JPH0116975B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an internal combustion engine whose compression ratio can be changed with good responsiveness during operation.

[Conventional technology]

In an internal combustion engine, in order to increase its output and reduce fuel consumption, it is sufficient to increase the compression ratio, but increasing the compression ratio causes knocking in the high load range and low rotation range. For this reason, in conventional internal combustion engines with a constant compression ratio, the compression ratio is
Since the value must be set to a value that does not cause knocking in the low rotation range, it is not possible to produce sufficient output and sufficient fuel efficiency in the low load and high rotation ranges.

Therefore, Japanese Patent Application Laid-open No. 54-20220 as a prior art discloses that a sub-piston for increasing or decreasing the volume of the combustion chamber is slidably inserted into a sub-cylinder that opens into the combustion chamber, and the sub-piston is It is proposed that the compression ratio be changed by moving the sub-piston back and forth by supplying and discharging hydraulic oil to and from a hydraulic chamber formed on the back surface of the sub-piston.

In this prior art variable compression ratio internal combustion engine, a hollow stem is integrally connected from the back of the auxiliary piston, and the hollow stem is provided with hydraulic oil in the hydraulic chamber to a portion inside the hydraulic chamber. A spill port is bored into the hollow stem, and a control rod having an oil passage communicating with the atmosphere is slidably inserted into the hollow stem. By moving the auxiliary piston back and forth in response to the load in the internal combustion engine, the opening and closing position of the spill port is displaced in the axial direction of the stem, and the sub piston is moved back and forth. Although it has the advantage of being able to automatically change and control according to the load, it has the following problems.

[Problem that the invention seeks to solve]

That is, in the prior art, the opening/closing position of a spill port in a hollow stem is displaced in the axial direction of the stem by a control rod slidably inserted into the hollow stem, and the control rod is moved back and forth. In this case, the hydraulic pressure in the hydraulic chamber acts to prevent the control rods from moving back and forth, and a large force is required to move the control rods back and forth. The operating mechanism becomes large.

Moreover, the spill port, which is opened and closed by the control rod, is provided inside the hydraulic chamber. In other words, the sliding portion between the hollow stem and the control rod is located at the inner part of the hollow stem. Therefore, it is extremely difficult to mechanically finish the sliding part between the hollow stem and the control rod with high precision so that there is no leakage of hydraulic oil from the sliding part. The cost required for this mechanical processing increases significantly, and the maintenance and maintenance required to maintain good sliding conditions between the hollow stem and control rod
Inspection was difficult.

Moreover, in the prior art, the forward movement of the sub-piston is performed by the pressure in the hydraulic chamber, and the backward movement of the sub-piston is performed by the pressure in the combustion chamber. When the pressure rises, it moves forward due to the pressure in the hydraulic chamber, and when the pressure rises during the explosion stroke, it retreats to its original position, so it repeats a reciprocating motion once in one cycle.
The sliding parts between the auxiliary piston and the auxiliary cylinder, and the sliding parts between the stem and the control rod suffer from a lot of wear, resulting in low durability.

In addition, since the forward movement of the secondary piston is performed by stopping the flow of hydraulic oil from the hydraulic chamber, the responsiveness when moving the secondary piston forward in response to a decrease in the load of the internal combustion engine is good; When the auxiliary piston moves backward in the intake stroke as described above to follow the increase in load on the internal combustion engine, the backward movement of the auxiliary piston in response to the increase in load occurs during the intake stroke. In other words, knocking occurs because the response to a low compression ratio in response to an increase in load is low.

On the other hand, the auxiliary cylinder that opens into the combustion chamber needs to be installed near the ignition plug so that it is easily affected by the ignition caused by the ignition plug. However, in the prior art described above, when a sub cylinder for variable compression ratio is provided in the cylinder head in addition to the spark plug, intake port, and exhaust port, the above relationship is not met. It does not disclose any techniques for preserving such sequences.

Moreover, in the prior art, the operating mechanism for moving and operating the control rods is provided on the side of the cylinder head, which increases the width of the internal combustion engine, leading to an increase in the size of the internal combustion engine. There was also a problem with the

An object of the present invention is to provide a variable compression ratio internal combustion engine that eliminates these problems.

