JPS6187913A - Variable cam device for valve opening/closing of internal-combusion engine - Google Patents

Abstract

PURPOSE:To enhance the rate of fuel consumption at low revolving speeds of engine as well as increasing the output at high revolving speeds by moving relatively the contact position of a locker arm with a three-dimensional cam through a shifting mechanism by the muse of a switching means according to the revolving speed of the engine. CONSTITUTION:If, for ex., the engine is operating at a low speed with light load, a changeover control valve 7 of a shifting mechanism A puts the oil supply line 8 in communication with a passage C1, and the oil from the supply line 8 is sent through this passage C1 to flow into a pressure chamber 92 in the cylinder 9. Then the oil in another pressure chamber 91 is exhausted to a drain D2 through a passage C2 to move aside a cam shaft 2 in a certain direction with the aid of a partition wall 10, and then a three-dimensional cam 1 and a locker arm are set in the a-a position. This will lessen the amount of valve lift to lead to shortening of the overlap period in which both the suction and exhaust valves are open. Thus the rate of fuel consumption at a low revolving speed of engine with light load can be enhanced.

Description

[Detailed description of the invention] Industrial application field of the present invention
Regarding the valve opening cam 1 which has a different ∆NJ, moreover, the valve ref h dj and timing can be varied.
This is the bolt that is attached to the variable hm device.

[Prior Art 1] In a 4-cycle engine, there is an overlap period at the end of the exhaust stroke in which both the intake valve and the exhaust valve open at the same time.

This overlap period continues from before the end of the exhaust stroke until the intake stroke, and the length of this period has a large effect on engine performance 17.

In other words, shortening the overlap period improves startability and stability at idle, but it is not possible to obtain sufficient output at high rotations. On the other hand, if the overlap period is made longer, the charging efficiency at high revolutions will be increased and the output will be improved17, but the startability tB and the stable f production at the time of engine 11 will be reduced by 1q.

Therefore, we designed the overlap period to be long during high-speed rotation, and short during low-speed rotation.
For example, is it possible to make the valve closing timing variable depending on the operating condition of the engine?
+1 is already known. but,
The three-dimensional cam used in the device disclosed in this prior art is provided with a rising portion that changes in the axial direction,
Since this rising portion slightly changes in a curved manner in the axial direction, there is a problem in that it is difficult to mold and it is also difficult to obtain a high processing Ha.

[Object of the Invention] In view of the above problems, the present invention uses a simple-shaped three-dimensional cam to make the valve lift and valve timing of the valve train variable, thereby improving output and fuel efficiency. The object of the present invention is to provide a variable cam device for opening and closing an internal combustion (interlayer) valve that is improved as described above.

Structure of the Invention) In order to achieve the above object, the present invention provides a cam ridge that rotates integrally with the camshaft and extends along a line that is inclined at a predetermined angle with respect to the axis of the camshaft in the internal combustion (interlayer valve train 11). A rocker arm having a convex portion that makes point contact with a cam surface of the three-dimensional cam, a moving mechanism that moves the rocker arm or the cam shaft in the axial direction, and a switching means that controls the moving mechanism. The valve lift and timing are made variable by relatively moving the contact position between the rocker arm and the three-dimensional cam according to the engine speed.

[Example] Hereinafter, an example of the present invention will be specifically described with reference to the drawings.

FIG. 1 shows a variable cam device according to the present invention, in which a three-dimensional cam 1 is provided on a cam shaft 2 so as to rotate integrally therewith. The cam ridge of the three-dimensional cam 1 is the cam shaft 2 with the point P as a reference.
Inclined line Y-Y tilted at a predetermined angle θ with respect to the axis x-X of
It is formed in a straight line parallel to the Y-Y line. The three-dimensional cam 1 is movable in the axial direction integrally with the cam shaft 2, and therefore the three-dimensional cam 1 is movable relative to the rocker arm 3. The rocker arm 3 has a convex portion 4 on the contact surface with the cam so that it can slide in point contact with the three-dimensional cam 1 when the three-dimensional cam 1 rotates.
have. In the OHV type efengine valve system, by making the cam contact surface of the tappet a spherical surface, the sliding parts of the three-dimensional cam 1 and the pet can maintain a point contact state.

