JPH10317929A - Valve system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the freedom degree of the design of the upper portion of a cylinder head, reduce the size of the cylinder head and feed a sufficient quantity of lubricating oil to the sliding portions of a piston and a cylinder part in a lost-motion mechanism and the contact portions of the piston and the second valve drive member, in a valve system having that mechanism for elastically pressing the second valve drive member freely movable to an intake valve toward a camshaft. SOLUTION: A lost-motion mechanism 38 is arranged in a supporter 37 on an engine body E above a second valve drive member 26 such that the lower end 40a of its piston 40 is brought into contact with the drive member 26. The supporter 37 is formed with oil feed passages 47 and 48 for feeding lubricating oil to the sliding portions of the piston 40 and a cylinder part 39 both in the mechanism 38.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve gear for an internal combustion engine, and more particularly, to a camshaft which rotates in conjunction with a crankshaft and a camshaft which rotates in conjunction with a crankshaft. A first valve driving member connected thereto and a second valve driving member which can be free with respect to the intake valve are interposed, and these valve driving members can be switched between connection and disconnection thereof. The engine body includes a piston abutting on a second valve driving member, a cylinder portion for fitting and supporting the piston in a vertically slidable manner, and a second valve driving member. And a valve spring having a lost motion mechanism for urging the second valve driving member toward the camshaft side, the spring having a spring resilient in a contact direction with the valve driving device.

[0002]

2. Description of the Related Art Conventionally, a valve train having the above structure is known, for example, from Japanese Patent Application Laid-Open No. 63-57806.

[0003]

By the way, in the above-mentioned prior art, a lost motion mechanism is provided in the cylinder head in order to elastically urge the second valve driving member from below. However, in such a valve operating device, an intake / exhaust port, a guide cylinder for guiding an engine valve, a valve spring for biasing the engine valve in a valve closing direction, and the like are disposed above the cylinder head. In order to secure a space for disposing the lost motion mechanism, the degree of freedom in design such as the shape of the port and the spring load of the valve spring (valve spring outer diameter) is reduced, and the cylinder head is compact. It will also be difficult to convert.

Further, in the above-mentioned conventional apparatus, in order to lubricate a sliding portion between a piston and a cylinder portion of a lost motion mechanism, an oil supply passage for supplying lubricating oil to the sliding portion is provided in a cylinder head. However, even in such a case, the contact portion between the upper end of the piston and the second valve drive member is located at a higher position than the sliding portion, so that the lubricating oil supplied to the sliding portion is applied to the contact portion. There is a problem that the contact cannot be sufficiently supplied.

[0005] The present invention has been made in view of the above circumstances, has increased the degree of freedom in the design of the upper part of the cylinder head and made it possible to reduce the size of the cylinder head. It is an object of the present invention to provide a valve operating device for an internal combustion engine, which is capable of sufficiently supplying lubricating oil not only to a sliding portion with a portion, but also to a contact portion between a piston and a second valve driving member.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a method according to claim 1, wherein an intake valve spring-biased in a valve closing direction and a camshaft which rotates in conjunction with a crankshaft. A first valve drive member interlocked with and connected to the intake valve, and a second valve drive member that can be free with respect to the intake valve are interposed. A connection switching mechanism capable of switching between connection and disconnection is provided; a piston abutting on the second valve driving member; a cylinder portion slidably fittingly supporting the piston; And a spring resiliently resilient in the direction of contact with the second valve drive member, and a lost motion mechanism for biasing the second valve drive member toward the camshaft is provided. In the apparatus, the lost motion mechanism comprises: The piston is attached to a support provided on the engine body above the second valve drive member so that a lower end portion of the piston contacts the second valve drive member. An oil supply path for supplying lubricating oil to a sliding portion with the piston is provided. According to this configuration,
Since the lost motion mechanism is disposed above the second valve driving member, it is not necessary to secure a space for disposing the lost motion mechanism below the valve driving member.
It is necessary to ensure sufficient space below the valve driving member to dispose an exhaust port, a guide cylinder for guiding the engine valve, a valve spring for biasing the engine valve in the valve closing direction, and the like. It becomes possible. Moreover, the lubricating oil supplied from the oil supply passage of the support to the sliding portion between the piston and the cylinder portion of the lost motion mechanism lubricates and flows down the sliding portion, reaches the lower end of the piston, and contacts the lower end of the piston. The contact portion with the second valve drive member can be sufficiently lubricated.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the engine body is provided with a plurality of camshaft holding portions for rotatably supporting the camshaft. The support is constituted by a connecting wall that integrally connects the camshaft holding portions, and the oil supply path is provided on the connecting wall. According to such a configuration, the connecting walls of the plurality of camshaft holding portions can effectively improve the rigidity of each of the camshaft holding portions having a relatively large load load, thereby increasing the supporting rigidity of the camshaft. Also, the support rigidity of the lost motion mechanism is greatly improved. In addition, since the oil supply path to the lost motion mechanism can be formed without difficulty using the connection wall, lubricating oil can be sufficiently supplied to the lost motion mechanism without particularly complicating the structure of the oil supply path.

