JPH0116976B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a variable compression ratio internal combustion engine in which the compression ratio of the internal combustion engine is automatically changed according to the operating conditions of the internal combustion engine. It is something.

[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. is configured to move back and forth via an actuator in accordance with the load on the internal combustion engine, thereby displacing the opening/closing position of the spill port in the axial direction of the stem and moving the sub piston back and forth. Although it has the advantage of being able to automatically change and control the compression ratio depending on 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 order to move the control rod back and forth according to the load of the internal combustion engine, the hydraulic pressure in the hydraulic chamber acts to prevent its forward and backward movement, and a large force is required to move the control rod forward. Therefore, the actuator must be made larger.

However, the spill port, which is opened and closed by the control rod, is provided inside the hydraulic chamber. In other words, the sliding part between the hollow stem and the control rod is located in 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; moves forward as described above during the intake stroke, and this forward movement causes hydraulic oil to flow into the hydraulic chamber, so when the sub piston is moved backward to follow the increase in the load of the internal combustion engine, the load increases. The backward movement of the auxiliary piston following this is delayed by the amount of forward movement during the intake stroke.In other words, the responsiveness to a low compression ratio in response to an increase in load is low, causing knocking. Ta.

On the other hand, the occurrence of knotting in an internal combustion engine is
Although it is proportional to the temperature in an internal combustion engine,
In the prior art, the compression ratio is not related to the temperature of the internal combustion engine, so if the initial setting of the compression ratio is set so that knocking does not occur when the temperature is high, it will not cause knocking when the temperature is low. There will be too much leeway for Notsking, and
There was a problem in that if the temperature was set accordingly when the temperature was low, knocking would occur when the temperature rose.

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 a cylinder head with an auxiliary cylinder opening into the combustion chamber, a auxiliary piston slidably inserted into the auxiliary cylinder,
A hydraulic chamber equipped with a hydraulic oil supply port is formed on the back surface of the sub-piston, and a spring means is provided on the sub-piston for biasing the sub-piston in the backward direction. A stem extending from the cylinder head is connected to the stem, the tip of the stem projects into the upper chamber of the cylinder head, and the protruding end of the stem includes:
A spill port is provided to allow the hydraulic oil in the hydraulic chamber to flow out, and the spill port is closed on the outer periphery of the protruding end of the stem when the stem moves backward, and the spill port closes when the stem moves forward. a spill body which is configured to open, is fitted so that the spill body can open and close the spill port in a relatively movable manner such that the opening/closing position of the spill port by the spill body can be displaced in the axial direction of the stem;
The stem is connected to the internal combustion engine via an actuator so as to be moved and actuated in accordance with one or both of the load and rotation speed in the internal combustion engine, while the spill body or the stem has a The opening/closing position of the spill port is
The structure is such that a temperature correction means is provided to correct and displace the stem in the axial direction depending on the temperature of the internal combustion engine.

[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. Since it will stop when the spill port is closed to the extent that the spill port is closed, the sub piston can be moved forward or backward by moving the spill body.

Therefore, by relating the spill body to the internal combustion engine via an actuator so as to move and actuate it in accordance with either or both of the load and the rotation speed of the internal combustion engine, the compression ratio can be changed. It is possible to automatically change and control the load and rotation speed in a stepless manner according to changes in either or both of the load and rotation speed.

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 actuator for moving the spill body back and forth in accordance with the load etc. 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. Therefore, it is possible to improve the responsiveness when moving the auxiliary piston backward in response to changes in load, etc., and as a result, the occurrence of knocking due to a delay in controlling the compression ratio to low in response to changes in load, etc. can be improved. It can definitely be prevented.

In addition, the present invention provides the spill body or stem with an opening/closing position of the spill port relative to the spill.
This system is equipped with a temperature correction means that corrects and displaces the stem in the axial direction according to the temperature of the internal combustion engine. With this configuration, the opening/closing position of the spill port relative to the spill can be changed to the position where the opening/closing position of the spill port is adjusted to the combustion chamber when the temperature of the internal combustion engine is low. When the temperature rises, the compression ratio can be corrected and moved away from the combustion chamber. When the temperature is high, the compression ratio can be automatically adjusted according to the temperature so that it is high when the temperature is low and low when the temperature is high. It is possible to reliably prevent knocking from occurring in the engine or from having too much margin for knocking when the temperature is low, and as a result, the output and fuel efficiency of the internal combustion engine can be improved without knocking.

