JPH04116209A - Valve system four-cycle - Google Patents

Abstract

PURPOSE:To limit the overall height of an engine and improve cooling property by making an intake side two-stage laminated structure and an exhaust side bucket structure, and setting the distance between the exhaust side camshaft and the spring seat to be smaller than that for the intake side. CONSTITUTION:The outer diameter of an intake side energizing spring 22 is made approximately same as that of an intake lifter 18. The upper end of the intake side energizing spring 22 is located to the lower end of the intake lifter 18. The outer diameter of an exhaust side energizing spring 23 is made slightly smaller than the inner diameter of an exhaust lifter 17, and the upper part of the exhaust side energizing spring 23 is inserted into the exhaust lifter 17. A two-stage laminated structure is employed for the intake side, and a bucket structure is employed for the exhaust side. The distance L2' between the exhaust port and the spring seat can be increased since the distance L2 between the exhaust side camshaft and the spring seat is set to be smaller than the distance L1 between the exhaust port and the spring seat. The cooling efficiency can thus be improved by securing an exhaust side jacket 31b sufficiently while limiting the overall height of the engine.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a valve train structure for a four-stroke engine, and in particular, when each cylinder is provided with three intake valves and two exhaust valves, the overall height of the engine can be suppressed. The present invention also relates to improvements in the arrangement structure of valve biasing springs and lifters that can increase the size of the cooling jacket on the exhaust side or increase the amount of valve lift.

[Conventional technology]

Three intake valves to improve engine filling efficiency.
A five-valve engine with two exhaust valves has been proposed. In this type of engine valve mechanism, a lifter is mounted so as to come into contact with the upper end surface of the valve, and a biasing spring is interposed between the retainer fixed to the top of the valve and the valve seat. The lid is configured to be pressed by a camshaft.

[Problem to be solved by the invention]

Incidentally, in the above-mentioned five-valve engine, since the number of exhaust valves is small, the exhaust valves have a larger diameter than the intake valves, and therefore are often relatively heavy, and the valve lift amount is also set to be large. Therefore, the biasing spring for the exhaust valve needs to have a large diameter with a large spring constant so that it can reliably bias the relatively heavy exhaust valve, and a spring with a long length to increase the amount of lift. On the other hand, if you try to reduce the overall height of the engine, you will have to position the spring seat lower, which will make the cooling jacket on the exhaust side smaller and reduce the cooling performance. There is a concern that sufficient valve lift cannot be secured.

Furthermore, since there are a large number of intake valves (three), the intervals between the intake valves become narrow, making it difficult to secure a space for arranging the one-stroke lifter.

The present invention has been made in view of the above-mentioned conventional circumstances, and it is possible to improve cooling performance by reducing the overall height of the engine, arranging the intake lifter without difficulty, and enlarging the cooling jacket on the exhaust side.
Another object of the present invention is to provide a valve operating system for a four-stroke engine that can ensure a sufficient amount of valve lift.

[Means to solve the problem]

The invention of claim fl) is provided with three intake valves and two exhaust valves having a larger diameter than the intake valves per cylinder, and the upper ends of each intake valve and exhaust valve are formed on the cylinder head. An intake/exhaust biasing spring for biasing the answering valve in the closing direction is disposed between the intake/exhaust spring seats, and an intake/exhaust lifter is attached so as to come into contact with the upper end surface of the answering valve. In a valve operating system for a four-cycle engine in which the intake valve and the exhaust valve are driven to open and close by an intake camshaft and an exhaust camshaft, respectively, via each lifter, the outer diameter of the intake bias spring and the outer diameter of the intake lifter are provided. are set to be substantially the same, and the upper end of the intake biasing spring is located near the lower end of the lifter, and the outer diameter of the exhaust biasing spring is set to be smaller than the inner diameter of the exhaust lifter, so that the exhaust biasing spring is located near the lower end of the lifter. The upper part of the exhaust camshaft is inserted into the exhaust lifter, and the invention of claim (2) is characterized in that the dimension from the axis of the exhaust camshaft to the spring seat is the dimension from the axis of the intake camshaft to the spring seat. It is characterized by being set smaller. Further, the invention according to claim (3) is characterized in that the dimension from the axis of the exhaust camshaft to the spring seat is set to be the same as the dimension from the axis of the intake camshaft to the spring seat.

