JPS631705A - Valve operating timing varying device for engine - Google Patents

Abstract

PURPOSE:To unnecessitate a large operating force and reduce the power loss of an engine by applying tension of a timing belt applied to a swing arm in a direction of arrangement of an eccentric pin and its support shaft when the swing arm is positioned at a swing limit. CONSTITUTION:In an engine operation at low speed and low load, a rod 32 is pushed by a diaphragm device 31 to rotate an arcuate gear 33 clockwise and rotate a pinion 34 counterclockwise. As a result, an eccentric pin 35 is moved upwardly, and the eccentric pin 35 and an axis of its support shaft are arranged on a circle about a center of swing of the swing arm 18, thereby swinging the swing arm 18 counterclockwise. Then, a roller 17 of a left cylinder train is tightened, and accordingly a timing belt 16 is relatively moved to the roller 17 to thereby rotate each intake cam gear 13 counterclockwise. As a result, an opening timing of an intake valve is retarded to shorten an overlap period between the intake valve and an exhaust valve.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention presses the outer surface of a timing belt wound between a crankshaft and two intake and exhaust camshafts to control the operation of the intake valve and exhaust valve. This relates to the improvement of a variable valve timing device that changes the phase, and in particular, in a device in which this variable device is operated by a reciprocating drive means such as a diaphragm device or a solenoid device, the tension of the belt that acts as a reaction force on the reciprocating drive means. The present invention relates to a device that reduces as much as possible.

[Conventional technology and its problems]

Generally, in a four-stroke engine, in order to adjust the opening and closing timing of the valves, separate camshafts are provided for intake and exhaust, and pressure is applied to the outer surface of a timing chain or belt wound on the intake side. A device for changing the phase of this exhaust camshaft has been proposed (for example, Japanese Utility Model Application Publication No. 57-92807).

However, the diaphragm, solenoid, or 1! that presses the belt in the timing chain! It uses motivation, etc.

Therefore, not only when changing the opening and closing timing of the valve, but also when maintaining it in a specific state, a large operating force is constantly required to counteract the reaction force from the belt, resulting in a large power loss for the engine. occurs.

[Object of the invention, characteristics of the structure]

The purpose of this invention is to eliminate the above-mentioned problems and reduce power loss as much as possible at times other than when changing the phase of the camshaft. It is equipped with an intake camshaft and an exhaust camshaft, and presses a cola supported by a swinging arm onto the outer surface of a timing belt wound around one of the camshafts. An eccentric cam mechanism is provided, which includes a support shaft having an eccentric pin engaged with the support shaft, and the support shaft is connected to an actuation shaft that is linked to an actuation means, and at least the swinging arm swings on one side and the other side. The device is characterized in that when the device swings at limit 1, the axes of the eccentric pin and its support shaft are set to lie approximately on a circle centered around the center of swing of the swing arm.

[Effect]

At least when the swinging arm is at its swinging limit position, the tension of the timing belt acting on the swinging arm via the pulley is:
Since the force acts in the direction in which the eccentric pins and their support shafts are arranged, no force acts on the eccentric pins to resist the force that operates them.

[Embodiment 5A] Hereinafter, the present invention will be explained with reference to the illustrated embodiment. In Fig. 2, 1 is a ■-shaped six-cylinder engine, and two cylinder rows R1L each having three cylinders are provided. . The cylinder has a cylinder hole 2a formed in the cylinder block 2,
Cylinder head 3 and cylinder hole 2a covering its upper surface
It includes a combustion chamber 5 consisting of a piston 4 fitted into the combustion chamber 5. 6 is a crankshaft, and 7 is a connecting rod.

■Intake passage 8 is on the inside of the bank, and exhaust passage 9 is on the outside.
are open and connected to the combustion chamber 5 via an intake valve 8a and an exhaust valve 9a, respectively.

11 is an intake camshaft that opens and closes the intake valve 8a, and 12 is an exhaust camshaft that opens and closes the exhaust valve 9a.