According to a third aspect of the present invention, in addition to the structure of the first or second aspect, the lost motion mechanism is assembled by integrally incorporating the piston and the spring into a cylinder constituting the cylinder portion. A three-dimensional structure is formed, and the cylindrical body is inserted into a mounting hole of the lower end opening formed in the support so as to be able to be pulled out from its open side, and the mounting hole engages with the cylindrical body and has an upper limit. A stopper portion for defining a position is provided, and a communication hole is formed in the cylinder so that an opening end of the oil supply path on the attachment hole side communicates with a sliding portion between the piston and the cylinder. According to such a configuration, the lost motion mechanism can be handled as a single unit housed in the cylinder, and the cylinder is inserted into the mounting hole of the support from the opening side thereof. By simply inserting the lost motion mechanism until it is engaged, it is possible to easily and accurately assemble the lost motion mechanism.

According to a fourth aspect of the present invention, in addition to the configuration of the third aspect, the oil supply path is formed along a common tangent to the plurality of mounting holes formed in the support. You. According to this configuration, it is possible to efficiently supply oil to a plurality of lost motion mechanisms without complicating the oil supply path.

Further, according to the invention of claim 5, claim 1,
In addition to the configuration of the invention of 2, 3 or 4, a contact portion between the camshaft and the second valve driving member is disposed immediately below the lost motion mechanism. According to this configuration, it is possible to sufficiently lubricate the contact portion between the camshaft and the second valve driving member.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below based on one embodiment of the present invention illustrated in the accompanying drawings.

In the accompanying drawings, FIG. 1 is a plan view of a main part of an upper part of an engine body, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG.
FIG. 3 is a sectional view taken along line 3-3 of FIG.

1 and 2, a main part of an engine body E of an SOHC type multi-cylinder internal combustion engine comprises a cylinder block 1 and a cylinder head 2 connected to an upper surface of the cylinder block 1. Cylinder block 1 spaced apart in the axial direction of the shaft
The pistons 4 having the depressions 4 a on the upper surface are slidably fitted to the plurality of cylinders 3 provided in the cylinders 3, respectively, and the combustion chambers 5 are formed between the upper surface of each piston 4 and the cylinder head 2.

A cylinder head 2 corresponding to each cylinder 3
Has a pair of intake valve ports 6 and 6 opening to the ceiling surface of the combustion chamber 5.
And a pair of exhaust valve ports 7 are provided.
Is a single intake port opening on one side of the cylinder head 2.
8 and both exhaust valve ports 7 are on the other side of the cylinder head 2.
It is connected to a single exhaust port 9 opening on the surface. Double intake valve port
6 can be opened and closed individually._I1, V_I2Is
To a pair of guide cylinders 10 disposed on the
And is slidably fitted and protrudes from each guide tube 10.
Each intake valve V_I1, V_I2Fixed to the upper end of the
Each suction space is provided between the retainers 11, 11 and the cylinder head 2.
Ki valve V_I1, V_I2Valve springs 12, 12 surrounding the
Are provided, and each intake valve is controlled by the valve springs 12 and 12.
V_I1, V _I2Are biased upward, that is, in the valve closing direction. Also
A pair of exhaust valves V that can open and close both exhaust valve ports 7 individually_E1, V
_E2Is a pair of guide cylinders 1 disposed on the cylinder head 2.
3 are slidably fitted to the respective guide cylinders 1
Each exhaust valve V protruding from 3 _E1, V_E2At the top of each
Between the fixed retainers 14 and 14 and the cylinder head 2
Between each exhaust valve V_E1, V_E2Coiled valve spring
15 and 15 are interposed, and the valve springs 15 and 15
Each exhaust valve V_E1, V_E2Is biased upward, that is, in the valve closing direction.
It is.

