JPH0583722B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable valve operation device for a four-stroke engine mainly used in motorcycles and other vehicles, and more particularly, the present invention relates to a variable valve operation device for a four-stroke engine used mainly in motorcycles and other vehicles, and more particularly, it relates to a variable valve operation device for at least an intake valve and an exhaust valve provided in the same cylinder of the engine. The present invention relates to a variable valve operation device in which a pair of valves are arranged side by side, and the pair of valves can be switched between a state in which the valves are opened and closed in an integrated manner and a state in which they are separated and operated independently.

Conventionally, this type of device is provided with a pair of rocker arms corresponding to a pair of valves, one of the rocker arms is engaged with a valve drive cam, and the other rocker arm is engaged with and disengaged from the one rocker arm by a fluid actuator. an inflow passage and a discharge passage that are connected to an oil pump or other fluid pressure source driven by an engine via a control valve, and a fluid passage that introduces fluid pressure into the actuator to actuate it in the engaging direction; When the fluid passage is connected to the inflow passage, both rocker arms are engaged with each other, and a valve operating cam that engages one of the rocker arms causes the pair of valves to be connected together through the two rocker arms. When the valve is opened and closed, and when the fluid passage is connected to the discharge passage, both the rocker arms are disengaged, and only one valve is opened and closed via one of the rocker arms that engages with the valve operating cam. It is known that when the engine is stopped, the operation of the fluid pressure source is also stopped, and the control valve is moved to the pressure source side. Even if the switch is switched to , both rocker arms are not engaged with each other, and the other rocker arm that does not engage with the valve drive cam is no longer interlocked with the valve drive cam, making it difficult to accurately adjust the tappet of the other rocker arm. Therefore, when adjusting the tappet, it is desirable to operate a fluid actuator using fluid pressure from a pressure source such as a separately prepared compressor or oil pump so that the two rocker arms can be engaged with each other.
In this case, it is further desired to improve workability by connecting the pressure source to the fluid passage without tampering with the piping of the device.

An object of the present invention is to provide a device that satisfactorily meets such demands. A fluid inlet is provided in the middle by branching off from this passage, and by introducing fluid pressure from the inlet into the branching part of the passage, one half of the passage extending from the branching part to the fluid actuator side and the other half of the passage are connected. The present invention is characterized in that a switching valve is provided to cut off the communication with the half part and communicate the inlet with the one half part.

Next, an example in which the present invention is implemented as a valve stop device will be described with reference to the drawings.

In the drawings, reference numeral 1 indicates an engine, and the engine 1 is equipped with a pair of intake and exhaust valves 3 in the same cylinder 2, and cylinder heads 4 are provided with valves 3 corresponding to the valves 3 for each cylinder 2. A pair of first and second rocker arms 5 ₁ , 5 ₂ for intake and exhaust are respectively pivotally supported on a common rocker arm shaft 6 , and each rocker arm 5 ₁ , 5 ₂ is connected to a tapepet adjustment screw 7 at the tip thereof. The rocker arms 5 1 and 5 2 are brought into contact with the valve stems 3 a of the respective valves 3 so that the valves 3 can be opened and closed by swinging the rocker arms 5 ₁ and 5 ₂ .

Then, one of the first and second rocker arms 5 ₁ and 5 ₂ , for example, the first rocker arm 5 ₁ is engaged with the valve operating cam 9 at a slipper 8 formed thereon, and the other second rocker arm 5 ₂ is connected to the fluid actuator 10 . This makes it possible to freely engage and disengage the first rocker arm ₅₁ . To explain this in more detail, the fluid actuator 10 is constituted by a cylinder 10b on the first rocker arm ₅₁ that advances and retreats an engagement pin 10a provided between the two rocker arms ₅₁ and ₅₂ , for example. , when fluid pressure is introduced into the cylinder 10b, the engagement pin 10a moves into the second rocker arm 5.
The locker arms 5 _{1 and} 5 2 are inserted into the engagement hole 11 formed in the cylinder 10 b against the cushion pin 12 so that the locker arms 5 1 and 5 ₂ are engaged with each other. The pin 10a is pushed out from the engagement hole 11 by the cushion pin 12, and the locker arms 5 ₁ and 5 ₂ are disengaged. Drawing 13 shows a control valve provided outside the cylinder head 4, which control valve 13 has a fluid passage 1 in a valve housing 14 leading to the fluid actuator 10.
5 to an inflow passage 16 that connects to an oil pump (not shown) or other fluid pressure source driven by the engine 1.
and a spool valve 1 which is switchably connected to the discharge passage 17 and the discharge passage 17.
8, the spool valve 18 is switched via an electromagnetic solenoid 19 depending on the operating state, and the fluid passage 15 is connected to the inflow passage 16 to engage the locking arms 5 ₁ and 5 ₂ described above. movement and
The fluid passageway 15 is connected to the discharge passageway 17 to enable its disengagement.

In the drawing, 20 indicates an accumulator connected to the inflow passage 16.

Although the above is not particularly different from that of the conventional example described above, according to the present invention, at least one of the fluid passage 15, the inflow passage 16, and the discharge passage 17 described above is provided.
A fluid inlet 21 is provided in the middle of a passage, for example, a discharge passage 17, branched from this, and fluid pressure is introduced from the inlet 21 into the branch part 22 of the passage 17, so that the fluid actuator is connected to the fluid actuator from the branch part 22. 10 side and the other half of the passage 17, that is, in the case of the discharge passage 17, the upstream half 17a leading to the spool valve 18 and the drain port 23 to the cylinder head 4. The inlet 21 is inserted into the upstream half 17a by cutting off the communication with the downstream half 17b.
A switching valve 24 is provided to communicate with each other. In this case, the switching valve 24 may be configured as a spool type, but in the illustrated one, the switching valve 24 is
As clearly shown in the figure, the plunger 2 is pushed by the fluid pressure introduced from the inlet 21 and closes the open end of the downstream half 17b facing the branch 22.
5, and the upstream half 17 is attached to the plunger 25.
A plunger internal passage 26 connected to the inlet port 21 and a valve hole 27 connected to the inlet 21 are formed, and a check valve 28 biased in a direction to close the valve hole 27 is attached to the plunger internal passage 26. The switching valve 24
This made it possible to downsize the device.

