JPS6339390Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is applicable to variable compression ratio internal combustion engines.
The present invention relates to a device for controlling the compression ratio according to the load and rotational speed of an engine.

[Conventional technology]

In an internal combustion engine, increasing the compression ratio can improve output and reduce fuel consumption, but increasing the compression ratio causes knocking in the high load range and low rotation range. Therefore, as a prior art, JP-A-56-
Publication No. 88926 discloses that when changing the compression ratio by moving back and forth an auxiliary piston for variable compression ratio inserted into an auxiliary cylinder that communicates with a combustion chamber, the tip of a rod protrudes from the auxiliary piston to the outside of the auxiliary cylinder. is in contact with a plunger in a hydraulic cylinder provided on the same axis as this, and when the intake negative pressure in the engine is in a low load range greater than a certain value and the rotational speed is higher than a certain value, the hydraulic cylinder The compression ratio is increased by sending hydraulic pressure to move the auxiliary cylinder forward, and when the intake negative pressure is lower than a certain value in the high load range and the rotation speed is lower than a certain value at low rotations, the hydraulic pressure of the hydraulic cylinder is released. It is proposed that the compression ratio be lowered by retracting the sub-cylinder.

[Problem that the invention attempts to solve]

However, in this case, the compression ratio control is an ON-OFF type control in which the compression ratio suddenly changes from high to low or from low to high after a certain load value and a certain rotation speed. It is not possible to smoothly control the compression ratio according to the number and load, and when the compression ratio suddenly changes, engine torque fluctuation becomes large and drivability deteriorates.

The present invention allows the compression ratio to be adjusted without increasing the size of the actuator for moving the auxiliary piston for variable compression ratio back and forth according to the load and rotational speed of the engine.
The purpose of this invention is to enable stepless and smooth control according to the load and rotational speed of the engine, and to improve the responsiveness of the control.

[Means for solving problems]

In order to achieve this object, the present invention forms a sub-cylinder in the cylinder head that communicates with the combustion chamber, a sub-piston is slidably inserted into the sub-cylinder, and a hydraulic chamber is provided on the back surface of the sub-piston. form,
A port for supplying hydraulic oil is connected to the hydraulic chamber, and a stem extending in the axial direction of the sub-cylinder is connected to the back surface of the sub-piston, with the tip of the stem protruding into the upper chamber of 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 so that the spill port closes when the stem moves backward. A spill body in which the spill port is opened by the forward movement of the spill 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. The actuator is connected to an actuator that moves the spill body backward away from the combustion chamber as the load of the engine increases and advances toward the combustion chamber as the load decreases. The related structure is such that the actuator moves in the backward direction of the spill body as the rotation speed decreases and in the forward direction of the spill body as the rotation speed increases.

[Functions and effects of the idea]

In such a configuration, when the spill body is moved forward so as to close the spill port, the flow of hydraulic oil from the spill port stops or decreases, and the sub-piston moves 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 backward to widen the spill port, the amount of hydraulic oil flowing out from the spill port will increase. According to
The secondary piston moves backward from the combustion chamber due to the pressure within the combustion chamber, and this backward movement causes the spill port to move back until 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. Since the sub-piston is stopped when closed, the sub-piston can be moved forward or backward by moving the spill body.

Therefore, by connecting this spill body to an actuator related to the load of the engine, and by connecting this actuator to the rotation speed of the engine, the compression ratio can be adjusted steplessly according to the load and rotation speed of the engine. It is possible to control the changes.

In this case, the present invention provides a spill body for opening and closing the spill port in the stem,
Since the spill body is fitted so as to be movable relative to the outer periphery of the stem, the spill body can be moved back and forth in the same manner as when the spill body is slidably inserted into a hollow stem (for example, 54-20220), the hydraulic pressure of the hydraulic oil in the hydraulic chamber does not act to impede the forward and backward movement of the spill body, and in other words, the spill body is light regardless of the hydraulic pressure of the hydraulic oil in the hydraulic chamber. It can be moved forward and backward with force.

