JPH08232623A - Valve system for internal combustion engine - Google Patents

Abstract

PURPOSE: To embody a compact cylinder head as well as to increase the degree of freedom in the design of the cylinder head upper part by arranging a lost motion mechanism for elastically energizing a free locker arm to a cam shaft side above the free locker arm, and on an engine main body. CONSTITUTION: A driving locker arm interlocked with and connected to intake valves V11 , V12 , and a free locker arm 26 to be free in relation to the intake valves V11 , V12 are interposed between the intake valves V11 , V12 and a cam shaft 16, and a connection switching mechanism 50 is provided on respective locker arms 25, 26. A supporting plate 37 is fixed on both sides of respective cylinders 3 so as to link a holder 19 erected on a cylinder head 2, and a lost motion mechanism 38 for elastically energizing the free locker arm 26 toward a high-speed cam 21 is provided on this supporting plate 37. This lost motion mechanism 38 is slidably fitted to a guide member 39 and provided with a piston 40 provided with a tapered contact part 40a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive rocker arm which is interlocked with and connected to an intake valve between at least an intake valve and a camshaft of an intake valve and an exhaust valve which are spring-biased in a valve closing direction. , A free rocker arm that can be free with respect to the intake valve is provided, and each rocker arm has
The present invention relates to a valve operating system for an internal combustion engine, which is provided with a connection switching mechanism capable of switching between connection and disconnection thereof, and which is provided with a lost motion mechanism for elastically urging the free rocker arm toward the camshaft on the engine body.

[0002]

2. Description of the Related Art Conventionally, such a valve gear is known, for example, from Japanese Patent Laid-Open No. 63-57806.

[0003]

By the way, in the above-mentioned conventional apparatus, the cylinder head is provided with the lost motion mechanism in order to elastically urge the free rocker arm from below. However, in such a valve operating device, an intake / exhaust port, a guide cylinder for guiding the engine valve, a valve spring for urging the engine valve in the valve closing direction, etc. are arranged at the upper part of the cylinder head. In order to secure a space for disposing the lost motion mechanism, the degree of freedom in designing the shape of the port, the spring load of the valve spring (outer diameter of the valve spring), etc. is narrowed, and the cylinder head is compact. It will also be difficult to convert.

The present invention has been made in view of the above circumstances, and provides a valve operating device for an internal combustion engine, which increases the degree of freedom in designing the upper portion of the cylinder head and enables the cylinder head to be made compact. With the goal.

[0005]

In order to achieve the above object, according to the present invention, the lost motion mechanism is disposed in the engine body above the free rocker arm.

[0006]

[Operation] According to the above configuration, it is sufficient to dispose the intake and exhaust ports, the guide cylinder for guiding the engine valve, the valve spring for urging the engine valve in the closing direction, and the like. It is possible to secure a space below each rocker arm.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below based on an embodiment of the present invention illustrated in the accompanying drawings.

1 is a plan view of an essential part of an upper portion of an engine body, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG.
3 is a sectional view taken along line 3-3 of FIG.

First, in FIGS. 1 and 2, a main part of an engine body E in a SOHC type multi-cylinder internal combustion engine is composed of a cylinder block 1 and a cylinder head 2 connected to the upper surface of the cylinder block 1, and a crank (not shown) is provided. Cylinder block 1 with a gap in the axial direction of the shaft
Pistons 4 each having a recess 4a in the upper surface are slidably fitted in the plurality of cylinders 3 provided in the cylinder 3, and combustion chambers 5 are formed between the upper surface of each piston 4 and the cylinder head 2.