In FIG. 1 above, the high position of the cam mountain of the three-dimensional cam 1,
In other words, at the bb position, the positional relationship between the rocker arm 3 and the three-dimensional cam 1 is shown when the valve lift m is large and the engine is in a high-speed, high-load state. At the low position, that is, the aa position, the positional relationship between the rocker arm 3 and the three-dimensional cam 1 is shown when the valve lift is small and the engine is in a low rotation and low load state.

Figure 2 shows the a-a position and b- position of the three-dimensional cam 1 in Figure 1.
The figure shows a cross section at position b, where the nom shape indicated by the solid line 5 is the cross section at the bb position, and the cam shape indicated by the dotted line G is the cross section at the aa position. Further, the symbol δ is the difference between the axes of the cam cross sections at the aa position and the bb position.

Fig. 3 shows an example of a moving mechanism for moving the camshaft 2 in the axial direction. This utilizes the supply oil line 8.
The oil supplied from the passage C via the switching control valve 7
1 or passage C2, and brought to the cylinder section 9. The cylinder portion 9 is divided into two chambers, a pressure chamber 91 and a pressure chamber 92, by a partition wall 10 provided on the camshaft 2. One of the pressure chambers 92 is connected to a passage C1, and the other pressure chamber 91 is connected to a passage C1. They are each communicated with C1.

FIG. 4 J5 and FIG. 5 show embodiments of the VJ switching control valve 7 not shown in FIG. 3, and the switching operation of this switching control valve 1 is as follows.

In FIG. 4, a solenoid 14 is provided at the end of the rod 13 of the piston valve 12 and operates by sensing the engine speed and negative pressure in the suction pipe, and the piston valve 12 is further biased by a return spring 11. ing. Therefore, when the engine is at low rotation speed and low load, the piston valve 12 is positioned upward by the solenoid 14, and the oil from the supply oil passage 8 flows into the pressure chamber 92 through the passage C1, and the partition wall 10 is opened as shown in FIG. As the pressure chamber 91 moves to the left, the oil in the pressure chamber 91 is discharged 1111 from the drain D2 via the passage Cz. Therefore, the camshaft 2 moves to the left in FIGS.
The opening/closing characteristics of the I-air valve are shown in △1. in Fig. 6. It will look like A2. The size 41 straw, 111 air valve shows a low lift curve like 1, and the lift curve 4 like suction (8t(+a△,
As shown in the picture, the 111 air valve and the intake valve are open/1
-Haratsuno Akima 3 is short.

Next, in Figure 5, when the engine is at high speed and under high load,
■The piston valve 12 is located downward by the lensoid 14,
The oil from the supply oil passage 8 is pumped through the passage Cz to the pressure iJ chamber 91.
The partition wall 10 moves to the right, and the oil in the pressure bar 92 is discharged to the drain D1 through the passage C1.

Therefore, the cam @2 moves toward J5 in FIGS. 1 and 3, and the rocker arm 3 and the three-dimensional cam 1 are set at the bb position. At this time, the opening and closing characteristics of the valve lift 1 and the intake and exhaust valves are shown in 81 in FIG. It will look like B2.

In other words, since the exhaust valve shows a high lift curve like B1, and the intake valve shows a lift l-curve like Bz,
Overlap period B3 during which the exhaust valve and intake valve are open
is long.

In this embodiment, in J5, the camshaft 2 is moved in the axial direction by movement 1;1i blue, but the cam ll'+
+12 is fixed and the rocker arm is moved by 3 positions to +1
It goes without saying that it may be moved in the direction of 1jh.

