JPH0621568B2 - Variable compression ratio mechanism of internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a variable compression ratio mechanism for an internal combustion engine that varies the compression ratio by increasing or decreasing the volume of a fuel chamber at the top dead center of a piston.

(Prior Art) Conventionally, as such a variable compression ratio mechanism of an internal combustion engine,
For example, there is a technique disclosed in Japanese Patent Laid-Open No. 58-91340. This prior art (hereinafter referred to as the first prior art)
Eccentric bearing is interposed between the piston and the connecting rod, the relative position of the piston with respect to the connecting rod can be changed according to the rotation of the eccentric bearing, and the eccentric bearing can be fixed to the connecting rod by a hydraulically operated lock pin. By releasing the fixation, the compression ratio of the internal combustion engine is made variable.

Another conventional technique is disclosed in, for example, Japanese Patent Laid-Open No. 54-106724. This conventional technology (hereinafter referred to as the second conventional technology) is a hydraulic pressure in a hydraulic chamber formed by an inner upper end surface of a piston and an upper end surface of a piston guide by a hydraulic action from a hydraulic control device provided on the cylinder block side. To change the relative position of the piston with respect to the piston guide, thereby changing the volume of the combustion chamber of the internal combustion engine and making the compression ratio variable.

(Problems to be Solved by the Invention) However, in the first conventional technique, the working hydraulic pressures from the two main oil passages for high compression ratio and low compression ratio formed in the cylinder block are supplied to the crankshaft and the crankpin. Since it is applied to the hydraulically actuated lock pin via the connecting rod and the connecting rod, a space for forming an oil passage for the control hydraulic pressure is required for each bearing metal of the crankshaft and the crankpin, which is limited. In each bearing metal arranged in the space, it may be difficult to secure the space of the oil passage other than securing the bearing function.

Further, since the switching between the two main oil passages is performed in the cylinder block on the upstream side of the main oil passage, that is, a portion where a switching command for fixing or unlocking the lock pin is far away from the lock pin. Because it is issued from
It is difficult to quickly follow the lock pin for fixing or releasing the fixing, and therefore the response when changing the compression ratio (hereinafter referred to as "response to change in compression ratio") is poor.

On the other hand, also in the second conventional technique, since the control hydraulic pressure from the hydraulic control device is supplied to the hydraulic chamber via the crankshaft, the crankpin and the connecting rod, each bearing of the crankshaft and the crankpin is provided. Spaces for forming oil passages for passing control hydraulic pressure through the metal are required respectively. Therefore, in order to ensure the lubrication function and space of the oil passage in each of the bearing metals, first, an oil passage for control oil pressure is provided separately from the lubricating oil passage, or secondly, the control oil pressure is provided. Must be set to a value that does not hinder lubrication in both the low hydraulic pressure side and the high hydraulic pressure side, and it must be formed so that the control oil passage and the lubricating oil passage can be used in common. Space becomes difficult, and in the latter case, the minimum value of the control oil pressure on the low oil pressure side is limited to fulfill the lubrication function, so the value on the high oil pressure side becomes excessive, which causes the oil pressure control device to be too large. However, there was a problem that the capacity of the piston became excessively large, or the weight of the piston structure increased. Also in this conventional technique, the control hydraulic pressure acting on the hydraulic chamber is
Since it is controlled by the hydraulic control device separated from the hydraulic chamber, it is difficult to quickly follow the relative position change of the piston with respect to the piston pin, and therefore the response of the compression ratio change is poor.

(Object of the Invention) The present invention has been made to solve the problems of the prior art, and the response of the compression ratio change can be achieved by adding a simple structure without changing the conventional structure such as the crankshaft. It is an object of the present invention to provide a variable compression ratio mechanism for an internal combustion engine that can improve the performance.