Cylinder head 2 corresponding to each cylinder 3.
Includes a pair of intake valve openings 6 that open to the ceiling surface of the combustion chamber 5.
And a pair of exhaust valve ports 7 are provided, and both intake valve ports 6
Is a single intake port that opens on one side of the cylinder head 2.
8 and the two exhaust valve ports 7 are on the other side of the cylinder head 2.
It is connected to a single exhaust port 9 that opens to the surface. Both intake valve openings
A pair of intake valves V that can open and close 6 individually_I1, V_I2Is Siri
Each of the pair of guide cylinders 10 arranged on the rear head 2
It is slidably fitted and protrudes from each guide tube 10.
Each intake valve V_I1, V_I2Fixed to the upper end of
Between the retainers 11, 11 and the cylinder head 2, each suction
Ki valve V_I1, V_I2Coiled valve springs 12, 12 surrounding the
And the valve springs 12 and 12 are provided for each intake valve.
V_I1, V _I2Is urged upward, that is, in the valve closing direction. Also
A pair of exhaust valves V that can open and close both exhaust valve openings 7 individually_E1, V
_E2Is a pair of guide cylinders 1 arranged on the cylinder head 2.
3 are slidably fitted in the respective guide cylinders 1.
Exhaust valves V protruding from 3 _E1, V_E2On the upper end of
Of the fixed retainers 14, 14 and the cylinder head 2
Each exhaust valve V in between_E1, V_E2Coiled valve spring surrounding
15 and 15 are interposed, and by the valve springs 15 and 15,
Exhaust valve V_E1, V_E2Is biased upward, that is, in the valve closing direction
Be done.

A rotary motion of the cam shaft 16 is provided between the intake valves V _I1 and V _I2 and a single cam shaft 16 which is interlocked and connected to a crank shaft (not shown) at a reduction ratio of 1/2. A first drive rocker arm 24, a second drive rocker arm 25, and a free rocker arm 26 are provided to convert the opening and closing motions of the intake valves V _I1 and V _I2.
A pair of exhaust side rocker arms 29, 30 is provided between _E1 and V _E2 and the cam shaft 16 to convert the rotational movement of the cam shaft 16 into the opening / closing movement of the exhaust valves V _E1 and V _E2 .

Referring also to FIG.
Is a cylinder head 2 and holders 19 and 19 respectively coupled to the cylinder head 2 on both sides of each cylinder 3 along the axis of the crankshaft.
It is rotatably supported while having a horizontal axis perpendicular to the axis of the. The camshaft 16 has a high-speed cam 21
And a low speed cam 22 adjacent to one side of the high speed cam 21.
And a raised portion 20 adjacent to the high speed cam 21 on the opposite side of the low speed cam 22 are integrally provided, and the exhaust valve cams 23, 23 are provided on both sides of the low speed cam 22 and the raised portion 20.
23 is integrally provided. The high-speed cam 21 has a shape for opening and closing both intake valves V _I1 and V _I2 in the high-speed operation range of the engine, and includes a base circular portion 21a and a radial direction outward from the base circular portion 21a. Higher part 21b overhanging
Have and. The low speed cam 22 has a shape for opening and closing the intake valve V _I1 in the low speed operation range of the engine, and the base circular portion 22a and the amount of extension of the cam shaft 16 outward in the radial direction are high speed. The cam 21 has a high portion 22b which is smaller than the high portion 21b and extends over the base circular portion 22a over a central angle range narrower than the high portion 21b. The raised portion 20 is basically formed to have a circular outer surface centered on the axis of the camshaft 16 so that the intake valve V _I2 is substantially at rest in the low speed operation region of the engine. However, the high-speed cam 21 and the low-speed cam 22 are provided with slightly protruding projections at positions corresponding to the high-order portions 21b and 22b. Moreover, the width of the raised portion 20 in the direction along the axis of the camshaft 16 is set to be relatively narrow. Further, the exhaust valve cam 23,
_{Reference numeral} 23 denotes both exhaust valves V _E1 and V _E2 regardless of the operating state of the engine.
It has a shape for opening and closing.