In the drawing, 25a is a return spring of the plunger 25;
28a and 28b are the biasing springs of the check valve 28 and their spring receiving pieces; 29 is a joint tool for connecting external piping that also serves as a stopper in the return direction of the plunger 25 attached to the inlet 21; and 30 is the joint. A cap applied to tool 29 is shown.

Next, to explain its operation, when stopping the engine 1 and adjusting the tappet, the cap 30
is removed and a separately prepared pressure source is connected to the fluid inlet 21 via a joint 29. According to this, the plunger 25 of the switching valve 24 is pushed by the fluid pressure introduced from the inlet 21. The opening end of the downstream half 17b of the discharge passage 17 is closed, the communication between the upstream half 17a and the downstream half 17b is cut off, and the check valve 28 is opened to open the inlet 21. It is communicated with the upstream half portion 17a. Thus, by connecting the fluid passage 15 and the discharge passage 17 via the control valve 13, the fluid pressure from the inlet 21 is transferred between the upstream half 17a and the fluid passage 15 without escaping to the downstream half 17b. When the crankshaft is slightly rotated, the first and second rocker arms 5 ₁ and 5 _{2 are engaged with each other, and the second rocker arm 5 2} that does not directly engage with the valve drive cam 9 is introduced into the fluid actuator 10 via the valve drive cam _{9 .} is also engaged with the valve operating cam 9 via the first rocker arm ₅₁ , and the tappet of the second rocker arm ₅₂ is adjusted in the usual way by using the tappet adjusting screw 7.
It can be done accurately by rotating.

Note that the fluid introduction port 21 may be provided in the fluid passage 15 or the inflow passage 16;
Since high fluid pressure acts on the locker arms 5 ₁ and 5 ₂ when the locker arms 5 1 and 5 2 are engaged, leakage of fluid from the inlet 21 becomes a problem. Providing the inlet 21 is advantageous because it does not have such problems. Furthermore, in the case where a plurality of fluid actuators 10 are provided as shown in the figure,
It is preferable to provide a fluid inlet 21 at a passage position that communicates with each of these actuators 10 so that the fluid inlet 21 can be shared.

Although an example in which the present invention is implemented in a valve stop device has been described above, it can also be implemented in a device in which rocker arms of a pair of valves with different lifts are mutually engaged and disengaged.

As described above, according to the present invention, there is provided a fluid passage connected to a fluid actuator that operates to engage a pair of rocker arms with each other, and an inflow passage and a discharge passage that are switchably connected to the fluid actuator via a control valve. A fluid inlet is provided in a branched manner at one of the two, and a switching valve is provided at the branch to operate to supply fluid pressure only to the actuator side by introducing fluid pressure from the fluid inlet. By simply connecting a separately prepared pressure source to the port, the pair of rocker arms can be engaged with each other, making it easy to adjust the tappet when the engine is stopped. It can be installed in existing equipment by partially changing the passage configuration, and has the effect of being easy to apply to existing equipment.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view of an example of an engine to which the present invention is applied, FIG. 2 is a cross-sectional plan view thereof, and FIG. 3 is an enlarged cross-sectional plan view of the main parts thereof. 1...Engine, 2...Cylinder, 3...Valve,
5 ₁ , 5 ₂ ... Rocker arm, 10 ... Fluid actuator, 13 ... Control valve, 15 ... Fluid passage,
16... Inflow passage, 17... Discharge passage, 21...
Fluid inlet, 22... Branch, 24... Switching valve,
25...Plunger, 26...Plunger internal passage, 27...Valve hole, 28...Check valve.

Claims (1)

[Scope of Claims] 1 A pair of at least one of an intake valve and an exhaust valve provided in the same cylinder of an engine is arranged in parallel, a pair of rocker arms corresponding to the pair of valves are provided, and one of the valves is provided in parallel. A fluid actuator is used to freely engage and disengage the other rocker arm from the other rocker arm, and a fluid passageway that introduces fluid pressure into the actuator to actuate it in the engaging direction is connected to the fluid driven by the engine via the control valve. In a variable valve operation device for an engine, which can be switched and connected to an inflow passage and an exhaust passage connected to a pressure source, the valve actuation device is configured to branch off in the middle of at least one of the fluid passage, the inflow passage, and the exhaust passage. A fluid inlet is provided at a branching part of the passage, and communication is established between one half of the passage extending from the branching part to the actuator side and the other half by introducing fluid pressure from the inlet. 1. A variable valve operation device for an engine, characterized in that a switching valve is provided in one half of the one side to communicate with the inlet. 2. The variable valve operation device for an engine according to claim 1, wherein the passage in which the inlet is provided is the discharge passage. 3. The switching valve is provided with a plunger that is pushed by fluid pressure introduced from the inlet to close the open end of the other half facing the branching part, and the plunger is configured to close the open end of the other half facing the branch part. A plunger internal passage connected to the inlet and a valve hole connected to the inlet are formed, and a check valve biased in a direction to close the valve hole is attached to the plunger internal passage. A variable valve operation device for an engine according to claim 1 or 2.