[Means for solving problems]

To achieve this object, the present invention provides an internal combustion engine in which the cylinder head is provided with an auxiliary cylinder having a spark plug, an intake port with an intake valve, an exhaust port with an exhaust valve, and an auxiliary piston for varying the compression ratio. An ignition plug is disposed approximately at the center of the cylinder bore, and the intake port and exhaust port are disposed on one side of the parallel longitudinal centerline of the crankshaft through the center of the cylinder bore, and the sub-cylinder is disposed on the other side. and forming a hydraulic chamber equipped with a hydraulic oil supply port on the back surface of the sub-piston,
The sub-piston is provided with a spring means for biasing the sub-piston in the backward direction, and a stem extending in the axial direction of the sub-cylinder is connected to the sub-piston so that the tip of the stem is placed above the cylinder head. A spill port is provided at the protruding end of the stem to allow the hydraulic oil in the hydraulic chamber to flow out, and a spill port is provided on the outer periphery of the protruding end of the stem to prevent spillage from occurring when the stem moves backward. A spill body in which the port is closed and the spill port is opened by the forward movement of the stem is fitted so as to be relatively movable so that the opening/closing position of the spill port by the spill body can be displaced in the axial direction of the stem, and An operating mechanism for moving and operating the spill body in accordance with the load in the internal combustion engine is provided in the upper chamber of the cylinder head at a portion between the intake valve, the exhaust valve, and the stem.

[Action/effect of the invention]

In such a configuration, when the spill body is moved to close the spill port, the flow of hydraulic oil from the spill port is stopped or reduced, and the sub-piston is moved into the hydraulic chamber. The hydraulic oil supplied to the hydraulic chamber moves forward toward the combustion chamber, and this forward movement causes the spill to reach a position where the amount of hydraulic oil flowing out from the spill port is approximately equal to the amount of hydraulic oil supplied to the hydraulic chamber. It will stop when the port opens, and if the spill body is moved to open the spill port widely, the amount of hydraulic oil flowing out from the spill port will increase. According to
The auxiliary piston moves backward from the combustion chamber due to the pressure within the combustion chamber and the spring means, and this backward movement occurs at a position where the amount of hydraulic oil flowing out from the spill port and the amount of hydraulic oil supplied to the hydraulic chamber are approximately equal. It will stop when the spill port closes to the point where it stops. Therefore, by moving the spill body using the actuating mechanism, the auxiliary piston can be moved forward or backward, and the compression ratio can be changed stepwise.

Therefore, by providing the spill body with an operating mechanism for moving and operating it according to the load on the internal combustion engine, the compression ratio can be automatically changed and controlled according to the load on the internal combustion engine.

In this case, the present invention has the spill body for opening and closing the spill port in the stem fitted onto the outer periphery of the stem, so that the hydraulic pressure in the hydraulic chamber acts to prevent the back and forth movement of the spill body. Since the spill body can be moved back and forth with a light force, the operating mechanism for moving the spill body back and forth in accordance with the load can be made smaller and lighter.

Furthermore, by protruding the stem into the upper chamber of the cylinder head and providing a spill port and a spill body at this protruding end, the sliding portion between the stem and the spill body is completely closed by the spill port. Since high-precision mechanical processing to achieve this can be performed much more easily than in the case of the prior art, the cost required for mechanical processing can be reduced and the processing accuracy can be improved. Moreover, maintenance and inspection to maintain a good sliding condition between the stem and the spill body can be performed extremely easily.

Furthermore, by providing a spring means for the sub-piston, the distance when the sub-piston moves forward during the intake stroke can be reduced, so that the sliding part between the sub-piston and the sub-cylinder and the stem and spill body can be reduced. This reduces wear on the sliding parts of the piston and improves its durability.In addition, the spring means not only reduces the distance that the secondary piston moves forward during the intake stroke, but also accelerates the backward movement of the secondary piston. This improves the responsiveness when moving the auxiliary piston backward in response to changes in load, and as a result, the control to lower the compression ratio in response to changes in load is delayed, ensuring that knocking does not occur. It can be prevented.