[0013] On one of the intake valves V _I1 interlocking the first driving rocker arm 24, is connected, the other intake valve V _I2 interlocking second driving rocker arm 25, is connected, the intake valves V _I1,
The free rocker arm 26 allows the first and second drive rocker arms 24, 25 to be free with V _I2.
Located adjacent to each other. Thus, each rocker arm 24, 2
The intermediate portions of the holders 5 and 26 have an axis parallel to the cam shaft 16 at a position above the cam shaft 16 and the holder 1
A rocker arm shaft 27 on the intake side fixedly supported by 9, 19, ... Is swingably supported. The pair of exhaust side rocker arms 29 and 30 are individually interlocked and connected to the exhaust valves V _E1 and V _E2 , respectively, and are arranged above the cam shaft 16 in parallel with the intake side rocker arm shaft 27 so that the holders 19 and 19 are disposed. Both exhaust side rocker arms 29 and 30 are fixed to the exhaust side rocker arm shaft 28 fixedly supported by.
The middle part of the is swingably supported.

At one end of the first drive rocker arm 24, a roller 31 which is in sliding contact with the low speed cam 22 provided at the cam shaft 16 is pivotally supported, and at one end of the second drive rocker arm 25, the cam shaft 16 is provided. A slipper 32 slidably contacting the raised portion 20 is provided with a narrow width corresponding to the raised portion 20, and a free rocker arm 26 is provided with a cam slipper 33 slidably contacting a high speed cam 21 provided on the camshaft 16. . In addition, both exhaust side rocker arms 2
Rollers 34, which are in sliding contact with the exhaust valve cams 23, 23 provided on the cam shaft 16, are pivotally supported at one ends of the shafts 9, 30, respectively.

First and second drive rocker arms 24, 2
At the other end of 5, the intake valves V_I1, V_I2Touch the upper edge of
The pet screws 35 are respectively screwed so that they can move back and forth.
Depending on the rocking operation of both intake side rocker arms 24, 25,
Intake valve V_I1, V_I2Will open and close. Also both
Each exhaust valve V is attached to the other end of the kicker arm 29, 30._E1, V _E2
The tappet screw 36 that touches the upper end of the
Is screwed to the rocker arms 29 and 30 on both exhaust sides.
Each exhaust valve V according to the swing operation_E1, V_E2Open and close
Becomes

A support plate 37 is fixed to the upper ends of holders 19, 19 ... Standing on the cylinder head 2 on both sides of each cylinder 3 so as to connect the holders 19, 19 ,. The support plate 37 is provided with a lost motion mechanism 38 that elastically urges the free rocker arm 26 from above toward the high speed cam 21.

The lost motion mechanism 38 includes a support plate 37.
A cylindrical guide member 39 with a bottom is fitted to the guide member 39, and an abutting portion 40a which is slidably fitted to the guide member 39 and abuts on the free rocker arm 26 at the end on the free rocker arm 26 side is tapered. A stopper 41 detachably fixed to the inner surface near the opening end of the guide member 39 so as to engage with the piston 40;
First and second springs 42 and 43 interposed between the piston 40 and the guide member 39 to resiliently urge the zero in the direction of contact with the free rocker arm 26.

On the support plate 37, each free rocker arm 26 is attached.
Bottomed cylindrical portion 37 opened downward at a position corresponding to
a is provided, and the guide member 39 is fitted into the bottomed cylindrical portion 37a with the open end of the guide member 39 positioned downward.
A spring chamber 44 is defined between the piston 40 and the guide member 39, and a retainer 45 housed in the spring chamber 44 is defined.
And a piston 40, a first spring 42 having a relatively small spring constant is contracted, and a second spring having a relatively large spring constant is provided between the retainer 45 and the closed end of the guide member 39.
The spring 43 is contracted.

