JPH041407A - Valve system for multicylinder engine - Google Patents

Abstract

PURPOSE:To rapidly change over cams by providing a check valve capable of opening an oil path communicating to each cam change-over drive means to the drain side in the oil path and opening and closing the check valve according to working oil pressure in the oil path. CONSTITUTION:In the high load or high speed running of an engine, the discharge pressure of an oil pump 14 is conducted to a main oil path 11 through an electromagnetic change-over valve 13 and a check valve 18 cuts off working oil outflow to a drain path 19 against a return spring 24. Thus, high pressure working oil is supplied to respective oil chambers 10 and respective sub-rocker arms 2 move against respective springs 4 to restricted positions where respective subrocker arms 2 are united with a main rocker arm 1. On the other hand, as the rotational frequency or load of the engine are reduced, the check valve 18 is moved to the opening position by energizing force of the return spring 24. As a result, since the working oil from the main oil path 11 flows out of two directions of the change-over valve 13 and check valve 18, the working oil in the respective chambers 10 can be rapidly discharged.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a valve actuation device for a multi-cylinder ennon, and particularly to one that switches valve lift characteristics according to operating conditions of the ennon.

(Prior art) Conventionally, in order to improve the fuel efficiency, output performance, etc. of an engine, the lift characteristics of the intake valve or exhaust valve are varied depending on the operating condition, thereby controlling the intake/exhaust timing or intake/exhaust amount. It is known to do.

For example, in Japanese Patent Application Laid-Open No. 62-294709, in a multi-cylinder engine, a plurality of cams with different valve lift characteristics and a cam switching drive means for switching the cams involved in opening and closing the valves via hydraulic pressure are installed for each cylinder. An electromagnetic switching valve is disclosed that controls the hydraulic pressure guided to an oil passage communicating with the cam switching drive means of each cylinder in accordance with engine operating conditions.

(Problem to be Solved by the Invention) However, in such a conventional device, the oil pressure of the cam switching drive means provided for each cylinder is low! Since the adjustment is performed by a single electromagnetic switching valve, it takes a long time to return the hydraulic oil that flows out when the cam switching drive means operates to the oil pan side, which worsens the switching response of the cam. was there.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a valve actuation Ha in which a cam switching operation is quickly performed.

(Means for solving the problem) This invention has different valve lift characteristics! Each cylinder is equipped with a cam and a cam switching drive means for switching the valve list characteristics involved in the opening/closing operation of the valve, and is equipped with an oil passage communicating with each cam switching drive means, and the hydraulic pressure guided to this oil passage. Hydraulic pressure liI is controlled according to engine operating conditions.
In a valve actuation device for a multi-cylinder engine equipped with g means,
A check valve that can open the oil passage to the drain side is provided in the oil passage, and a return spring is provided that biases the check valve in the opening direction. The drain side is closed at the same time, and the drain side is opened when the hydraulic pressure drops beyond a predetermined value.

(Function) When the hydraulic pressure in the oil passage is increased by the operation of the oil pressure adjustment means in accordance with the engine operating conditions, the check valve closes the drain side and pressurizes the cam switching drive means provided for each cylinder. Oil is supplied, and the cams are switched in response to this hydraulic pressure.

On the other hand, if the hydraulic pressure in the oil passage decreases beyond a predetermined value due to the operation of the oil pressure adjustment means, a check valve opens the oil passage to the drain side, and a check valve is provided for each cylinder. The hydraulic oil flowing out from the cam switching drive means can be quickly returned to the drain side to improve the cam switching response (Example) As shown in Figs. 1 and 2, the main roto arm 1 is The swinging tips come into contact with the two intake valves 9 and can slide against the low-speed cam 6 which has a relatively small profile, while the sub rocker arms 2 provided on both sides of the main lower arm 1 come into contact with the intake valves 9. It has no contact area, and slides into contact with the high-speed cam 7 having a relatively large profile due to the biasing force of the lost motion spring 3.

