JPH08284702A - Variable compression ratio device for internal combustion engine - Google Patents

Abstract

PURPOSE: To make a connecting pin, which is provided on an eccentric wheel, actuating by utilization of oil in an engine lubricating oil gallery so that the eccentric wheel, which is rotatably fitted between a crank pin and the large end of a connecting rod, may be alternately switched over from a low compression ratio state connected to one side of the crank pin and the large end of the connecting rod to a high compression ratio state connected to the other side. CONSTITUTION: A first connecting oil passage 20, which energizes the oil pressure to a connecting pin 14 toward the fitting position of the connecting pin 14 to a first connecting recessed part 15 of a crank pin 5P for the purpose of obtaining a low compression ratio state, and a second connecting oil passage 21, which energizes the oil pressure to the connecting pin 14 toward the fitting position of the connecting pin 14 to a second connecting recessed part 16 of a connecting part large end part 8B for the purpose of obtaining a high compression ratio state, are connected to an engine lubricating oil gallery and a leak jet 22 is provided on the first connecting oil passage 20. A control valve 28 is provided between the second connecting oil passage 21 and the oil gallery and changeover of the connecting pin 14 is performed only by opening and closing the second connecting oil passage 21 by the control valve 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine in which a large end of a connecting rod having a small end connected to a piston is supported by a crankpin of a crankshaft, and a variable compression capable of changing the compression ratio into two stages, high and low. The present invention relates to a ratio device, and more particularly to improvement of a variable compression ratio device in which an eccentric ring whose inner and outer peripheral surfaces are eccentric to each other is interposed between a crankpin and a connecting rod large end.

[0002]

2. Description of the Related Art A variable compression ratio device of this type is already known, as disclosed, for example, in Japanese Patent Laid-Open No. 62-121837.

[0003]

In the above publication, the eccentric wheel is connected to the large end of the connecting rod so that the eccentric direction can be switched to the opposite direction, and the eccentric wheel is moved in the opposite direction. Although it is disclosed that it is connected to the crank pin so that it can be switched, in the above, the piston stroke does not change even when the eccentric direction of the eccentric wheel is switched, and the position of the piston's top and bottom dead centers is simply changed. Since there is only a change in the compression ratio, there is little change in the compression ratio.In the above, the piston stroke increases and decreases due to switching of the eccentric direction of the eccentric ring, but in the high compression ratio state where the piston stroke is increased, Since the dead center position is lowered, the compression ratio cannot be increased sufficiently. Therefore, in any of the above cases, if a large change in the compression ratio is required, an eccentric ring with a large eccentricity is required, and the size of the engine must be increased.

Therefore, the applicant of the present invention considers that the eccentricity of the outer peripheral surface of the eccentric ring can be maximally utilized to effectively change the compression ratio without increasing the size of the engine. An eccentric ring whose inner and outer peripheral surfaces are eccentric to each other by a predetermined amount is rotatably fitted between the surface and the inner peripheral surface of the connecting rod large end portion, and the eccentric wheel is connected to the crankpin. Previously proposed was one equipped with connection switching means capable of selectively establishing a connected state and a second connected state in which the eccentric wheel is connected to the connecting rod large end (Japanese Patent Application No. 6-1615).
44).

It is an object of the present invention to provide a variable compression ratio device for an internal combustion engine, which is a further improvement of the above proposed device and which can easily switch the compression ratio by hydraulic pressure.

[0006]

In order to achieve the above object, the present invention provides an inner and outer peripheral surface eccentric to each other by a predetermined amount between the outer peripheral surface of a crankpin and the inner peripheral surface of a connecting rod large end portion surrounding the crankpin. The eccentric wheel is rotatably fitted, and the eccentric wheel is connected to one of the crank pin and the connecting rod large end to achieve a low compression ratio state in which the piston stroke is minimized. A variable compression ratio device for an internal combustion engine, comprising connection switching means capable of selectively establishing a high compression ratio state that maximizes piston stroke, wherein the connection switching means connects one side wall of the eccentric wheel. A pin hole penetrating in the radial direction, and a connecting pin slidably supported by the pin hole so that the inner and outer ends can alternately project from the pin hole,
A first connecting recess provided on the outer peripheral surface of the crank pin, into which the inner end of the connecting pin fits, and a second connecting recess provided on the inner peripheral surface of the large end of the connecting rod, into which the outer end of the connecting pin fits. , A first connecting oil passage for supplying oil for hydraulically urging the connecting pin to a fitting position with one of the predetermined connecting recesses to obtain a low compression ratio state, and a high compression ratio state And a second connecting oil passage for supplying oil for hydraulically urging the connecting pin toward the predetermined fitting position with the other connecting recess, and these first and second connecting oils. An oil gallery for engine lubrication connected upstream of the passage, a control valve provided to open and close between the oil gallery and the second connecting oil passage, and the hydraulic pressure of the first connecting oil passage to the second connecting oil passage. The pressure reducing means provided in the first oil passage to control the pressure lower than that of the first oil passage. And butterflies.

In addition to the above characteristics, the present invention has a second characteristic that the pressure reducing means is constituted by a leak jet that leaks oil in the first connecting oil passage.

Further, in addition to the second feature, the present invention has the third feature that the leak jet is provided at the large end of the connecting rod so as to open toward the piston connected to the small end of the connecting rod. And

Furthermore, the present invention is directed to the first, second or third aspect.
In addition to the above feature, the fourth feature is that the end face of the large end portion of the connecting rod is provided with an oil groove that opens from its inner peripheral edge toward the piston.