〔Example〕

Embodiments of the present invention are shown below in the drawings (Figs. 1 to 3).
In the figure, reference numeral 1 is a cylinder block, reference numeral 2 is a cylinder head, reference numeral 3 is a main piston that slides back and forth within the cylinder bore 4 of the cylinder block 1, and reference numeral 5 is a concave portion on the lower surface of the cylinder head 2. The combustion chambers 5 each have an ignition plug 6 extending into the combustion chamber 5 at approximately the center thereof, and an intake port and an exhaust port (not shown) are open therein.

Reference numeral 7 denotes a sub-cylinder bored in the cylinder head 2, and the sub-cylinder 7 has a lower side facing the combustion chamber 5.
The upper side thereof opens into the upper chamber of the cylinder head on the upper surface of the cylinder head 2, and the opening to the upper chamber of the cylinder head of the sub-cylinder 7 is provided with a cover plate 8 for closing the opening.
is provided.

Reference numeral 9 denotes an auxiliary piston slidably inserted into the auxiliary cylinder 7. When the auxiliary piston 9 moves forward in the direction of the combustion chamber 5, the volume of the combustion chamber 5 decreases and the compression ratio increases. When the sub piston 9 retreats in a direction away from the combustion chamber 5, the volume of the combustion chamber 5 increases and the compression ratio decreases, and
This sub-piston 9 is provided with a spring 10 for urging the sub-piston 9 in the backward direction, and a spring 10 is provided on the back surface of the sub-piston 9 (the surface on the back side with respect to the combustion chamber 5). A stem 11 extending axially from the center of 9 is connected to the stem 11 .
is slidably penetrated through the cover plate 8 and protrudes into the upper chamber of the cylinder head, while a hydraulic chamber 12 is formed between the back surface of the sub-piston 9 and the cover plate 8, and in the hydraulic chamber 12, Hydraulic oil from a hydraulic source is supplied through a port 14 with a check valve 13.

Further, the stem 11 is provided with a passage 15 communicating with the hydraulic chamber 12, and the stem 11 is provided with a passage 15 communicating with the hydraulic chamber 12.
A groove-shaped spill port 16 for discharging the hydraulic oil in the hydraulic chamber 12 to the cylinder head upper chamber is bored in a portion that projects further into the cylinder head upper chamber. It is tilted at an appropriate angle θ upward to the right with respect to the axis of .

Reference numeral 17 denotes a spill ring, which is an example of a spill body rotatably and slidably fitted onto the protruding end of the stem 11. A relief port 18 is provided which communicates with the spill port 16 when the stem 11 moves forward in the direction and closes with respect to the spill port 16 when the stem 11 moves backward in the direction away from the combustion chamber 5.

A ring body 19 having a gear 24 on its outer peripheral surface is disposed concentrically with an annular gap 20 between it and the outer peripheral surface of the spill ring 17 on the outside of the spill ring 17. 19 to the cover plate 8
The ring body 19 and the spill ring 17 are rotatably supported by a bearing bracket 21 formed integrally with the bimetal plate 21 provided so as to extend in the circumferential direction within an annular gap 20 between them. In this connection, when the bimetal plate 21 thermally expands in the circumferential direction as the temperature rises, the spill ring 17 rotates clockwise in the direction of arrow A with respect to the ring body 19. 21 is provided with a rack rod 22 that meshes with a gear 24 on the outer periphery of the ring body 19, slidably in a direction perpendicular to the axis of the stem 11, and an actuator 23 related to the load of the engine is connected to the rack rod 22. hand,
As the load on the engine increases, the ring body 19 moves in the direction of arrow B.
The ring body 19 is configured to rotate clockwise in the direction of arrow C, and as the load on the engine decreases, the ring body 19 rotates counterclockwise in the direction of arrow C.

