JPH0533681A - Valve on-off motion changeover system - Google Patents

Abstract

PURPOSE:To regularize an output torque characteristic in keeping with a variation in engine speed ranging from a low speed range to the high speed one. CONSTITUTION:Low speed cams 47a, 48a, 57a, 58a and high speed cams 47b, 48b, 57b, 58b are all adopted in a cam opening or closing a valve in response to each of cylinders 1-6, thereby making a valve lift value alterable. In addition, an oil feed pipe 9 is connected to the cylinders 1-3 at the lower side via a solenoid valve 11, and the oil feed pipe 9 is connected to other cylinders 4-6 at the upper side via a solenoid 12 in the same manner. With these solenoid valves 11, 12 operated separately, the cam is changed over from the low speed cams 47a, 48a, 57a, 58a to the high speed cams 47b, 48b, 57b, 58b successively, thus the valve lift value is altered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve opening / closing switching method capable of smoothing the shaft torque characteristic of an engine.

[0002]

2. Description of the Related Art Conventionally, in rocker arm type cam devices provided to open and close intake / exhaust valves of OHC (overhead camshaft) type engines for automobiles, etc., rocker arms are mutually connected or disconnected. As a result, the opening / closing timing and opening / closing amount of the intake / exhaust valve corresponding to the operating state are obtained. That is, in such an engine, a high-speed cam that is a high-speed cam and a low-speed cam that is a low-speed cam are equipped on the cam shaft, and the high-speed cam is a cam that can obtain the opening / closing timing corresponding to high-speed operation. With a profile,
The low speed cam has a cam profile that can obtain the opening / closing timing corresponding to the low speed operation. And
By selecting and using one of the high speed cam and the low speed cam, the opening / closing timing of the intake / exhaust valve corresponding to the operating state can be obtained.

According to this method for replacing the cam, the valve operates as shown in the relationship diagram between the crankshaft rotation angle and the valve lift shown in FIG. However, A111 represents the operation of the exhaust valve in the low speed state, C111 also represents the operation of the intake valve, B111 represents the operation of the exhaust valve in the high speed state, and D111 also represents the operation of the intake valve.

FIG. 8 shows the relationship between the engine speed and the shaft torque according to this method. However, F101 represents the shaft torque in the low speed state, F102 represents the shaft torque in the high speed state, and P101 represents the switching point.

[0005]

When performing valve switching of an engine having a plurality of cylinders by the above-mentioned means, each cylinder can be adjusted only as a unit. Therefore,
There is a problem in that a region where the axial torque becomes low occurs near the switching point P101 of the valve, and a flat axial torque characteristic cannot be obtained.

Further, since adjustments such as replacement of all cams are performed at the same time, there is a problem that a large amount of hydraulic oil is required and a hydraulic circuit having a large capacity is required. Since all cylinders are adjusted at the same time, the switching time becomes long and the response is poor.

[0007]

A valve opening / closing switching method according to the present invention operates a cam switching member for switching a cam between a low speed cam and a high speed cam mounted on a cam shaft to operate the engine in a valve open state. In the valve opening / closing switching method for switching according to the state, the cam switching member is divided into a plurality of groups, and the cam switching timing is sequentially shifted for each group to switch the cam between the low speed cam and the high speed cam. It is a feature.

[0008]

The cam switching member is operated to switch the valve open / closed state in accordance with the engine rotation state. In this switching, a plurality of groups forming the cam switching member are individually operated to sequentially switch the cams between the low speed cam and the high speed cam to change the valve open / closed state.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A structure to which an embodiment of a valve opening / closing switching method according to the present invention is applied is shown in FIGS. 1 to 4, and this structure will be described with reference to these drawings.

As shown in FIG. 1, the engine 16 is formed with six cylinders from cylinder 1 to cylinder 6, and a camshaft 41 on the intake side and a camshaft 51 on the exhaust side are cylinders 1 and 2, respectively. , 3, 4, 5, 6
Is supported by the cylinder head 7 so as to correspond to.

Then, the camshaft 41 on the intake side is
Six sets of low-speed cams and high-speed cams are mounted corresponding to the cylinders 1, 2, 3, 4, 5, and 6. The three low speed cams 47a corresponding to the cylinders 1, 2 and 3 have the same cam profile as each other.
The three high speed cams 47b corresponding to 3 are the low speed cams 47a.
The cam profiles are larger and have the same shape. Further, the three low speed cams 48a corresponding to the cylinders 4, 5 and 6 have larger cam profiles than the low speed cam 47a and have the same cam profile, and the three high speed cams 48b are larger than the high speed cam 47b. The cam profiles are the same as each other.