A drive system for the intake camshaft 11 and the exhaust camshaft 12 is shown in FIG. An intake cam gear 13 and an exhaust cam gear 14 are attached to each shaft 11, 12, and a timing belt 16 is wound between them and a timing gear 15 attached to the crankshaft 6. Although a toothed belt is shown as the timing belt 16 in this example, it goes without saying that a chain may be used instead. Also, the arrow on the outside of the timing gear 15 indicates the crankshaft 6.
indicates the direction of rotation.

In this invention, the timing belt 16 is connected to the intake cam gear 13.
The exhaust cam gear 14 is drawn into the crankshaft 6 side through the space between the exhaust cam gear 14 and wound around a roller 17 provided there. 18
a is an idle roller.

The roller 17 is connected to the swinging arm 18 as shown in FIGS. 7 and 8.
It is rotatably supported via a ball 17b by a support @17a protruding from the support. The swinging arm 18 is swingably supported by a bolt 21 via a collar 19 supported on the cylinder block 2 and a ball bearing 20, and is connected to two guide holes 22 provided near the roller 1T. The other bolt 23 provided prevents bending due to the tension of the belt 16.

That is, the bolt 23 is screwed onto the mounting seat 24 provided on the cylinder block 2 through a flanged collar 25 made of hard synthetic resin and a washer 26 made of hard synthetic resin, and the collar 25 only slides into the guide hole 22. The fit is as precise as possible.

The swinging arm 18 is actuated by an actuating device. In this embodiment, the actuating device consists of a diaphragm device 31 and an eccentric cam mechanism C, including an arcuate gear 33 connected via a rod 32, and a pinion 34 meshing with the arcuate gear 33.
including. The pinion 34 is supported by a support shaft S, and an eccentric pin 35 is provided on the opposite end surface of the pinion 34, and the support shaft S also functions as the support shaft S of the eccentric pin 35. This connection between the eccentric pin 35 and the swinging arm 18 is made up of a long hole 36 and a hard synthetic resin slider 3T slidably fitted into the long hole 36, and the eccentric pin 35 is inserted into the hole 37a provided in this. are playing together. In this way, the long hole 36, the eccentric pin 35, and the pinion 34 form an eccentric cam.

Mechanism C is configured.

In addition, the diaphragm device [31 is a computer (
(not shown).

As the actuating device, it is also possible to use an electric motor M instead of the diaphragm device 31. An example of this is shown in FIG.

Next, to explain the operation of this valve mechanism, when the engine starts and the crankshaft 6 rotates in the direction of the arrow, the timing belt 16 and the gears 13 and 14 driven by it
rotate in the same direction.

When the engine is operated in the low speed and low load range indicated by ■ in FIG. 9, the diaphragm device 31 pushes the rod 32 halfway, the arc gear 33 rotates clockwise, and the pinion 34 rotates counterclockwise. As shown in Fig. 3, (il, i
! #As a result of the pin 35 moving upward in the figure, the eccentric pin 35
The axis of the support shaft S is aligned on the circle A with the center of swing of the swing arm 1B as the axis, and the swing arm 18 swings counterclockwise to the limit as far as possible. 7 Roller 1 of cylinder row R
While the tension of roller 7 is relaxed, roller 1 of the left cylinder row
T tension is applied to the timing belt 16 between both rollers 17.
moves relatively from the roller 1T on the right cylinder row R side toward the roller 17 on the left cylinder row, and each intake cam gear 1
3. Rotate 13 counterclockwise. As a result, the opening timing of the intake valve 8a is delayed, and the overlapping period between the intake valve 8a and the exhaust valve 91 is shortened.

Furthermore, when the engine is operated in the high-load, high-speed range shown by ■ in FIG. As a result of the eccentric pin 35 pressing the slider 37 against the left end of the elongated hole 36, as shown in FIG. 4, further rotation is prevented. As a result, the swing arm 18 is prevented from rotating clockwise under the tension of the timing belt 16. Therefore, while the tension on the rollers IT in the left cylinder row is relaxed, the tension on the rollers 17 in the right cylinder row R increases, and as a result, the bacteria-containing belt 1
8 relatively moves from the roller 17 of the left cylinder row to the roller 17 of the right cylinder row R, and each intake cam gear 13.1
3 clockwise to advance the opening/closing timing of the intake valve, that is, to advance the opening/closing timing and expand the overlap period.

