JP3854049B2 - Four cycle engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a handheld four-cycle engine mainly serving as a power source for trimmers and other portable work machines, and in particular, from a crankcase having a crank chamber, a cylinder block having a cylinder bore, and a cylinder head having an intake port and an exhaust port. The engine body, the crankshaft supported by the crankcase and housed in the crankcase, the intake and exhaust valves attached to the cylinder head to open and close the intake and exhaust ports, and the rotation of the crankshaft The present invention relates to an improvement of a four-cycle engine including a valve mechanism that opens and closes an intake valve and an exhaust valve.
[0002]
[Prior art]
Such a four-cycle engine is already known as disclosed in, for example, Japanese Patent Application Laid-Open No. 10-317931.
[0003]
[Problems to be solved by the invention]
In the four-cycle engine disclosed in the above publication, an oil tank for storing lubricating oil for the crankshaft and the valve mechanism is disposed at the lower part of the crankcase, so that the overall height of the engine becomes high, This makes it difficult to downsize. In addition, since the valve mechanism is lubricated by a single lubrication system, it may be difficult to lubricate the valve mechanism from corner to corner.
[0004]
The present invention has been made in view of the above points, and provides the above four-cycle engine that is compact and has a low overall height, and that enables the valve mechanism to be lubricated uniformly to every corner. With the goal.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an engine body comprising a crankcase having a crank chamber, a cylinder block having a cylinder bore, and a cylinder head having an intake port and an exhaust port, and a crankcase supported by the crankcase. A crankshaft that is housed, an intake valve and an exhaust valve that are attached to the cylinder head to open and close the intake port and the exhaust port, and a valve mechanism that opens and closes the intake valve and the exhaust valve in conjunction with the rotation of the crankshaft. In a four-cycle engine, a valve timing mechanism is arranged on the outer side of the engine body and connected to one end of the crankshaft, and the rotational force on the driven side of the timing transmission is opened and closed. And a cam device that transmits the force to the intake and exhaust valves, and the first valve chamber that houses the timing transmission device is provided with the timing transmission device. And continuously provided integrally with the oil tank disposed on one outer side of the same side of the engine body, the lower end of the timing belt guide tube forming part of the first valve chamber extends to the crankshaft near the oil tank while manner, at least a portion the second valve-operating chamber for accommodating a formed in the cylinder head, the stored oil in the oil tank to generate an oil mist supplied to the second valve-operating chamber and the crank chamber of the cam device A pair of oil slinger that stirs and scatters is fixed to the crankshaft across the timing transmission , and a through hole is provided in the crankshaft for supplying oil mist generated in the oil tank to the crank chamber. in that a open end of the oil tank between the timing transmission device and the oil slinger to Features.
[0006]
According to features of this, since the disposed oil tank to an outside of the engine body, the total height of the engine can be drastically reduced.
[0007]
In addition, since the first valve chamber for housing the timing transmission device is integrally connected to the oil tank, a part of the timing transmission device can be accommodated in the oil tank, and the engine can be made compact. it can.
[0008]
Further, the lubrication system of the valve mechanism includes a system that lubricates the timing transmission device in the first valve chamber with the scattered oil in the oil tank, and a cam device in the second valve chamber by the oil mist generated in the oil tank. Therefore, the load on each lubrication system is reduced, and the entire valve mechanism can be lubricated uniformly.
[0009]
In addition, a pair of oil slinger fixed to the crankshaft is provided across the timing transmission device, so that the stored oil in the oil tank can be agitated in any operating position of the engine without being interrupted by the timing transmission device. The oil mist can be generated effectively by scattering.
[0010]
In addition , the lower end of the timing belt guide cylinder extends to the vicinity of the crankshaft in the oil tank, and a through hole for supplying oil mist generated in the oil tank to the crank chamber is provided in the crankshaft. Having placed the open end of the tank between the timing transmission device and the oil slinger, the open end of its, the timing transmission device and without being obstructed by the oil slinger in the center or near the oil tank and can be arranged, in any operating position of the engine, it is possible to prevent direct flow of the hole of the stored oil in the oil tank, further, it facilitates the generated oil mist through hole of the timing belt guide tube and the crankshaft Ru can lead to.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.