In this configuration, when the ring body 19 is rotated to the left in the direction of arrow C from the position shown by the solid line in the figure, the spill ring 17 connected to the ring body 19 by the bimetal plate 21 is also rotated to the left, and the relief port 18 of the ring body 19 is also rotated to the left. position, the opening/closing position of the relief port 18 relative to the spill port 16 moves backward in the direction away from the combustion chamber 5, and the spill port 16 closes in a non-communicating state with respect to the relief port 18. The leakage of lubricating oil from 16 has stopped,
Since the pressure in the hydraulic chamber 12 to which hydraulic oil is supplied from the port 14 with the check valve 13 increases, the sub-piston 9 moves forward toward the combustion chamber 5, and this forward movement causes the spill port 16 to escape from its position. port 18
When the hydraulic fluid in the hydraulic chamber 12 reaches a point where it is partially in communication with the hydraulic chamber 12, the hydraulic fluid in the hydraulic chamber 12 starts flowing out from the spill port 16 and the relief port 18, and when the amount of this outflow and the amount of supply to the hydraulic chamber 12 are balanced, The forward movement of the piston 9 is stopped. Further, the ring body 19
When rotated clockwise in the direction of arrow B from the position indicated by the solid line in the figure, the relief port 18 of the spill ring 17 connected to the ring body 19 via the bimetal plate 21 will be in the position, and the relief port 18 will be in the position relative to the spill port 16. The opening/closing position moves forward to approach the combustion chamber 5, and the spill port 16 becomes the relief port 1.
Spill port 1 is in communication with 8 in a fully open state.
6 increases and the pressure in the hydraulic chamber 12 decreases, the secondary piston 9 retreats away from the combustion chamber 5 due to the pressure in the combustion chamber 5 and/or the spring 10, and this retreat , when the flow progresses to a point where the spill port 16 and the position relief port 18 partially communicate with each other, the amount of outflow from these decreases, and when the amount of outflow and the amount of supply are balanced, the backward movement of the sub piston 9 is stopped. By the rotation of the ring body 19 and, by extension, the rotation of the spill ring 17, the sub-piston 9 can be moved back and forth in a stepless manner.

In this case, the ring body 19 is configured to rotate clockwise as the engine load increases and rotate counterclockwise as the load decreases by the actuator 23 related to the engine load. As the load increases, the compression ratio becomes lower, and as the load decreases, the higher the compression ratio becomes. It is also possible to automatically control the compression ratio so that it gradually increases as the speed increases, or to automatically control the compression ratio in relation to both load and rotation speed.

During the engine's explosion stroke, when the sub-piston 9 receives a large explosive force, the sub-piston 9 moves back a little due to this explosive force, and at the same time, the stem 11 also moves back a little, causing the spill port 16 to close to the relief port 18. While the communication is closed, the pressure inside the hydraulic chamber 12 momentarily increases and the check valve 13 closes.
Since the hydraulic fluid in the hydraulic chamber 12 is confined within the hydraulic chamber 12, it bears a large explosive force against the secondary piston 9. In this case, the spill port 16 is connected to the relief port 18. The slight outflow of hydraulic oil and subsequent rise in oil pressure until the piston is closed absorbs and alleviates the explosion impact on the sub-piston 9.

On the other hand, the occurrence of knocking increases as the engine temperature increases, so if the compression ratio value is automatically controlled in relation to the engine load and/or rotational speed and is set to match when the engine temperature is low. ,
Knocking occurs frequently when the temperature of the engine increases, but as described above, in the present invention, the annular gap 20 between the inner periphery of the ring body 19 and the outer periphery of the spill ring 17 is A bimetallic plate 21 is provided to connect the bimetallic plate 21.
is warmed by the hydraulic oil flowing out from the relief port 18, while the hydraulic oil reaches a temperature approximately proportional to the engine temperature as it passes through the hydraulic chamber 12, the oil passage 14 of the cylinder head 2, etc. As the temperature of the engine increases, the bimetal plate 21 thermally expands in the circumferential direction, and the spill ring 17 is moved to the ring body 19 and to the stem 11 in the direction of arrow A, that is, the spill port 16 of the stem 11. Since the communication area of the relief port 18 increases with respect to the spill port 16, the amount of flow from the spill port 16 increases, and the secondary piston 9
As a result, the compression ratio decreases as the outflow amount from the spill port 16 is in balance with the supply amount.