Here, setting the outer diameter of the intake biasing spring and the outer diameter of the intake lifter to be approximately the same means that they are set to such a size that they interfere with each other, and when the biasing spring can be inserted into the intake lifter. This includes both cases where the size is set so that there is not enough clearance for relative movement between the two.

[Effect]

According to the valve train according to the invention of claim 1, the intake valve side has a so-called two-stage structure in which the upper end of the biasing spring is located near the lower end of the lifter, and the exhaust valve side has an attached structure. Since it has a so-called packet structure in which the upper part of the spring is inserted into the lifter, the overall height of the engine can be suppressed and three intake lifters can be arranged without difficulty.

Further, according to the invention of claim (2), the camshaft of the exhaust valve example ~
Since the spring seat dimension is set smaller than that on the intake valve side, the spring seat on the exhaust valve side can be raised to increase the dimension between the exhaust opening and the spring seat.The cooling jacket on the exhaust valve side can be enlarged while keeping the overall height of the engine down. Cooling performance can be improved accordingly.

Further, according to the invention of claim (3), the two-stage structure and the packet structure are adopted, and the dimension between the camshaft and the spring seat on the exhaust valve side is set to be the same as that on the intake valve side, so that the exhaust bias is Since the spring can be made relatively long, the lift amount can be increased while suppressing the overall height of the engine, and the exhaust efficiency can be improved despite the small number of exhaust valves.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 3 are diagrams for explaining a valve train for a four-stroke engine according to an embodiment of the invention of claims (1) and (2), and FIG. FIG. 2 is a plan view of the upper head, and FIG. 3 is a front view of the engine of this embodiment.

In the figure, 1 is a water-cooled 4-cycle ■ type engine in which the device of this embodiment is adopted, and this is a cylinder block 2.
The crankcase 3 is mounted on the lower surface of the , and a pair of left and right cylinder heads 4 are mounted on the upper surface. It has a structure in which head force bars 5 are stacked and fastened together. A plurality of cylinders (cylinder bores) 6 are formed in the cylinder block 2 so as to form a 7-shape when viewed in the direction of the crankshaft, and a piston 7 inserted into each cylinder 6 has a convex loft 8 and a crankshaft 9. is connected to.

The cylinder head 4 has a lower head 10 and an upper head 1.
), and a combustion recess 12 is formed in the lower surface of the lower head 10 and forms a combustion chamber with the upper surface of the piston 7. This combustion recess 12
There are three intake openings 12a to 12C and two exhaust openings 12d.

128 is formed along the periphery of the combustion recess 12, and a spark plug insertion hole 12i is formed in the center.

The exhaust openings 12d and 12e are exhaust passages 13d and 13g.
is led out to the V-bank outer wall 10b of the cylinder hood 4. Further, the intake openings 122 to 12C are led out to the V-bank inner wall 10a of the cylinder head 4 by the intake passages 13a to 13c, and are merged at an extension portion 1)c extending upward to the upper portion of the cylinder head 1). Part 13f
is formed into a horizontally long ellipse in the direction of the crankshaft. Mounting hole lid formed in the center intake passage 13b part
A fuel injection valve 30 is attached to the extension portion lie, and a slide valve 39 for opening and closing the merging portion 13f is provided on the extension portion lie, and an air horn 40 is further connected to the extension portion lie. Note that 41 is a cover that prevents dirt and the like from entering the air horn 41.

Further, a water cooling jacket is formed in the lower head 1O so as to cover the upper part of the combustion recess 12. This water cooling jacket includes an intake side jacket 31a located from the intake passages 13a to 13c to the inner wall 10a side of the lower head 10, and the exhaust passages 13d and 1.
It consists of an exhaust side jacket 31b located from the portion 3e to the outer wall 10b side, and a central jacket 31c located between the intake passage and the exhaust passage. Further, at a position connecting the upper ends of the center jacket 31c and the intake side jacket 31a, the left and right intake passages 13a,
A communicating hole 31e is formed by drilling at the position sandwiching the hole 13e.
is formed. The cooling water is supplied from the water cooling jacket (not shown) of the cylinder block 2 to the exhaust side pipe.
-31b, passes through the central jacket 31C, the intake side jacket 31g, and flows out to the drain port 31d. Moreover, when the supply of cooling water is started, the air in the central jacket 31C is transferred to the intake side jacket 3Ia through the communication hole 31e.
Exhaust to the side.