[0012]
1 is a perspective view showing an example of use of the hand-held four-cycle engine of the present invention, FIG. 2 is a longitudinal side view of the four-cycle engine, FIG. 3 is a sectional view taken along line 3-3 in FIG. 2, and FIG. 4 is a cross-sectional view taken along line 4-4, FIG. 5 is an enlarged cross-sectional view of the main portion of FIG. 2, FIG. 6 is an exploded view of the main portion of FIG. 8 is a sectional view taken along line 9-9 of FIG. 8, FIG. 10 is a sectional view taken along arrow 10-10 of FIG. 5 (bottom view of the head cover), and FIG. 11 is a sectional view taken along line 11-11 of FIG. FIG. 12, FIG. 12 is a lubrication route diagram of the engine, FIG. 13 is a diagram corresponding to FIG. 4 showing the inverted state of the engine, and FIG. 14 is a diagram corresponding to FIG. 4 showing the engine lying sideways.
[0013]
As shown in FIG. 1, the handheld four-cycle engine E is attached to the drive unit as a power source of a power trimmer T, for example. Power trimmer T is because it is used toward the cutter C in the direction of the seed s by its working conditions, each time the engine E is also tilted larger, or is upside down, the driving position is not constant.
[0014]
First, the structure of the outer periphery of the handheld four-cycle engine E will be described with reference to FIGS.
[0015]
A carburetor 2 and an exhaust muffler 3 are attached to the front and rear of the engine body 1 of the handheld four-cycle engine E, respectively, and an air cleaner 4 is attached to the inlet of the carburetor 2. A synthetic resin fuel tank 5 is attached to the lower surface of the engine body 1. Both ends of the crankshaft 13 project outward from both the engine body 1 and the oil tank 40 adjacent to one side of the engine body 1, and the crankshaft 13 is connected to a driven member 84 fixed to the one end. A possible recoil starter 42 is mounted on the outer surface of the oil tank 40.
[0016]
A cooling fan 43 that also serves as a flywheel is fixed to the other end of the crankshaft 13. A plurality of mounting bosses 46 (one of which is shown in FIG. 2) are formed on the outer surface of the cooling fan 43, and a centrifugal shoe 47 is pivotally supported by each mounting boss 46 so as to be swingable. Is done. This centrifugal shoe 47 constitutes a centrifugal clutch 49 together with a clutch drum 48 fixed to the drive shaft 50, which will be described later, and when the rotational speed of the crankshaft 13 exceeds a predetermined value, the centrifugal shoe 47 has its own centrifugal force. The output torque of the crankshaft 13 is transmitted to the drive shaft 50 by being pressed against the inner peripheral wall of the clutch drum 48 by force. The cooling fan 43 has a larger diameter than the centrifugal clutch 49 .
[0017]
An engine cover 51 that covers the engine main body 1 and attached devices other than the fuel tank 5 is fixed to an appropriate position of the engine main body 1, and a cooling air intake 19 is provided between the engine cover 51 and the fuel tank 5. Therefore, the outside air is taken in from the cooling air intake 19 by the rotation of the cooling fan 43 and is used for cooling each part of the engine E.
[0018]
The engine cover 51 is secured frustoconical bearing holder 45 arranged in the crank shaft 13 coaxially, the bearing holder 45 supports the drive shaft 50 for rotationally driving the cutter C via a bearing 59.
[0019]
Thus, with the engine body 1 in between, the oil tank 40 and the starter 42 are arranged on one side, and the cooling fan 43 and the centrifugal clutch 49 are arranged on the other side, so that the right and left weight balance of the engine E is good. , The center of gravity of the engine E can be brought close to the center of the engine body 1, and the handling performance of the engine E is improved.
[0020]
Further, since the cooling fan 43 having a larger diameter than the centrifugal shoe 47 is fixed to the crankshaft 13 between the engine body 1 and the centrifugal shoe 47, it is possible to avoid the engine E from being enlarged by the cooling fan 43 as much as possible.
[0021]
Next, the structure of the engine body 1 and the oil tank 40 will be described with reference to FIGS. 2 to 5, 6, 10, and 11.
[0022]
In Figures 2-5, the engine body 1, intake, exhaust ports 9 and 10 which open into the cylinder block 7, and a combustion chamber 8a and the indoor 8 a having a crankcase 6, a cylinder bore 7a having a crank chamber 6a A plurality of cooling fins 38 are formed on the outer periphery of the cylinder block 7 and the cylinder head 8.
[0023]
The crankshaft 13 accommodated in the crank chamber 6a is rotatably supported on the left and right side walls of the crankcase 6 via ball bearings 14 and 14 '. At this time, the left ball bearing 14 is provided with a seal, and an oil seal 17 is provided adjacent to the outside of the right ball bearing 14 '. A piston 15 fitted to the cylinder bore 7a is connected to the crankshaft 13 via a connecting rod 16 as usual.