On the other hand, six sets of low speed cams and high speed cams are attached to the exhaust side cam shaft 51 along the cylinders 1, 2, 3, 4, 5, and 6. The three low speed cams 57a corresponding to the cylinders 1, 2 and 3 have the same cam profile and the three high speed cams 57a.
b is a cam profile larger than that of the low speed cam 57a and has the same cam profile. Further, the three low speed cams 58a corresponding to the cylinders 4, 5 and 6 have a cam profile larger than that of the low speed cam 57a and have the same cam profile as each other.
b is a cam profile larger than the high-speed cam 57b and has the same cam profile. The order of ignition of the cylinders is: cylinder 1 → cylinder 5 → cylinder 3 →
The order of cylinder 6 → cylinder 2 → cylinder 4 is set.

On the other hand, as shown in FIG. 1, a hydraulic pump 14 connected to feed hydraulic oil from an oil tank 13 has an oil feed pipe extending to the cylinder head 7 via a check valve 15 and a relief valve 15a. 9 is connected.
Further, the solenoid valve 11 is located in the lower path of the oil supply pipe 9 branched off from the check valve 15, and the solenoid valve 11 is located inside the cylinder head 7 on the cylinder 1, 2, 3 side. Switching between oil supply to and suspension of oil supply.

On the other hand, in the upper path of the oil feed pipe 9,
The solenoid valve 12 is located, and the solenoid valve 12 switches between oil supply to the cylinders 4, 5, 6 in the cylinder head 7 and stop of oil supply. The respective solenoid valves 11 and 12 are connected to the computer 10
The computer 10 controls the operation of the solenoid valves 11 and 12 based on input information such as the engine speed, the oil temperature in the engine, the water temperature, and the intake air amount.

A cam switching member having a structure to which this embodiment is applied is shown in FIGS. 2 to 4 by taking the intake side of the cylinder 1 as an example.
A description will be given based on these figures.

As shown in FIGS. 2 to 4, a low speed cam 47 having a cam profile for low speed operation is provided on a cam shaft 41 which rotates in conjunction with the crankshaft 32 of the engine.
a and a high speed cam 47b as a driving member having a cam profile for high speed operation are arranged in parallel, and these serve as a valve opening / closing member.

The characteristics of the cam profiles for low speed operation and high speed operation are shown by solid lines C31 and D31 in FIG.

On the other hand, a primary rocker arm 64 driven by the low speed cam 47a and a secondary rocker arm 73 driven by the high speed cam 47b are arranged in parallel on the rocker shaft 69 arranged in parallel with the cam shaft 41. There is. The primary rocker arm 64 is pivotally attached to the arm shaft 69 so as to be freely rotatable, but the movement of the lock pin 70 causes the arm shaft 69 to move.
It can also rotate together with.

Further, the arm portion of the primary rocker arm 64 is provided with a shaft 66 on which a roller bearing 65 is mounted, and the upper portion of the roller bearing 65 is engaged with the low speed cam 47a. That is, the primary rocker arm 64 receives the driving force from the low speed cam 47 a via the roller bearing 65 and the shaft 66.

An adjusting screw 67, which is appropriately adjusted in position and fixed by a nut 68, is mounted on the tip of the primary rocker arm 64, and a valve 61 as a driven body is mounted on the lower end surface of the adjusting screw 67. The valve stem upper end 61a of is engaged.
The valve stem upper end 61a is biased obliquely upward in FIG. 2 by the valve spring 62. Therefore, the rotation of the low speed cam 47a causes the primary rocker arm 6 to rotate.
The tip of 4 is swung in the vertical direction in FIG. 2, and the valve 61 is driven vertically through the adjusting screw 67.

On the other hand, the arm portion of the secondary rocker arm 73 is provided with a shaft 74 on which a roller bearing 75 is mounted.
The upper part of the is engaged with the high speed cam 47b. That is, the secondary rocker arm 73 receives the driving force from the high speed cam 47b via the roller bearing 75 and the shaft 74. This secondary rocker arm 73
Is also pivotally supported by the rocker shaft 69, but a secondary rocker arm 73 is fixed by a half-moon key 72 interposed therebetween so that the secondary rocker arm 73 and the rocker shaft 69 always rotate integrally.

