kurihara et al., which are incorporated herein by reference, disclose a useful prior art small four-cycle engine construction for portable power tools driven by a vertical or horizontal power shaft, to shorten the length of axial direction is required yet.
It is a further object of the present invention to provide a small four-cycle utility engine having a short axial length and speed control system enabling the engine to be run at a desired speed at any load, which is especially suitable for both vertical and horizontal power shaft engines.
It is yet a further object of the invention to provide a commonality of main parts between vertical and horizontal engines, which is especially suitable for both vertical and horizontal power shaft engines to reduce manufacturing cost.
These and other objects, features, and advantages of the present invention will become apparent upon further review of the remainder of the specification and the accompanying drawings.
In order to achieve the above objects, a four-cycle, utility engine is provided which is suitable for both vertical and horizontal power shaft engines.
The four-cycle, vertical shaft utility engine is provided with an engine block having at least one cylindrical bore oriented in a substantially horizontal orientation having an enclosed crankshaft chamber. A vertical crankshaft is pivotably mounted within the engine block. An enclosed oil reservoir is formed with the engine block and a crank shaft cover and is located below the crankshaft chamber. The enclosed oil reservoir when properly filled, enables the engine to rotate at least 30 degrees about the crankshaft axis in either direction without oil within the reservoir rising above the level of the crankshaft counter weight. A pump is connected drivably to a cam gear-cam assembly or to a speed governor assembly, said pump inhales lubrication oil from the oil reservoir through an inhale passage on a wall of the cylinder block to splash oil into the cylinder and valve train. Said inhale passage of the oil pump is extended to near the crank shaft cover, which is located below the cylindrical bore when the power shaft of said engine is oriented to be horizontal.
A sister engine, which is a horizontal shaft utility engine, is provided. Main parts of both vertical and horizontal engine are substantially common. The sister engine has an engine block having at least one cylindrical bore oriented in a substantially vertical orientation having an enclosed crankshaft chamber. A horizontal crankshaft is pivotably mounted within the engine block. An enclosed oil reservoir formed with the engine block and a crank shaft cover and is located below the crankshaft chamber. The enclosed oil reservoir when properly filled, enables the engine to rotate at least 30 degrees about the crankshaft axis in either direction without oil within the reservoir rising above the level of the crankshaft counter weight. A pump is connected drivably to a cam gear-cam assembly or to a speed governor assembly, and said pump inhales lubrication oil from the oil reservoir through an inhale passage on the cylinder block to splash oil into the cylinder and valve train.
In both the vertical and horizontal engine, a breathing system is provided at a location in which an oil level within the reservoir is not above the breathing system.
The cylinder block 1 forms a crankshaft chamber 19.
The lower case 91 and the crankshaft cover 93 provide an enclosed oil reservoir 20 in a vertical shaft engine as illustrated in
A crankshaft 3 is a power shaft and is pivotably mounted within the engine block 1 in a conventional manner. A piston 4 slides within the cylinder bore 2 and is connected to the crankshaft 3 by a connecting rod 5. A cylinder head 6 is affixed to the engine block 1 to define an enclosed combustion chamber 7.
In
A horizontal crankshaft 3 is pivotably mounted within the engine block 1. An enclosed oil reservoir 21 is formed within the engine block 1 and a crank shaft cover 93 and is located below the crankshaft chamber 19. The enclosed oil reservoir 21 when properly filled, enables the engine to rotate at least 30 degrees about the crankshaft axis 92 in either direction without oil within the oil reservoir 21 rising above the level of the crankshaft counter weight.
As illustrated in
The oil reservoir 20 or 21 is relatively deep so that there is ample clearance between the crankshaft 3 and the level of the oil within the oil reservoir during normal use (vertical or horizontal orientation of the crankshaft).
The crankshaft 3 is provided with an axial shaft 22 coupled to an output end 23 adapted to be coupled to a counterweight web 24.
A crankpin 25 is affixed to counterweight web 24 and is parallel to and radially offset from the axial shaft 22. The crankpin 25 pivotally cooperates with connecting rod 5.
The axial shaft 22 of crankshaft 3 is pivotably attached to the cylinder block 1 by a bearing 27.
Another axial shaft 28 of the crankshaft 3 is coupled to a counterweight web 26 and is pivotably attached to the cylinder block 1 by a bearing 29.
At the side of bearing 27 is a crank gear 30.
A camshaft drive and valve lifter mechanism is best illustrated in
The crank gear 30 is mounted on the crankshaft 3, which in turn drives a cam gear 31 with twice the number of teeth as the crank gear 30 resulting in the camshaft 32 rotating at one-half engine speed. The cam gear 31 is affixed to the camshaft 32 which includes a rotary cam lobe 33.
In the embodiment illustrated, a single cam lobe 33 is utilized for driving both the intake and exhaust valves 11, 15.
Followers 34 and 35 are pivotably connected to the cylinder block 1 by a pivot pin 36.
Push rods 37 and 38 extend between camshaft followers 34 and 35 and rocker arms 39 and 40 located within the cylinder head 6. The cam lobe 33, push rods 37, 38 and rocker arms 39, 40 are part of a valve train assembly. Affixed to the cylinder head 6 is a valve cover 41 which defines therebetween an enclosed valve chamber 42.