The intake openings 12a to 12c, the exhaust opening 12d,
12e has an intake valve 14. Valve plate portion 14a, 1 of exhaust valve 15
5a are arranged respectively.

The upper ends of the valve stems 14b, 15b of the counter valves 14, 15 are formed in the guide holes 1)a, llb formed in the upper head 1).
Located within. These guide holes 1) a and llb are
Three pieces each and two pieces each are formed so as to be continuous in the radial direction, that is, to a size that eliminates the boundary wall,
Reinforcing intake and exhaust inserts 16, 17 are cast into each guide hole IIa, Ilb. And the above intake.

A bottomed cylindrical intake/exhaust lifter 18.19 is slidably inserted into the sliding hole formed in the exhaust insert 16.17, and the above-mentioned valve is installed inside the bottom surface of the intake/exhaust lifter 18.19. The upper end surfaces of the rods 14b and 15b are in contact with each other via pads. Further, a retainer 2°21 is attached near the upper end of the valve stems 14b and 15b, and the retainer 20
．． 21, a spring seat 12g formed on the lower head,
A double-structured air/exhaust biasing spring 22 and 23 is interposed between the air pump 12h and the air pump 12h. As a result, the above intake and exhaust valves 1
4.15 is biased in the direction of closing the intake opening and the exhaust opening. Further, an intake camshaft 24 and an exhaust camshaft 25 are arranged so as to be in rolling contact with the intake lifter 18 and the exhaust lifter 19. Each of the camshafts 24.25 is pivotally supported by a bearing portion formed in the upper head 1) and a cam cap 32 fixed by a port 32a, and the cam ridges of each camshaft 24.25 Intake valve 14. by depressing each intake and exhaust lifter 18.19. The exhaust valve 15 is lowered.

Here, the outer diameter of the intake biasing spring 22 is approximately the same diameter as the intake lifter 18, and the retainer 20. and the height position of the spring seat 12g.

As a result, the intake camshaft side portion has a structure in which the intake lifter 18 and the intake bias spring 22 are stacked in two stages.

Further, the outer diameter of the exhaust biasing spring 23 is slightly smaller than the inner diameter of the exhaust lifter 17, and the exhaust retainer 21. and the height position of the spring seat 12h. As a result, the exhaust camshaft side portion has a so-called packet structure in which the upper part of the exhaust biasing spring 23 is covered with the exhaust lifter 19.

In addition, the dimension L2 from the axis of the exhaust camshaft 25 to the exhaust spring seat 12h is from the axis of the intake camshaft 24 to the intake spring seat 12h.
As a result, the dimension L2' of the central bracket 7) from the exhaust port 12e to the exhaust spring seat 12h is set smaller than the dimension L1 from the intake opening 12C to the intake spring seat 1.
It is larger than the central jacket dimension Ll' up to 2g. Note that the dimensions from the axis of the camshaft to the opening are approximately the same on both the intake and exhaust sides.

Next, the effects of this embodiment will be explained.

In the engine of this embodiment, the number of exhaust valves 15 is two compared to three intake valves, so a larger diameter than the intake valve 14 is used to increase the exhaust opening area per exhaust valve. The valve lift amount is set to a large value. Therefore, the exhaust biasing spring 23 has a large spring constant, a large diameter, and a long spring length. There is a concern that the position of the exhaust spring seat may become higher and the overall height of the engine becomes higher, or conversely, the position of the exhaust spring seat may become lower and that sufficient exhaust side jacket (31b) may not be secured. By adopting a bucket structure on the exhaust side, the camshaft to spring seat dimension L2 on the exhaust side is set lower than the camshaft to spring seat dimension Ll on the intake side, so the exhaust opening on the exhaust side
The spring seat space dimension L2' can be increased, and the exhaust side jacket 31b can be secured sufficiently to improve cooling efficiency while suppressing the overall height of the engine.