Further, in the present invention, the ignition plug is arranged approximately at the center of the cylinder bore, and the intake port and the exhaust port are arranged on one side across a longitudinal centerline parallel to the crankshaft through the center of the cylinder bore, and on the other side. By arranging the auxiliary cylinders on each side, the ignition plug is located approximately at the center of the entire combustion chamber surrounding the intake port, exhaust port, and auxiliary cylinder, while the auxiliary cylinder is positioned closest to the ignition plug. The ignition plug can be positioned close to the engine, and the ignition effect of the ignition plug can be strongly exerted over the entire area of the combustion chamber and inside the auxiliary cylinder. This makes it possible to reliably prevent deterioration in combustibility caused by the provision of

Furthermore, by arranging the intake port and the exhaust port on one side and the sub-cylinder on the other side across a longitudinal centerline that passes through the center of the cylinder bore and is parallel to the crankshaft, the intake port of the intake port is arranged. The valve operating mechanism for the valve and the exhaust valve of the exhaust port, and the stem with a spill body for the sub-piston can be arranged to the left and right with the longitudinal center line in between, without being constrained by each other, making it easier to manufacture and inspect them.・It can improve the workability of repairs.

Furthermore, as described above, the present invention provides the intake port and the exhaust port on one side and the sub-cylinder on the other side of the longitudinal center line that passes through the center of the cylinder bore and is parallel to the crankshaft. In addition, by arranging the operating mechanism for the spill body in a region between the intake valve and exhaust valve and the stem, the space between the intake valve and exhaust valve and the stem can be used for the operation of the stem. Coupled with the fact that the mechanism can be made smaller, it can be effectively used for installing the operating mechanism, so there is no increase in the width dimension of the internal combustion engine, and as a result, it is possible to prevent the internal combustion engine from becoming larger.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 indicates a cylinder block, reference numeral 2 indicates a cylinder head, reference numeral 3 indicates a main piston that reciprocates within the cylinder bore 4 of the cylinder block 1, and reference numeral 5 indicates the cylinder head. A combustion chamber formed by recessing the lower surface of the cylinder head 2; reference numeral 6 denotes a spark plug that looks into the combustion chamber 5; reference numeral 7 indicates the cylinder head 2;
When viewed from above, a longitudinal centerline 9 passing through the center 8 of the cylinder bore 4 and parallel to the crankshaft (not shown)
An intake port 11 communicates between the left side surface 10 parallel to the longitudinal center line 9 and the combustion chamber 5;
Exhaust ports communicating with each other are shown.

The spark plug 6 is provided near the center 8 of the cylinder bore 4 in plan view, and the opening 7a of the intake port 7 to the combustion chamber 5 and the opening 11a of the exhaust port 11 to the combustion chamber 5 are Intake valves 12 and exhaust valves 13 are disposed in a region to the left of the longitudinal centerline 9, and openings 7a and 11a of both boats 7 and 11 to the combustion chamber 5 are provided with intake valves 12 and exhaust valves 13, respectively. .

Reference numeral 14 denotes a sub-cylinder bored in the cylinder head 2, and the sub-cylinder 14 is located in a region on the right side of the longitudinal center line 9 in a plan view of the cylinder head 2, that is, in the opening 7a of the intake port 7.
and are located in an area opposite to the opening 11a of the exhaust port 11 across the longitudinal centerline 9, and open into the combustion chamber 5 on the lower side and into the upper chamber of the cylinder head on the upper surface of the cylinder head 2 on the upper side. A cover plate 15 is provided at the opening of the sub-cylinder 14 to the upper chamber of the cylinder head to close the opening.

Reference numeral 16 denotes a sub-piston that is slidably inserted into the sub-cylinder 14. A plurality of piston rings 17 are provided on the outer periphery of the sub-piston 16, and the sub-piston 16 extends in the direction of the combustion chamber 5. As the secondary piston 16 moves forward, the volume of the combustion chamber 5 decreases and the compression ratio increases, and as the sub piston 16 moves backward away from the combustion chamber 5, the volume of the combustion chamber 5 increases and the compression ratio decreases. Moreover, this sub-piston 16
is biased in the backward direction by a spring 18 fitted on the outside thereof, and there is a shaft on the back side of the sub-piston 16 (the surface on the back side with respect to the combustion chamber 5) from the center of the sub-piston 16. A stem 19 extending in the direction is integrally provided, and the tip of the stem 19 slidably penetrates the cover plate 15 and projects into the upper chamber of the cylinder head, while the rear side of the sub-piston 16 and the cover plate 15 A hydraulic chamber 20 is formed between the hydraulic chamber 20 and the hydraulic chamber 20, and hydraulic oil from a hydraulic source (not shown) is supplied to the hydraulic chamber 20 via a port 22 with a check valve 21.

