JPH042767B2 - - Google Patents

Abstract

PURPOSE:To improve the responsiveness of an actuator by letting lubricating oil to flow through an oil path disposed in a rocker shaft for driving the actua tor adapted to connect and disconnect rocker arms even during medium-low speed operation of an engine. CONSTITUTION:During medium-low speed operation of an engine, a spool 32 of a solenoid valve 30 is placed at a position shown in the drawing, so that the first and second ports 35, 38 communicate with each other. Therefore lubri cating oil flows through oil paths 39, 16 in order to lubricate a cam for low speed. A part of the lubricating oil flows from the first leak passage 54 connecting the first end third ports 35, 40 in an oil path 42 in a rocker shaft 8 through an oil path 41. A part of the lubricating oil flows through an oil path 44, an orifice 45 and an oil path 17 in order, and then it lubricates a cam for high speed or the like. Since a little lubricating oil flows through an oil path 42 even during medium-low speed operation, the lubricating oil can be heated so that the first to third rocker arms 5-7 can be connected favorably by a actuator 43.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a hydraulic circuit for a valve operation timing control device that varies the operation timing of an intake valve or an exhaust valve of an internal combustion engine.

<Prior art> As one method for controlling the output of an internal combustion engine,
For example, as disclosed in Japanese Patent Application Laid-open No. 19911/1983, by making the valve operating timing variable between low-speed and high-speed engine operation, the combustion chamber can be controlled over a wide operating range. Techniques are known to improve the efficiency of filling air-fuel mixture into the air-fuel mixture. This kind of valve operation timing control device uses the inside of the rocker shaft as an oil passage, and has a structure in which hydraulic pressure is supplied from the engine side to a coupling mechanism consisting of a hydraulic actuator built into the rocker arm to switch the valve. It's summery.

The hydraulic circuit for supplying this oil pressure is closed in the engine's medium and low speed range, but when the engine speed reaches a predetermined set speed, it opens and lubricating oil, which also serves as hydraulic oil, is released from the engine side. Forced to the actuator.

That is, the lubricating oil used as the hydraulic oil flows only when the actuator is operated. For this reason, when the oil is cold, the lubricating oil in the oil passage has a low temperature, so its fluidity decreases, and even if an activation signal for valve switching is issued, the hydraulic response is poor, making it difficult for the valve to switch smoothly. There was a problem that it was not done.

<Problems to be Solved by the Invention> Therefore, an object of the present invention is to provide a valve operation timing control device for an internal combustion engine that has excellent responsiveness of hydraulic pressure even in cold conditions, and that allows smooth valve switching at all times. The objective is to provide a hydraulic circuit that can be used to

<Means for Solving the Problems> According to the present invention, the above-mentioned object is to provide an oil passage installed in the rocker shaft for supplying hydraulic oil to an actuator for variable valve operation timing control installed in the rocker arm. The switching valve for selectively applying hydraulic pressure from one end is provided with a leak passage to allow some hydraulic oil to flow into the oil passage even when the actuator is not operating, and the other end of the oil passage is connected to the valve through an orifice. This is achieved by providing a hydraulic circuit for a valve timing control device, which is characterized in that it communicates with a lubricating oil path of the device.

<Function> By doing this, the lubricating oil that also serves as hydraulic oil will constantly flow in the hydraulic oil supply path to the actuator, ensuring the fluidity of the actuator hydraulic oil in the oil path even when it is cold. can do.

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

FIG. 1 shows a valve train for an internal combustion engine to which a hydraulic circuit according to the present invention is applied. In this valve mechanism, the valve operation timing is variable in the engine's medium-low speed range and high-speed range, and a pair of intake valves 1a and 1b provided on the engine body (not shown) are connected to the crankshaft ( 1/2 of (not shown)
A pair of low-speed cams 3 having an egg-shaped cross section are integrally provided with a camshaft 2 that is driven synchronously at a speed of
a, 3b, and a single high-speed cam 4, and first to third rocker arms 5 to 7 as cam followers that engage with these cams 3a, 3b, and 4 to perform rocking motion.
It is designed to open and close by working with.
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 above-mentioned intake valves 1a and 1b.

The first to third rocker arms 5 to 7 are pivotally supported adjacent to each other so as to be able to swing freely on a rocker shaft 8 that is fixed below the camshaft 2 and parallel to the camshaft. ，
7 have basically the same shape, their bases are pivotally supported by the rocker shaft 8, and their respective free ends extend above both intake valves 1a, 1b.
Tappet screws 9a and 9b that abut the upper ends of the intake valves 1a and 1b are screwed into the free ends of both of these locking arms 5 and 7 so as to be movable forward and backward, and each tappet screw is connected to a lock nut 10.
a and 10b, respectively, to prevent loosening.