Furthermore, in this case, on the intake side, a structure in which the intake lifter I8 and the intake biasing spring 22 are stacked in two stages is adopted, meaning that there is no need to insert the biasing spring into the lifter. It only requires a relatively small diameter, so 3
Two intake lifters 18 can be arranged without difficulty.

In the above embodiment, the exhaust side camshaft to spring seat dimension L2 is set smaller than the intake side camshaft to spring seat dimension L1, but the exhaust side dimension L2 can also be set to be the same as the intake side dimension L1. , Since it is set in this way, the claim of the present application (
This is the invention of 3).

In this way, when the exhaust side camshaft-spring seat dimension L2 is set to be the same as the intake side dimension L1, the exhaust biasing spring 23
As a result, a spring with an even longer length can be used. Therefore, the amount of valve lift can be further increased while suppressing the overall height of the engine, and as a result, sufficient exhaust efficiency can be ensured while the number of exhaust valves is smaller than that of intake valves.

〔Effect of the invention〕

As described above, according to the valve train for a four-stroke engine according to the invention of claim fil of the present application, the intake side has a two-stage stacked structure and the exhaust side has a packet structure, so that the intake lifter cannot be easily installed while suppressing the overall height of the engine. claim +2)
According to the invention, since the dimension between the camshaft and the spring seat on the exhaust side is set smaller than the dimension on the intake side, the dimension between the exhaust opening and the spring seat on the exhaust side becomes correspondingly larger. According to the invention of claim (3), since the dimension between the camshaft and the spring seat on the exhaust side is set to be the same as that on the intake side, the spring of the exhaust biasing spring This has the effect of increasing the valve lift amount and improving exhaust efficiency while suppressing the overall engine height.

[Brief explanation of drawings]

Figures 1 to 3 are claims +1). (This is a diagram for explaining a valve train for a four-stroke engine according to an embodiment of the invention in No. 21, in which FIG. 1 is a cross-sectional front view of the norinda head portion thereof, FIG. 2 is a plan view of the upper head, and FIG. Figure 3 is a front view of a four-stroke engine in which the device of this embodiment is adopted.In the figure, 1 is a 4-stroke engine, 4 is a cylinder head, 6 is a cylinder, 12g and 12h are spring seats, 14 is an intake valve, 15 is an exhaust valve, 18.19 is an intake and exhaust lifter, 2
2.23 is the intake and exhaust biasing springs, 24.25 is the intake and exhaust camshafts, Ll is the dimension from the axis of the intake camshaft to the spring seat, and L2 is the dimension from the axis of the exhaust camshaft to the spring seat. It is. Patent Applicant Yamaha Motor Co., Ltd. Agent Patent Attorney Tsutomu Shimofu Figure 1

Claims (3)

[Claims] (1) Three intake valves and two exhaust valves with a larger diameter than the intake valves are provided per cylinder, and intake and exhaust spring seats are formed at the upper end of each intake and exhaust valve and the cylinder head. An intake/exhaust biasing spring for biasing each valve in the closing direction is disposed between the valves, and an intake/exhaust lifter is attached so as to come into contact with the upper end surface of each of the valves. In the valve operating system for a four-cycle engine in which the intake valve and the exhaust valve are driven to open and close by an intake camshaft and an exhaust camshaft, respectively, the outer diameter of the intake bias spring and the outer diameter of the intake lifter are approximately the same. The upper end of the intake biasing spring is located near the lower end of the lifter, and the outer diameter of the exhaust biasing spring is set to be smaller than the inner diameter of the exhaust lifter, so that the upper end of the exhaust biasing spring is positioned near the lower end of the lifter. A valve train for a four-stroke engine, characterized in that the valve is inserted into the engine. (2) Claim (1) is characterized in that the dimension from the axis of the exhaust camshaft to the exhaust spring seat is set smaller than the dimension from the axis of the intake camshaft to the intake spring seat.
Valve gear for cycle engines. (3) The four-cycle cycle according to claim (1), characterized in that the dimension from the axis of the exhaust camshaft to the exhaust spring seat is set to be the same as the dimension from the axis of the intake camshaft to the intake spring seat. Engine valve gear.