JPS61118510A - Timing mechanism of variable valve for internal combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a variable timing mechanism for an internal combustion engine.

[Prior art]

As is well known, varying the opening and closing of exhaust and intake valves provides desirable advantages. For example, by opening the intake valve earlier and closing it later, and opening the exhaust valve earlier, the output can be increased at high speeds. At low speeds, the same effect can be achieved by delaying the opening of the exhaust valves to reduce the overlap of valve openings;
Furthermore, the amount of exhaust gas emissions is reduced.

British Patent Specification No. 1,522,405 makes a proposal for changing the timing of the valve. In that proposal, each cylinder is provided with a separate camshaft and the camshafts are driven eccentrically.

Eccentricity can be changed to change valve timing. The camshafts are driven by a gear located between the centers of the two camshafts, which results in an undesirably high height of the valve gear cover.

Another proposal for varying valve timing is made in British Patent Specification No. 2,066.361.

In that proposal, a separate camshaft for each cylinder is coupled to a drive shaft located along the length of the cylinder head inside the hollow camshaft. The drive shaft reciprocates to drive the camshaft with varying degrees of eccentricity. Since the camshaft is driven by a gear provided on the outside of the valve gear cover, the valve gear cover can be lowered, but the length of the cylinder head is limited by the means for connecting the camshaft to the drive shaft. become longer.

[Summary of the invention]

The present invention includes a valve actuating cam on a hollow camshaft mounted for rotation, and a shaft extending through the hollow camshaft and driving the camshaft, the shaft being aligned with the axis of rotation of the cam. the shaft is capable of reciprocating motion relative to the camshaft, and the shaft has a lateral projection, the projection driving the camshaft with varying degrees of eccentricity as the shaft is moved to vary the timing of the valve. provides a variable valve timing mechanism for an internal combustion engine that is coupled to a cam lobe.

By using cam lobes as part of the means for connecting the drive shaft and the individual camshafts, the length of the cylinder head can be shortened and the height of the valve gear cover can be reduced by
This can be lower than the prior art disclosed in J Book No. 1, 522, 405.

It is advantageous to mount two cams on the camshaft and to arrange the bearing for the camshaft between the two cams.

Advantageously, a separate camshaft is provided for each cylinder. Each camshaft can have one cam to change the timing of a single valve (intake or exhaust valve), or to operate an intake and exhaust valve, or to operate a pair of exhaust valves. Therefore, each camshaft should have two
Attach multiple cams. When operating a pair of exhaust valves, separate cams are provided for each cylinder such that one camshaft is provided for a pair of intake valves and one camshaft is provided for a pair of exhaust valves. A shaft can be provided.

It is advantageous to provide a slot in the cam lobe or preferably in the lateral projection. Into the slots are received slides that are respectively connected to cam lobes or transverse projections. The slider transmits the rotational drive force, yet is free to make the necessary relative radial movements.

The lateral projection can be provided on an arm extending from a sleeve that is fixed to the shaft. A protrusion can be provided at each end of the sleeve.

Each protrusion is connected to a cam lobe for a different cylinder's valve.

The invention can be used in spark ignition or compression ignition engines.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

The illustrated engine is a closed cylinder series engine with two intake valves and two exhaust valves in each cylinder.

A variable valve timing camshaft mechanism is provided for all intake valves, and a separate variable valve timing camshaft mechanism is provided for all exhaust valves.

The figure shows parts of the mechanism for the intake valve. The parts of the mechanism for the exhaust valve are the same.

The mechanism for the intake valve consists of a drive shaft, indicated generally by the reference numeral 1, a hollow camshaft 2, 3 for the two adjacent cylinders, and an intermediate drive member driving the camshaft from the drive shaft. 4
Equipped with. The cam lobe of the camshaft 2.3 operates the tappet (not shown) in the normal direction.

The drive shaft 1 has a serrated section 5, and the intermediate drive member 4 is also provided with a serrated section 6 inside, so that the two mesh with each other.

The intermediate drive member 4 consists of a sleeve 1 having internal serrations and two transverse integral ridges 8, 9 extending in the radial direction of the shaft 1. The sleeve I is mounted within the bearing 10. The bearing 1o is moved to the arrow 11 by means to be described later.
．． It can move in 12 directions.

The inner diameter of each hollow camshaft 2, 3 is large enough to allow the drive shaft 1 to move laterally. Each hollow camshaft 2.
3 has a pair of identical cam lobes 13 and 14 (14 not shown), respectively.

Each hollow camshaft 2, 3 has a fixed bearing l/Using 1! It can be rotated to + and 16, respectively.

The cam lobes 13.14 are each connected to the transverse projections 8.9 by pin and slot joints. The structure of the connection is shown only with respect to the cam lobe 13. Therefore, the pin I is inserted into the hole of the cam lobe 13.
T is inserted. The pin is also inserted into the hole 1B of the square slider 19. The slider 1S can freely slide in a radial slot 20 provided on one side of the transverse projection 8 (FIG. 3). Further, the slider 19 can vibrate relative to the pin 1T about the axis of the pin 1T.

When the axis of the drive shaft 1 coincides with the axes of the hollow camshafts 2 and 3, the angular velocity of the camshaft is harmonized with the angular velocity of the drive shaft 1. When the bearing 10 is moved in the direction of the arrow 11.12, the axis of the drive shaft 1 no longer coincides with the axis of rotation of the camshaft.