(Means for Solving the Problem) The gist of the present invention for achieving such an object is to provide a variable compression ratio of an internal combustion engine for varying the compression ratio by increasing or decreasing the volume of the fuel chamber at the top dead center of the piston of the internal combustion engine. In the mechanism,
Combustion chamber volume changing means for increasing / decreasing the combustion chamber volume according to the operating oil pressure supplied through an oil passage provided in the connecting rod; and a part of the connecting rod exposed on the outer surface of the connecting rod. And a hydraulic control valve for controlling the supply of the working hydraulic pressure to the combustion chamber volume varying means, and a cylinder block side provided to face the exposed portion of the hydraulic control valve, and the working hydraulic pressure is provided to the exposed portion. Includes drive means for driving the hydraulic pressure control valve by directly applying drive forces of different drive sources from the cylinder block side.

(Operation) The hydraulic control valve provided on the connecting rod is driven by the drive means provided on the cylinder block side, and the operating hydraulic pressure acts on the combustion chamber volume varying means to obtain the change state of the compression ratio.

(Embodiment) Hereinafter, each embodiment of the present invention will be described with reference to the accompanying drawings. In the description of each embodiment, the same parts are designated by the same reference numerals, and the duplicated description will be omitted.

1 to 3 show a first embodiment of the present invention, and FIG. 1 is a diagram showing the overall configuration of a variable compression ratio mechanism.

As shown in FIG. 1, a cylinder liner wall 1 of an internal combustion engine
The piston 2 which reciprocates inside is composed of a movable piston top portion 3 (the right half and the left half are shown in a divided manner in order to facilitate understanding of operation) and a piston base 4. There is. Here, the movable piston top portion 3 is assembled to the piston base portion 4 so as to be relatively displaceable by a fixed amount h, and between the movable piston top portion 3 and the piston base portion 4 there is a high compression ratio side hydraulic chamber 5 and a low pressure chamber 5. The compression ratio side hydraulic chamber 6 and the compression ratio side hydraulic chamber 6 can be formed respectively. The piston pin 7 is pressed into the small end of the connecting rod 8, while
It is rotatably inserted in the piston pin hole 4a of the piston base 4. The connecting rod 8 and the piston pin 7 are connected to the high compression ratio side oil passage 8H, which are always in communication with each other.
7H and low compression ratio side oil passages 8L and 7L are respectively formed. In the piston base 4, the high compression ratio side oil passage 7H and the low compression ratio side oil passage 7L of the piston pin 7 near the bottom dead center of the piston 2 are connected to the high compression ratio side hydraulic chamber 5 and the low compression ratio side hydraulic chamber. 6, the high compression ratio side oil passage 4H and the low compression ratio side oil passage 4 respectively.
L is formed. Furthermore, connecting rod 8
First, the operating oil pressure from the lubricating oil passage 9a of the crank pin 9 is passed to the high compression ratio side oil passage 8H or the low compression ratio side oil passage 8L through the groove and the hole 10a formed in the bearing metal 10 of the crank pin 9. An oil passage 8a to be actuated is formed.

A spool valve 11 as a hydraulic control valve is provided between the high compression ratio side oil passage 8H and the low compression ratio side oil passage 8L of the connecting rod 8 and the oil passage 8a.
Reference numeral 1 denotes a high compression ratio side position (position shown in FIG. 1) where the oil passage 8a communicates with the high compression ratio side oil passage 8H and a low compression ratio side position where the oil passage 8a communicates with the low compression ratio side oil passage 8L. (The position displaced to the right from the position shown in the figure). As shown in FIG. 2, the spool (valve body) 1 of this spool valve 11
An annular groove 12 is formed on the la 1a, and a click stop mechanism 13 is provided on the la. The click stop mechanism 13 is provided for holding the position and preventing the spool 11a from coming off when the spool 11a moves.
4 and concave ring grooves 12H, 1 formed at both ends of the annular groove 12
It is composed of a steel ball 15 that can be engaged with 2L. When the spool valve 11 is in the high compression ratio side position, the steel ball 1
5 and 5 engage with the concave ring groove 12H of the annular groove 12, and when the spool valve 11 is at the low compression ratio side position, the steel ball 15 has the concave ring groove of the annular groove 12. Engage with 12L.