A small-diameter hole 40b having a bottom is coaxially formed in the inner surface of the closed end of the piston 40, and the first spring 42 having a relatively small spring constant is accommodated in the small-diameter hole 40b, whereby the first spring is formed. The fall of 42 is prevented. Also piston 4
The air contact hole 40a, which is in contact with the zero contact portion 40a, has an air vent hole 46 for communicating the spring chamber 44 to the outside in order to prevent the spring chamber 44 from being pressurized and depressurized when the piston 40 slides. It is formed in a cross shape that opens to the outer surface of 40a.

Further, on the support plate 37, a bottomed cylindrical portion 37 is provided.
An oil groove 47 extending parallel to the camshaft 16 is provided adjacent to the base end of the cylinder a. The oil flowing through the oil groove 47 is supplied to the base end of the bottomed cylindrical portion 37a and the guide member 39 by a spring. An oil passage 48 leading into the chamber 44 is provided. By circulating the lubricating oil supplied from the lubricating oil supply pump 49 through the oil groove 47, the piston 40 and the guide member 39
It becomes possible to supply lubricating oil in the meantime.

The first drive rocker arm 24, the second drive rocker arm 25 and the free rocker arm 26 are provided with a connection switching mechanism 50 capable of switching connection and disconnection thereof.

The connection switching mechanism 50 includes a connection piston 51 for connecting the first drive rocker arm 24 and the free rocker arm 26, a connection pin 52 for connecting the free rocker arm 26 and the second drive rocker arm 25, and a connection piston 51, A regulation member 53 that regulates the movement of the coupling pin 52, and a return spring 54 that urges the coupling piston 51, the coupling pin 52, and the regulation member 53 toward the coupling release side are provided.

In the first drive rocker arm 24, a bottomed first guide hole 55 opened to the free rocker arm 26 side is bored in parallel with the intake side rocker arm shaft 27, and the connecting piston is connected to this first guide hole 55. 51 is slidably fitted, and a hydraulic chamber 56 is defined between one end of the connecting piston 51 and the closed end of the first guide hole 55. A communication passage 57 communicating with the hydraulic chamber 56 is formed in the first drive rocker arm 24, and a hydraulic pressure supply passage 58 communicating with a hydraulic pressure supply source (not shown) is provided in the intake side rocker arm shaft 27. Is the communication passage 57, that is, the hydraulic chamber 5 regardless of the swinging state of the drive rocker arm 24.
Always communicate with 6.

A guide hole 59 corresponding to the first guide hole 55 is formed in the free rocker arm 26 in parallel with the intake side rocker arm shaft 27 between both side surfaces, and one end is provided at the other end of the connecting piston 51. The abutting connecting pin 52 is slidably fitted in the guide hole 59.

In the second drive rocker arm 25, a second bottomed guide hole 60 corresponding to the guide hole 59 is opened to the free rocker arm 26 side and is bored in parallel with the intake side rocker arm shaft 27, and is connected. A bottomed cylindrical regulating member 53 that abuts the other end of the pin 52 is slidably fitted in the second guide hole 60. The regulating member 53 is arranged with its open end facing the closed end side of the second guide hole 60, and the flange portion 53a protruding outward in the radial direction at the open end has the second guide hole 60. Slide on the inner surface of. The return spring 54 includes the closed end of the second guide hole 60 and the restriction member 53.
The connecting piston 51, the connecting pin 52, and the restricting member 53, which are contracted between the closed ends and abut against each other by the spring force of the return spring 54, are urged toward the hydraulic chamber 56. Moreover, a communication hole 61 for removing air and oil is formed at the closed end of the second guide hole 60.