As shown in FIG.
In the restraining position where the two are fitted together, the double-ended hook arm 1,
2 swing together and drive each intake valve 9 to N close according to the profile of the high speed cam 7. At this time, the main farm 11 is floating above the low speed cam 6 which has a relatively small profile.

On the other hand, each sub-rocker arm 2 is separated from the main lower arm 1 due to the biasing force of each spring 4, and the recess 1
In the non-restricted position where the fitting between a and the convex portion 2a is released, the double-ended hook arms 1 and 2 swing independently from each other, and the low-speed cam 6
Each intake valve 9 is driven to open and close according to the feel of the valve.

As a cam switching drive means for switching each cam 6.7,
Oil chamber 10 that expands and contracts as each sub-rocker arm 2 moves
is defined, and when the hydraulic pressure led to the oil chamber 10 increases by 1 beyond a predetermined value, each sub-rocker arm 2 releases each spring 4.
When the sub-rocker arm 2 moves to the restraining position against the
It is held in the unrestricted position by the urging force of.

This four-cylinder engine is equipped with the above-mentioned cam switching drive means for each cylinder, and has a main oil passage 11 passing through the lower oak +7 and 8.
The four branch oil passages 12 are divided into four branch oil passages 12 which communicate with the oil chamber 10 provided in the cam switching device of each cylinder.

The main oil passage 11 is connected to the discharge side passage 15 of the oil reservoir 34 via the electromagnetic switching valve 13 as a hydraulic pressure IIg means for controlling the working oil pressure of the main oil passage 11 according to the engine operation conditions.
It is selectively connected to a drain passage 17 communicating with an oil pan 16.

A mount control unit (not shown) that electronically controls the switching operation of the electromagnetic switching valve j3 receives an engine rotation signal, a cooling water temperature signal, a lubricating oil temperature signal, a supercharging pressure signal of U-air from the supercharger, and an opening of the throttle valve. The low-speed cam 6 and the high-speed cam 7 are smoothly switched while suppressing rapid fluctuations in the engine torque based on these detected values.

As is the gist of the present invention, a check valve 18 communicating with a drain passage 19 is provided at one end of the main oil passage 11.

As shown in FIG.
0 and provided at both ends of the housing 20.
A return spring 24 is installed in the valve seat 21 @ to bias the check valve 18 in the opening direction.

As shown in FIG. 5, one valve seat 22 has four protrusions 25 on which the check valve 18 is seated, and as shown in FIG. In the valve open position where the main oil passage 11 is seated, the hydraulic oil in the main oil passage 11 flows out into the drain passage 19 through the gap between the check valve 18 and the valve seat 22 and the through hole 30 in the valve seat 21.

The other valve seat 21 has a conical seat surface 26 , and in the closed position where the check valve 18 is seated on the seat surface 26 , the through hole 30 is closed and the hydraulic oil flows from the main oil passage 11 to the drain passage 19 . It is designed to prevent leakage.

The return spring 24 has one end seated on the check valve 18 and the other end seated on the valve seat 21.

The spring constant and initial contraction amount of the return spring 24 and the opening length of each valve seat 21 and 22 are set arbitrarily, and the oil pump 1 is connected via the electromagnetic switching valve 13.
In the operating state in which the discharge pressure of No. 4 is led to the main oil passage 11, as shown in FIG. In an operating state in which the main oil passage 13 is communicated with the drain passage 17 via the electromagnetic switching valve 13 while blocking the hydraulic oil flowing into the drain passage 19, the return valve is in the fully extended state as shown in FIG. The hydraulic pressure received by the check valve 18 is smaller than the biasing force of the spring 24, and the hydraulic oil is allowed to flow out into the drain passage 19.

Next, the effect will be explained.