[0024]
An oil tank 40 adjacent to the outside is integrally connected to the left side wall of the crankcase 6, and the oil tank 40 is disposed so that the end of the crankshaft 13 on the side of the ball bearing with seal 14 passes therethrough. . An oil seal 39 is attached to the outer wall of the oil tank 40 that passes through the crankshaft 13.
[0025]
A timing belt guide tube 86 having a flat cross section that extends vertically and penetrates the ceiling wall of the oil tank 40 and that opens at both ends is integrally provided. The lower end of the belt guide tube 86 extends to the vicinity of the crankshaft 13 in the oil tank 40, and the upper end portion is integrally connected to the cylinder head 8 so as to share the cylinder head 8 and the partition wall 85. . A series of annular seal beads 87 are formed at the upper peripheral edges of the cylinder head 8 and the belt guide tube 86, and the partition wall 85 projects upward from the seal beads 87.
[0026]
On the other hand, as shown in FIGS. 6, 10, and 11, an annular seal groove 88 a corresponding to the seal bead 87 is formed on the lower end surface of the head cover 36, and an annular seal groove 88 a is formed on the inner surface of the cover 36. A linear seal groove 88b communicating between both sides is formed, an annular seal 89a is mounted on the annular seal groove 88a, and a linear seal 89b integrally formed with the annular seal 89a is installed in the linear seal groove 88b. Installed. The head cover 36 is coupled to the cylinder head 8 by bolts 37 so that the seal beads 87 are pressed against the annular packing 89a and the partition walls 85 are pressed against the linear packing 89b.
[0027]
Thus, the first valve chamber 21a is defined by the timing belt guide tube 86 and one half of the head cover 36, and the second valve chamber 21b is defined by the cylinder head 8 and the other half of the head cover 36. The two valve chambers 21 a and 21 b are partitioned by the partition wall 85.
[0028]
2 to 5 again, the engine main body 1 and the oil tank 40 are divided into two, an upper block Ba and a lower block Bb, on a plane passing through the axis of the crankshaft 13 and orthogonal to the axis of the cylinder bore 7a. That is, the upper block Ba is formed by integrally connecting the upper half of the crankcase 6, the cylinder block 7, the cylinder head 8, the upper half of the oil tank 40, and the belt guide tube 86, and the lower block Bb 6 and the lower half of the oil tank 40 are integrally connected. The upper and lower blocks Ba and Bb are individually casted and processed into a plurality of bolts. 12 (see FIG. 4).
[0029]
The cylinder head 8 is provided with an intake valve 18i and an exhaust valve 18e that open and close the intake port 9 and the exhaust port 10, respectively, in parallel with the axis of the cylinder bore 7a, and an ignition plug 20 is connected to the center of the combustion chamber 8a. It is screwed in close proximity to.
[0030]
Next, the valve mechanism 22 for opening and closing the intake valve 18i and the exhaust valve 18e will be described with reference to FIGS.
[0031]
The valve mechanism 22 includes a timing transmission device 22a disposed from the oil tank 40 to the first valve chamber 21a, and a cam disposed from the first valve chamber 21a to the second valve chamber 21b. It is comprised with the apparatus 22b.
[0032]
The timing transmission device 22a includes a drive pulley 23 fixed to the crankshaft 13 in the oil tank 40, a driven pulley 24 rotatably supported on an upper portion of the timing belt guide tube 86, and the drive and driven pulley 23. , 24, and a cam 26 forming a part of the cam device 22b is integrally coupled to the end face of the driven pulley 24 on the partition wall 85 side. In this way, the cam 26 is disposed with the driven pulley 24 on one side of the cylinder head 8. The driving and driven pulleys 23 and 24 are toothed, and the driving pulley 23 drives the driven pulley 24 through the belt 25 with a reduction ratio of 1/2.
[0033]
A support wall 27 is integrally formed on the outer wall of the belt guide tube 86 so as to stand up inside the annular seal bead 87 and come into contact with or close to the inner surface of the head cover 36. Both ends of the support shaft 29 are rotatably supported by the hole 28a and the bottomed hole 28b provided in the partition wall 85, and the driven pulley 24 and the cam 26 are rotatably supported by the intermediate portion of the support shaft 29. The support shaft 29 is inserted into the shaft hole 35 and the bottomed hole 28b of the driven pulley 24 and the cam 26 from the through hole 28a before the head cover 36 is attached. After the insertion, the head cover 36 is inserted into the cylinder head 8. When the head cover 36 is joined to the belt guide tube 86, the inner surface of the head cover 36 faces the outer end of the support shaft 29 to prevent it from coming off.
