JPS58165542A - Variable compression ratio device in internal-combustion engine - Google Patents

Abstract

PURPOSE:To change compression ratio without causing the worsening of combustion performance, by inserting a subpiston into a subcylinder communicated to a combustion chamber and displacing the subpiston through operation of an oil pressure regulating spill ring further discharging leaked oil to the atmospheric side. CONSTITUTION:If a spill ring 17 is moved by an actuator 22 to a position as shown by a chain line in the drawing to close a spill port 16 provided to a stem 11 integrally formed with a subpiston 9, pressure of working fluid supplied into a pressure oil chamber 12 from a port 14 rises to displace the subpiston 9 downward. Then if the subpiston 9 is displaced to a position where the port 16 is opened, working fluid begins to flow out from the port 16, at a point of time when this outflow amount and supply amount to the chamber 12 are balanced, the subpiston 9 is stopped to change compression ratio. At an explosion stroke, the working fluid in the chamber 12 is leaked to a slide contact part between the subpiston 9 and a subcylinder 7, and this leaked oil flows out to the outside of the subcylinder 7 through an annular groove 19 and a through hole 20.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a compression ratio variable device that can change the compression ratio of an internal combustion engine during operation.

In an internal combustion engine, increasing the compression ratio can improve output and reduce fuel consumption, but increasing the compression ratio causes knocking in high load ranges. For this reason, in a conventional internal combustion engine with a constant compression ratio, the compression ratio must be set to a value that does not cause knocking in a high load range, and therefore sufficient fuel efficiency cannot be achieved in a low load range.

Therefore, Japanese Patent Application Laid-open No. 56-88926 as a prior art discloses that the compression ratio can be varied by inserting an auxiliary piston into an auxiliary cylinder that communicates with the combustion chamber, and by moving the auxiliary piston back and forth with respect to the combustion chamber. In this step, the tip of the rod protruding from the sub-piston to the outside of the sub-cylinder is brought into contact with a plunger in a hydraulic cylinder provided on the same axis as the rod,
It has been proposed to make the compression ratio variable during engine operation by moving the auxiliary piston back and forth by advancing the plunger by supplying and discharging hydraulic pressure into the hydraulic cylinder.

However, providing a hydraulic cylinder with a plunger outside the auxiliary cylinder in this way not only complicates the structure, but also, in the case of a multi-cylinder engine, a hydraulic cylinder for variable compression ratio must be provided for each cylinder. Due to the increased space required for its installation, the engine becomes significantly larger, and the weight of the engine also increases.Also, as in the prior art, the secondary piston: the mouth protruding from the cylinder, When the rod comes into contact with the plunger in the auxiliary piston, the explosive force momentarily acts on the sub-piston, causing the rod to slam against the plunger, and this banging is repeated every cycle, which not only generates large vibrations and noise, but also generates large vibrations and noise. The contact area between the rod and the plunger was severely damaged.

In this invention, the sub-piston is inserted into the sub-cylinder communicating with the combustion chamber, and the compression ratio is varied by the back-and-forth movement of the sub-piston with respect to the combustion chamber. Hydraulic oil is continuously supplied to this as a hydraulic chamber via a reverse ratio valve, and a stem is provided so as to protrude from the sub-piston to the outside of the sub-cylinder, and the stem is configured to release the hydraulic oil in the hydraulic chamber. and a spill body that closes the spill boat when the stem moves backward, and opens the spill boat when the stem moves forward,
By configuring the opening/closing position of the spill boat to be changed along the axial direction of the spill body system by sliding or rotating the spill body system in the axial direction, the structure of the variable compression ratio device can be simplified. This prevents the engine from increasing in size and weight, and also absorbs and alleviates the explosion impact on the compression ratio variable sub-piston, thereby eliminating vibration and noise.

However, forming the rear chamber of the sub-piston into a hydraulic chamber and supplying hydraulic oil to it as described above means that the hydraulic oil in the hydraulic chamber is caused by sliding contact between the outer circumferential surface of the sub-piston and the inner circumferential surface of the sub-cylinder. This leakage not only significantly increases the consumption of hydraulic oil required to move the sub-piston back and forth, but also significantly worsens exhaust gas due to combustion of the hydraulic oil leaked into the combustion chamber. Therefore, the present invention provides an annular groove surrounding the circumference of the sub-piston in the contact sliding portion between the outer peripheral surface of the sub-piston and the inner circumferential surface of the sub-cylinder, and communicates the groove with the outside of the sub-cylinder. , by causing the hydraulic oil leaking from the hydraulic chamber into the annular groove via the contact sliding part to flow out from the annular groove to the outside of the sub-cylinder.
This reduces leakage of hydraulic oil from the hydraulic chamber to the combustion chamber side.