Further, the lower end surface of the secondary rocker arm 73 on the swinging end side (that is, the roller bearing 75) is provided with the cylinder head 7 through the piston 76 with the support spring 76a.
The urging force of the support spring 76a acts as a restoring force when the secondary rocker arm 73 swings. Therefore, when the high-speed cam 47b rotates, the rocker shaft 69 is constantly rotated at the same time as the secondary rocker arm 73 swings.

Further, a lock pin 70 is loosely inserted in the rocker shaft 69 so as to be movable in the radial direction of the rocker shaft 69, and a hydraulic passage 69a extending along the axis of the rocker shaft 69 at the center thereof. A hydraulic pressure supply hole 70 b connecting the lock pin 70 and the bottom of the lock pin 70 is formed in the lock pin 70. The hydraulic passage 69a is connected to the oil feed pipe 9, and a spring 71 that pushes the lock pin 70 toward the bottom side is installed in the rocker shaft 69 when the hydraulic oil is not fed from the oil feed pipe 9 side. ..

From the above, when the engine is operating in the low speed range, the hydraulic pressure is not supplied to the hydraulic passage 69a in the rocker shaft 69, so that the lock pin 70 is removed from the rocker shaft 69 as shown in FIGS. It is not projected. Therefore, the primary rocker arm 6
4 is free from the rocker shaft 69, the movement of the rocker shaft 69 is not transmitted to the primary rocker arm 64, and the cam lift of the low speed cam 47a is transmitted to the primary rocker arm 64 via the roller bearing 65 and the shaft 66. Then, the primary rocker arm 64 swings corresponding to the cam profile of the low speed cam 47a.

Since the valve 61 is driven by the swing of the primary rocker arm 64, the valve 61 is shown in FIG.
The reciprocating motion corresponding to the cam profile of the low speed cam 47a as shown in FIG.

On the other hand, when the engine is operated in the high speed range, the hydraulic passage 69a in the rocker shaft 69 is provided.
Hydraulic pressure is supplied to the lock pin 70 and the lock pin 70
It projects from the outer periphery of 9, and enters into the pin lock hole 64a of the primary rocker arm 64 and is fitted therein. As a result, the rocker shaft 69 and the primary rocker arm 64 are fixed so as to rotate integrally.
High speed cam 47 through the secondary rocker arm 73.
Since the drive force (cam lift) from b is received and driven by this drive force, the primary rocker arm 64 is also driven by the cam lift of the high speed cam 47b.

That is, the secondary rocker arm 73 is swung by the high-speed cam 47b, and this swing is caused by the rotation and swing of the rocker shaft 69 to cause the primary rocker arm 64 to move.
It is transmitted as a swing of.

This is as shown in FIG.
This is because the cam lift of b is larger than the cam lift of the low speed cam 47a, and the swing of the primary rocker arm 64 by the high speed cam 47b is prioritized over the swing by the low speed cam 47a. The valve 61 is oscillated corresponding to 47b, and the valve 61 is opened and closed at a timing corresponding to high-speed operation.

Next, a method according to an embodiment using the above structure will be described with reference to FIGS.

FIG. 5 is a relationship diagram between the crankshaft rotation angle and the valve lift according to the switching method of the embodiment. Figure 6
[Fig. 4] is a relationship diagram of engine speed and shaft torque.

As shown in FIG. 5, when the engine 16 is rotating at a low speed, the exhaust valve and the intake valve respectively located on the cylinder head 7 have low speed cams 47a and 48a.
a, 57a, 58a are opened and closed, and solid lines A31, A3
2 shows valve lifts represented by C31 and C32.
That is, the cam profiles of the exhaust cam (valve lift is represented by a solid line A32) and the intake cam (valve lift is represented by a solid line C32) corresponding to the cylinders 4, 5, 6 are the exhaust cams (cylinders 1, 2 and 3) of the exhaust cams ( Solid line A3 for valve lift
1) and intake cam (valve lift is represented by a solid line C31), which are larger than the cam profiles, and the valve lift amount is also high.

The engine speed is, for example, 3000r.
pm-4000 rpm or more and high speed,
The computer 10 detects this, and the cylinders 1, 2, 3
Corresponding solenoid valve 11 and cylinders 4, 5,
The solenoid valve 12 corresponding to 6 is the computer 1
0, the exhaust valve and the intake valve are opened / closed by the high speed cams 47b, 48b, 57b, 58b, and the valve lift is shown by the solid lines B31, B32, D31, D3.
2 is represented.