[0034]
The partition wall 85 is integrally formed with a pair of bearing bosses 30i and 30e protruding in parallel with the support shaft 29 on the second valve chamber 21b side. The cam device 22b includes the cam 26 and the bearing boss 30i. , 30e are rotatably supported by an intake rocker shaft 31i and an exhaust rocker shaft 31e, respectively, and fixed to one end of these rocker shafts 31i, 31e in the first valve operating chamber 21a, and the tip is slidably contacted with the lower surface of the cam 26. The intake cam follower 32i and the exhaust cam follower 32e to be driven, and the second valve chamber 21b are fixed to the other ends of the intake and exhaust rocker shafts 31i and 31e, respectively, and the intake is brought into contact with the upper ends of the intake valve 18i and the exhaust valve 18e. An intake valve mounted on the rocker arm 33i and the exhaust rocker arm 33e, and the intake valve 18i and the exhaust valve 18e, respectively, and biases them in the valve closing direction. 34i and is made from an exhaust spring 34e.
[0035]
In the above, the support shaft 29 and the intake and exhaust rocker shafts 31i, 31e are disposed above the upper end of the annular seal bead 87 of the cylinder head 8 and the belt guide tube 86.
[0036]
And Thus, during rotation of the crankshaft 13, the drive pulley 23 which rotates therewith Ru rotates the driven pulley 24 and the cam 26 through the belt 25, the cam 26 the intake and exhaust cam followers 32i, 32e timely rocking is dynamic, they swing, each corresponding rocker shafts 31i, intake and exhaust through 31e rocker arms 33i, is transmitted to 33e, so cause them to swing the intake and exhaust springs 34i, 34e Collaboration with Thus, the intake and exhaust valves 18i and 18e can be opened and closed in a timely manner.
[0037]
In the timing transmission device 22a, the driven pulley 24 and the cam 26 are rotatably supported on a support shaft 29, and the support shaft 29 is also rotatably supported on both side walls of the first valve chamber 21a. during rotation of 24 and the cam 26, is dragged by the friction support shaft 29 becomes to rotate, reduced rotation speed difference between the driven pulley 24 and the cam 26 and the support shaft 29, the rotating and sliding portion of the wear This can be reduced and can contribute to the improvement of durability.
[0038]
By the way, the relatively large-diameter cam 26 is disposed on one side of the cylinder head 8 together with the driven pulley 24. The intake and exhaust rocker arms 33i and 33e and the relatively small-diameter intake and exhaust rocker shaft 31i are directly above the cylinder head 8. , 31e is not disposed, the valve operating mechanism 22 is not greatly bulky above the cylinder head 8, and the overall height of the engine E can be reduced, and thus the engine E can be made compact.
[0039]
The support shaft 29 and the intake and exhaust rocker shafts 31i, 31e are disposed above the series of annular seal beads 87 at the upper end of the cylinder head 8 and the belt guide tube 86, thus, in a state of detaching the head cover 36 What like without being obstructed by the above-mentioned sealing bead 87, the support shaft 29 and the intake and exhaust rocker shafts 31i at its upper, 31e are possible for assembling and disassembling, assembling property and maintainability is very good.
[0040]
Next, the lubrication system of the engine E will be described with reference to FIGS.
[0041]
4 and 5, the oil tank 40 stores a predetermined amount of lubricating oil O injected from the oil supply port 40a. In the oil tank 40, a pair of oil slinger 56a, 56b arranged in the axial direction with the drive pulley 23 interposed therebetween is fixed to the crankshaft 13 by press fitting or the like. These oil slinger 56a, 56b are directed to opposite radial directions and bent so that their tips are separated from each other in the axial direction. When the oil slinger 56a, 56b is driven to rotate by the crankshaft 13, At least one of the both oil slinger 56a and 56b stirs and scatters the stored oil O in the oil tank 40 to generate oil mist. At this time, the generated oil splashes are sprinkled on the part of the timing transmission device 22a exposed in the oil tank 40 from the first valve operating chamber 21a or enter the first valve operating chamber 21a to adjust the oil. The hour transmission device 22a is directly lubricated, and this is one lubrication system.
[0042]
As shown in FIGS. 3 to 5 and FIG. 12, the other lubrication system includes a through hole 55 provided in the crankshaft 13 to communicate between the inside of the oil tank 40 and the crank chamber 6a, and a crank chamber. An oil feed conduit 60 disposed outside the engine body 1 to connect the lower part of 6a to the lower part of the second valve chamber 21b, and a cylinder head 8 for sucking up the liquefied and accumulated oil in the second valve chamber 21b. An oil suction chamber 74 provided in the cylinder, an oil return passage 78 formed between the cylinder head 8 and the oil tank 40 to communicate the oil suction chamber 74 with the oil tank 40 through the first valve chamber 21a, a crank And a one-way valve 61 that is installed in the lower portion of the chamber 6a and allows oil mist to flow from the crank chamber 6a to the oil feed conduit 60 in only one direction.