The present invention will be described below with reference to the embodiment shown in FIG. 1. In the figure, (1) is a cylinder block, (2) is a cylinder head, and (3) is a cylinder that slides reciprocally within the cylinder bore (4) of the cylinder block (1). The piston (5) indicates a combustion chamber formed by recessing the lower surface of the cylinder head (2), and the combustion chamber (5) has an ignition screw screwed onto the cylinder head (2) approximately in the center thereof. As the stopper (6) rises,
An intake boat and an exhaust boat (not shown) are open.

(7) is an auxiliary cylinder bored in the cylinder head (2), and the auxiliary cylinder (7) has an opening in the combustion chamber (5) on the lower side and an upper chamber in the cylinder head on the upper surface of the cylinder head (2) on the upper side. A cover plate (8) is provided at the opening of the sub-cylinder (7) to the upper chamber of the cylinder head to close the opening. (9) is an auxiliary piston that is slidably inserted into the auxiliary cylinder (7), and a piston ring (9)' is provided on the outer periphery of the auxiliary piston (9) near the combustion chamber (5). When the secondary piston (9) moves forward toward the combustion chamber (5), the volume of the combustion chamber decreases and the compression ratio increases, and when the secondary piston (9) retreats away from the combustion chamber (5), combustion occurs. The volume of the chamber is increased and the compression ratio is lowered, and this sub-piston (9) is urged in the backward direction by a spring QI, and the rear surface of the sub-piston (9) (combustion chamber) 5) on the back side) is the secondary piston (9).
) is integrally provided with a stem 0υ extending in the axial direction from the center of the auxiliary piston (9). A hydraulic chamber (2) is formed between the lid plate (8) and the hydraulic chamber Vt
, hydraulic oil from a hydraulic source (not shown) is continuously supplied via a boat Q41 equipped with a check valve a.

Furthermore, the stem 0D has a passage Q communicating with the hydraulic chamber (2).
A spill boat α→ for discharging (Fl!fb in the hydraulic chamber (2) to the upper chamber of the cylinder head is provided at the portion where the giant stem αD protrudes outward from the cover plate (8). to drill.

Q7) shows a spill ring which is an embodiment of the spill body, and the spill ring Q71 is slidably fitted onto the stem αp, so that when the stem αp is retracted, the spill boat qQ is moved by the spill ring Q71. Closed, stem O
The length of the billboard M is configured to open when P moves forward, and the length of the billboard M is adjusted in the axial direction of the stem (II) by rotation of a lever Q119 whose tip is engaged with the cutting pill ring αη. Configure.

Then, the outer circumferential surface of the sub piston (9) or the sub cylinder (7
) is provided with an annular groove 0* on the inner circumferential surface of the stem (Ql) or both so as to surround the circumference of the sub-piston (9), and the annular groove 01 is connected to the cylinder via a through hole bored in the stem Ql). It is open to the upper chamber of the head, and on the outer peripheral surface of the sub-piston (9),
An O-ring Q1) whose outer periphery is in contact with the inner peripheral surface of the sub-cylinder (7) is provided in a portion closer to the combustion chamber (5) than the annular groove α.

In this configuration, moving the spill ring αη in the direction of the combustion chamber (5), that is, in the direction of closing the spill boat aQ, as shown by the two-dot chain line in FIG.
When the valve is closed, the flow of hydraulic oil from the spill boat qo is stopped, and the pressure in the hydraulic chamber (2), which is constantly supplied with hydraulic oil from the reverse ratio valve α boat Q4), increases, so that the sub piston (9 ) moves forward toward the combustion chamber (5), and when this □° advance advances to the point where the spill boat αQ is opened, hydraulic oil starts flowing out from the JIIl, spill boat q, and the tank. The forward movement of the sub piston (9) stops when the amount of supply to the chamber α bottle is balanced.Also, when the spill ring (171) 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 boat 06
is fully opened, the amount of outflow from the spill boat increases, and the pressure in the hydraulic chamber Q4 decreases, so the secondary piston (9) is moved to the combustion chamber (5) by the pressure in the combustion chamber (5) and/or the spring αQ.
This retreat moves away from the spill boat uQ.
When it advances to the point where it closes with the spill ring q7), the amount of outflow from the spill ring q7) decreases, and when the outflow amount balances with the supply amount, the backward movement of the sub piston (9) stops. Therefore, the compression ratio can be changed arbitrarily by changing the position of the sub-piston (9) by moving the spill ring (17).