The rotational motion of the camshaft 16 is provided between the intake valves V _I1 and V _I2 and a single camshaft 16 which is interlocked and connected to a crankshaft (not shown) at a reduction ratio of 1/2. the first driving rocker arm 24 so as to convert the opening and closing motion of the intake valves V _I1, V _I2, the second driving rocker arm 25 and the free rocker arm 26 is interposed, said both exhaust valves V
Between the _E1, V _E2 and the cam shaft 16, a pair of exhaust-side rocker arms 29 and 30 so as to convert the rotational motion of the camshaft 16 to the opening and closing movement of the exhaust valves V _E1, V _E2 is interposed. Thus, the first and second rocker arms 24 and 25 constitute a first valve driving member, and the free rocker arm 26 constitutes a second valve driving member.

Referring also to FIG. 3, the camshaft 16
Is composed of a cylinder head 2 and holders 19, 19 respectively connected to the cylinder head 2 on both sides of the cylinder 3 along the axis of the crankshaft.
It is rotatably supported while having a horizontal axis perpendicular to the axis. The holders 19 constitute a plurality of camshaft holders provided on the engine body E to rotatably support the camshaft 16.

The camshaft 16 has a high-speed cam 2
1 and a low-speed cam 2 adjacent to one side of the high-speed cam 21.
2 and a ridge 20 adjacent to the high-speed cam 21 on the side opposite to the low-speed cam 22 are integrally provided, and the exhaust valve cams 2 are provided on both sides of the low-speed cam 22 and the ridge 20.
3, 23 are provided integrally. The high-speed cam 21 has a shape for opening and closing the two intake valves V _I1 and V _I2 in the high-speed operation range of the engine.
Higher part 2 projecting radially outward from base circle part 21a
1b. The low-speed cam 22 has a shape for opening and closing the intake valve _VI1 in a low-speed operation range of the engine. Higher part 21b of the cam 21
Higher portion 22 that is smaller than and extends from base circle portion 22a over a central angle range narrower than higher portion 21b.
b. The raised portion 20 is basically formed to have a circular outer surface centered on the axis of the camshaft 16 so as to make the intake valve V _I2 substantially at rest in the low-speed operation range of the engine. However, at positions corresponding to the high-order portions 21b and 22b of the high-speed cam 21 and the low-speed cam 22, a slightly protruding projection is provided. Moreover, the raised portion 20 in the direction along the axis of the cam shaft 16
Is set relatively narrow. Further, the exhaust valve cam 2
3, 23 are both exhaust valves V _E1 , regardless of the operating state of the engine.
It has a shape for allowing opening and closing the V _E2.

[0018] 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 is free from V _I2 while the first and second drive rocker arms 24, 25
It is adjacently arranged between them. Thus, each rocker arm 24, 2
The intermediate portion between the holders 5 and 26 has an axis parallel to the camshaft 16 at a position above the camshaft 16 while holding the holder 1.
The rocker shaft 27 is swingably supported by an intake-side rocker shaft 27 fixedly supported at 9, 19. Further, a pair of exhaust side rocker arms 29 and 30 are individually linked to the respective exhaust valves V _E1 and V _E2 ,
The holder 19 is connected to the intake side rocker shaft 27 at a position above the camshaft 16 so as to be in parallel with the intake side rocker shaft 27.
Exhaust side rocker shaft 28 fixedly supported at 19 ...
The intermediate portion between the two exhaust side rocker arms 29, 30 is swingably supported.

