JP3433089B2 - Overhead valve engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overhead valve engine. 2. Description of the Related Art As a prior art of an overhead valve engine, an intake port and an exhaust port are led out of an intake valve port and an exhaust valve port in mutually opposite directions, and a valve shaft of the intake valve is moved in a direction in which the intake port is drawn out. Some are tilted, and the valve shaft of the exhaust valve is tilted in the direction in which the exhaust port is led out. In this type of engine, a large intake / exhaust valve can be provided, and since the bending of the intake / exhaust port can be reduced, there is an advantage that the intake / exhaust efficiency can be improved. In the above prior art, since the intake and exhaust valves are arranged in a V-shape, a so-called overhead cam type valve operating mechanism is employed. In this valve operating mechanism, a wrapping transmission is provided in front of a cylinder block with the direction of the central axis of the crankshaft as the front-rear direction, and a valve operating camshaft and a tappet are provided in a cylinder head. [0004] The above prior art has the following problems. A wrapping transmission is provided in front of the cylinder block, and is composed of relatively large parts such as a drive wheel, a driven wheel, a wrapping transmission band, a tension, and a transmission cover that integrally covers these. I have. For this reason, the size of the engine in the front-rear direction becomes longer. [0005] Since the wrapping transmission is provided in front of the cylinder block, when performing a series of maintenance from the wrapping transmission to the intake and exhaust valves, a transmission cover in front of the cylinder block and a head cover of the cylinder head are provided. It is necessary to remove both, and to perform maintenance from two directions, the work becomes complicated. In addition, since the maintenance conditions are severe, the types of devices to be mounted are greatly restricted. Since the valve head camshaft and the tappet are provided on the cylinder head, the size of the engine in the direction of the cylinder center axis becomes longer. The main structure of the invention of claim 1 is as follows (see FIGS. 1 and 2). The intake port (1) and the exhaust port (2) are the intake valve port (3) and the exhaust valve port
The valve shaft of the intake valve (5) is tilted in the direction of the intake port (1), and the valve shaft of the exhaust valve (6) is oriented in the direction of the exhaust port (2). In the tilted overhead valve engine, when viewed in a direction parallel to the cylinder center axis (7), the direction of the crankshaft center axis (8) is the front-rear direction, and the direction orthogonal to the crankshaft center axis (8) is the left-right direction. , Valve cam shaft (9), valve shaft of each valve (5) (6) and each port (1) (2)
Are both long in the front-rear direction, and the valve cam shaft
(9) Tappet (10) (10) and push rod (11)
(11) are arranged on the left and right sides of the cylinder block (12), and the rocker arms (40) and (40) are connected to the cylinder head (1).
4), rocker arm pivots (13), (13) oriented long in the left-right direction are arranged side by side in front and back, and each rocker arm output (15), (15) is connected to each rocker arm pivot (1).
3) From one end of (13), rocker arm pivot (13) (1)
3) The rocker arm input portions (16) and (16) are led out in the opposite direction to that between the rocker arm pivot portions (13) and (13).
The rocker arm input portions (16) and (16) are led out from the other end of the rocker arm pivot portions (13) and (13) , and are arranged side by side between the rocker arm pivot portions (13) and (13).
When viewed in a direction parallel to the mandrel axis (7), each cam of the valve cam shaft (9)
Between the rocker arm pivots (13) and (13).
Arranged front and back with the center part in between, with rocker arm
The force parts (16) and (16) are aligned with the central axis (9b) of the valve cam shaft (9).
It is arranged on the left and right, sandwiched between, and one combustion chamber (17)
And only one intake valve (5) and one exhaust valve (6) are provided,
Each valve (5) viewed in a direction parallel to the cylinder center axis (7)
The valve shaft of (6) is pushed lower than the crankshaft center axis line (8).
(11), (11) side, and a rocker
Arm output parts (15) and (15) are brought into contact with the head cover (2).
0) A spark plug (21) is inserted into the outer spark plug insertion hole (22).
Is inserted, a combustion chamber (17) is a pentroof type, Siri
Each port (1) viewed in a direction parallel to the
(2) is the direction opposite to the inter-portion portion (18) from each valve port (3) (4)
And viewed in a direction parallel to the crankshaft center axis (8).