The second rocker arm 6 is pivotally supported on the rocker shaft 8 between the first and third rocker arms 5 and 7, and is connected to the rocker shaft 8 from both the intake valves 1a and 1.
It extends slightly towards the middle of b. A cam slipper 6a is formed on the upper surface of the second rocker arm 6 and is in sliding contact with the high-speed cam 4, and the upper end surface of the lost motion spring 11 is in contact with the lower end of the cam slipper 6a. This lost motion spring 11
has a built-in coil spring to apply an upward biasing force to the second rocker arm 6 so that the high-speed cam 4 and the cam slipper 6a are always in sliding contact.

The camshaft 2 is rotatably supported above the engine body, and has low-speed cams 3a and 3b formed in a cam profile with a relatively small lift that is suitable for low-speed engine operation, and low-speed cams 3a and 3b that are suitable for high-speed engine operation. A high-speed cam 4 formed in a cam profile having a larger lifting height over a wider angle than the low-speed cams 3a and 3b is integrally connected. The low speed cams 3a, 3b are adapted to come into sliding contact with cam slippers 5a, 7a formed on the upper surfaces of the first and third rocker arms 5, 7, respectively, on their outer peripheral surfaces. Also, these first to third
The rocker arms 5 to 7 are arranged in a state in which they can swing integrally according to the engine speed by means of a coupling device installed in a hole drilled through the center of the rocker shaft 8 and parallel to the rocker shaft 8. It is designed so that it can be switched to a state where it can be angularly displaced.

Retainers 12a and 12b are provided above the intake valves 1a and 1b, respectively, and a valve spring 13a surrounding the stems of the intake valves 1a and 1b is provided between the retainers 12a and 12b and the engine body. , 13b are interposed,
Both intake valves 1a and 1b are biased toward the valve closing direction.

Above the camshaft 2 are low speed cams 3a and 3b.
An oil supply pipe 14 for the high-speed cam 4 and an oil supply pipe 15 for the high-speed cam 4 are arranged, and lubricating oil is supplied from the engine side to oil passages 16 and 17 provided inside them. ing. Injection holes 18a and 18b that open above the low-speed cams 3a and 3b are bored in the outer peripheral surface of the oil supply pipe 14, and the oil passage 16
The lubricating oil supplied through the cams is sprayed onto each of the low-speed cams 3a and 3b in a shower manner.

Two branch pipes 23 and 24 are connected to the other oil supply pipe 15 at right angles to its axial direction, and their free ends 23a and 24a sandwich the high-speed cam 4, respectively, and are connected to the front and rear of the high-speed cam 4. It extends to a position facing the sliding surface between the cam and the cam slipper 6a.
A nozzle 25 is attached to the free end 23a of the branch pipe 23, and the nozzle 25 opens toward the sliding surface of the high-speed cam 4 and the cam slipper 6a. The lubricating oil is injected in the same direction as the rotational direction A. Similarly, a nozzle 26 that opens toward the sliding surface from the opposite side of the cam 4 is attached to the free end 24a of the other branch pipe 24, and is opened from the rear side of the cam 4 in the opposite direction of rotation A. It is designed to spray lubricating oil in the opposite direction. Furthermore, the lubricating oil supplied through the oil passage 17 is supplied to passages 19a and 19 connected to the oil supply pipe 15.
The journals 20a and 20b integrally formed on the camshaft 2 are also lubricated via the camshaft 9b.

FIG. 2 schematically shows a hydraulic circuit applied to a valve timing control device for a four-cylinder internal combustion engine equipped with the valve operating mechanism shown in FIG. The solenoid valve 30 is configured such that the spool 32 that slides into the guide hole 31 is attracted upward, that is, to the position shown in the figure, when the solenoid 34 is energized, and is displaced downward by the biasing force of the spring 33 when the solenoid 34 is deenergized. It's summery. The first port 35 is an inlet for hydraulic pressure, and communicates with an oil pump 37 of the engine via an oil passage 36. The second port 38 is connected to the oil path 3
9, it communicates with an oil passage 16 for supplying oil to the low-speed cams 3a, 3b. The third port 40 is
It communicates with an oil passage 42 provided inside the rocker shaft 8 via an oil passage 41, and supplies hydraulic pressure to a coupling mechanism 43 consisting of a hydraulic actuator provided inside each rocker arm. is lubricated. An oil passage 44 is connected to the rear end of the oil passage 42, and an orifice 4 is connected to the oil passage 44.
5 is provided and communicates with an oil passage 17 for supplying oil to the high-speed cam 4. Oil passage 17 is passage 1
The journals 20a to 20e of the camshaft 2 are also lubricated via the bearings 9a to 19e. A drain hole 46 is bored at the lower end of the guide hole 31, and the lubricating oil leaking from the gap between the spool 32 and the guide hole 31 flows into a cylinder hole (not shown) without staying in the guide hole 31. It's becoming like that.

The operating procedure of the hydraulic circuit of this embodiment will be explained below.

