JPH0417705A - Valve actuating device of multi-cylinder engine - Google Patents

Abstract

PURPOSE:To ease the engine torque fluctuation along with cam switching actuation by providing orifice means for reducing the cross section areas of oil passages at positions between cylinders in the middle of a main oil passage for distributing the specified pressure working oil to a drive means for switching the cams. CONSTITUTION:A main working oil passage 11 is provided to distribute the specified pressure working oil to the drive means for switching the cam of each cylinder according to engine driving state. Orifices 21 to 23 are provided at the positions between junction passages 12 in the middle of the main passage 11 to reduce the cross section areas of oil flow passages. By this constitution, even when a cam is changed-over at a driving point where generated torque is different from each other, the torque generated by the engine steppingly varies for each cylinder. Therefore, the torque shock of the engine generated at the time of switching cams can be reduced.

Description

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

(Prior art) Conventionally, in order to improve the output performance of an engine, it has been possible to vary the intake valve or exhaust valve characteristics depending on the operating condition, and thereby control the exhaust timing or intake/exhaust amount. Are known.

For example, in Japanese Unexamined Patent Publication No. 62-294709, in a multi-cylinder engine, two cams with different valve opening characteristics and a cam switching drive means for switching the cams involved in opening and closing the valves are provided for each cylinder. An oil passageway communicating with a cam switching drive means is disclosed, and the cam is switched for each position in response to pressurized hydraulic oil supplied through the oil passage.

(Problem to be Solved by the Invention) By the way, in such a conventional device, in order to prevent the torque generated by the engine from changing greatly when switching the cams, switching is performed at an operating point where the torque generated by each cam is the same. It needed to be done.

Therefore, the setting of torque characteristics is restricted depending on each cam. For example, one cam is set to a small valve operating angle for low-load operation to improve fuel efficiency, and the other cam is set for high-load operation. If a relatively large valve operating angle is set to correspondingly increase the generated torque, a problem arises in that a large torque change occurs when each cam is switched.

For example, as shown in FIG. 10, there are three cams 1, 2.3 with different valve operating angles, each cam].

If the generated torques according to 2.3 are significantly different from each other, a large torque change will occur when switching from the small working angle cam 1 to the medium working angle cam 2 at a certain rotation speed n. Figure 11 shows the throttle opening change characteristics required when each cam 1, 2, 3 is switched in turn as the generated torque increases at the rotation speed n+, starting with the cam with the larger valve operating angle. When switching to a smaller cam and trying to maintain the generated torque, it is necessary to take in air in a shorter amount of time in response to the shortened valve opening period, and the throttle opening must be increased.

In addition, even if the cam is set to switch at an operating point where there is little change in torque, as in the slave device described above,
There was a possibility that the torque change during cam switching would increase due to deterioration of the valve operating device over time.

The second invention has been made in view of the above-mentioned conventional problems, and aims to provide a valve actuation device that alleviates engine torque fluctuations caused by cam switching operations.

(Means for Solving the Problems) The second invention provides a common valve with a plurality of cams having different valve characteristics, and a cam switching drive that switches the cams involved in the WRwi operation of the valve using hydraulic pressure. A main oil passage is provided for distributing a predetermined amount of pressurized hydraulic oil to the cam switching drive means of each cylinder according to the engine operating conditions. A throttle means is provided between the front cam switching drive means and gradually reduces the cross-sectional area of the flow path along the hydraulic oil pressurizing direction.

(Function) In an operating state where the working oil pressure of the main oil passage is lower than a predetermined value, each valve is switched to #41IP by a predetermined cam via a cam switching drive means provided for each valve. When a predetermined pressurized hydraulic pressure is supplied to the main oil passage depending on the engine operating conditions, this pressurized hydraulic oil passes through the main oil passage to the cam switching drive means provided for each cylinder. The cams are switched in response to this hydraulic pressure.