[0043]
The open end 55a into the oil tank 40 of the hole 55 is in any posture of the engine E, always, as exposed above the liquid surface of the oil O within the oil tank 40, in the tank 40 Arranged at or near the center. A drive pulley 23 which is fixed to the crankshaft 13 and one of the oil slingers 56a are not to block the opening end 55a, is spaced between the open end 55a.
[0044]
The one-way valve 61 (see FIG. 3) is constituted by a reed valve in the illustrated example, and closes when the crank chamber 6a becomes negative pressure due to the reciprocating motion of the piston 15, and opens when positive pressure is reached. It is supposed to be.
[0045]
The lower end of the oil feed conduit 60 is a lower connecting pipe 62a (see FIG. 3) protruding from the outer surface of the crankcase 6, and the upper end is an upper connecting pipe protruding from the outer surface of the cylinder head 8. 62b (see FIGS. 4 and 8) are fitted and connected to each other. The inside of the upper connection pipe 62b communicates with the lower part of the second valve chamber 21b through a communication path 63 (see FIGS. 8 and 9) formed on the cylinder head 8 and having a large passage area. The oil return passage 78 communicates with the orifice-shaped bypass 64 (see FIG. 8).
[0046]
As shown in FIGS . 5, 6, 10, and 11, a partition plate 65 defining a breather chamber 69 is provided on the ceiling wall of the head cover 36 so as to project from the ceiling wall. The breather chamber 69 is attached with a plurality of struts 66 and a clip 67 locked thereto, and the breather chamber 69, on the other hand, has a channel area projecting toward the second valve chamber 21b formed integrally with the partition plate 65. It communicates with the second valve chamber 21b through a large communication pipe 68 and a gap g between the inner surface of the head cover 36 of the partition plate 65, and communicates with the air cleaner 4 through the breather pipe 70 (see FIG. 3). Is done. The breather chamber 69 performs gas-liquid separation of mixed oil and blow-by gas, and a maze wall 72 for promoting the gas-liquid separation projects from the inner surface of the ceiling wall of the head cover 36.
[0047]
A T-shaped box 79 is welded to the partition plate 65 between the upper surface of the partition plate 65 and the oil suction chamber 74 in a plan view, so that the oil suction chamber 74 is also T-shaped.
[0048]
The partition plate 65 is integrally provided with two suction pipes 75 communicating respectively with two locations corresponding to both ends of the T-shaped horizontal bar of the oil suction chamber 74. These suction pipes 75 have their respective distal ends extending to the vicinity of the bottom surface of the second valve operating chamber 21b, and the respective distal end openings serve as orifices 75a.
[0049]
Further, on the upper wall of the box 79, three sucking pipes 76 that respectively communicate with three positions corresponding to the tip portions of the T-shaped horizontal bar and vertical bar of the oil sucking chamber 74 are integrally projected. These suction pipes 76 have their respective distal ends extending to the vicinity of the ceiling surface of the breather chamber 69, and their distal end openings serve as orifices 76a.
[0050]
More upper wall of the box body 79, an orifice 80 which communicates the recess portion 79a of the upper surface in wicking chamber 74 is bored.
[0051]
The partition plate 65 is integrally provided with a single conduit 81 communicating with the portion of the oil suction chamber 74 that contacts the tip of the T-shaped vertical bar. The tip of the conduit 81 is connected to the second valve chamber. A grommet 82 is fitted into an inlet 78a of the oil return passage 78 opened at the bottom surface of 21b. Thus, the suction chamber 74 is connected to the oil return passage 78. The conduit 81 is disposed in the vicinity of one inner side surface of the second valve operating chamber 21b, and an oil suction orifice that communicates the second valve operating chamber 21b in the conduit 81 with a portion close to the inner side surface. 81a is drilled.
[0052]
Thus, since the breather chamber 69 communicates with the air cleaner 4 via the breather pipe 70, the pressure of the breather chamber 69 is maintained at substantially atmospheric pressure even when the engine E is in operation, and flows into the breather chamber 69. The second valve operating chamber 21 b communicating with the communication pipe 68 having a small path resistance has substantially the same pressure as the breather chamber 69.