That is, the valve lift of the exhaust cams of the cylinders 1, 2, 3 is represented by the solid line B31, the valve lift of the intake cams is represented by the solid line D31, and the valve lift of the exhaust cams of the cylinders 4, 5, 6 is represented by the solid line B32. Similarly, the valve lift of the intake cam is represented by the solid line D32.
In this case, by shifting the switching timing of the solenoid valves 11 and 12 based on the rotational speed, it is possible to change the characteristic of the shaft torque while preventing the fluctuation of the shaft torque.

That is, as shown in FIG. 6, the axial torque generated from the cylinders 1, 2 and 3 in the low speed state is indicated by a broken line D1, and the axial torque generated from the cylinders 4, 5 and 6 is also indicated by a dashed line D2. The solid line F1 represents the average value of these shaft torques. Then, as the engine speed increases, first, only the solenoid valve 11 is switched at the switching point P1 to prevent the shaft torque from decreasing. After that, when the engine speed increases and reaches the switching point P2, The solenoid valve 12 is switched to change the characteristic of the shaft torque to the average value of the shaft torque in the high speed state indicated by the solid line F2. The broken line E1 is the axial torque generated on the cylinder 1, 2 and 3 side in the high speed state, and
2 is the axial torque generated on the cylinders 4, 5 and 6 side, and the solid line F3 is the axial torque between the switching points P1 and P2.

As described above, the method of the present embodiment is characterized in that the setting of the switching points P1 and P2 by the solenoid valves 11 and 12 is made to correspond to the engine speed.

That is, the cam switching members are divided into a group operated by the solenoid valve 11 and a group operated by the solenoid valve 12, and the cam switching timing is shifted for each group.

The valve lift position and the valve lift amount in the high speed state in each of the above-described embodiments can be applied as those in the idling state of the engine.

Further, in this embodiment, the cylinders 1, 2,
The solenoid valve 11 controls the cylinders 1, 2, 3 side and the solenoid valve 12 controls the cylinders 4, 5, 6 according to the ignition order of 3, 4, 5, 6.
As a result, the cylinders controlled by the solenoid valves 11 and 12 are scattered, the fluctuation of the engine rotation is reduced, and the cylinders controlled by the solenoid valves 11 and 12 are grouped together, which facilitates the oil layout.

[0039]

According to the valve opening / closing switching method of the present invention, the valve opening state is changed by mutually shifting the switching timings of the low speed and high speed cams in the cylinder head. Fluctuations in shaft torque were prevented even in the high-speed rotation range, and it became possible to obtain flat shaft torque characteristics over the entire range.

Further, since the opening and closing movements of all the valves are not switched at once, the amount of hydraulic oil required at the time of switching is reduced and the switching time of each valve is shortened.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an engine and an oil feeding system to which an embodiment of the present invention is applied.

FIG. 2 is a sectional view of an essential part of an engine to which an embodiment of the present invention is applied.

FIG. 3 is a sectional view taken along the line GG in FIG.

FIG. 4 is a sectional view taken along the line HH of FIG.

FIG. 5 is a relationship diagram between a crankshaft rotation angle and a valve lift according to the switching method of the embodiment of the present invention.

6 is a relationship diagram between the engine speed and the shaft torque in FIG.

FIG. 7 is a relationship diagram between a crankshaft rotation angle and a valve lift according to a conventional method.

FIG. 8 is a relationship diagram between engine speed and shaft torque according to a conventional method.

[Explanation of symbols]

 7 Cylinder Head 9 Oil Pipe 10 Computer 11, 12 Solenoid Valve 13 Oil Tank 14 Hydraulic Pump 15 Check Valve 16 Engine 41, 51 Camshaft 45, 55 Cam Sprocket 47a, 48a, 57a, 58a Low Speed Cam 47b, 48b, 57b, 58b High-speed cam 61 Valve 64 Rocker arm 69 Rocker shaft 70 Lock pin

Claims (1)

Claim: What is claimed is: 1. A valve opening / closing operation for operating a cam switching member for switching a cam between a low speed cam and a high speed cam mounted on a cam shaft to switch a valve open state in accordance with an engine rotation state. In the switching method, the cam switching member is divided into a plurality of groups, and the cam switching timing is sequentially shifted for each group to switch the cam between the low speed cam and the high speed cam. ..