As illustrated in
In order to lubricate the engine, a trochoid pump 43 is placed at the cam chamber cover 50.
The pump 43 has an inner rotor 44 and outer rotor 45. In other embodiments of the present application, a gear pump may be used.
The camshaft 32 drives the inner rotor 44 and the outer rotor 45 is rotated following the rotation of the inner rotor 44.
Lubrication oil is inhaled from a passage 46, which is extended to the crank shaft cover 93. An oil seal 47 is installed on the cylinder block 1 to prevent leakage of oil from the crank shaft chamber 19.
An end of the passage 46 leads to the oil entrance of the pump. The other end of passage 46 is connected to an oil entrance at oil reservoir 20 or 21.
In the vertical shaft engine as illustrated in
In the horizontal shaft engine as illustrated in
The pump 43 and the cylinder 90 can be commonly used between the vertical shaft engine as in
The oil pushed out by the pump 43 is lead simultaneously to a hole 49 at the cylinder wall and to a hole 94 formed in the outer wall of the cam shaft 32 and a hole 95 in the cylinder 90 through an inner through hole 48 of the camshaft 32 and into the cylinder bore 2 as illustrated in
Any other hole (not shown) at the wall of the camshaft 32 may lead oil to the valve actuating train. Accordingly, the engine parts inside the cylinder and crankcase are mist lubricated by the oil splashed by means of the rotation of and/or the centrifugal force generated by the rotating parts such as the web 24, 26 and the cam gear 31.
In the engine of
As shown in
As illustrated in
On the governor holder 52, a set of fly weights 68 for speed control of the engine is provided. The fly weights 68 are pivotably inserted by pin to the governor holder 52.
As shown in
When engine runs, the fly weight 68 is spread outwardly by centrifugal force and pushes the slide piece 69 to slide. On the other end of the slide piece 69, a contact face 72 is provided to contact the lever 73, which is affixed by a rotatable shaft 74.
The shaft 74 is pivotably provided on the wall of cylinder 1. Rotation of said shaft 74 controls engine speed with said carburetor 10.
A cam chamber cover 55 is attached to the wall of the cylinder 90. An end of the camshaft 32 is journaled to the wall of cylinder bore 2 of the cylinder 90. The other end of said cam shaft 32 is journaled to a cam chamber cover 55. An end of the pivot pin 36 is supported at the wall of cylinder bore 2 and the other end of said pivot pin is supported by the cam chamber cover 55. Cylinder 90 and cam chamber cover define a cam chamber 18.
In
A governor holder 52 is installed on said governor shaft 51 to be able to rotate. On the outer surface of said governor holder a governor gear 53 is provided to mate with the crank gear 30. By the rotation of the crank shaft 3, said governor gear 53 is rotated.
On the governor holder 52, a set of fly weights 68 for speed control of the engine is provided. The fly weights 68 are pivotably inserted by pin to the governor holder 52. The governor holder 52 is connected to the inner rotor 44 of said pump and drives the inner rotor 44 and the outer rotor 45 is rotated following the rotation of the inner rotor 44.
Lubrication oil is inhaled from a passage 46, which is extended to the crank shaft cover 93.
An end of the passage 46 leads to the oil entrance of the pump. The other end of passage 46 is connected to an oil entrance at oil reservoir 20 or 21.
In the vertical shaft engine as illustrated in
In the horizontal shaft engine as illustrated in
The pump 43 and the cylinder 90 can be commonly used between the vertical shaft engine as in
The oil pushed out by the pump 43 is lead simultaneously to a hole 49 at the cylinder wall and to a hole 94 formed in the outer wall of the cam shaft 32 and a hole 95 in the cylinder 90 through an inner through hole 48 of the camshaft 32 and into the cylinder bore 2 as illustrated in
In the embodiments of the present application illustrated in
It is believed that small light-weight four cycle engines made in accordance with the present invention will be particularly suitable for use with utility power tools having a horizontal or vertical power shaft and is sufficiently manufactured to use common parts between vertical and horizontal shaft engines. In the prior art, U.S. Pat. No. 6,250,273 to Ryuu et al. discloses a prior art utility engine for horizontal and vertical shaft orientations. However, constructions are complicated because a speed controlling system having inclined shaft to a crankshaft or a camshaft are necessary for lubrication and speed control. Further, the side cover which supports a cam shaft and a governor shaft is large sized and the mating plane to the cylinder block is inclined, so that machining procedure is complicated and manufacturing cost is expensive.
On the other hand, present inventions as illustrated in
Further, in the embodiment illustrated in
Further, in the embodiment illustrated in
Further, in the embodiment illustrated in
Further, in the present invention, as illustrated in
While the present invention is discussed in relation to the engine to be used with a small utility engine for stationary power tools, a person having ordinary skill in the art will readily realize that it can be also used with hand-held power tools or larger power equipment.
Other parts not specifically referenced to in the foregoing relate to conventional four-cycle engines. A spark plug 82 is installed in a spark plug hole formed in the cylinder head. A coil 83 is an ignition coil. A re-coil starter, not shown, having a re-winding rope is provided at a side of a flywheel 84, which inhales cooling air for the engine generated by rotation of blade 85 on the flywheel 84.
In vertical shaft engines as shown in
In horizontal shaft engines such as those of
The breathing system works by the check valve 58 and pressure in the crankcase chamber 19 is kept normal during operation.