[0053]
Since the crank chamber 6a discharges only the positive pressure component of the pressure pulsation generated by the raising and lowering of the piston 15 during the operation of the engine E from the one-way valve 61 to the oil feed conduit 60, the crank chamber 6a is in an average negative pressure state. Thus, the second valve operating chamber 21b receiving the positive pressure communicates with the breather chamber 69 through the communication pipe 68 having a small flow path resistance, and therefore has substantially the same pressure as the breather chamber 69. The negative pressure in the crank chamber 6a is transmitted to the oil tank 40 through the through hole 55 of the crankshaft 13, and further transmitted to the suction chamber 74 through the oil return passage 78. Therefore, the suction chamber 74 is connected to the second valve chamber. The oil tank 40 and the first valve operating chamber 21a have a lower pressure than the suction chamber 74.
[0054]
Therefore, as shown in FIG. 12, the pressure of the crank chamber 6a is Pc, the pressure of the oil tank 40 is Po, the pressure of the first valve chamber 21a is Pva, the pressure of the second valve chamber 21b is Pvb, and the suction chamber 74 , Ps, and Pb of the breather chamber 69, the magnitude relationship can be expressed by the following equation.
[0055]
Pvb = Pb>Ps> Po = Pva> Pc
As a result, the pressure in the second valve chamber 21b and the breather chamber 69 moves to the suction chamber 74 through the suction pipes 75 and 76 and the orifice 80, further to the oil tank 40 through the oil return passage 78, and to the crank chamber 6a.
[0056]
During operation of the engine E, oil mist is generated in the oil tank 40 by the oil slinger 56a, 56b rotated by the crankshaft 13 stirring and scattering the lubricating oil O. The splash of oil generated at that time is sprinkled on a part of the timing transmission device 22a exposed from the belt guide tube 86 into the oil tank 40, that is, a part of the drive pulley 23 and the timing belt 25, or the first valve valve. As described above, the timing transmission device 22a is directly lubricated by entering the chamber 21a.
[0057]
The oil mist generated in the oil tank 40 is sucked into the crank chamber 6a through the through hole 55 of the crankshaft 13 according to the pressure flow described above, and lubricates the piston 15 around the crankshaft 13. Next, when the crank chamber 6a reaches a positive pressure due to the lowering of the piston 15, the one-way valve 61 opens, and the oil mist rises along with the blow-by gas generated in the crank chamber 6a along the oil feed conduit 60 and the communication passage 63 to the second motion. It is supplied to the valve chamber 21b and lubricates each part of the cam device 22b in the chamber 21b, that is, the intake and exhaust rocker arms 33i and 33e.
[0058]
In this case, a part of the oil mist passing through the communication path 63 is short-circuited from the orifice-shaped bypass 64 to the oil return path 78. Therefore, the amount of oil mist supplied to the second valve chamber 21b can be adjusted by appropriately setting the flow path resistance of the bypass 64.
[0059]
The oil mist and blow-by gas in the second valve chamber 21 b move to the breather chamber 69 through the gap g around the communication pipe 68 and the partition plate 65 . When, is gas-liquid separated by the collision interaction between expansion agent and labyrinth walls 72 when the blow-by gas during the intake stroke of the engine E, is drawn into the engine E via the breather pipe 70 and the air cleaner 4 sequentially .
[0060]
In the erecting state of the engine E, the oil liquefied in the breather chamber 69 accumulates in the recess 79a on the top surface of the box 79 or flows down through the communication pipe 68 and the gap g and accumulates on the bottom surface of the second valve chamber 21b. The suction chamber 74 is sucked up to the suction chamber 74 by the orifice 80 or the suction pipe 75 standing by at those locations. In the inverted state of the engine E, the liquefied oil accumulates on the ceiling surface of the head cover 36 and is sucked up to the sucking chamber 74 by the sucking pipe 76 waiting at the place.
[0061]
The oil sucked into the suction chamber 74 in this way returns to the oil tank 40 from the conduit 81 through the oil return passage 78. In this case, as shown in the example, when the oil return passage 78 is communicated with the oil tank 40 via the first valve chamber 21a , the oil that has exited the oil return passage 78 is sprinkled on the timing transmission device 22a. It will contribute to lubrication and is convenient.
[0062]
On the other hand, in the oil tank 40, when the engine E is turned upside down as shown in FIG. 13, the stored oil O moves to the ceiling side of the tank 40, that is, to the first valve operating chamber 21a side. The opening end of the valve operating chamber 21a into the oil tank 40 is set by the belt guide cylinder 86 so as to occupy a position higher than the liquid level of the stored oil O. Therefore, the storage end in the first valve operating chamber 21a is set. Inflow of oil O is not allowed, excessive oiling of the timing transmission 22a can be prevented, a predetermined amount of oil is secured in the oil tank 40, and oil mist is continuously generated by the oil slinger 56a, 56b. Is possible.