As shown in FIG. 1, as a drive means for driving the spool valve 11 between a high compression ratio side position and a low compression ratio side position,
The high compression ratio side drive means 16 and the low compression ratio side drive means 17 are provided on the cylinder block side of the internal combustion engine. The high compression ratio side driving means 16 and the low compression ratio side driving means 17 include lubricating oil pressure sources 18, 18 for the internal combustion engine, a high compression ratio side oil jet pipe 19, a low compression ratio side oil jet pipe 22, and a lubricating oil pressure source. A high compression ratio side solenoid valve and a low compression ratio side solenoid valve 23 for injecting or stopping the injection of the oil from 18 to the spool 11a via the Pouleau jet pipes 19 and 22, and the piston 2 of the piston 2 in response to the crank angle signal. It is composed of an electronic control unit 21 which operates the solenoid valves 20 and 23 for a predetermined crank angle across a bottom dead center or for a predetermined time. The oil jet pipes 19 and 22 are arranged so as to match the spool valve 11 when the piston 2 reaches the bottom dead center (position in FIG. 1).

The operation of the variable compression ratio mechanism of the internal combustion engine having the above configuration will be described below.

When the high compression ratio state of the internal combustion engine is set in accordance with the operating state or the like, the high compression ratio side solenoid valve 20 is operated by the electronic control unit 21 for a predetermined crank angle sandwiching the bottom dead center of the piston 2 or for a predetermined time. And the low compression ratio side solenoid valve 23 is deactivated. As a result, the solenoid valve 20 supplies the oil from the lubricating oil pressure source 18 to the oil jet pipe 19. At this time, oil jut pipe 1
Since 9 is located at the position matching the spool 11a, the oil jet pipe 19 injects oil toward the spool 11a to switch the spool 11a to the high compression ratio side position shown in FIG. Therefore, the oil passage 8a and the high compression ratio side oil passage 8H communicate with each other via the annular groove 12 of the spool 11a,
Further, the steel ball 15 is engaged with the concave ring groove 12H of the ring groove 12 by the urging force of the spring 14 to hold the spool 11a at the high compression ratio side position. As a result, the operating oil pressure from the lubricating oil passage 9 a of the crank pin 9 is applied to the groove and the hole 10 of the bearing metal 10.
a, oil passage 8a, spool 11a, and high compression ratio side oil passage 8
It acts on the high compression ratio side hydraulic chamber 5 via H, 7H and 4H, and the movable piston top portion 3 moves upward relative to the piston base portion 4 as shown in the left half of FIG. As a result, the volume of the combustion chamber 1a of the internal combustion engine is reduced and a high compression ratio state is realized.

Next, when the internal combustion engine is brought into the low compression ratio state in accordance with the operating state or the like, the electronic control unit 21 controls the low compression ratio side for a predetermined crank angle sandwiching the bottom dead center of the piston 2 or for a predetermined time. The solenoid valve 23 is activated and the high compression ratio side solenoid valve 20 is deactivated. At this time, since the oil jet pipe 22 is located at the position matching the spool 11a, the oil jet pipe 22 injects the supplied oil toward the spool 11a, so that the spool 11a moves to the first position.
The high compression ratio side position in the figure is displaced to the right to switch to the low compression ratio side position. As a result, the oil passage 8a and the low compression ratio side oil passage 8L communicate with each other through the annular groove 12 of the spool 11a, and the steel ball 15 engages with the concave annular groove 12L to move the spool 11a to the low compression ratio side position. Hold on. As a result, the operating oil pressure from the lubricating oil passage 9a of the crankpin 9 is changed to the groove and hole 10a of the bearing metal 10, the oil passage 8a, the spool 11a.
And acting on the low compression ratio side hydraulic chamber 6 via the low compression ratio side oil passages 8L, 7L, 4L, the movable piston top portion 3 moves downward with respect to the piston base portion 4 as shown in the right half of FIG. Move relatively. Thereby, the combustion chamber 1a of the internal combustion engine
The volume is increased and a low compression ratio state is realized.