The cylinder (19) is inclined and the cylinder block (1
Of the left and right sides of 2), the valve cam shaft (9) and the tape
(10) (10) and push rods (11) (11)
An overhead valve engine characterized by being made. The following functions and effects are obtained (see FIGS. 1 and 2). Valve operating cam shaft (9) and tappet (10) (10)
And push rods (11) and (11) are cylinder blocks
(12) Since the valve mechanism disposed on one side of the left and right is used, the size of the engine in the front-rear direction is smaller than that of an overhead cam type valve mechanism that requires a wrapping transmission in front of the cylinder block. Can be shortened. In addition, since the valve train can be made more compact than the wrapping transmission, the size of the engine in the left-right direction does not become so large. When performing a series of maintenance from the push rod (11) to the valves (5) and (6), the head cover (20) of the cylinder head (14) may be removed and maintenance may be performed from one direction. , Its work is simplified. In addition, since the maintenance conditions are mild, there are few restrictions on the models to be mounted. A rocker arm is attached to the cylinder head (14).
(40) Although (40) is provided, the size of the engine in the direction of the cylinder center axis (7) can be shortened as compared with the overhead cam type in which the valve head camshaft or tappet is provided on the cylinder head. Since the rocker arm input portions (16) and (16) are arranged side by side between the rocker arm pivot portions (13) and (13), the respective rocker arm input portions (16) and (13) are compared with the case where they are provided in abutting manner. Since the length can be ensured by appropriately setting the portions (16) (16) and the respective rocker arm output portions (17) (17), the reliability of the operation of the valve train can be improved. Further, the following operation and effect can be obtained (FIG. 1A).
reference). When viewed in a direction parallel to the cylinder center axis (7), each cam (9a) (9a) of the valve operating cam shaft (9) sandwiches a central portion between the rocker arm pivots (13) (13). The rocker arm input sections (16) (16) are arranged in front and back, and the valve operating cam shaft (9)
Are arranged on the left and right with the center axis (9b) of
(11) By setting the inclination angle of (11) uniformly small, the reliability of the operation of the valve train can be improved. Further, the following operation and effect can be obtained (FIG. 1A).
reference). An intake valve (5) and an exhaust valve for one combustion chamber (17)
(6) are provided only one each , and the cylinder center axis (7)
When viewed in a direction parallel to, the valve shafts of the valves (5) and (6) are arranged closer to the push rods (11) and (11) than the crankshaft center axis (8), and the rocker arm output is provided at each valve shaft end. Department (15) (15)
, The rocker arm pivots (13) (1)
3) is formed short and its twist can be reduced, so that the accuracy of the valve timing is further improved. Further, the following operation and effect can be obtained (FIG. 1C).
reference). Since the combustion chamber (17) is of a pent roof type, the valves (5) and (6) can be arranged without difficulty and the combustion performance can be enhanced. Further, the following operation and effect can be obtained (FIG. 1A).
reference). Since the ports (1) and (2) are led out of the valve ports (3) and (4) in the direction opposite to the inter-portion portion (18), a cross-flow method can be adopted, and the combustion chamber (17) can be used. ) Can improve the scavenging efficiency. (Invention of claim 6) Further, the following operation and effect can be obtained (see FIG. 2). The cylinder (19) is inclined when viewed in a direction parallel to the crankshaft center axis (8), and the valve cam shaft (9) and the tappet (10) ( Since the push rods (11) and (11) are arranged, the height of the engine can be reduced. Embodiments of the present invention will be described with reference to the drawings. 1 and 2 are diagrams for explaining an embodiment of the present invention. In this embodiment, an air-cooled single-cylinder spark ignition tilt engine is used. The structure of this engine is as follows. As shown in FIG. 2, the crankcase
A cylinder block (12) is formed by the cylinder (19) and the cylinder head (19).
(14) is assembled to the cylinder head (14) and to the head cover (20). A crankshaft (2) is attached to the crankcase (42).