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

First and second drive rocker arms 24, 2
5, the other end of each intake valve V_I1, V_I2Touching the top of
The pet screws 35 are respectively screwed forward and backward freely,
Each rocker arm 24, 25 swings
Intake valve V_I1, V_I2Will be opened and closed. In addition,
The other ends of the cocker arms 29 and 30 have respective exhaust valves V_E1, V _E2
Tappet screws 36 that contact the upper end of
To both exhaust side rocker arms 29, 30.
Each exhaust valve V according to the swing operation_E1, V_E2Can be opened and closed
And

At the upper ends of the holders 19, 19,... Erected on the cylinder head 2 on both sides of each cylinder 3, a support 37 as a connecting wall for integrally connecting the holders 19, 19,. The support 37 is formed in a plate shape, and a lost motion mechanism 38 for resiliently urging the free rocker arm 26 toward the high-speed cam 21 from above is provided with the adjacent holder 19. , 1
9 respectively.

The lost motion mechanism 38 includes a support plate 37
A cylindrical guide member 39 having a bottom, a piston 40 fitted to the guide member 39 so as to be vertically slidable and having a tapered lower end 40a slidably in contact with the free rocker arm 26; A stopper 41 which is detachably fixed to the inner surface near the opening end of the guide member 39 so as to engage with the guide member 40, and between the piston 40 and the guide member 39 to resiliently urge the piston 40 in a direction in which the piston 40 contacts the free rocker arm 26. It has first and second springs 42 and 43 interposed therebetween and can be handled as one assembly.
Thus, the guide member 39 constitutes a cylinder portion and a cylindrical body which slidably fit and support the piston 40.
As is clear from FIG. 2, the contact portion between the free rocker arm 26 and the camshaft 16 (the high-speed cam 21) is disposed directly below the lost motion mechanism 38.

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

A small-diameter hole 40b having a bottom is formed coaxially on 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. 42 is prevented from falling down. Also piston 4
In the lower end portion 40a of the piston 40, an air vent hole 46 communicating the spring chamber 44 to the outside is provided at the lower end portion 40a in order to prevent the inside of the spring chamber 44 from being pressurized and depressurized when the piston 40 slides. It is pierced in the shape of a cross that opens on the outside surface of the horn.

The inner peripheral surface of the bottomed cylindrical portion 37a is
An attachment hole 37h for inserting a guide member 39 as a cylindrical body from below is formed, and an upper end wall 37s of the cylindrical portion 27a is engaged with the guide member 39 as a cylindrical body to define an upper limit position thereof. It constitutes a stopper part.

Further, on the support 37, a bottomed cylindrical portion 37
An oil groove 47 extending parallel to the camshaft 16 (according to the common tangent of the plurality of mounting holes 37h for the lost motion mechanism) is provided adjacent to the base end of the cylindrical portion 37a. An oil passage 48 for guiding the oil flowing through the oil groove 47 into the spring chamber 44 through the communication hole 39a formed in the peripheral wall of the guide member 39 is provided at the base end of the spring member 44. Thus, by allowing the lubricating oil supplied from the lubricating oil supply pump 49 to flow through the oil groove 47, lubricating oil can be supplied between the piston 40 and the guide member 39. The oil groove 47 and the oil passage 48 constitute an oil supply passage provided in the support body 37 as a connecting wall, and a mounting hole 37 of the oil supply passage is provided.
An opening end on the h side (an inner opening end of the oil passage 48) communicates with the communication hole 39a of the guide member 39 as a cylindrical body.

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 between connection and disconnection.

The connection switching mechanism 50 includes a connection piston 51 that can connect the first drive rocker arm 24 and the free rocker arm 26, a connection pin 52 that can connect the free rocker arm 26 and the second drive rocker arm 25, a connection piston 51, It has a regulating member 53 for regulating the movement of the connecting pin 52, and a return spring 54 for urging the connecting piston 51, the connecting pin 52 and the regulating member 53 to the uncoupling side.

The first drive rocker arm 24 has a bottomed first guide hole 55 opened toward the free rocker arm 26 in parallel with the intake side rocker shaft 27. 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 a hydraulic chamber 56 is formed in the first drive rocker arm 24, and a hydraulic supply path 58 communicating with a hydraulic supply source (not shown) is provided in the intake side rocker shaft 27. Is always in communication with the communication passage 57, that is, the hydraulic chamber 56, regardless of the swinging state of the drive rocker arm 24.

A guide hole 59 corresponding to the first guide hole 55 is formed in the free rocker arm 26.
A connecting pin 52, which is formed in parallel with both sides and extends between both side surfaces and whose one end is in contact with the other end of the connecting piston 51 slidably fits in the guide hole 59.