[0063]
As shown in FIG. 14, when the engine E is placed on its side, the stored oil O moves to the side surface of the tank 40. However, the open end of the first valve chamber 21a into the oil tank 40 Is set to occupy a position higher than the liquid level of the stored oil O by the belt guide cylinder 86. Therefore, in this case as well, the stored oil O is not allowed to flow into the first valve operating chamber 21a, and the timing is adjusted. Excess oiling of the transmission 22a can be prevented, and a predetermined amount of oil can be secured in the oil tank 40, and oil mist can be continuously generated by the oil slinger 56a, 56b.
[0064]
Thus, the lubrication system of the valve mechanism 22 includes a system that lubricates part of the oil tank 40 and the timing transmission device 22a and the cam device 22b in the first valve chamber 21a with the scattered oil in the oil tank 40, and the first system. Since the oil mist transferred to the second valve chamber 21b is divided into two systems, the system that lubricates the remaining portion of the cam device 22b in the second valve chamber 21b, the burden on each lubrication system is reduced. Thus, the entire valve mechanism 22 can be lubricated uniformly. In addition, the use of oil splashes and oil mist can reliably lubricate each part of the engine in any operating position of the engine.
[0065]
Also, since the oil mist in the oil tank 40 is circulated using the pressure pulsation of the crank chamber 6a and the one-way transfer function of the one-way valve 61, the oil mist is circulated. An oil pump is unnecessary, and the structure can be simplified.
[0066]
In addition to the oil tank 40, the oil feed conduit 60 that connects the crank chamber 6a and the second valve chamber 21b is disposed outside the engine main body 1. Therefore, the engine main body 1 is prevented from being thinned and made compact. Therefore, it can greatly contribute to the weight reduction of the engine E. In particular, the externally arranged oil feed conduit 60 is not easily affected by heat from the engine body 1 and easily dissipates heat, so that cooling of the oil mist passing therethrough can be promoted.
[0067]
Further, since the oil tank 40 is disposed on the outer side of the engine body 1, the overall height of the engine E can be greatly reduced, and a part of the timing transmission device 22a is housed in the oil tank 40, so that the engine The increase in the width of E can be suppressed as much as possible, and the size can be reduced.
[0068]
The present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the scope of the gist thereof. For example, instead of the one-way valve 61, it is possible to provide a rotary valve that operates in conjunction with the crankshaft 13 so that the oil feed conduit 60 is turned on when the piston 15 is lowered and shut off when the piston 15 is raised. Further, the number and installation locations of the oil suction pipes 75 and 76 and the suction orifices 80 and 81a can be freely selected.
[0069]
【The invention's effect】
According to the onset light as described above, accommodating the engine body comprising a cylinder head having a cylinder block and an intake port and an exhaust port, and the crank chamber is supported on a crankcase having a crankcase, a cylinder bore having a crank chamber A crankshaft, an intake valve and an exhaust valve attached to a cylinder head for opening and closing an intake port and an exhaust port, and a valve operating mechanism for opening and closing the intake valve and the exhaust valve in conjunction with rotation of the crankshaft In a four-cycle engine, a valve gearing mechanism is arranged on the outer side of the engine body and connected to one end of the crankshaft, and the rotational force on the driven side of the gearing transmission is used as an opening / closing force. And a cam device that transmits to the intake and exhaust valves, and the first valve chamber that houses the timing transmission device is provided on the same side as the timing transmission device. Engine and continuously provided integrally with the oil tank disposed on one outer side of the body, the lower end of the timing belt guide tube forming part of the first valve-operating chamber to extend to the crankshaft near the oil tank On the other hand, a second valve operating chamber for accommodating at least a part of the cam device is formed in the cylinder head, and the stored oil in the oil tank is agitated to generate oil mist to be supplied to the second valve operating chamber and the crank chamber. A pair of oil slinger to be scattered is fixed to the crankshaft with the timing gearing in between, and a through hole is provided in the crankshaft for supplying oil mist generated in the oil tank to the crank chamber. because disposed between the open end of the timing transmission device and the oil slinger, and the arrangement of the oil tank to the first outer engine body, the overall height of the engine can be drastically reduced , A part of the timing transmission device by being housed in the oil tank, it is possible to reduce the size of the engine. The valve system lubrication system includes a system that lubricates the timing transmission device in the first valve chamber with the scattered oil in the oil tank, and a cam device in the second valve chamber by the oil mist generated in the oil tank. Therefore, the load on each lubrication system is reduced, and the entire valve mechanism can be lubricated uniformly. In addition, a pair of oil slinger fixed to the crankshaft is provided across the timing transmission device, so that the stored oil in the oil tank can be agitated in any operating position of the engine without being disturbed by the timing transmission device. The oil mist can be generated effectively by scattering.