3) and the valve operating cam shaft (9) are installed in parallel. The piston (25) is fitted inside the cylinder (19), and the crankshaft (2)
3) and the piston (25) are connected by a connecting rod (24). The valve gear cam gear (26) meshes with the crank gear (34), and the valve gear cam shaft (9) is driven by the crank shaft (23). The idle gear (27) meshes with the crank gear (34), the governor gear (28) meshes with the idle gear (27), and the governor (32) is driven by the crank shaft (23). The construction of the cylinder head (14) and the valve train is as follows. As shown in FIG. 1 (C), the intake port
(1) and the exhaust port (2) are the intake valve port (3) and the exhaust valve port (4)
And the valve shaft of the intake valve (5) is tilted in the direction in which the intake port (1) is drawn out, and the valve shaft of the exhaust valve (6) is tilted in the direction in which the exhaust port (2) is drawn out. I have. As shown in FIG. 1A, when viewed in a direction parallel to the cylinder center axis (7), the direction of the crankshaft center axis (8) is the front-rear direction, and is orthogonal to the crankshaft center axis (8). The valve cam shaft (9), the valve shafts of the valves (5) and (6), and the ports (1) and (2) are all long in the front-rear direction, with the direction being the left-right direction. The valve cam shaft (9) is oriented parallel to the crankshaft center axis (8). Cylinder center axis
Looking at the direction parallel to (7), each valve (5) (6) and each port (1)
(2) is oriented along the crankshaft center axis (8). The valve cam shaft (9), tappets (10) (10) and push rods (11) (11) are connected to the cylinder block (1).
The rocker arm (40) (4)
0) is provided on the cylinder head (14), rocker arm pivots (13) (13) oriented long in the left-right direction are arranged in front and rear, and each rocker arm output (15) (15) is connected to each rocker arm pivot. Each rocker arm input portion (16) is led out from one end of the support portion (13) in a direction opposite to the direction between the rocker arm pivot portions (13) (13), and the rocker arm input portions (16) (16) are connected to the rocker arm pivot portions (13) (13). ) From the other end of the rocker arm pivot
(13) Derived between (13) and each rocker arm input section (1
6) and (16) are arranged side by side between the rocker arm pivots (13) and (13). When viewed in a direction parallel to the cylinder center axis line (7), each cam (9a) (9a) of the valve operating cam shaft (9) has a center portion between the rocker arm pivot shafts (13) (13). The rocker arm input sections (16) and (16) are arranged on the left and right with the center axis (9b) of the valve operating cam shaft (9) interposed therebetween. The rocker arm pivots (13) (13) have a rocker arm (40) on a pivot that is long in the left-right direction.
The boss portion of (40) is fitted externally. Each rocker arm input section (16) (16) is a push rod (11)
(11) is connected to the output end of each rocker arm output
(15) and (15) are in contact with the valve shaft ends of the valves (5) and (6). When viewed in a direction parallel to the cylinder center axis (7), the rocker arm pivot portion (13) is oriented along a direction orthogonal to the crankshaft center axis (8). Each of the valves (5) and (6) is biased toward the valve closing side by a valve spring (31) (31). As shown in FIG. 1C, one combustion chamber (1
7) the intake valve (5) and an exhaust valve (6) is provided <br/> each Ichiko only for, as shown in FIG. 1 (A), the cylinder center axis
When viewed in a direction parallel to (7), the valve shafts of the valves (5) and (6) are arranged closer to the push rods (11) and (11) than the crankshaft center axis line (8), and each valve shaft end Rocker arm output section (15)
(15) is contacted. The combustion chamber (17) is of a pent roof type. As shown in FIG. 1 (B), each valve port (3) (4) is provided on the piston facing surface (39) of the cylinder head (14).
And a spark plug insertion opening (22). head
Plug the spark plug into the ignition plug (22 ) outside the cover (20)
(21) is inserted, and its electrode part is arranged at the center of the combustion chamber (17). As shown in FIG. 1 (A), when viewed in a direction parallel to the cylinder center axis (7), each port (1) (2) is
From (3) and (4), they are led out in the direction opposite to the interportion (18). As shown in FIG. 2, the center axis of the crankshaft
When viewed in a direction parallel to (8), the cylinder (19) is inclined,
On the lower side of the left and right sides of the cylinder block (12), the valve operating camshaft (9), tappets (10) and (10) and the push rod
(11) and (11) are arranged. The valve operating cam shaft (9) is disposed on the lower side of the crankcase (42), and the governor (32)
Are located on the higher side of the crankcase (42). A fuel tank (29) is disposed above the crankcase (42), and an air cleaner is disposed above the cylinder head (14).