In other words, since the spill body that moves the sub-piston for variable compression ratio back and forth can be moved back and forth with extremely light force, it is necessary to use a large actuator to move this spill body back and forth according to the engine load. In other words, it is possible to reduce the size and weight of the actuator, and it is also possible to improve responsiveness when automatically controlling the compression ratio according to the load and rotational speed of the engine.

Moreover, in the present invention, the stem projects into the upper chamber of the cylinder head, and the spill port and spill body are provided at the projecting end, so that the sliding part between the stem and the spill body is completely replaced by the spill port. Machining to close the sliding part between the stem and the spill body, for example, in JP-A-54-20220
As described in the publication, it is easier to do this than when it is installed inside the hydraulic chamber, so the cost required for machining can be reduced and machining accuracy can be improved. It also has the effect of facilitating maintenance and inspection to maintain good sliding conditions with the body.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 is a cylinder block, reference numeral 2 is a cylinder head, and reference numeral 3 is a piston that reciprocates within the cylinder bore 4 of the cylinder block 1.
Reference numeral 5 indicates a combustion chamber formed by recessing the lower surface of the cylinder 2, and the combustion chamber 5 includes an ignition plug 6 screwed onto the cylinder head 2, and an intake port and an exhaust port (not shown) are open. are doing.

Reference numeral 7 designates a sub-cylinder bored in the cylinder head 2. The sub-cylinder 7 opens at its lower side into the combustion chamber 5 and at its upper side into the upper chamber of the cylinder head 2. The sub-cylinder 7 opens into the upper chamber of the cylinder head of the sub-cylinder 7. A cover plate 8 is provided at the opening to close the opening.

Reference numeral 9 denotes a sub-piston that is slidably inserted into the sub-cylinder 7, and the sub-piston 9 is inserted into the combustion chamber 5.
When the secondary piston 9 moves forward in the direction of , the volume of the combustion chamber 5 decreases and the compression ratio becomes high, and when the sub piston 9 moves backward away from the combustion chamber 5, the volume of the combustion chamber 5 increases and the compression ratio becomes low. Moreover, this sub-piston 9 is urged in the backward direction by a spring 10, and the sub-piston 9 is provided on the back side of the sub-piston 9.
A stem 11 is integrally provided that extends in the axial direction from the center of the piston, and the stem 11 penetrates the cover plate 8 and projects to the outside of the cylinder head 2. A hydraulic chamber 12 is formed in the hydraulic chamber 12, and hydraulic oil from a hydraulic source is continuously supplied to the hydraulic chamber 12 through a port 14 with a check valve.

Further, the stem 11 is formed into a hollow shaft communicating with the hydraulic chamber 12, and a spill port 15 is bored at the end protruding from the cover plate 8 to allow the hydraulic oil in the hydraulic chamber 12 to flow out.

Reference numeral 16 indicates a spill ring which is one embodiment of the spill body, and the spill ring 16
is slidably fitted onto the outer periphery of the protruding end of the stem 11 and when the spill ring 16 is moved forward in the direction of the combustion chamber 5, the spill port 15 is closed and the spill ring 16 is moved away from the combustion chamber 5. The spill port 15 is configured to open when the vehicle moves backward.

Furthermore, reference numeral 17 denotes a swinging lever whose midway portion is pivotally connected to the upper chamber of the cylinder head by a shaft 18. One end of the swinging lever 17 is engaged with the spill ring 16, while the other end is engaged with the actuator. Pressure-operated diaphragm mechanism 1 in one embodiment
Connect to 9.

This diaphragm mechanism 19 has a base end connected to a pin 20.
The diaphragm mechanism 19 has a built-in diaphragm 23 connected to the other end of the swing lever 17 via a rod 22, and a The pressure chamber chamber 24 is provided with a spring 25 that urges the rod 22 in the protruding direction, that is, the spill ring 16 in the backward direction, and is connected to the engine through a flexible negative pressure transmission passage 26 such as a hose. By connecting to an intake manifold (not shown), when the intake negative pressure increases toward vacuum as the engine load decreases, the spill ring 1 is connected to the intake manifold (not shown).
6 moves forward and as the engine load increases, the intake negative pressure decreases toward atmospheric pressure, the spill ring 1
6 is configured to move backward.