Furthermore, when the engine is operated in the medium-low-speed, high-load region indicated by 1 in FIG. As a result of rotating clockwise and moving the i-core pin 35 downward in the figure as shown in FIG. Arranged in a circle with the center as the axis. As a result, the swinging arm 18 swings clockwise to its limit. Therefore, while the tension of the rollers 17 of the left cylinder row B is relaxed, the tension of the rollers 1T of the stone cylinder row R is increased, and the timing belt 16 is moved from the rollers 17 of the left cylinder row to the rollers 17 of the right cylinder row R. , and rotates each intake cam gear 13, 13 clockwise to advance the opening/closing timing of the intake valve, thereby expanding the early tB overlap period.

〔Effect of the invention〕

As described above, this invention includes an intake camshaft and an exhaust camshaft that are driven from a crankshaft via a timing belt, and the timing belt 16, which is wound around one of the camshafts, swings toward the outer surface of the timing belt 16. It is supported by the arm 18 and presses the nine rollers 17, and an elongated hole 36 provided in the swinging arm and an eccentric pin 3 held therein.
An eccentric cam mechanism C consisting of a support shaft S with The axis of the eccentric pin 35 and its support shaft S is set so that when the swing arm swings to the swing limit on both sides, the axis of the eccentric pin 35 and its support shaft S is located approximately on a circle A centered on the swing center of the swing arm. It is. Therefore, when the swinging arm 1B swings and is at its limit position, the tension of the timing belt 16 acting on the swinging arm 18 through the a-' S is lined up on a tangent to a circle A whose axis is the center of swing of the swing arm 18. Therefore, if used in this steady state, the actuating device 30 does not need to resist the tension of the timing belt when maintaining the opening/closing timing of the intake valve at a predetermined timing, and does not require a large actuating force at all times. First, it has the effect of reducing engine power loss.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which reference numeral 111 is a front view of the engine showing the winding state of the timing belt, drawing g2 is a cross-sectional view of the engine, and drawings 3 and 5 are shown in FIG. Fig. 6 is a bamboo perspective view of the main part showing another embodiment, Fig. 7 is a sectional view taken along ■-■ in Fig. 1, and Fig. 8 is a cross-sectional view taken along ■-■ in Fig. 1. -■ sectional view and FIG. 9 are operating characteristic diagrams. 11... Salary intake camshaft, 12... Exhaust camshaft, 1
6... Timing belt, 18@... Rocking arm, 33...
- Single arc gear, 3411...Pinion, 35...
Eccentric pin, 3611...long hole.

Claims (5)

[Claims] (1) An intake camshaft and an exhaust camshaft are driven from the crankshaft via a timing belt, and a roller supported by a swinging arm is attached to the outer surface of the timing belt wound around one of the camshafts. At the same time as pressing, an eccentric cam mechanism consisting of a long hole provided in this swinging arm and a support shaft having an eccentric pin engaged with the long hole is provided, and the support shaft is connected to an operating shaft that is interlocked with the operating means. At the same time, when the swinging arm swings at least to the swinging limits on one side and the other side, the axis of the eccentric pin and its supporting shaft is located approximately on a circle centered around the swinging center of the swinging arm. An engine valve opening/closing timing variable device set as follows. (2) The variable valve opening/closing timing device for an engine according to claim 1, wherein the timing belt is a toothed belt. (3) Claim 1 that the timing belt is a chain
The valve opening/closing timing variable device for the engine as described in . (4) The variable valve opening/closing timing device for an engine according to claim 1, wherein the reciprocating drive means is an electromagnetic solenoid. (5) The variable valve timing device for an engine according to claim 1, wherein the reciprocating drive means is a diaphragm.