During high load or high speed operation of Ennon, use solenoid switching valve 1.
When the discharge pressure of the oil pump 14 is introduced to the main oil passage 11 through the main oil passage 11 through the main oil passage 11, the check valve 18 resists the return spring 24 and blocks the hydraulic oil flowing out to the drain passage 19, as shown in Fig. 14. High-pressure hydraulic oil is supplied to each oil chamber 10, and each sub-rocker arm 2 moves to a restraining position where it is integrated with the main lower arm 1 against each suspension ring 4, thereby following the profile of each high-speed cam 7. Each intake valve 9 is driven to open and close.

When switching from the high-speed cam 7 to the low-speed cam 6 due to a decrease in engine speed or load, the electromagnetic switching valve 1
3, the oil pump 14 is connected to the main oil passage 11.
When the discharge side passage 15 of the main oil passage 11 is blocked and the r lane passage 17 is opened, each oil chamber
0 hydraulic oil flows into the main oil passage 11, and each sub-rocker arm 2 moves to an unrestricted position where it can swing independently of the main lower arm 1 due to the biasing force of the spring 4. Each intake valve 9 is driven to open and close according to the profile.

At this time, as the hydraulic oil in the main oil passage 11 begins to flow out to the drain passage 17 via the electromagnetic switching valve 13,
As shown in the figure, the hydraulic pressure applied to the check valve 18 becomes smaller than the biasing force of the return spring 24 in the most expanded state, and the check valve 18 is moved to the open position by the biasing force of the return spring 24. As a result, the main oil passage 11
Since the empty hydraulic oil flows out from the two directions of the switching valve 13 and the check valve 18, the hydraulic oil in each oil chamber 10 is quickly flowed out, and the switching from the high speed cam 7 to the low speed cam 6 is performed. The required opening time can be shortened.

Next, another embodiment shown in FIGS. 7 and 8 will be described. Between one main rocker arm 41.42 whose swinging tip abuts each intake valve 9 and each main rocker arm 41.42. A sub-rocker 7-arm 43, which is provided in the main rocker arm 41 and has no contact portion with each intake valve 9, is swingably supported by a common rocker shaft 47, and a low-speed cam 6 is mounted on each main rocker arm 41 and 42, respectively. Sub rocker arm 4
A high-speed cam 7 having a relatively larger profile than the low-speed cam 6 is slidably contacted with each of the high-speed cams 1 and 1.

At a swinging position a predetermined distance 1It111 from the rocker shaft 47, in a direction parallel to the rocker shaft 47, a cylindrical blunt gear 45.46 that responds to hydraulic pressure slides across each rock arm opening 41, 43.42. Each plunger 45 is movably provided in the lower arm 41, 43, 42.
In the restraint position where each rocker arm 41,
43 and 42 swing together to open and close each intake valve 9 according to the profile of the high-speed cam 7. At this time, each main loaf 41 is lifted from the low-speed cam 6 having a relatively small profile.

In addition to this, each blunt 45.46 is a spring 4
In the unrestricted position in which the arms 41, 43 are accommodated by the biasing force of 8, the arms 41, 43, 42 of each port 7 swing independently of each other, and each intake valve 9 follows the profile of the low-speed cam 6. Drives opening and closing.

As a cam switching drive means for switching each cam 6.7,
An oil chamber 49 is defined at one end of the plunger 45.
When the hydraulic pressure led to the hydraulic pressure 9 increases beyond a predetermined value, each plunger 45, 46 moves to the restraining position against the spring 48, and when the hydraulic pressure decreases beyond the predetermined value, the plungers 45 and 46 move to the restraining position due to the biasing force of the spring 48. held in an unrestrained position.

This multi-cylinder ennon is equipped with the above-mentioned cam switching device for each cylinder, and the main oil passage 50 passing through the rocker shaft 47 has a plurality of branch oil passages communicating with an oil chamber 49 provided in the cam switching position of each cylinder. 51 branches, and the working oil pressure is guided to each oil chamber 49, which is adjusted in two stages according to operating conditions via an oil pressure adjusting means (not shown).