Referring again to FIGS. 1 and 2, a spark plug 64 is disposed in the central portion of the ceiling surface of the combustion chamber 5, and a plug pipe 6 for inserting the spark plug 64 is inserted.
5 is arranged in the cylinder head 2. Thus, the pair of exhaust valve-side rocker arms 29 and 30 includes the first drive rocker arm 24 and the free rocker arm 26 which are arranged adjacent to each other.
Further, it is arranged on both sides of the second drive rocker arm 25 so as to be in sliding contact with the exhaust valve cams 23 of the cam shaft 16. As a result, both exhaust side rocker arms 29, 3
A relatively wide space can be secured between the two exhaust valves, and the exhaust valves V _E1 and V _E2 can also be arranged with a relatively wide interval therebetween. Therefore, the plug pipe 65 is arranged in the cylinder head 2 so as to be located between the exhaust valves V _E1 and V _{E2 and} between the exhaust valve side rocker arms 29 and 30, and is inserted into the plug pipe 65. The spark plug 64 is screwed to the cylinder head 2 so as to face the central portion of the ceiling surface of the combustion chamber 5.

To explain the operation of this embodiment, the hydraulic pressure of the hydraulic chamber 56 in the connection switching mechanism 50 is released during low speed operation of the engine, and the spring force of the return spring 54 causes the connection piston 51 and the connection pin 52. Has a contact surface corresponding to the first drive rocker arm 24 and the free rocker arm 26, and a contact surface of the connecting pin 52 and the restricting member 53 corresponds to the position between the free rocker arm 26 and the second drive rocker arm 25. . Therefore, the rocker arms 24, 25, and 26 are in a state capable of relative angular displacement with respect to each other.

In the uncoupled state, the first drive rocker arm 24 swings in response to the sliding contact with the low speed cam 22 due to the rotational operation of the cam shaft 16, and one intake valve V _I1 has the low speed cam. The opening / closing operation is performed at a timing and a lift amount according to the shape of 22. In addition, the second drive rocker arm 25 that is in sliding contact with the raised portion 20 is substantially in a resting state, and the other intake valve V _I2 can be substantially resting. Moreover, the intake valve V _I2 does not completely rest, but slightly operates in the opening direction when one intake valve V _I1 opens, so the intake valve V I generated when the valve is completely closed.
It is possible to prevent the _{I2 from} sticking to the valve seat. Further, the free rocker arm 26 swings in response to the sliding contact with the high speed cam 21, but the swinging motion does not have any influence on the first and second drive rocker arms 24 and 25. Further, the exhaust valves V _E1 and V _E2 are opened / closed at timings and lift amounts according to the shapes of the exhaust valve cams 23.

By the way, the first drive rocker arm 24, which is in an operating state in a low speed region in which the ratio of the friction loss of the valve train to the friction loss of the entire engine is large, is brought into sliding contact with the low speed cam 22 via the roller 31. Therefore, it is possible to contribute to the reduction of the valve system friction loss in the low speed range, that is, the reduction of the friction loss of the entire engine. Moreover, both exhaust side rocker arms 29,
30 also includes exhaust valve cams 23, 2 via rollers 34, 34
Since it is in sliding contact with No. 3, it is possible to further reduce friction loss in the low speed range.

High hydraulic pressure is supplied to the hydraulic chamber 56 during high speed operation of the engine. As a result, in the connection switching mechanism 50, the connection piston 51 tries to move in the direction of increasing the volume of the hydraulic chamber 56 against the spring force of the return spring 54 while pressing the connection piston 52, and the first guide hole 45, the guide hole 5
6 and the second guide hole 57 are aligned with each other, that is, when the rocker arms 24 to 26 enter the stationary state, the connecting piston 41 is fitted into the guide hole 56, and accordingly, the connecting pin 42 is moved to the second guide. By fitting the holes 57, the rocker arms 24 to 26 are connected.

When the rocker arms 24 to 26 are connected in this manner, the swinging amount of the free rocker arm 26 slidingly contacting the high speed cam 21 is the largest, so that the first and second rocker arms 26 to 26 are connected.
The drive rocker arms 24 and 25 swing together with the free rocker arm 26, and the intake valves V _I1 and V _I2 are opened and closed at the timing and lift amount according to the shape of the high speed cam 21. Further, both exhaust side rocker arms 29 and 30 open and close both exhaust valves V _E1 and V _E2 at the timing and lift amount according to the shape of the exhaust valve cams 23 and 23 as in the low speed operation.