Therefore, the leakage ring (171) engaged with the spill ring (171)
08) At the other end, an actuator (
A) is connected, and the spill ring α is connected by the actuator blade.
By retracting η from the position indicated by the two-dot chain line in proportion to the increase in engine load, the compression ratio can be automatically controlled so that it gradually decreases as the engine load increases and gradually increases as the load decreases. In addition to being related to this load, it is also possible to automatically control the compression ratio so that it gradually increases as the engine speed increases, and the actuator (a) can be connected to a knocking sensor installed in the engine. Relatedly, 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 (9) receives a large explosive force during the engine's explosion stroke, the secondary piston (9) moves back slightly due to this explosive force and the spill boat of5 closes, while the inside of the hydraulic chamber (2) The pressure increases momentarily, the check valve (to) closes, and the hydraulic fluid in the hydraulic chamber a2 flows into the corresponding hydraulic chamber (6).
), which bears a large explosive force against the secondary piston. The rise is caused by the explosion and combustion of the air-fuel mixture in the combustion chamber (5).
9) It absorbs and alleviates the impact.

Further, as mentioned above, the hydraulic oil in the hydraulic chamber (6), which is constantly supplied and becomes high pressure due to the explosion impact on the secondary piston (9) during the explosion stroke, is transferred to the secondary piston (9).
Leakage flows toward the combustion chamber (5) from the contact sliding part between the outer circumferential surface and the inner circumferential surface of the sub-cylinder (7), but there is an annular groove 0I open to the atmosphere through a through hole in the middle. Therefore, the pressure of the hydraulic oil leaking from the contact sliding part toward the combustion chamber (5) drops to atmospheric pressure when it enters the annular groove θ, and from there it flows through the through hole. This will flow out of the auxiliary cylinder (7), that is, into the atmosphere.

Therefore, it is possible to significantly reduce the amount of hydraulic oil leaking from the annular groove toward the combustion chamber (5), and in this case, as in the embodiment, the part closer to the combustion chamber (5) than the annular groove θ By providing an O-ring Q0 in the combustion chamber (5), leakage of hydraulic oil toward the combustion chamber (5) can be further reduced.
:1 In addition, the hydraulic oil that is always supplied to the hydraulic chamber @1 degree is lubricating oil in an engine (or hydraulic oil in a power steering mechanism of an automobile, or hydraulic oil in an automatic transmission of an automobile). However, when using lubricating oil in the engine, there is a reverse flow from the main gear rally to the hydraulic pipe (2) that distributes the lubricating oil from the lubricating oil pump to various rotating or sliding parts of the engine. While directing the spilled oil from the spill boat QQ in the stem Ql) and the oil spilled from the through hole (a) to the upper chamber of the cylinder head,
Generally speaking, the valve mechanism (
cylinder block (1
) The structure is simple because it can be returned to the lower oil pan (not shown). When using hydraulic oil in an automobile's power steering IJ', YG mechanism, or hydraulic oil in an automatic transmission as hydraulic oil to the hydraulic pipe α, a passage branched from these hydraulic oil pumps is used as shown in Fig. 4. Transfer the wire to the hydraulic chamber (2),
While connecting to boat α→ with check valve C13, cover plate (8
): A cover is provided on the outside that covers the spill ring Q7) and the stem 0η, and the spilled oil from the spill boat OQ and the through hole is removed from the power steering mechanism or through the passage (c) connected to the cover (c). Automatic - Just return it to the oil reservoir (not shown) in the transmission.

In addition, although the above-mentioned embodiment shows a case where a spill ring αη is used as an embodiment of the spill body, as shown in FIG. 5, the stem (lla) is formed into a hollow shaft,
a) A spill body (17a) is slidably inserted into the inside, and by slidingly operating the spill body (17a), the opening/closing position il of the spill boat (16a) is displaced along the axial direction of the stem (11a). Alternatively, as shown in FIGS. 6 and 7, the spill boat in the stem (llb) may be formed into an inclined spill boat (16b) that is inclined with respect to the axis of the stem (11b). On the other hand, there is a gear-type spill ring (
17b) is rotatably and slidably fitted, and the spill ring (17b) is pivotally supported to the cylinder head (2) by a bearing (not shown). ) A relief port member is provided so as to match the inclined spill boat (16b) when the motor moves after the movement, and a relief port member is provided on the teeth on the outer periphery of this spill ring (17b) in a direction perpendicular to the stem (llb). The inclined spill boat (16) of the stem (llb) is engaged with the provided rack rod (E), and the spill ring (17b) is rotated by sliding in the longitudinal direction of the rack rod (C).
For b), move the escape boat (c) to (1) position or (1)
) position, the spill boat (16
The opening/closing position of b) may be configured to be displaced along the axial direction of the stem (1lb) (in this case, the stem (1lb) is held slidably but not rotatably, and the spill It goes without saying that the mechanism for rotating the ring (17b) is not limited to the rack and pinion shown in the embodiment, but other means may be used. Furthermore, it goes without saying that the positions of the inclined spill boat provided on the stem and the relief boat provided on the spill ring may be reversed.