In the case of this embodiment, a check valve 18 is provided for each cylinder, which communicates one end of each oil chamber 49 with the drain side (oil pan side). As in the previous embodiment, the check valve 18 closes the return spring 2 when the hydraulic pressure is higher than a predetermined value.
4, the drain side is closed, and the drain side is opened when the temperature drops below a predetermined value.

When the engine is operating under high load or at high speed, high-pressure hydraulic oil is supplied to each oil chamber 49 via an electromagnetic switching valve (not shown), and each plunger 45, 46 moves to each main lower arm 41.
42 and the sub-rocker arm 43 are integrated into a restraining position, the profile of the high-speed cam 7 is
Each intake valve 9 is then driven to open and close.

When switching from the high-speed cam 7 to the low-speed cam 6 due to a decrease in engine speed or load, the main oil passage 50
As the hydraulic pressure decreases, the hydraulic oil in each oil chamber 49 flows into the main oil passage 5.
At the same time, the hydraulic oil in each oil chamber 49 directly flows out from each check valve 18 to the oil pan side, so that the hydraulic oil in each oil chamber 49 quickly flows out, and the high-speed cam 7 The time required for switching from to low speed cam 6 can be further shortened.

(Effects of the Invention) This invention provides a plurality of cams with different 7F characteristics and a valve L! ? ! Each cylinder is provided with a cam switching drive means for switching the cams involved in the closing operation, an oil passage communicating with each cam switching drive means, and a hydraulic pressure adjustment means for controlling the operating hydraulic pressure of the oil passage according to the engine operating conditions. In the valve operating device for a multi-cylinder ennon, a check valve is provided that communicates the oil passage with the drain side, and the check valve closes the drain side when the working oil pressure of the oil passage is higher than a predetermined value, and closes the drain side when the hydraulic pressure of the oil passage is higher than a predetermined value. When descending, the drain side is configured like a leapfrog, so the hydraulic oil flowing out from the cam switching drive means for each cylinder is quickly returned to the drain side, increasing the cam switching response and reducing the engine noise that occurs when switching the cam. It can reduce torque shock and improve the drivability of automobiles, etc.

[Brief explanation of drawings]

Fig. 2 is a configuration diagram of a valve operating device showing an embodiment of the second invention;
Figures 2 and 3 are cross-sectional views, Figure 4 is a cross-sectional view of the check valve in the closed position, Figure 5 is a front view of the valve seat, and Figure 6 is a cross-sectional view of the check valve in the open position. It is a diagram. FIG. 7 is a sectional view of the valve actuating device showing another example of the top and bottom;
FIG. 8 is also a perspective view. 1...Main rocker arm, 2...Sub rocker arm, 6...Low speed cam, 7-...High speed cam, 9...
・Intake valve, 10...Oil chamber, 11...Main oil passage, 12
... Branch passage, 13 ... Solenoid switching valve, 14 ... Oil pump, 16 ... Oil pan, 18 ... Check valve, 21.22 ... Valve seat, 24 ... Return spring . Figure 8

Claims (1)

[Claims] Each cylinder is equipped with a plurality of cams that have different valve lift characteristics for a common valve, and a cam switching drive means that uses hydraulic pressure to switch the valve list characteristics involved in opening and closing the valve. In a valve actuation device for a multi-cylinder engine, the valve actuation device for a multi-cylinder engine is provided with an oil passage that communicates with the oil passage and a hydraulic pressure adjustment means that controls the hydraulic pressure led to the oil passage according to engine operating conditions, in which the oil passage can be opened to the drain side. A check valve is provided in the oil passage, and a return spring is provided that biases the check valve in the opening direction.The check valve closes the drain side when the hydraulic pressure in the oil passage is higher than a predetermined value, and is also activated. A valve operating device for a multi-cylinder engine, characterized in that the drain side is opened when oil pressure decreases beyond a predetermined value.