According to the above-mentioned embodiment, since the spool valve 11 as the hydraulic control valve is installed near the high compression ratio side and low compression ratio side hydraulic chambers 5 and 6, the oil passage becomes short and the compression ratio changes. The responsiveness of can be improved.

Further, according to the above-described embodiment, the piston 2 reaches the vicinity of the bottom dead center and the oil jet pipes 19 and 22 move to the spool 1.
When the oil jet pipes 19 and 2 match with 1a,
Since the oil is injected from two, the oil injection amount can be small, and the action time of the injected oil on the spool valve 11 can be relatively long.

In the above-mentioned embodiment, the combustion chamber volume changing means is composed of the movable piston top 3, the piston base 4, the high compression ratio side hydraulic chamber 5, the low compression ratio side hydraulic chamber 6, the high compression ratio side oil passages 4H, 7H,
8H and low compression ratio side oil passages 4L, 7L, 8L.

Next, a second embodiment of the present invention will be described with reference to FIG.

In the second embodiment, instead of the driving means 16 and 17 for driving the spool valve 11 using the pressure oil injection in the first embodiment, a driving means 24 for driving the spool valve 11 'using electromagnetic force is provided. It is used. This drive means is a power source 2
5, a changeover switch 26 which is controlled by the electronic control unit 21 and a pair of electromagnets 27, 27, and the spool valve 11 'is a spool 11 made of a permanent magnet having extremes (S, N) at both ends. ′ A, and electromagnets 27, 27 are arranged opposite to each other on both magnetic pole sides.

In the variable compression ratio mechanism of the internal combustion engine having such a configuration, the changeover switch 26 is controlled by the electronic control unit 21 to change to the fourth mode.
When switching to the high compression ratio side shown by the solid line in the figure, the spool 1
Since the polarities of the electromagnets 27, 27 located on both sides of 1'a are S, the spool 11'a moves to the left in FIG. 4 to take a high compression ratio position, and a high compression ratio state is realized. . Further, when the changeover switch 26 is changed over to the low compression ratio side indicated by the broken line in the figure by the electronic control unit 21, the spool 11'a
The polarities of the electromagnets 27 located on both sides of N are reversed and become N, whereby the spool 11'a moves to the right from the high compression ratio position of FIG. Is realized.

Next, a third embodiment of the present invention will be described with reference to FIG.

In the third embodiment, the low compression ratio side hydraulic chamber 6 and the low compression ratio side oil passage 4 which constitute the combustion chamber volume varying means in the first embodiment.
L, the low compression ratio side oil passages 8L, 7L, etc. are omitted. In this case, in order to obtain a low compression ratio state, the spool 11a is provided with the leak groove 11L that can communicate with the high compression ratio side oil passage 8H.
Is formed. The other structure is similar to that of the first embodiment.

In the variable compression ratio mechanism of the internal combustion engine having such a configuration, when the internal combustion engine is brought into the high compression ratio state in accordance with the operating state or the like, the electronic control unit 21 is used as in the first embodiment.
Thus, the high compression ratio side solenoid valve 20 is operated and the low compression ratio side solenoid valve 23 is not operated for a predetermined crank angle or a predetermined time with the bottom dead center of the piston 2 interposed therebetween.
Spool the oil with the oil jet pipe 19
Then, the spool valve 11 is switched to the high compression ratio side position shown in FIG. At this time, the steel ball 15 as the click stop mechanism causes the annular groove 12 to move by the urging force of the spring 14.
Engaging with the concave ring groove 12H to hold the spool 11a at the high compression ratio side position, whereby the working hydraulic pressure from the lubricating oil passage 9a of the crank pin 9 acts in the high compression ratio side hydraulic chamber 5. The movable piston top portion 3 moves upward relative to the piston base portion 4, and as a result, the volume of the combustion chamber 1a of the internal combustion engine is reduced and a high compression ratio state is realized. It is the same.

