JPH0313403B2 - - Google Patents

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a valve mechanism for an internal combustion engine having a plurality of intake valves or exhaust valves that are driven to open via a rocker arm by a cam that rotates in synchronization with a crankshaft. related to hydraulic circuits.

<Conventional technology> Regarding the internal combustion engine described above, in order to optimize the intake and exhaust efficiency over the entire rotation range from low speed to high speed, the number of activated intake and exhaust valves is changed according to the engine speed. Valve deactivation mechanisms are known. In addition, Japanese Patent Application Laid-Open No. 1983-1999 by the applicant of the present application
The specification of No. 19911 describes a method for improving the filling efficiency of air-fuel mixture into the combustion chamber over a wide operating range by changing the timing of valve operation between low-speed and high-speed engine operation. Proposed.

These valve operating mechanisms operate a solenoid valve in response to the rotational speed of the engine to open and close a hydraulic circuit, thereby moving a piston built into one rocker arm to connect or disconnect the other adjacent rocker arm. However, both rocker arms are operated together or separately to switch the valves. On the other hand, it is important to provide sufficient lubrication to the cam and the rocker arm in sliding contact with the cam in response to valve switching.

A certain amount of lubricating oil held in the engine is pumped into these hydraulic circuits and lubricating oil passages by an oil pump, but if hydraulic pressure is supplied and controlled separately for each, the oil supply system There is a risk that sufficient oil supply may not be provided to each of the parts. Therefore, in order to always supply the necessary and sufficient hydraulic pressure to ensure valve switching operation and to provide sufficient lubrication, it is necessary to adjust the hydraulic pressure in consideration of economy so that lubricating oil can be used as effectively as possible. It is necessary to configure the circuit and to easily control it.

<Problems to be Solved by the Invention> Therefore, an object of the present invention is to effectively use the oil pressure supplied from the engine side to reliably switch the valves in accordance with the engine speed, and at the same time It is an object of the present invention to provide a hydraulic circuit for a valve mechanism for an internal combustion engine, which provides necessary and sufficient oil supply to the engine and which can be easily controlled.

<Means for Solving the Problems> According to the present invention, the above-mentioned object is achieved by providing a plurality of intake valves or exhaust valves biased in the valve closing direction, and a rock shaft corresponding to the intake valves or exhaust valves. a plurality of rocker arms that are swingably supported and swingably driven by a cam that rotates in synchronization with a crankshaft; a connecting means that can selectively connect or disconnect adjacent rocker arms by the action of hydraulic pressure; In a valve operating mechanism for an internal combustion engine having a hydraulic circuit for supplying hydraulic pressure to a means, and an oil supply passage for lubricating the cam, the hydraulic circuit and the oil supply passage are connected in series through a throttle means. , the lubricating oil is distributed so that the lubricating oil supplied from the engine side flows from the oil supply passage side to the hydraulic circuit side when the engine is running at low speed, and from the hydraulic circuit side to the oil supply passage side when the engine is running at high speed. This is achieved by providing a hydraulic circuit for a valve mechanism for an internal combustion engine, characterized in that it is equipped with a switching means for switching the direction.

<Function> By doing this, by switching the direction of lubricating oil supplied from the engine with a single control operation, the valve can be reliably switched between high-speed and low-speed engine operation. At the same time, the cam can be appropriately lubricated in response to this valve switching.

<Examples> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 schematically shows a valve operating mechanism for an internal combustion engine to which a hydraulic circuit according to the present invention is applied. A pair of intake valves 1 and 2 provided in an engine body (not shown) are urged in the valve closing direction by springs 3 and 4. Both intake valves 1 and 2 include a cam 6 having an egg-shaped cross section that is integrally provided with a camshaft 5 that is synchronously driven at a rotation speed of 1/2 of a crankshaft (not shown), and a rock shaft that is parallel to the camshaft 5. It is designed to be opened and closed by rocker arms 8 and 9 which are swingably supported by rocker arms 7 and 7. Further, this engine is equipped with a pair of exhaust valves (not shown), which are driven to open and close in the same manner as the intake valves 1 and 2 described above.

Both rocker arms 8 and 9 are arranged adjacent to each other, and tappet screws 10 and 11 that come into contact with the upper ends of each valve 1 and 2 can be moved forward and backward at the free ends that extend above both intake valves 1 and 2. The tappet screws 10 and 11 are secured by lock nuts 12 and 13 to prevent them from loosening. Further, a cam slipper 14 is formed on the upper surface of the first rocker arm 8 so as to be in sliding contact with the cam 6. Further, above the camshaft 5, there is an oil supply passage 25 inside.
A lubricating oil pipe 26 is provided, and lubricating oil is sprayed toward the cam 6 from an injection hole 27 formed above the cam 6.

As shown in FIG. 2, both rocker arms 8,
9 has a built-in connecting device that connects or disconnects them depending on the engine speed.
This coupling device includes a piston 16 that is slidably housed in a first guide hole 15 that is bored inside the first rocker arm 8, and a piston 16 that is slidably housed in a first guide hole 15 that is bored inside the second rocker arm 9 in correspondence with the guide hole 15. The stopper 22 is biased toward the first rocker arm 8 by a coil spring 23 in the second gas hole 21 .
A hydraulic chamber 18 is defined on the bottom side of the first guide hole 15, and a hydraulic chamber 18 is provided through a passage 19 to the rock shaft 7.
It is designed to constantly communicate with an oil passage 20 provided inside.