Further, the stem 19 is provided with a passage 23 communicating with the hydraulic chamber 20, and the stem 19 is provided with a passage 23 communicating with the hydraulic chamber 20, and the stem 19
The part that protrudes into the upper chamber of the cylinder head from 5 has a
A spill port 24 is provided for draining the hydraulic oil in the hydraulic chamber 20 to the upper chamber of the cylinder head.

Reference numeral 25 indicates a spill ring which is an embodiment of the spill body, and the spill ring 25 is slidably fitted onto the stem 19, so that when the stem 19 moves backward, the spill port 24 is connected to the spill ring. 25, and its spill port 24 is configured to open when the stem 19 moves forward.

On the other hand, in the upper chamber of the cylinder head, a lever 26, which is an embodiment of the operating mechanism of the spill ring 25, is disposed between the intake valve 12, the exhaust valve 13, and the stem 19. By engaging the tip of the lever 26 with the spill ring 25, rotation of the lever 26 adjusts the movement of the spill ring 25 in the axial direction of the stem 19. be.

In this configuration, the spill ring 25 is
As shown by the two-dot chain line in the figure, if the movement is performed in the direction of the combustion chamber 5, that is, in the direction of closing the spill port 24, the flow of hydraulic oil from the spill port 24 will be stopped by closing the spill port 24. Since the pressure in the hydraulic chamber 20 to which hydraulic oil is supplied from the port 22 with the check valve 21 increases, the secondary piston 1
6 moves forward toward the combustion chamber 5, and when this forward movement progresses to the point where the spill port 24 opens, hydraulic oil starts flowing out from the spill port 24, and the amount of this outflow and the amount of supply to the hydraulic chamber 20 become equal. The forward movement of the sub piston 16 is stopped when the balance is achieved. Also, when the spill ring 25 is moved in the backward direction from the position indicated by the two-dot chain line to the position indicated by the solid line, the spill port 2
4 is fully opened, the flow loss increases, and the pressure in the hydraulic chamber 20 decreases, so the sub piston 16 retreats away from the combustion chamber 5 due to the pressure in the combustion chamber 5 and/or the spring 18, and this retreat is spill port 24
When the flow progresses to the point where it closes at the spill ring 25, the amount of outflow from the spill port 24 decreases,
When the outflow amount is balanced with the supply amount, the backward movement of the sub piston 16 is stopped, and by moving the spill ring 25, the sub piston 1
6 can be moved back and forth steplessly.

Therefore, an actuator 27 related to the engine load is connected to the other end of the lever 26 that engages with the spill ring 25, and the actuator 27
By moving the spill ring 25 backward in proportion to the increase in engine load, it is possible to automatically control the compression ratio so that it gradually decreases as the load increases, or in other words, gradually increases as the load decreases. Furthermore, the actuator 27 can be automatically controlled in relation to the engine rotational speed so that the compression ratio gradually increases as the rotational speed increases. In conjunction with the provided knocking sensor, it is also possible to control the compression ratio so that it is high when there is no knocking and lowered accordingly when knocking occurs.

When the secondary piston 16 receives a large explosive force during the engine's explosion stroke, this explosive force causes the secondary piston 16 to retreat slightly and close the spill port 24, while the pressure inside the hydraulic chamber 20 instantly decreases. When the pressure rises, the check valve 21 closes, and the hydraulic oil in the hydraulic chamber 20 becomes trapped within the hydraulic chamber 20, thereby bearing a large explosive force against the sub-piston 16. In this case, the outflow of the hydraulic oil until the spill port 24 closes and the subsequent increase in the pressure of the hydraulic oil act as a cushion, which absorbs the impact on the sub-piston 16 due to explosive combustion of the air-fuel mixture in the combustion chamber 5.・It's alleviation.