When the engine is operating at medium to low speeds, the spool 32 is in the position shown in the figure, so the first port 35 and the second port 38 communicate with each other, and lubricating oil supplied from the engine side flows into the oil path 16 via the oil path 39. supplied,
Lubricate the low speed cams 3a and 3b. Spool 32
is provided with a first leak passage 54 that communicates the first port 35 and the third port 40 in a demagnetized state, and a part of the lubricating oil supplied from the engine side passes through the oil passage 41. The oil is designed to flow into an oil passage 42 in the rock shaft 8. When the lubricating oil supplied to the oil passage 42 passes through the oil passage 44, it is throttled by an orifice 45 and flows slightly toward the oil passage 17 to lubricate the high-speed cam 4 and the cam slipper 6a. In this way, a slight flow of lubricating oil is formed in the oil passage 42 inside the rocker shaft 8 even when the engine is operating at low to medium speeds, that is, when the actuator 43 is in a non-operating state.

When the engine is running at high speed, the spool 32 is sucked upward by the solenoid 33, so the first
The port 35 and the third port 40 communicate with each other, and lubricating oil supplied from the engine side is mainly supplied to the oil passage 42 inside the rocker shaft 8. As a result, the actuator 43 is driven, the first to third rocker arms 5 to 7 are integrally connected, and the valves are switched. This actuator 43 is a known one disclosed in, for example, Japanese Patent Laid-Open No. 19911/1983. The lubricating oil supplied to the oil passage 42 is adjusted in flow rate by an orifice 45 and then transferred to the oil passage 17.
, and lubricates the high-speed cam 4, cam slipper 6a, and journals 20a to 20e.

Further, since the solenoid valve 30 is provided with a second leak passage 55 that communicates the first port 35 and the second port 38 in the above-mentioned excited state, a portion of the lubricating oil is also at this spool position. Flows from the first port 35 to the second port 38 and passes through the oil path 39 to the oil path 1
6 to lubricate the low speed cams 3a, 3b and cam slippers 5a, 7a.

In the above embodiment, the lubricating oil flowing out from the rear end of the oil passage 42 through the orifice 45 is used to lubricate the high-speed cam 4, the cam slipper 6a, and the journal. It can also be used to oil the low-speed cams 3a, 3b, etc.

<Effects of the Invention> As described above, according to the present invention, an orifice is provided at the rear end of the oil passage provided in the rocker shaft to drive the actuator that connects and releases the rocker arm, and the operation of the actuator is controlled. By providing a leak passage in the solenoid valve for this purpose, lubricating oil that also serves as hydraulic oil will always flow through the oil passage, regardless of whether the actuator is activated or not. Since the temperature of the lubricating oil inside can be raised, the responsiveness of valve switching is significantly improved. Furthermore, by using the lubricating oil leaked from the orifice to lubricate each cam, rocker arm, or journal, the lubricating oil can be used effectively.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically illustrating a valve train for an internal combustion engine to which the present invention is applied. FIG. 2 is an explanatory diagram showing the hydraulic circuit of the present invention. 1a, 1b... Intake valve, 2... Camshaft, 3a, 3b... Low speed cam, 4... High speed cam, 5... First rocker arm, 5a... Cam slipper, 6... Second rocker arm, 6a... ...Cam slipper, 7...Third rocker arm, 7a...Cam slipper, 8...Rotsuka shaft, 9a, 9b...
Tappet screw, 10a, 10b... Lock nut, 11... Lost motion spring, 12
a, 12b...retainer, 13a, 13b...valve spring, 14, 15...oil supply pipe, 16,
17... Oil passage, 18a, 18b... Injection hole, 19
a to 19e... passage, 20a to 20e... journal, 23... branch pipe, 23a... free end, 2
4... Branch pipe, 24a... Free end, 25, 26
... Nozzle, 30 ... Solenoid valve, 31 ... Guide hole, 32 ... Spool, 33 ... Spring, 3
4...Solenoid, 35...1st port, 36...
...Oil passage, 37...Oil pump, 38...Second port, 39...Oil passage, 40...Third port, 4
1, 42... Oil path, 43... Connection mechanism, 44...
Oil passage, 45...orifice, 46...drain hole,
54...first leak passage, 55...second leak passage.

Claims (1)

[Claims] 1. Variable valve operation timing control provided on a rocker arm for opening an intake valve or an exhaust valve that is oscillated by a cam that rotates in synchronization with the crankshaft and is biased in the valve-closing direction. A valve operation timing control device for an internal combustion engine, which selectively applies hydraulic pressure from one end of an oil passage installed in a rocker shaft that pivotally supports the rocker arm using a switching valve in order to supply hydraulic oil to an actuator for the engine. In the hydraulic circuit, the switching valve has a leak passage for allowing some hydraulic oil to flow into the oil passage even when the actuator is not in operation, and the other end of the oil passage is connected to the oil passage through an orifice. A hydraulic circuit for a valve timing control device, characterized in that it communicates with an oil path for lubricating a valve train.