When a predetermined hydraulic pressure is supplied from the engine side to the hydraulic chamber 19 via the oil passage 20, the piston 16 moves to the second position.
It is pushed out to the rocker arm 9 side, and presses the stopper 22 while resisting the biasing force of the spring 23 to reach the second position.
It enters into the guide hole 21 and integrally connects the first rocker arm 8 and the second rocker arm 9. When the hydraulic pressure acting on the hydraulic chamber 18 is released, the piston 16 is pushed back into the first guide hole 15 by the biasing force of the spring 23, and both rocker arms 8, 9
are again separated for relative angular displacement. In this way, the valves are switched between when the engine is operating at medium to low speeds and when operating at high speeds.

As clearly shown in Figure 2, the oil tank 3
The lubricating oil stored in the oil pump 31 is pumped toward the flow rate adjustment switching valve 32 by the oil pump 31. The flow rate adjustment switching valve 32 consists of a spool valve 33 and a variable orifice 34.
When the port 36 is in communication with the solenoid 37 and the solenoid 37 is energized, the first port 35 and the third port 38 are in communication with each other. A variable orifice 34 is provided downstream of the second port 36 and communicates with the cam oil supply passage 25 . The third port 38 communicates with the oil passage 20 in the rock shaft 7. Further, the cam oil supply passage 25 and the oil passage 20 are connected in series via an orifice 39.

The operating range of this hydraulic circuit will be explained below.

When the engine is running at medium to low speed, the spool valve 33
Since the first port 35 and the second port 36 are in communication with each other, the lubricating oil pumped from the engine has its flow rate adjusted by the variable orifice 34, and then
The oil flows into the oil supply passage 25 to lubricate the cam 6 and the cam slipper 14, and at the same time, the flow rate is further adjusted by the orifice 39, and then introduced into the oil passage 20.

In this way, by providing the variable orifice 34 on the upstream side of the oil supply passage 25 and the fixed orifice 39 between the oil supply passage 25 and the oil passage 20, the amount of oil supplied to the cam 6 and the inside of the oil passage 20 can be controlled. Hydraulic pressure can be controlled. That is, if the pressure of the lubricating oil pumped from the engine side is P ₀ , the oil pressure in the oil supply passage 25 is P ₁ , and the oil pressure in the oil passage 20 is P ₂ , then P ₀ >
The relationship P ₁ > P ₂ holds true. Here, if the valve switching hydraulic pressure that can drive the piston 16 of the coupling device is P ^* , it is necessary that P ₂ < P*, but even if the hydraulic pressure P ₀ supplied from the engine side varies according to the engine speed. Even if it increases, P ₂ can always be maintained below P* by adjusting the variable orifice 34.

During high-speed operation of the engine, the solenoid 37 is operated to communicate the first port 35 and the third port 38, and the hydraulic pressure supplied from the engine side is directly supplied to the oil passage 20. In this case, the oil pressure P ₀ ≒
Since the relationship P ₂ >P* is established, the piston 16 is driven to connect the first rocker arm 8 and the second rocker arm 9, and the valves are switched. Oil road 2
The lubricating oil supplied to the cam oil supply passage 25 is supplied to the cam oil supply passage 25 with its flow rate adjusted by the orifice 39.
Lubricate the cam 6 and cam slipper 14.

<Effects of the Invention> As described above, according to the present invention, the cam oil supply passage and the oil passage for the coupling device are connected in series through an orifice, and the spool valve is used to connect the cam oil supply passage and the oil passage for the coupling device in series, and the lubricant is supplied from the engine side using the spool valve. By switching the direction of oil flow, it is possible to simultaneously control the cam oil supply system and the operation of the coupling device with a single control operation, and the lubricating oil can be used effectively to adjust the cam flow according to the engine operating conditions. It is possible to provide necessary and sufficient lubrication.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing a valve train to which the present invention is applied. FIG. 2 is a hydraulic system diagram showing a hydraulic circuit according to the present invention. 1, 2...Intake valve, 3, 4...Spring, 5...
...Camshaft, 6...Cam, 7...Rock shaft, 8...First rocker arm, 9...Second rocker arm, 10, 11... Tappet screw, 12,
13...Rocknut, 14...Kamsuritsupa,
15...First guide hole, 16...Piston, 18
... Hydraulic chamber, 19 ... Passage, 20 ... Oil passage, 21
...Second guide hole, 22...Stopper, 23...
Coil spring, 25... Oil supply passage, 26... Oil supply pipe, 27... Injection hole, 30... Oil tank, 3
1...Oil pump, 32...Flow rate adjustment switching valve,
33... Spool valve, 34... Variable orifice,
35...First port, 36...Second port, 37
...Solenoid, 38...Third port, 39...
Orifice.

Claims (1)

[Scope of Claims] 1. A plurality of intake valves or exhaust valves biased in the valve closing direction, pivotably supported on a rocker shaft in correspondence with the intake valves or exhaust valves, and rotating synchronously with a crankshaft. a plurality of rocker arms rockingly driven by a cam, a connecting means that can selectively connect or disconnect the adjacent rocker arms by the action of hydraulic pressure, a hydraulic circuit that supplies hydraulic pressure to the connecting means, and a hydraulic circuit that lubricates the cam. In the valve operating mechanism for an internal combustion engine, the hydraulic circuit and the oil supply passage are connected in series through a throttle means, and the lubricating oil supplied from the engine side is used to control the low speed operation of the engine. The lubricating oil is characterized by comprising a switching means for switching the direction of flow of the lubricating oil so that the lubricating oil flows from the oil supply passage side to the hydraulic circuit side at times, and from the hydraulic circuit side to the oil supply passage side during high-speed operation. Hydraulic circuit for valve train for internal combustion engine.