The throttle means is located in the middle of the main oil passage and gradually reduces the flow passage cross-sectional area along the hydraulic oil pressurizing direction.The throttle means passes through the main oil passage and drives the cam switching of each cylinder. Resistance is applied to the flow of hydraulic oil distributed to the means, thereby delaying the rise of the hydraulic pressure guided to the cam switching drive means of the cylinder located downstream of the throttle means. As a result, the cam switching drive means for each cylinder operates with a predetermined time difference, so even if the cams are switched at operating points where the generated torque is significantly different from each other, the generated torque of the engine will change in stages for each cylinder. This can alleviate sudden torque fluctuations. Furthermore, by making the cam switching time different for each cylinder, there is no need to suddenly change the throttle opening.

(Implementation) Embodiments of the present invention will be described below with reference to the accompanying drawings.

Figures 1, 2, and 3 show an engine with four generosities (1) a valve train in which two power-oriented cams 6.7 are switchably provided for each cylinder; An example in which the present invention is applied will be shown below.

To explain this one point, the main rocker arm 1 has its swinging tip contacting the two intake valves 9, and is also able to come into sliding contact with the low-speed, high-load cam 6 which has a relatively small profile. The two sub-rocker arms 2 provided on both sides of the sub-rocker arm 1 do not have a portion that contacts the intake valve 9, but slide into contact with the high-speed, high-load cam 7 having a relatively large profile due to the biasing force of the lost bone spring 3.

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

On the other hand, each sub-rocker arm 2 is separated from the main rocker arm 1 by the biasing force of each spring 4, and in the unrestricted position where the recess 1a and each protrusion 2a are disengaged, the double-ended lock arms 1, 2 swing independently from each other, and drive each intake valve 9 to open and close according to the profile of the low-speed, high-load cam 6.

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 rises above 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 rocker shaft 8.
Four branch oil passages 12 are branched to communicate with the oil chambers 10 of each cylinder. A plug body 19 is press-fitted into one end of the main oil passage 11.

The main oil passage 11 serves as a hydraulic pressure adjustment means for controlling the working oil pressure of the main oil passage 11 according to engine operating conditions, and the main oil passage 11 is a drain communicating with a discharge side passage 15 of an oil pump 14 and an oil pan 16 via an electromagnetic switching valve 13. The passage 17 is selectively connected to the passage 17.

A control unit (not shown) that electronically controls the switching operation of the electromagnetic switching valve 13 receives an engine diagram 1 signal, a cooling water temperature signal, a lubricating oil temperature signal, an intake boost pressure signal from a supercharger, and a throttle valve opening signal. etc., and the low-speed, high-load cam 6 and the high-speed, high-load cam 7 are switched based on these detected values.

As a gist of the present invention, the main oil passage 11 has three throttle means located between each branch oil passage 12 and arranged between each cylinder in the main oil passage 11 to reduce the cross section of the flow passage. Orifices 21, 22, and 23 are provided, respectively.

The flow passage cross-sectional area of each orifice 21, 22, 23 is formed to gradually decrease along the hydraulic oil pressurizing direction, that is, it is located downstream with respect to the flow of hydraulic oil sent from the electromagnetic switching valve 13 to each cylinder. The smaller the ratio is, the smaller the ratio is set.

The low-speed, high-load cam 6 and the high-speed, high-load cam 7 are each integrally formed on a common camshaft, and are rotationally driven in synchronization with the engine. The low-speed, high-load cam 6 has relatively small valve depth and valve operating angle to improve generated torque in response to low-speed, high-load operation of the engine, while the high-speed cam 7 has a relatively small valve depth and valve operating angle. Both the amount of torque and the valve operating angle are made relatively large in order to improve the generated torque during high-load operation.

Next, the effect will be explained.

When the engine speed or load is lower than the set value ν and under predetermined operating conditions, the main oil passage 11 is closed off from the discharge side passage 15 of the oil pump 14 by the electromagnetic switching valve 13 and communicated with the drain passage 17. The hydraulic pressure led to the oil chamber 10 decreases, and each sub-rocker arm 2 is held in an unrestricted position where it can swing independently from the main rotor arm 1 by the biasing force of the spring 4. Each intake valve 9 is driven to open and close according to the profile shown in FIG.

Under predetermined operating conditions where the engine speed or load is higher than the set value, the electromagnetic switching valve 13 operates to shut off the drain passage 17 from the main oil passage 11, and at the same time, the discharge side passage 15 of the oil pump 14 moves slowly. When high-pressure hydraulic oil is supplied from the main oil passage 11 to each oil chamber 10 through the branch oil passage 2, each sub-rocker arm 2 resists each spring 4 and is restrained to be integrated with the main rotary arm 1. As a result, each intake valve 9 is driven to open and close according to the profile of each high-speed, high-load cam 7.