In addition to the spark plug 6, the intake port 7, and the exhaust port 11, the cylinder head 2 is provided with an auxiliary cylinder 14 for varying the compression ratio. While the ignition plug 6 is arranged nearby, the opening 7a of the intake port 7 and the opening 11a of the exhaust port 11 are placed on one side across the longitudinal center line.
By disposing the auxiliary cylinder 14 on the other side, the ignition plug 9 can
a and the sub-cylinder 14, while being located approximately in the center of the entire area of the combustion chamber 5 surrounding the sub-cylinder 14.
Since it can be brought close to the ignition plug 6, the ignition effect of the ignition plug 6 can be strongly exerted over the entire area of the combustion chamber 5 and inside the auxiliary cylinder 14. Also, in a plan view of the cylinder head 2, By arranging the intake port 7 and the exhaust port 11 on one side of the longitudinal centerline 9, and the sub-cylinder 14 and the sub-piston 16 fitted therein on the other side,
The valve operating mechanism (not shown) for the intake/exhaust valves 12 and 13 in the intake port 7 and exhaust port 11, and the stem 19 and spill ring 25 for the sub-piston 9 are distributed to the left and right with the longitudinal centerline 9 in between. Therefore, it can be provided as follows.

In the above embodiment, the hydraulic oil constantly supplied to the hydraulic chamber 20 may be lubricating oil in an engine, hydraulic oil in a power steering mechanism of an automobile, or hydraulic oil in an automatic transmission of an automobile.

Further, in the above embodiment, a spill ring 25 was used as an embodiment of the spill body, but as shown in FIGS. 4 and 5, the stem 19
The spill port at a is formed as an inclined spill port 24a that is inclined with respect to the axis of the stem 19a, and a gear-type spill ring 25a is rotatably and slidably fitted on the outer periphery of the stem 19a. The spill ring 25a is pivotally supported on the cylinder head 2 by a bearing (not shown), and the spill ring 25a has one shaft that matches the inclined spill port 24a when the stem 19a slides back and forth. The escape port 28 is bored, and the stem 1 is attached to the teeth on the outer periphery of the spill ring 25a.
Spill ring 2
5a to open the escape port 28 relative to the inclined spill port 24a of the stem 19a.
By shifting the spill port 24a to the () position or () position, the opening/closing position of the spill port 24a can be adjusted to the stem 1.
The stem 19a may be configured to be displaced along the axial direction of the spill ring 9a (in this case, the stem 19a is held slidably but not rotatably, and the mechanism for rotating the spill ring 25a here is (It goes without saying that other means may be used, not limited to the rack and pinion shown in the example). In addition, it goes without saying that the inclined spill port provided on the stem and the relief port provided on the spill ring may be reversed. However, part or all of the sub-piston may be made of ceramic.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view of the main parts of the engine, FIG. 2 is a bottom view of FIG. 1, and FIG. 3 is a sectional view of FIG. This figure is another example of a spill body and a spill port, and FIG. 5 is a plan view of FIG. 4. 1... Cylinder block, 2... Cylinder head, 4... Cylinder bore, 5... Combustion chamber, 6...
Spark plug, 7... Intake port, 8... Center of cylinder bore, 9... Longitudinal center line, 11... Exhaust port, 12... Intake valve, 13... Exhaust valve, 14...
Sub cylinder, 16... Sub piston, 18... Stem, 20... Hydraulic chamber, 22... Hydraulic oil supply port, 24, 24a... Spill port, 25, 25
a... Spill body, 26... Lever, 27... Actuator.

Claims (1)

[Claims] 1. In an internal combustion engine in which the cylinder head is provided with an ignition plug, an intake port with an intake valve, an exhaust port with an exhaust valve, and an auxiliary cylinder containing an auxiliary piston for variable compression ratio, the ignition plug is located approximately in the center of the cylinder bore. while the intake port and the exhaust port are arranged on one side across the parallel longitudinal centerline of the crankshaft through the center of the cylinder bore,
The sub-cylinders are each disposed on the other side, a hydraulic chamber having a hydraulic oil supply port is formed on the back surface of the sub-piston, and a spring means is provided in the sub-piston for biasing the sub-piston in a backward direction. On the other hand, a stem extending in the axial direction of the sub-cylinder is connected to the sub-piston, the tip of the stem projects into the upper chamber of the cylinder head, and the protruding end of the stem is connected to the hydraulic oil in the hydraulic chamber. A spill port is provided on the outer periphery of the protruding end of the stem so that the spill port is closed by the backward movement of the stem and opened by the forward movement of the stem. The body is fitted so as to be relatively movable so that the opening/closing position of the spill port by the spill body can be displaced in the axial direction of the stem, and further, the intake valve, the exhaust valve, and the stem are fitted in the upper chamber of the cylinder head. A variable compression ratio internal combustion engine, characterized in that an operating mechanism for moving and operating the spill body in accordance with a load in the internal combustion engine is provided at a portion between.