Next, when the internal combustion engine is brought into the low compression ratio state in accordance with the operating state or the like, the electronic control unit 21 controls the low compression ratio side for a predetermined crank angle sandwiching the bottom dead center of the piston 2 or for a predetermined time. The solenoid valve 23 is operated and the high compression ratio side solenoid valve 20 is deactivated, and the oil jet pipe 22 injects the supplied oil toward the spool 11a, so that the spool 11a is moved to the high compression ratio side in FIG. Displace to the right from the position and switch to the low compression ratio side position. As a result, the communication between the oil passage 8a and the high compression ratio side oil passage 8H is cut off, and the steel ball 15 engages with the concave ring groove 12L and the spare 11a.
Is held at the low compression ratio side position. At this time, the oil passage 8H on the high compression ratio side faces the leak groove 11L, so that the oil in the oil passage 8H on the high compression ratio side passes through the leak groove L and reaches the crank pin 9.
Fall to the side. As a result, the action of the hydraulic pressure in the high compression ratio side hydraulic chamber 5 is cut off, and the movable piston top portion 3 moves downward relative to the piston base portion 4. That is, the volume of the combustion chamber 1a of the internal combustion engine is increased to realize the low compression ratio state.

In the above embodiment, other than the valves (spool valves 11, 11 ') constituting the hydraulic control valve, a rotary valve type, a flat cam type, etc. may be used.

Further, according to the present invention, as the combustion chamber volume varying means, an eccentric bearing or an offset piston pin (eccentric piston pin) as in the above-mentioned conventional example is used, and an eccentric bearing or offset is provided by a hydraulically operated lock pin. It goes without saying that it is possible to use a type in which the compression ratio of the internal combustion engine is made variable by fixing or releasing the fixed piston pin to the connecting rod or piston.

Alternatively, for example, an oil passage communicating with the hydraulic chamber of the piston 2 may be appropriately formed to obtain a continuously variable compression ratio.

(Effects of the Invention) As described above, according to the present invention, the variable compression ratio mechanism for an internal combustion engine that varies the compression ratio by increasing or decreasing the fuel chamber volume at the top dead center of the piston of the internal combustion engine is provided on the connecting rod. Combustion chamber volume varying means for increasing or decreasing the combustion chamber volume according to the operating oil pressure supplied through the oil passage,
A part of the connecting rod is exposed to the outer surface of the connecting rod to control the supply of the operating oil pressure to the combustion chamber volume varying means, and a cylinder block side of the hydraulic control valve. And a driving means which is provided so as to face the exposed portion, and which causes a driving force of a driving source different from the working hydraulic pressure to directly act on the exposed portion from the cylinder block side to drive the hydraulic pressure control valve. Therefore, the switching of the working oil pressure to the high compression ratio side oil passage or the low compression ratio side oil passage is performed by the hydraulic control valve in the connecting rod close to the combustion chamber volume changing means, and the driving means changes the combustion chamber volume. Since the driving force of the driving source different from the working oil pressure is directly applied to the exposed part of the hydraulic control valve without contact, there is no delay in switching the hydraulic control valve and the response when changing the compression ratio. It is possible to improve the.

Further, since the operating hydraulic pressure for the combustion chamber volume varying means and the driving force for driving the hydraulic control valve are supplied through different paths, the control hydraulic pressure for driving the hydraulic control valve is supplied to each bearing metal of the crankshaft and the crankpin. There is no need for a space to pass through, and there is no need to change the conventional structure such as the crankshaft.