In such a valve operating system, a free rocker
Lost mode that elastically urges the mum 26 toward the camshaft 16 side.
The connection mechanism 38 connects the upper ends of the holders 19, 19 ...
The free rocker arm 26 is mounted on the support plate 37.
The camshaft 16 side is elastically urged from above. did
Intake port 8, exhaust port 9, intake valve V_I1, V _I2
And exhaust valve V_E1, V_E2Guide cylinder 1 for guiding
0, 13 and intake valve V_I1, V_I2And exhaust valve
V_E1, V_E2Springs 1 and 2 for urging the valve in the valve closing direction
Each rocker arm 2 has enough space to accommodate 5 etc.
It can be secured on the cylinder head 2 below 4-26.
It becomes possible, the shape of each of the ports 8 and 9, the valve spring 12,
Increased the degree of freedom in designing the spring load of 15 (outer diameter of valve spring), etc.
The cylinder head 2 can be made compact.
It will be possible.

[0033]

As described above, according to the present invention, since the lost motion mechanism is disposed in the engine body above the free rocker arm, the guide cylinder for guiding the intake and exhaust ports and the engine valve. Also, a sufficient space for arranging a valve spring etc. for urging the engine valve in the valve closing direction is secured below each rocker arm, increasing the degree of freedom in design and making the upper part of the engine body compact. Becomes

[Brief description of drawings]

FIG. 1 is a plan view of a main part showing an upper portion of an engine body according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

3 is a sectional view taken along line 3-3 of FIG.

[Explanation of symbols]

3 ……………… Cylinder 16 ……………… Camshaft 19 ……………… Holder 24,25 …… Drive rocker arm 26 ……………… Free rocker arm 27 ……………… Intake side rocker arm shaft 28… ………… Exhaust side rocker arm shaft 29, 30 …… Exhaust side rocker arm 37 ……………… Support plate 38 ……………… Lost motion mechanism 50 ……………… Connection switching mechanism E ……………… Engine Main body V _I1 , V _I2 …… Intake valve V _E1 , V _E2 …… Exhaust valve

Claims (3)

[Claims] 1. At least an intake valve (V _I1 , V _I2 ) and a camshaft (16) of an intake valve (V _I1 , V _I2 ) and an exhaust valve (V _E1 , V _E2 ) which are spring-biased in a valve closing direction. ) Between the intake valves (V _I1 , V _I2 ) and the drive rocker arms (24, 25) connected to the intake valves (V _I1 ,
Free rocker arm (2) that can be free to V _I2 )
6) is provided, each rocker arm (24-26) is provided with a connection switching mechanism (50) capable of switching connection and disconnection thereof, and the engine body (E) is provided with the free rocker arm (24). In a valve operating system for an internal combustion engine, which is provided with a lost motion mechanism (38) for elastically urging 26) toward the camshaft (16), the lost motion mechanism (38) is located above the free rocker arm (26). A valve train for an internal combustion engine, which is arranged in a main body (E). 2. An intermediate portion of a plurality of drive rocker arms (24, 25), one end of which is individually interlocked with and connected to a plurality of intake valves (V _I1 , V _I2 ), and a single free rocker arm (26). The intermediate part and the middle part are adjacent to each other and are supported by the intake side rocker arm shaft (27), and the exhaust valves (V _E1 , V _E2 )
The exhaust-side rocker arm (29, 30) supported at an intermediate portion by the exhaust-side rocker arm shaft (28) is interposed between the camshaft (16) and the camshaft (16). Valve drive for internal combustion engine. 3. The engine body (E) is provided with holders (19) for supporting the rocker arm shafts (27, 28) on both sides of the cylinder (3) along the crank axis thereof, and these holders (19) are erected. The valve operating system for an internal combustion engine according to claim 2, wherein a lost motion mechanism (38) is arranged on a support plate (37) connecting the upper ends of (19).