[0070]
In addition , the lower end of the timing belt guide cylinder extends to the vicinity of the crankshaft in the oil tank, and a through hole for supplying oil mist generated in the oil tank to the crank chamber is provided in the crankshaft. Having placed the open end of the tank between the timing transmission device and the oil slinger, the open end of the oil tank through hole of the crankshaft, without being obstructed by the timing transmission device and the oil slinger, oil and can be placed in the center or near the tank, in any operating position of the engine, it is possible to prevent direct flow of the hole of the stored oil in the oil tank, further, the timing belt guide tube the generated oil mist and Ru can be smoothly guided to the through hole of the crankshaft.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of use of a four-cycle engine of the present invention.
FIG. 2 is a longitudinal side view of the four-cycle engine.
3 is a cross-sectional view taken along line 3-3 in FIG.
4 is a cross-sectional view taken along line 4-4 of FIG.
5 is an enlarged cross-sectional view of the main part of FIG. 2. FIG. 6 is an exploded view of the main part of FIG.
7 is a cross-sectional view taken along line 7-7 in FIG.
8 is a cross-sectional view taken along line 8-8 in FIG.
9 is a cross-sectional view taken along line 9-9 in FIG.
10 is a view taken along arrow 10-10 in FIG. 5 (a bottom view of the head cover).
11 is a sectional view taken along line 11-11 in FIG.
FIG. 12 is a lubrication route diagram of the engine.
FIG. 13 is a view corresponding to FIG. 4, showing the engine in an inverted state.
14 is a view corresponding to FIG. 4, showing the engine on its side.
[Explanation of symbols]
E ··· Four cycle engine O ··· Oil 1 ··· Engine body 6 ··· Crankcase 6a · · · Crank chamber 7 ··· · Cylinder block 7a · · · cylinder bore 8 · · · cylinder head 9 · · · intake port 10 · · · exhaust port 13 · · · crankshaft 18i · · · intake Valve 18e ... Exhaust valve 21a ... First valve chamber 21b ... Second valve chamber 22 ... Valve mechanism 22a ... Timing transmission device 22b ... · Cam mechanism 40 ··· Oil tank 55 ··· through hole 55a ··· Open ends 56a and 56b to the oil tank of the through hole · Oil slinger
86 ... Timing belt guide tube

Claims (1)

Engine body (1) comprising a crankcase (6) having a crank chamber (6a), a cylinder block (7) having a cylinder bore (7a), and a cylinder head (8) having an intake port (9) and an exhaust port (10) ), A crankshaft (13) supported by the crankcase (6) and housed in the crank chamber (6a), and attached to the cylinder head (8) to open and close the intake port (9) and the exhaust port (10) An intake valve (18i) and an exhaust valve (18e), and a valve mechanism (22) for driving the intake valve (18i) and the exhaust valve (18e) to open and close in conjunction with the rotation of the crankshaft (13). In a four-cycle engine,
The valve mechanism (22), and is disposed on one outer side of the engine body (1) with a crankshaft (13) timing transmitting device which is connected to one end of the (22a), the timing transmission device (22a) And a cam device (22b) for transmitting the rotational force of the driven side to the intake and exhaust valves (18i, 18e) as an opening / closing force, and a first valve chamber (21a) for accommodating the timing transmission device (22a). ) Is integrally connected to an oil tank (40) disposed on the outer side of the engine body (1) on the same side as the timing transmission device (22a), and the first valve chamber (21a) A second valve that accommodates at least a part of the cam device (22b) while the lower end of a part of the timing belt guide tube (86) extends to the vicinity of the crankshaft (13) in the oil tank (40). The chamber (21b) is formed in the cylinder head (8). A pair of oil slinger (56a, 56b) that stirs and scatters the stored oil (O) in the oil tank (40) to generate oil mist to be supplied to the two-valve chamber (21b) and the crank chamber (6a), A through hole (55) that is fixed to the crankshaft (13) across the timing transmission (22a) and supplies oil mist generated in the oil tank (40) to the crank chamber (6a) is provided in the crankshaft (13). The opening end (55a) of the through hole (55) to the oil tank (40) is disposed between the timing transmission device (22a) and the oil slinger (56a). Cycle engine.

Images