In this case, if the drive means is configured to be driven near the bottom dead center of the piston, for example, when the hydraulic control valve is driven by pressure oil injection of the drive means, the drive means is driven at an appropriate timing. Since it is possible to control the pressure oil injection, the amount of pressure oil used is not wasted, and the working time of the pressure oil can be relatively long.

[Brief description of drawings]

1 to 3 show a first embodiment of the present invention,
FIG. 1 is a schematic diagram showing a variable compression ratio mechanism of an internal combustion engine, and FIG.
The figure is an enlarged cross-sectional view of a part of FIG. 1, and FIG. 3 is a cross-sectional view of FIG.
A sectional view taken along line III-III, FIG. 4 is a schematic view showing a variable compression ratio mechanism of an internal combustion engine according to a second embodiment of the present invention, and FIG. 5 is a partially enlarged view showing a third embodiment of the present invention. FIG. 1a ... Combustion chamber, 2 ... Piston, 5 ... High compression ratio side hydraulic chamber (combustion chamber volume varying means), 6 ... Low compression ratio side hydraulic chamber (combustion chamber volume varying means), 8 ... Connecting rod , 11, 11 '... Spool valve (hydraulic control valve), 13
...... Click stop mechanism (position control means), 16 ……
High compression ratio side driving means, 17 ... Low compression ratio side driving means, 2
4 ... Driving means.

Claims (10)

[Claims] Claim: What is claimed is: 1. A variable compression ratio mechanism for an internal combustion engine, wherein a combustion chamber volume at a top dead center of a piston of the internal combustion engine is increased / decreased to make a compression ratio variable. Operation supplied via an oil passage provided on a connecting rod. Combustion chamber volume varying means for increasing / decreasing the combustion chamber volume according to oil pressure, and a part of the connecting rod provided exposed to the outer surface of the connecting rod to supply the working oil pressure to the combustion chamber volume varying means. And a hydraulic control valve for controlling the hydraulic pressure control valve, which is provided on the cylinder block side so as to face the exposed portion of the hydraulic control valve.
A variable compression ratio mechanism for an internal combustion engine, comprising: driving means for directly driving a driving force of a driving source different from the working hydraulic pressure from the cylinder block side to drive the hydraulic pressure control valve on the exposed portion. 2. The variable compression ratio mechanism for an internal combustion engine according to claim 1, wherein the drive means drives the hydraulic control valve in the vicinity of the bottom dead center of the piston. 3. The variable compression ratio mechanism for an internal combustion engine according to claim 1 or 2, wherein the drive means drives the hydraulic control valve by pressure oil injection. 4. The variable compression ratio mechanism for an internal combustion engine according to claim 1, wherein the drive means drives the hydraulic control valve by an electromagnetic force. 5. The variable compression ratio mechanism for an internal combustion engine according to claim 4, wherein a valve body of the hydraulic control valve is formed of a permanent magnet. 6. The hydraulic control valve according to claim 1, wherein the hydraulic control valve has position regulating means for holding the valve bodies at predetermined positions after switching when the operating state of the operating hydraulic pressure is switched. The variable compression ratio mechanism for an internal combustion engine according to any one of claims. 7. The internal combustion engine according to claim 1, wherein the hydraulic control valve is a two-position switching valve for switching the compression ratio to a high compression ratio or a low compression ratio. Variable compression ratio mechanism. 8. The internal combustion engine according to claim 1, wherein the hydraulic control valve comprises a spool valve whose valve body is movable in a direction substantially parallel to the axial direction of the crankshaft. Variable compression ratio mechanism. 9. The internal combustion engine according to claim 6 or 7, wherein the hydraulic control valve switches an oil passage for changing the volume of the combustion chamber according to each state of a high compression ratio or a low compression ratio. Variable compression ratio mechanism. 10. The drive means moves the valve body by applying a driving force to the valve body from opposite portions in the cylinder block on both sides in the moving direction of the valve body of the hydraulic control valve. The variable compression ratio mechanism for an internal combustion engine according to claim 7, claim 8 or claim 9.