(30) and an exhaust muffler (not shown) are arranged. In this engine, the intake port (1) is led forward, and the exhaust port (2) is located rearward, with the cooling fan (not shown) facing forward, the valve camshaft (9) side facing left. The rocker arm (40) for the intake valve (5) is located at the front, the rocker arm (40) for the exhaust valve (6) is located at the rear, and the rocker arm input section (16) for the intake valve (5) is at the left. To
The rocker arm input sections (16) for the exhaust valve (6) are respectively located on the right.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view for explaining an engine according to an embodiment of the present invention. FIG. 1 (A) is a plan view of a cylinder head, and FIG. 1 (B).
FIG. 1 is a view of a piston facing surface of a cylinder head viewed from a piston side, and FIG. 1C is a longitudinal sectional side view of a main part of an engine in which a cylinder head and a cylinder block are vertically cut at different positions. FIG. 2 is a longitudinal rear view of the engine of FIG. 1; [Description of References] (1) ... intake port, (2) ... exhaust port, (3) ... intake valve port, (4) ... exhaust valve port, (5) ... intake valve, (6) ... exhaust valve,
(7)… Cylinder center axis, (8)… Crankshaft center axis,
(9) ... cam valve shaft, (9a) (9a) ... cam, (9b) ... center axis line, (10) ... tappet, (11) ... push rod,
(12) Cylinder block, (13) Rocker arm pivot, (14) Cylinder head, (15) Rocker arm output, (16) Rocker arm input, (17) Combustion chamber,
(18) ... between valve openings, (19) ... cylinder.

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Claims (1)

(57) Claims 1. An intake port (1) and an exhaust port (2) are led out of an intake valve port (3) and an exhaust valve port (4) in opposite directions, respectively, and an intake valve is provided. In an overhead valve engine in which the valve shaft of (5) is inclined in the direction in which the intake port (1) extends and the valve shaft of the exhaust valve (6) is inclined in the direction in which the exhaust port (2) extends, the cylinder center axis (7) ), The direction of the crankshaft center axis (8) is the front-rear direction, and the crankshaft center axis is
The valve operating camshaft (9), with the direction orthogonal to (8) as the left-right direction.
, The valve shafts of the valves (5) and (6) and the ports (1) and (2) are all long in the front-rear direction, and the valve cam shaft (9), tappets (10) and (10) and push Rods (11) and (11) are arranged on one side of the left and right sides of the cylinder block (12), and rocker arms (40) and (40) are provided on the cylinder head (14).
The rocker arm pivot (1
3) and (13) are arranged in front and back, and each rocker arm output section (1)
5) and (15) are led out from one end of each rocker arm pivot (13) (13) in a direction opposite to the direction between the rocker arm pivots (13) and (13), and each rocker arm input (16) (16) is The rocker arm pivots (13) are led out from the other end of the rocker arm pivots (13) and (13) to the rocker arm pivots (13) and (13).
3) are arranged side by side on the left and right, and viewed in a direction parallel to the cylinder center axis (7),
Each cam (9a) (9a) of (9) is a rocker arm pivot (13).
(13) Arranged in front and rear, with the central part between
The arm input sections (16) and (16) are the center axes of the valve operating cam shaft (9).
The intake valve (5) and the exhaust valve (6) are arranged on the left and right with the line (9b) interposed therebetween, and for one combustion chamber (17).
Only one is provided for each, and it is parallel to the cylinder center axis (7).
Looking in the direction, the valve axis of each valve (5) (6) is the center axis of the crankshaft.
It is arranged closer to the push rods (11) and (11) than (8),
The rocker arm output parts (15) and (15) contact the end of each valve shaft.
To ignite the spark plug insertion hole (22) outside the head cover (20).
The plug (21) is inserted, the combustion chamber (17) is of a pent roof type, and each port is viewed in a direction parallel to the cylinder center axis (7).
(1) and (2) are opposite to the inter-portion portion (18) from each valve port (3) (4)
In the direction parallel to the crankshaft center axis (8).
(19) is inclined, and the right and left sides of the cylinder block (12) are
Of which, on the lower side, the valve camshaft (9) and tappet (10) (10)
And the push rods (11) and (11) are arranged
Overhead valve engine.