Furthermore, the boat shapes provided on the stem and the spill ring may be combined with arbitrary shapes as shown by the two-dot chain line in FIG. 6, if necessary.

Although the embodiments have been described above, the present invention includes a sub-piston slidably inserted into a sub-cylinder communicating with a combustion chamber,
A hydraulic chamber is formed on the back surface of the sub-piston, and hydraulic oil is supplied to the hydraulic chamber via a check valve, while a stem is provided in the axial direction of the sub-piston so as to protrude from the sub-piston to the outside of the sub-cylinder. A spill boat is bored in the protruding end of the stem to allow the hydraulic oil in the hydraulic chamber to escape, and a spill body is provided in which the spill boat is closed by the backward movement of the stem, or the spill boat is opened by the forward movement of the stem. The spill boat is provided to be slidable in the axial direction of the stem or rotatable around the axis, and configured so that the opening/closing position of the spill boat along the axial direction of the stem is displaced by sliding or rotational operation of the spill body, and A contact sliding portion between the outer circumference of the sub-piston and the inner circumference of the sub-cylinder is provided with an annular groove that surrounds the circumference of the sub-piston and communicates with the outside of the sub-cylinder via a through hole. While the compression ratio can be freely varied by extremely simple operations such as movement or rotation, the back door of the sub-piston is formed in the hydraulic chamber.
X, >□□. . Me・1□:・1・5. . YO01, □□ Since it is variable, there is no need to provide a hydraulic cylinder outside the sub-cylinder as in the conventional device mentioned above, and the structure can be simplified and the space taken up can be reduced. Even when applied to a cylinder engine, it can prevent a significant increase in size and weight of the engine, and it can absorb and alleviate the large explosion shock that momentarily acts on the sub-piston, so it is suitable for variable compression ratio applications. There is no vibration or noise caused by the secondary piston.

Moreover, the present invention eliminates the disadvantages caused by forming the back surface of the sub-piston outside the sub-cylinder into a hydraulic chamber as described above.
The leakage of the hydraulic fluid in the hydraulic chamber from the contact sliding part of the sub piston to the sub cylinder into the combustion chamber can be significantly reduced by the annular groove provided on the outer periphery of the contact sliding part. This has the effect of reducing the amount of hydraulic oil consumed for moving the variable sub-piston back and forth, and preventing the hydraulic oil from degrading exhaust gas.

[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 engine part showing the first 1:1 embodiment, FIG. 2 is a 1-1 cross-sectional view of FIG. 1, and FIG. is an enlarged view of the main part of Figure 111, No. 4
The figure is a longitudinal sectional front view of the engine main part showing the second embodiment, FIGS. 5 and 6 are views of another embodiment of the spill boat and the spill body, and FIG. 7 is a plan view of FIG. 6. (1)・°° Cylinder block, (2)...Cylinder head, (5)...Combustion chamber, (7)...Sub-cylinder, (9)...Sub-piston, α...・Hydraulic chamber, (11
) - Stem, c* (16a) (t6b) Spill boat, αto... Check valve, Qη (17a) (17b
)... Spill body, 09... Annular groove, (A)... Through hole, 0°C... 0 ring. 7゛l'''y 5 1''': j <4', t 6: 1

Claims (2)

[Claims] (1) A sub-piston is slidably inserted into a sub-cylinder communicating with the combustion chamber, and a neck-curve oil chamber is formed in the sub-piston, and hydraulic oil is supplied to the hydraulic chamber via a check valve. At the same time, a stem is provided in the axial direction of the sub-piston so as to protrude from the sub-piston to the outside of the sub-cylinder, and a spill boat is bored at the protruding end of the stem to allow the hydraulic oil in the hydraulic chamber to escape. At the same time, a spill body is provided so as to be slidable in the axial direction of the stem or rotatable around the axis so that the spill boat is closed by the backward movement of the stem, and the spill boat is opened by the forward movement of the stem. The opening/closing position of the spill boat is configured to be displaced by the sliding or rotating operation of the spill body, and the contact sliding portion between the outer circumference of the sub-piston and the outer circumference of the sub-cylinder is provided with a sub-cylinder via a through hole. 8. A variable compression ratio device for an internal combustion engine, characterized in that an annular groove communicating with the outside is provided surrounding the circumference of a sub-piston. (2) The variable compression ratio device for an internal combustion engine according to claim 1, wherein an O'J song is provided on the outer periphery of the auxiliary piston at a location closer to the combustion chamber than the annular groove.