Orifices 21, 22, and 23 are provided in the middle of the main oil passage 11 to reduce the cross-sectional area of the flow passage by being located between the cylinders. By adding resistance to the flow of the hydraulic oil distributed to the oil chamber 10 of the cylinder, a pressure drop occurs before and after each orifice 21, 22. The rise of the working oil pressure guided to each oil chamber 10 of each cylinder is delayed.

As a result, the hydraulic pressure in the oil chamber 10 of each cylinder rises with a predetermined time difference, and the cylinders closest to the electromagnetic switching valve 13 are switched to the high-speed, high-load cam 7 with a predetermined time difference, so that the torque generated by the engine is reduced. The torque is increased to four levels for each cylinder, and sudden torque fluctuations are mitigated.

Therefore, even if the cams 6 and 7 are set to be switched at a soft point where torque changes are small, it is possible to prevent the torque change at the time of cam switching from increasing due to aging deterioration of the valve actuation device or the like.

Next, we will explain the example of the pond shown in Figure #14.
An oil reservoir chamber 24 having a predetermined volume is provided between each orifice 21, 22, and 23 in the middle of the main oil passage 11.

In this case, high-pressure hydraulic oil is passed from the main oil passage 11 through each branch oil passage 12 to each oil chamber 10 by the operation of the electromagnetic switching valve 13.
When the hydraulic oil is distributed to each oil chamber 24, the hydraulic oil force f passes through each branch oil passage 12 and enters each oil chamber 10 after being filled with hydraulic oil in each oil reservoir chamber 24.
Since the oil flows in, the time difference in cam switching performed between each cylinder can be arbitrarily set depending on the volume of the oil reservoir chamber 24.

Next, another embodiment shown in FIG. 5 will be described. Oil reservoir chambers 24 are provided in the middle of the main oil passage 11 between the orifices 21, 22, 23, and
A check valve 25 is provided which can open each oil reservoir chamber 24 to a drain passage 26.

As shown in FIG. 6, the spherical check valve 25 is housed in a cylindrical housing 30, and is interposed between two valve seats 31 and 32 provided at both ends of the housing 30. A return spring 34 is interposed on the side to bias the check valve 25 in the opening direction.

As shown in FIG. 5, one valve seat 32 has four projections 35 on which the check valve 25 is seated, and as shown in FIG. In the open position where the valve is seated on the protrusion 35, the hydraulic oil from the oil reservoir chamber 24 flows out into the drain passage 26 through the gap between the check valve 25 and the valve seat 32 and the through hole 37 in the valve seat 31. There is.

The other valve seat 31 has a conical seat surface 36 , and in the closed position where the check valve 25 is seated on this seat surface 36 , the through hole 27 is closed, and the hydraulic oil flows from the main oil passage 11 to the drain passage 26 . It is designed to prevent leakage.

The spring constant and initial contraction amount of the return spring 34 and the length between each pulp seat 31 and 32 are set arbitrarily, and the oil pump 1 is
In the operating state in which the discharge pressure of No. 4 is led to the main oil passage 11, as shown in Figure TIJIJ4, the hydraulic pressure received by the check valve 25 becomes greater than the urging force of the return spring 34 in the most contracted state, and the oil pressure is applied to the drain passage. In the operating state in which the main oil passage 13 is communicated with the drain passage 17 via the electromagnetic switching valve 13 while the hydraulic oil flowing out to the drain passage 17 is blocked, the return spring 34 is in the fully extended state as shown in FIG. The hydraulic pressure received by the check valve 25 is smaller than the biasing force of the check valve 25, so that the hydraulic oil flows out into the drain passage 26.

During high load or high speed operation of the engine, the discharge pressure of the oil pump 14 is reduced to the main oil passage 11 via the electromagnetic switching valve 13.
When the check valve 25 is guided to the return spring 3
4 is blocked from flowing into the drain passage 19, high-pressure hydraulic oil is supplied to each oil chamber 10 with a predetermined time difference for each cylinder, and the high-pressure hydraulic oil is supplied to each oil chamber 10 in order from the cylinder closest to the electromagnetic switching valve 13. It is switched to the high load cam 7.