A second guide hole 60 having a bottom corresponding to the guide hole 59 is formed in the second drive rocker arm 25 so as to be open to the free rocker arm 26 side and formed in parallel with the intake side rocker shaft 27. A cylindrical regulating member 53 having a bottom and abutting on the other end of the pin 52 is slidably fitted in the second guide hole 60. The restricting member 53 is disposed with its open end facing the closed end side of the second guide hole 60, and has a flange 53a that protrudes radially outward at the open end.
Are in sliding contact with the inner surface of the second guide hole 60. Return spring 54
Are connected between the closed end of the second guide hole 60 and the closed end of the restricting member 53, and the connecting piston 51 and the connecting pin 5 contact each other by the spring force of the return spring 54.
2 and the regulating member 53 are urged toward the hydraulic chamber 56 side. Moreover, a communication hole 61 for air and oil drainage is formed in the closed end of the second guide hole 60.

Referring again to FIGS. 1 and 2, an ignition plug 64 is provided at the center of the ceiling surface of the combustion chamber 5, and a plug pipe 6 for inserting the ignition plug 64 is provided.
5 is disposed on the cylinder head 2. Thus, the pair of exhaust valve side rocker arms 29 and 30 are composed of the first drive rocker arm 24 and the free rocker arm 26 which are arranged adjacent to each other.
Also, on both sides of the second drive rocker arm 25, they are disposed so as to be in sliding contact with the exhaust valve cams 23 of the camshaft 16. Thereby, both exhaust side rocker arms 29, 3
It is possible to secure a relatively large space between each other, and the two exhaust valves V _E1 and V _E2 can be arranged with a relatively large space between them. Therefore, the plug pipe 65, both the exhaust valves V _E1, V _E2 inter, and so as to be positioned on both exhaust valve side rocker arms 29 and 30 between each other are disposed in the cylinder head 2, inserted into the plug pipe 65 The ignition plug 64 is screwed to the cylinder head 2 so as to face the center of the ceiling surface of the combustion chamber 5.

Next, the operation of this embodiment will be described. When the engine is running at a low speed, the hydraulic pressure in the hydraulic chamber 56 of the connection switching mechanism 50 is released, and the connection piston 51 and the connection pin 52 are operated by the spring force of the return spring 54. Is located at a position corresponding to between the first drive rocker arm 24 and the free rocker arm 26, and a contact surface of the connecting pin 52 and the regulating member 53 is located at a position corresponding to between the free rocker arm 26 and the second drive rocker arm 25. . Therefore, each rocker arm 24, 25, 26 is in a state where relative angular displacement is possible.

In this disconnected state, the rotation of the camshaft 16 causes the first drive rocker arm 24 to swing in accordance with the sliding contact with the low-speed cam 22, and one of the intake valves _VI1 is driven by the low-speed cam. The opening / closing operation is performed at a timing and a lift amount according to the shape of 22. Further, the second drive rocker arm 25 that has slidably contacted the raised portion 20 is substantially in a rest state, and the other intake valve V _I2 can be substantially stopped. In addition, the intake valve V _I2 does not stop completely, but operates slightly in the opening direction when one of the intake valves V _I1 opens. Therefore, the intake valve V I that occurs when the valve is completely closed is maintained.
_I2 can be prevented from sticking to the valve seat. Further, the free rocker arm 26 swings in accordance with the sliding contact with the high-speed cam 21, but the swinging operation does not affect the first and second drive rocker arms 24 and 25 at all. The exhaust valves V _E1 and V _E2 are opened and closed at timings and lifts according to the shapes of the exhaust valve cams 23.

By the way, the first drive rocker arm 24 operating in the low speed region where the friction loss of the valve train accounts for a large proportion of the friction loss of the entire engine slides on 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,
The exhaust valve cams 23, 2 also pass through rollers 34, 34.
3, the friction loss in the low-speed range can be further reduced.

During high-speed operation of the engine, high hydraulic pressure is supplied to the hydraulic chamber 56. Accordingly, 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 and the guide hole 5
When the axes of the second guide hole 57 and the second guide hole 57 coincide with each other, that is, when each rocker arm 24-26 enters a stationary state, the connecting piston 41 is fitted into the guide hole 56, and the connecting pin 42 is accordingly moved to the second guide hole. By fitting into the hole 57, each rocker arm 24 to 26 is connected.