That is, the compression ratio, which is automatically changed and controlled in accordance with the load etc. of the internal combustion engine, is automatically controlled by the bimetal plate 21 so that it gradually decreases as the engine temperature increases during control according to the load etc. By correcting and adjusting the compression ratio, it is possible to reliably prevent the occurrence of knocking when the engine temperature is high, and the compression ratio value, which is automatically changed and controlled according to the engine load, etc. When the compression ratio is set to match when the engine temperature is high, the compression ratio when the engine temperature is low can be automatically corrected and adjusted to a higher value to suit that time.

Note that the hydraulic oil supplied to the hydraulic chamber 12 is not limited to lubricating oil in an engine, but may also be hydraulic oil in a power steering mechanism of an automobile or an automatic transmission of an automobile. When using hydraulic oil in this power steering mechanism or automatic transmission, the hydraulic oil that has entered the hydraulic chamber 12 is transferred to the sub piston 9.
After leading to the inner cavity chamber 25, the spill port 16
The temperature of the hydraulic oil may be made approximately proportional to the engine temperature by flowing out from the engine. Further, the positions of the inclined spill port 16 and the relief port 18 are reversed from those of the above embodiment, and the stem 11 is
The spill port 18 may be provided in the spill ring 17, and the inclined spill port 16 may be provided in the spill ring 17. Furthermore, the shape of the spill port 16 may be made into an arbitrary shape as shown by the two-dot chain line in FIG. good.

FIGS. 4 and 5 show a second embodiment, which includes a sub-piston 9 in a sub-cylinder 7.
A stem 11a that protrudes into the upper chamber of the cylinder head is connected to the back surface of the cylinder head, and a spill port 16a is formed at the protruding end of the stem 11a, and a spill ring 17a is provided for opening and closing the spill port 16a.
is rotatably and slidably fitted into the spill ring 1.
7a, and the midway part is connected to the cylinder head 2 by the shaft 2.
Via a lever 21 pivotably mounted at 6,
The actuator 23 is configured to slide back and forth by an actuator 23 that is related to either or both of the load and rotation speed of the internal combustion engine.

In this embodiment, the stem 11a is divided into two upper and lower stems 11a', 1 as shown in FIG.
The upper and lower stems 11a' and 11a'' are fitted together so that they can expand and contract in the axial direction.
A pipe-shaped bimetal 21 is inserted between 1a′ and 11a″.
a, and the opening/closing position of the spill port 16a relative to the spill body 17a can be corrected and displaced in the axial direction of the stem 11a according to the temperature by thermal expansion and contraction of the bimetal 21a in the axial direction. As a result, the compression ratio value when automatically changing control according to the engine load etc. can be automatically adjusted so that it becomes lower as the engine temperature rises and becomes higher as the temperature falls. .

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a longitudinal sectional front view of the main parts of the engine showing the first embodiment, FIG. 2 is an enlarged sectional view of the main parts of FIG. 1, and FIG. 3 is the second embodiment. of-
4 is a longitudinal sectional front view of the main parts of the engine showing the second embodiment, and FIG. 5 is an enlarged view of the main parts of FIG. 4. 1... Cylinder block, 2... Cylinder head, 5... Combustion chamber, 7... Sub cylinder, 9... Sub piston, 12... Hydraulic chamber, 11, 11a... Stem, 16, 16a... Spill port ,17,1
7a... Spill body, 23... Actuator, 2
1,21a...Bimetal.

Claims (1)

[Claims] 1. A cylinder head is provided with an auxiliary cylinder that opens into the combustion chamber, a auxiliary piston is slidably inserted into the auxiliary cylinder, and a hydraulic chamber equipped with a hydraulic oil supply port is formed on the back surface of the auxiliary piston, The sub-piston is provided with 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, and the tip of the stem is placed in the upper chamber of the cylinder head. A spill port is provided at the projecting end of the stem to allow the hydraulic oil in the hydraulic chamber to flow out, and a spill port is provided at the outer periphery of the projecting end of the stem by the backward movement of the stem. A spill body in which the spill port is opened by the forward movement of the closing 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 the stem is , is connected to an internal combustion engine via an actuator so as to move and operate according to one or both of the load and rotation speed in the internal combustion engine, and the spill port for the spill is connected to the spill body or stem. 1. A variable compression ratio internal combustion engine, characterized in that a temperature correction means is provided for correcting and displacing the opening/closing position of the stem in the axial direction of the stem according to the temperature of the internal combustion engine.