When switching from the high-speed, high-load cam 7 to the low-speed, high-load cam 6 as the engine speed or load decreases,
When the electromagnetic switching valve 13 is activated and the discharge side passage 15 of the oil pump 14 is cut off from the main oil passage 11 and the drain passage 17 is opened, each oil chamber opens as the oil pressure in the main oil passage 11 decreases. 10 hydraulic oil flows into the main oil passage 11, and at this time the check valve 25 opens and the hydraulic oil from the main oil passage 11 quickly flows out through each oil reservoir chamber 24, so that the low speed high load cam 6 The time required for switching can be shortened.

Even in operating conditions where each cam 6.7 is frequently switched,
Since the hydraulic oil is quickly discharged from each oil reservoir chamber 24 via the check valve 25, each orifice 21, 22.2
3, it is possible to secure the time difference in cam switching that occurs between cylinders.

Figures 8 and 9 show one fuel efficiency-oriented cam 1 and two power-oriented cams 2 and 3 for each cylinder in a four-cylinder engine.
1 shows an embodiment in which the present invention is applied to a valve train system in which the valve train is switchably provided.

To explain this, each cylinder is provided with a single rocker arm 81 corresponding to two intake valves 9. The base end of the rocker arm 81 is a rocker shaft 42 common to each cylinder.
The rocker arm 81 is swingably supported by the sill head via the rocker arm 81, and a hydraulic lash annoyaster 51 is provided at the tip of the rocker arm 81 to abut the top of the stem of each intake valve 9.
The valve clearance is automatically adjusted by the hydraulic pressure derived from 2.

A roller 44 is rotatably connected to the shaft 43 via a bearing to the opening 7 arm 81, and the cam 1 is brought into rolling contact with the roller 44.

The rocker arm 81 is formed into a substantially rectangular shape in a plan view, and two movable rollers 82, 83 are provided on the rocker arm 81 in line with the roller 44. Each of these movable 7 orrowers 82.
A base end of the rocker arm 83 is connected to the rocker arm 81 via the sub-rocker shaft 46 so as to be relatively rotatable.

Each movable 7-lower 82.83 does not have a part that comes into contact with the intake valve 9, and at the tip of each movable 7-lower 82.83, a cam 7-year-old lower part that slides into contact with the high-load cams 2 and 3 protrudes in an arc shape. The 7-year-old lower part of each cam is formed on the lower side of each cam 2.
, 3, respectively, are interposed with lost mora springs 45.

The rocker arm 81 is integrally formed with a hole 56 located directly below the movable roller 82 and into which the lost motor spring 45 is inserted. The lower end of the coiled lost motor spring 45 is seated on a stopper 58 fitted in a hole 56, and the upper end is seated on a lower end of the movable 7 lower 82 via a retainer 57 that is slidably fitted in the hole 56. 7
contact with the part.

In addition, the movable 7 lowerer 83 has a similar structure between the rocker arm 81 and the lost mole 1 spring 4.
5 is interposed.

The coupling pin 61 is slidably inserted into the hole formed in the movable 7 lowerer 82, and the coupling pin 6 is inserted into the rocker arm 81.
A coupling pin 63 and a return pin 64 are slidably fitted into two holes formed by sandwiching the return pin 64, and a return spring 68 is interposed behind the return pin 64.

Each coupling pin 61.63 against the return spring 68
An oil passage 67 for guiding hydraulic pressure behind the coupling pin 63 is disposed through the inside of the rocker arm 81 and the rocker shaft 42 as a connecting drive means for moving the movable roller 82 to the restraining position. The hydraulic pressure of the valve is designed to be guided. By holding each coupling pin 61, 63 in a restraining position where it fits across the movable 7 lower 82 and the mouth/two arm 81 by the hydraulic pressure, the mouth 7 lower arm 81 and the movable 7 lower 82 are integrally formed with each other. It sways. Since the coupling pins 61 and 63 are held in the unrestricted position in each hole through the return pin 64 by the biasing force of the return spring 63, the movable 7 lower 82 does not impede the swinging of the rocker arm 81.