When the rocker arms 24 to 26 are connected as described above, the swing amount of the free rocker arm 26 that is in sliding contact with the high-speed cam 21 is the largest.
The drive rocker arms 24 and 25 swing together with the free rocker arm 26, and the two intake valves V _I1 and V _I2 are opened and closed at timings and lifts according to the shape of the high-speed cam 21. The two exhaust-side rocker arms 29 and 30, allowed to opening and closing both the exhaust valves V _E1, V _E2 at the timing and lift amount corresponding to the shape of the exhaust valve cam 23 in the same manner as in the low-speed operation.

In such a valve train, the free rocker
Lost motor for urging the cam 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 disposed on the support 37.
From above, it urges toward the camshaft 16 side. did
The intake port 8, exhaust port 9, intake valve V_I1, V _I2
And exhaust valve V_E1, V_E2Guide tube 1 for guiding
0, 13 and intake valve V_I1, V_I2And exhaust valve
V_E1, V_E2Springs 12 and 1 for biasing the valve in the valve closing direction
5 Rocker Arms 2
It can be secured on the cylinder head 2 below 4 to 26
The shape of each of the ports 8, 9 and the valve springs 12,
Increased design freedom for 15 spring loads (valve spring outer diameter) etc.
The cylinder head 2 can be made more compact.
It becomes possible.

[0039]

As described above, according to the first aspect of the present invention,
In the lost motion mechanism, the lower end of the piston is
Is mounted on a support provided on the engine body above the second valve drive member so as to abut against the valve drive member, and the support has a sliding portion between the cylinder portion and the piston of the lost motion mechanism. Since the oil supply path for supplying the lubricating oil is provided, the lost motion mechanism can be arranged above the second valve driving member, and it is necessary to secure a space for disposing the lost motion mechanism below the valve driving member. Therefore, there is sufficient space below the valve drive member to accommodate suction and exhaust ports, a guide cylinder for guiding the engine valve, and a valve spring for biasing the engine valve in the valve closing direction. , The degree of freedom in design can be increased, and the upper part of the engine body can be made more compact. Moreover, from the oil supply passage of the support,
The lubricating oil supplied to the sliding part between the piston and the cylinder part of the lost motion mechanism lubricates and flows down the sliding part,
Since it reaches the lower end portion of the piston and is supplied to the contact portion between the lower end portion and the second valve driving member, not only the sliding portion between the cylinder portion and the piston, but also the piston and the second valve driving member. The contact portions can also be sufficiently lubricated, and early wear, seizure and the like of those portions can be effectively prevented.

According to the second aspect of the present invention, the engine body is provided with a plurality of camshaft holders for rotatably supporting the camshafts, and the plurality of camshaft holders are integrally connected to each other. The connecting wall is a support for mounting the lost motion mechanism, and an oil supply passage is formed in the connecting wall. And the rigidity of the lost motion mechanism itself can be increased, and the reliability of the lost motion mechanism itself can be enhanced. In addition, since the oil supply path to the lost motion mechanism can be formed without difficulty using the connection wall, lubricating oil can be sufficiently supplied to the lost motion mechanism without particularly complicating the structure of the oil supply path. In addition, since the connecting wall also serves as a reinforcing means for the camshaft holding portions, a mounting member for the lost motion mechanism, and an oil supply path forming member for the mechanism, the structure can be simplified accordingly.

According to the third aspect of the present invention, a lost motion mechanism assembly is formed by integrally incorporating a piston and a spring in a cylinder constituting the cylinder portion, and the cylinder is formed on a support. The lower end is provided in a mounting hole with an open lower end so as to be able to be pulled out from the open side thereof, and the mounting hole is provided with a stopper portion which engages with the cylinder and defines its upper limit position. Since a communication hole is formed to communicate an opening end of the oil supply path provided on the support body on the mounting hole side to a sliding portion between the piston and the cylinder, the lost motion mechanism is housed in the cylinder. It can be handled as a single unit, and the handling is simple, and the cylinder is simply inserted into the mounting hole of the support from its open side until it engages with the stopper. ,lost motion Since it is possible to perform good easily and accurately assembling the structure, workability is improved with the set.