The timing of the valves is then changed since the angular velocity of the camshaft is no longer in harmony with the angular velocity of the drive shaft 10.

Next, refer to FIG. A bearing housing 10 is mounted in a pivotable housing 21. The shaft 22 to be fixed is inserted into the hole at one end of the housing 21, and the no.
A cut 23 is provided at the other end of the housing 21. An eccentric member 24 attached to the fixed shaft 25 is inserted into the cut 23.

The housing 10 moves in the direction of the arrow it, 12 when the shaft 25 is turned and the eccentric acts on the incision.

Although only one intermediate drive member 4 has been shown, it is clear that in the case of a closed-cylinder engine one additional intermediate drive member must be provided between the two other 7-cylinder strain shafts. be. Other intermediate drive members have equivalent bearings and housings 1
It is installed inside the 0. .

The bearing housing 1G is mounted inside an equivalent pivotable housing 21. The shaft 22, 1.25 extends over the entire length of the cylinder head through the bearing housing and the housing, so that when the control rod 25 is twisted, both bearing housings move toward each other in the same orientation 11.12. Moved in harmony.

The drive shaft 1 has one end (not shown) driven by a pulley driven by a belt.

The lateral projections 8, 9 of the intermediate drive member 4 are connected to the cam lobes 13.
．． 14, so that the packet
Note that tappets can be used.

It is also possible to reduce the length of the cylinder head compared to that disclosed in GB 2,066.361, since the cam lobe is the means for coupling the camshaft to the drive member. It should also be noted that it constitutes a part of the

The intermediate drive member 4 is made of metal, and the slider 19 can be made of metal or synthetic material.

As previously mentioned, a structure similar to that described above is used for the exhaust valve.

It goes without saying that the embodiments of the present invention described above may be modified in various ways without departing from the gist of the present invention. For example, instead of driving the hollow camshaft 3 in only one cam lobe, as described above, between the two central cylinders, so that the hollow camshaft 3 can be driven in each rope by appropriate pins and transverse projections. A third intermediate drive member can be provided. If desired, each cam lobe of each hollow camshaft can be driven by a separate pin in order to reduce the stress on the hollow camshaft.

The cam lobe can also act via the rocker arm if desired.

The structure described above can be used with any number of in-line or opposed cylinders, or with V-shaped cylinder banks, or with any configuration of cylinders. Furthermore, if desired, this variable valve timing mechanism can be provided only on the intake valve or only on the exhaust valve, and the engine has 91 intake valves and one exhaust valve in a cylinder machine, or a pair of intake valves in a cylinder machine. It can also be used on engines that have a valve and a pair of exhaust valves.

Furthermore, in place of the hollow cam shaft 2.3 that supports a pair of intake valve cams or a pair of exhaust valve cams for each cylinder,
Each camshaft can support one intake valve cam or one exhaust valve cam for each cylinder. That is,
Two valves can be provided per cylinder.

Finally, the invention can be used in compression ignition engines as well as spark ignition engines.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a part of the valve timing mechanism of the present invention;
Figure 2 is a cross-sectional view taken along line 2-2 in Figure 1, and Figure 3 is a cross-sectional view along line 2-2 in Figure 1.
Figure 4 is an exploded perspective view of a portion shown in Figure 1.
FIG. 2 is a cross-sectional view taken along line 4--4 of FIG. 1 shown on a smaller scale; 1... Drive shaft, 2, 3... Hollow camshaft, 4...
...Intermediate drive member, γ...Sleeve, 8.9...
- Lateral protrusion, 1o... Bearing, 13.14...
-Cam lobe, 15.16...fist/bearing housing, 1
7... Φ pin, 19... slider, 21 Φ...
Swingable housing, 22.25@...fixed shaft, 2
3. Musical accompaniment 11e cut, 24... eccentric member.

Claims (9)

[Claims] (1) A valve operating cam mounted on a hollow camshaft so as to be rotatable, and a shaft for driving the camshaft, the shaft being able to reciprocate with respect to the rotational shaft of the cam, and the shaft being horizontal. a directional protrusion, the protrusion being coupled to the cam lobe to drive the camshaft with varying degrees of eccentricity as the axle is moved to vary the timing of the valve; Variable valve timing mechanism for internal combustion engines. (2) The mechanism according to claim 1, wherein the camshaft supports two cams, and the bearing of the camshaft is disposed between the two cams. (3) The mechanism according to claim 2, characterized in that one cam is for operating an intake valve, and the other cam is for operating an exhaust valve. Mechanism to do. (4) A device according to claim 2, characterized in that both cams are for intake valves or exhaust valves. (5) A mechanism according to any one of claims 1 to 4, characterized in that each cylinder has a separate camshaft. (6) The mechanism according to claim 5, characterized in that each cylinder is provided with two camshafts in order to change the valve timings of the intake valve and the exhaust valve separately. (7) A mechanism according to claim 5 or 6, wherein the camshafts are adjacent to each other by an intermediate drive member, each of which has an integrally formed lateral protrusion and includes a sleeve surrounding the driveshaft. A mechanism characterized by being driven. (8) The mechanism according to any one of claims 1 to 7, wherein the transverse protrusion or the cam lobe is provided with a slot, and a slider is fitted into the slot, and the slider is fitted into the slot. A mechanism characterized in that it is connected to a cam lobe or a lateral projection, respectively. 9. The mechanism of claim 8, wherein the slider is engaged with a pin, the pin extending through the lateral projection or cam lobe.