The movable 7-lower 83 also has a connecting pin 71, 72, a return pin 73, and a return spring 74 interposed between the rocker arm 81 and the rocker arm 81. 7-m81
and is provided through the inside of the rocker shaft 42.

This four-cylinder engine includes the above-mentioned cam switching drive means for each cylinder, and each oil passage 67 passing through the rocker shaft 8.
．． 76 is selectively connected to an oil pump and an oil pan via an electromagnetic switching valve.

The electromagnetic switching valve is operated by a control unit according to the engine operating state to switch each cam 1.2.3.

As a gist of the present invention, three orifices (not shown) are located between each cylinder and serve as throttling means located between each cylinder in the middle of each oil passage 67, 76 to reduce the flow passage cross section. The cross-sectional area of each orifice is gradually reduced along the direction in which the hydraulic fluid is pressurized.

As a result, when switching from cam 1 to each cam 2 and 3,
The discharge oil pressure of the oil pump is guided to the respective oil passages 67, 76 through switching valves (not shown) to meet predetermined operating conditions, and the resistance provided by each orifice causes each coupling pin 63, 76 of each cylinder to reach a predetermined operating condition.
The hydraulic pressure guided to 72 rises with a predetermined time difference, and is switched sequentially from the cylinder closer to the electromagnetic switching valve with a predetermined time difference, so that the torque generated by the engine is increased in four stages for each cylinder.

Each cam 1, 2, and 3 is integrally formed on a common camshaft, and is designed to satisfy the valve torque characteristics required for engine partial load operation, low speed high load cam, and high speed high load operation. are formed with different profiles.

Therefore, as shown in FIG. 10, each cam 1°2.3
The torque characteristics differ significantly depending on the rotation speed of 11. When the small working angle cam 1 is switched to the medium working angle cam 2, the torque generated by the engine changes from T to T2 in four stages for each cylinder due to the orifices provided in each oil passage 67, 76, and the torque is suddenly changed. Torque fluctuations can be alleviated. Furthermore, by making the cam switching time different for each cylinder, there is no need to suddenly change the throttle opening.

(Effects of the Invention) The present invention provides a valve actuation device for a multi-cylinder engine including a main oil passage that distributes a predetermined pressurized hydraulic oil to the cam switching drive means of each cylinder according to engine operating conditions. Since the configuration includes a curving means that is located between the cylinders and reduces the cross-sectional area of the flow path, even if the cams are switched at points where the generated torque is significantly different from each other, the generated torque of the engine will be the same for each cylinder. It changes in stages to reduce the engine torque shock that occurs when switching the cam, improving the drivability of automobiles, etc.As a result, the degree of freedom in setting the cam can be increased, improving the fuel efficiency of the engine. It is possible to simultaneously improve output performance.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a valve operating device showing an embodiment of the present invention;
2 and 3 are cross-sectional views, respectively. Fourth
The figure is a hydraulic circuit diagram showing another embodiment. FIG. 5 is a hydraulic circuit diagram showing still another embodiment, FIG. 6 is a sectional view of the check valve, and FIG. 7 is a front view of the valve seat. FIG. 8 is a plan view of a valve operating device showing still another embodiment, and FIG. 9 is a cross-sectional view taken along line XX in the figure. FIG. 10 is a torque characteristic diagram for explaining the present invention in detail, and FIG. 11 is a throttle opening characteristic diagram. 1...Rocker arm, 2--sub rocker arm, 6-
...Cam for low speed and high load, 7...Cam for high load, 9...
・Intake valve, ]O...Oil chamber, 11-...Main oil passage, 12
...Branch oil passage, 13...Solenoid switching valve, 14...
Oil pump, 21.22.23... orifice. Figure 4 M5F! jA l Figure 6 Figure 10 Figure 11 Shaft torque - Person

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 cams involved in opening and closing the valve. The main oil passage is equipped with a main oil passage that distributes a predetermined pressurized hydraulic oil according to the engine operating conditions, and is located between the cam switching drive means of each cylinder in the middle of this main oil passage to operate the flow passage cross-sectional area. A valve operating device for a multi-cylinder engine, characterized by comprising a throttle means that gradually decreases along the direction of oil pressurization.