Also, the crankshaft or camshaft 27 in the engine
A centrifugal governor mechanism 28 is provided on the rotating shaft of the rotor, etc., and the governor mechanism 28 and the control lever 21 to which the diaphragm mechanism 19 is attached are connected to the rod 29,
When the engine speed increases, the control lever 21 and diaphragm mechanism 19 move in the direction of arrow A, that is, in the forward direction of the spill ring 16, through the lever 31 with a return spring 30 and the wire 32, and rotate. When the number decreases, the spill ring 16 is interlocked and connected so as to move in the direction of arrow B, that is, in the backward direction of the spill ring 16.

In this configuration, when the spill ring 16 is moved forward from the position shown by the solid line in FIG. As the pressure in the hydraulic chamber 12, which is constantly supplied with hydraulic oil from the port 14 with the check valve 13, increases, the sub-piston 9 moves forward toward the combustion chamber 5, and this movement continues until the spill port 15 opens. As it progresses, hydraulic oil begins to flow out from the spill port 15,
When this outflow amount and the supply amount to the hydraulic chamber 12 are balanced, the sub piston 9 stops moving forward. Furthermore, when the spill ring 16 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 15 is fully opened, the amount of flow from the spill port increases, and the pressure in the hydraulic chamber 12 decreases. The piston 9 is retracted away from the combustion chamber by the pressure of the combustion chamber 5 and/or the spring 10, and when this retraction progresses to the point where the spill port 15 is closed by the spill ring 16, the amount of flow from the spill port increases. When the outflow amount is balanced with the supply amount, the backward movement of the sub-piston stops, and the position of the sub-piston 9 can be changed arbitrarily by moving the spill ring 16 back and forth. The ratio can be changed steplessly.

In this case, the spill ring 16 is configured to move forward via a lever 17 in relation to a diaphragm mechanism 19, which is an example of an actuator, as the load of the engine decreases, and move backward as the load increases. On the other hand, the diaphragm mechanism 19
In connection with the governor mechanism 28 via the wire 32 etc., as the engine rotational speed increases,
In other words, in the forward direction of the spill ring 16, as the rotation speed decreases, the spill ring 1
6 moves in the backward direction, the compression ratio gradually decreases as the load increases due to the movement of the spill ring 16 by the diaphragm mechanism 19. By moving the diaphragm mechanism 19 by the governor mechanism 28, the number can be automatically controlled so that it gradually increases as the rotational speed increases.

Note that the actuator that operates the spill ring in response to the engine load is not limited to the pressure-operated type, and may be of other types such as an electric type. The governor mechanism is not limited to the governor mechanism, and an electric type may be used.Furthermore, the hydraulic oil that is constantly supplied to the hydraulic chamber may be lubricating oil in the engine,
Alternatively, the hydraulic oil in the power steering mechanism of an automobile or the hydraulic oil in the automatic transmission of an automobile can be used.

[Brief explanation of the drawing]

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, and FIG. 2 is a sectional view taken from the side of FIG. 1. 1... Cylinder block, 2... Cylinder head, 5... Combustion chamber, 7... Sub cylinder, 9... Sub piston, 12... Hydraulic chamber, 11... Stem, 1
5... Spill port, 16... Spill ring as an example of a spill body, 19... Diaphragm mechanism as an example of an actuator, 28... Governor mechanism.

Claims (1)

[Scope of utility model registration request] A sub-cylinder communicating with the combustion chamber is formed in the cylinder head, a sub-piston is slidably inserted into the sub-cylinder, a hydraulic chamber is formed on the back of the sub-piston, and hydraulic oil is supplied to the hydraulic chamber. While connecting a supply port, a stem extending in the axial direction of the sub-cylinder is connected to the back surface of the sub-piston, and the tip of the stem projects into the upper chamber of 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 so that the spill port closes when the stem moves backward. A spill body in which 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. for,
An actuator is connected to the actuator, which moves the spill body backward away from the combustion chamber as the engine load increases and advances toward the combustion chamber as the load decreases. A compression ratio control device for a variable compression ratio internal combustion engine, characterized in that the spill body moves in a backward direction as the rotational speed decreases and in a forward direction as the rotational speed increases.