According to the fourth aspect of the present invention, since the oil supply passage is formed along a common tangent to a plurality of mounting holes for the lost motion mechanism formed in the support, the oil supply passage is complicated. It is possible to perform efficient refueling for a plurality of lost motion mechanisms without performing.

According to the fifth aspect of the present invention, since the contact portion between the camshaft and the second valve driving member is disposed immediately below the lost motion mechanism, the camshaft and the second valve driving member are connected to each other. Sufficient lubrication can also be performed on the contact portion of

[Brief description of the drawings]

FIG. 1 is a plan view of a main part showing an upper part 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.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

[Explanation of symbols]

3 ... Cylinder 16 ... Camshaft 19 ... Holder 24, 25 as camshaft holding part 24, 25 ... First and second drive rocker arms 26 as first valve drive members 26 ... Free rocker arm 37 as second valve drive member 37. Supporting body 37h as connecting wall 37h Mounting hole 37s Stopper 38. Lost motion mechanism 39 Guide member 39a as cylinder portion (cylindrical body) 39a Communication hole 40 Piston 40a Lower end portion 41, 42 First and second springs Spring 47 Oil groove as oil supply passage 48 Oil passage as oil supply passage 50 Connection switching mechanism E Engine body VI ₁ , VI ₂ … Intake valve

Claims (5)

[Claims] An intake valve spring-biased in a valve closing direction.
(V_I1, V_I2), And a motor that rotates in conjunction with the crankshaft
And an intake valve (V)_I1, V _I2)
First valve drive member (24, 25) interlocked with and connected to
And the intake valve (V_I1, V_I2) Can be free
A second valve driving member (26) is interposed, and
The members (24 to 26) are connected and disconnected from each other.
A connection switching mechanism (50) capable of switching between disconnection and
The body (E) abuts on the second valve drive member (26).
Piston (40) and the piston (40)
The cylinder part (39) that slidably fits and supports
Ton (40) in contact direction with second valve drive member (26)
The second valve drive having springs (42, 43)
B for urging the moving member (26) toward the camshaft (16).
Internal combustion engine provided with a strike motion mechanism (38)
In the valve train of Seki, the lost motion mechanism (38) has a piston
The lower end (40a) of (40) is the second valve drive member.
A support provided on the engine body (E) so as to abut against (26)
The holder (37) is mounted above the second valve drive member (26).
The support (37) is attached to the cylinder part.
Supply lubricating oil to the sliding part between (39) and piston (40)
It is noted that refueling channels (47, 48) for
A valve gear for an internal combustion engine. 2. The engine body (E) is provided with a plurality of camshaft holding portions (19) for rotatably supporting the camshaft (16), and the plurality of camshaft holding portions (19) are mutually connected. 2. The internal combustion engine according to claim 1, wherein the support is constituted by a connecting wall (37) that is integrally connected, and the oil supply path (47, 48) is provided on the connecting wall (37). 3. Valve gear. 3. A cylinder (39) constituting said cylinder portion.
The piston (40) and the springs (42, 43) are assembled together to form an assembly of the lost motion mechanism (38), and the cylinder (39) is formed on the support (37). Into the mounting hole (37h) with its lower end open so as to be able to be pulled out from its open side.
h) is provided with a stopper portion (37s) that engages with the cylinder (39) and defines the upper limit position thereof. The cylinder (39) has a lubrication passage (47, 48) The communication hole (39a) which connects the opening end of the said mounting hole (37h) side to the sliding part of the said piston (40) and a cylindrical body (39) is formed, The Claim 1 or 2 characterized by the above-mentioned. 3. The valve train for an internal combustion engine according to claim 1. 4. The fuel supply passage (47, 48) is formed along a common tangent to the plurality of mounting holes (37h) formed in the support (37). Item 4. A valve train for an internal combustion engine according to item 3. 5. A contact portion between said camshaft (16) and a second valve driving member (26) is provided with a lost motion mechanism (3).
8. The device according to claim 1, wherein the device is disposed directly below 8).
5. The valve operating device for an internal combustion engine according to 2, 3, or 4.