This embodiment is configured as described above, so when the engine is at low rotation speed and low zero load, the switching control r (valve opening 7
communicates the supply oil passage 8 with the passage C1, and since oil from the supply oil passage 8 flows into the pressure chamber 92 in the cylinder 9 via the passage C1, the oil in the pressure chamber 91 passes through the passage C2 and drains D2. The camshaft 2 moves to the left in FIG. 3 through the partition wall 10, and the three-dimensional cam 1 and rocker arm 3 are set at the a-a position in FIG.
In J3 in the figure, the valve lift amount is small and the overlap period △3 during which the exhaust valve and intake valve are open is short. Therefore, it is possible to improve fuel efficiency when the engine is running at low speeds and under low load.

Further, when the engine is at high speed and under high load, the switching control valve 7 of the moving mechanism communicates the supply oil passage 8 with the passage C1, and the oil from the supply oil passage 8 passes through the passage C2 and enters the pressure chamber 9 of the cylinder 9.
1, the oil in the pressure chamber 92 flows into the passage C.
The camshaft 2 moves to the right in FIG. 3 through the partition wall 10, and the three-dimensional cam 1 and rocker arm 3 are set at the bb position in FIG. 3.
In FIG. 6, the valve lift amount is large and the overlap period B3 during which the exhaust valve and the intake valve are open is long.

Therefore, it is possible to improve the output when the engine is running at high speed and under high load.

[Effects of the Invention] As described above, the present light includes a three-dimensional cam 1 that rotates integrally with the cam @ 2 and has a cam crest along a line inclined at a predetermined angle to the axis of the cam shaft 2; a rocker arm 3 having a convex portion 4 that makes point contact with the cam surface of the three-dimensional cam 1; a movement mechanism that moves the rocker arm 3 or the camshaft 2 in the axial direction;
It consists of a switching control valve 7 that controls the moving mechanism, and the contact position between the rocker arm 3 and the three-dimensional cam 1 is variable according to the engine speed, and is set to the a-a position when the engine is running at low speeds and under low load. , b-b at high speeds and high loads.
Since the valve lift and timing are made variable by setting the IJI valve to the J3 position, the overlap between the IJI valve and the intake valve can be shortened when the engine is running at low speeds and under low load, improving fuel efficiency and output at low speeds. You can also
When the engine is running at high speeds and under high load, the overlap between the exhaust valve and the intake valve can be lengthened to improve the output at high speeds.

As described above, in the present invention, by using a simple-shaped three-dimensional cam and adding a simple means for moving the rocker arm 3 or the camshaft 2 in the axial direction, it is possible to adjust the speed appropriately according to each rotation from low speed to high speed. Because it is valve timing,
It is possible to improve fuel efficiency and output, and the effects when put into practical use are significant.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the variable cam device for opening and closing a valve according to the present invention, FIG. 2 is a side view of FIG. 1, and FIG. 3 is a moving mechanism for operating the variable cam device according to the present invention. Schematic diagram, Figures 4 and 5 are the switching of Figure 3! 'J lit j
FIG. 6 is a schematic diagram showing an embodiment of i, and FIG. 6 is a valve lift characteristic diagram of the intake and exhaust valves. DESCRIPTION OF SYMBOLS 1... Three-dimensional cam, 2... Cam l1 (1, 3... Rocker arm, 4... Convex part, 7... Switching control valve, 8...
... Supply oil path, 10... Separator, 91.92... Pressure chamber, C1, Cz... Passage. Patent Applicant Fuji Heavy Industries Co., Ltd. Agent Patent Attorney Jundo Nobu Kobashi Patent Attorney Susumu Murai Figure 1 Figure 3 Figure 5 Yoshi Figure 4 ■ Figure 6

Claims (1)

[Claims] a three-dimensional cam that rotates integrally with the camshaft and has a cam ridge along a line inclined at a predetermined angle with respect to the axis of the camshaft; a rocker arm that has a convex portion that makes point contact with a cam surface of the three-dimensional cam;
It has a movement mechanism that moves the rocker arm or camshaft in the axial direction, and a switching means that controls the movement mechanism, and the valve lift is achieved by relatively moving the contact position between the rocker arm and the three-dimensional cam according to the engine rotation speed. and a variable cam device for opening and closing valves of an internal combustion engine, characterized by variable timing.