Further, in addition to the first, second, third or fourth feature of the present invention, the fifth aspect is that the length of the connecting pin is set shorter than the length of the pin hole of the eccentric wheel. Characterize.

[0011]

According to the first feature of the present invention, when the control valve is closed, the oil is supplied only from the oil gallery to the first connecting oil passage, so that the connecting pin receives the hydraulic pressure thereof and the predetermined one It is fitted in the connecting recessed portion and the state becomes a low compression ratio. Further, when the control valve is opened, oil is supplied from the oil gallery to the first and second connecting oil passages, but the oil pressure in the first connecting oil passage is reduced by the pressure reducing means. Due to the pressure difference of (1), the connecting pin is fitted into the predetermined other connecting recess, and a high compression ratio state is achieved.

As described above, since the oil in the oil gallery that distributes the lubricating oil to each part of the engine is used for the switching operation of the connecting pin, a dedicated hydraulic pressure source is not required and the first and second connecting oils are used. Oil around the eccentric ring can be lubricated by the oil flowing in the passage. Especially in the low compression ratio state
Since oil is supplied to the connecting oil passage and to both the first and second connecting oil passages in the high compression ratio state, suitable lubrication can be performed according to the output state of the engine.

According to the second aspect of the present invention, the depressurization control of the oil passage can be performed with an extremely simple structure in which the oil in the first connecting oil passage is leaked from the leak jet.

Further, according to the third feature of the present invention, the oil leaked from the leak jet can lubricate and cool the piston.

Further, according to a fourth aspect of the present invention,
Oil leaking from the first or second connecting oil passage can be supplied to the piston through the oil groove at the large end of the connecting rod to lubricate and cool the piston.

Further, according to the fifth feature of the present invention,
In the process of switching the connecting pin, there is a neutral position in which the connecting pin does not fit into either the first or the second connecting recess, and the locking phenomenon in which the crank pin and the connecting rod large end are fixed to each other by the connecting pin is avoided. To be done.

Further, according to the sixth feature of the present invention,
In the fitted state of the connecting pin with the second connecting recess, the slope of the side surface of the second connecting recess gives thrust to the first connecting pin in the direction of the second connecting recess due to relative rotation of the crank pin and the connecting rod large end. This can be used as a switching force to improve the switching performance.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, referring to FIGS. 1, 3 and 4, a cylinder block 1 having a plurality of cylinders 1a of an internal combustion engine.
A plurality of journal support walls 2 and a crankcase 3 that surrounds these and has an open lower surface are integrally connected to the lower end of the crankcase 3, and an oil pan 4 is joined to the lower surface of the crankcase 3.

A plurality of crank journals 5 _J of the crankshaft 5 accommodated in the crankcase 3 are supported by the corresponding journal support walls 2 and bearing caps 6 bolted to the journal support walls 2 via metal bearings 7. It Further, the large ends 8 _B of the corresponding connecting rods 8 are connected to the plurality of crank pins 5 _P of the crank shaft 5,
The small ends 8 _S are connected to the corresponding pistons 9 sliding in the corresponding cylinders 1a through piston pins 10.

Large ends 8 of connecting rods 8 connected to each other
Eccentric 1 is fitted between the _B and the crank pin 5 _P. The eccentric wheel 11 has an inner peripheral surface 11 _I rotatably fitted to the outer peripheral surface of the crank pin 5 _{P and} an outer peripheral surface 11 _O rotatably fitted to the inner peripheral surface of the large end portion 8 _B. With
Among them, the outer peripheral surfaces 11 ₁ and 11 _O are offset from each other by a constant distance ε.

The eccentric wheel 11 has a crank pin 5 _P
A first connection state (state of FIGS. 3 and 4) connected to
A connection switching means 12 for alternately controlling switching between the second connection state (FIGS. 9 and 10) connected to the large end portion 8 _B of the connecting rod 8 is provided, and the means 12 will be described in detail below.

A radial pin hole 13 is formed in the thickest portion of the eccentric ring 11, and a connecting pin 14 having a length slightly shorter than the pin hole 13 (that is, A <B in FIG. 4). )
Is slidably fitted. Also on the inner peripheral surface of the outer peripheral surface and the large end 8 _B of the crankpin 5 _P is the inner end and fitting the outer end portions are alternately of the connecting pin 9 in the bottom dead center of the crank pin 5 _P, separated First and second connecting recesses 15 and 16 are provided, respectively, and when the connecting pin 14 is fitted into the first connecting recess 15, the outer end of the connecting pin 14 escapes from the second connecting recess 16 and is in the first connected state. Further, when the connecting pin 14 is fitted into the second connecting concave portion 16, the inner end thereof is the first connecting concave portion 1.
The second connection state is established by disconnecting from 5.

As shown in FIG. 4, the outer peripheral surface of the crankpin 5 _P, the inner end of the connecting pin 14 over a range of approximately 270 ° to the rotation direction of the crank pin 5 _P from the first connecting concave portion 15 is slid A first guide groove 17 is provided, the groove depth of which gradually increases from zero towards the first coupling recess 15. Further, on the inner peripheral surface of the large end portion 8 _B , the connecting pin 1 extends from the second connecting concave portion 16 in a range of about 90 in the direction opposite to the rotation direction of the crank pin 5 _P.
A second guide groove is provided on which the outer end of 4 can slide, and the groove depth gradually increases from zero toward the second connection recess 16.

Further, the crank pin 5 of the second connecting recess 18
_The side surface of _{P on} the rotation direction side is formed as a slope 19 (see FIG. 4) that descends toward the eccentric wheel 11.

As shown in FIGS. 3 to 6, the eccentric 11
In order to obtain the first connection state, the first connection oil passage 20 that applies hydraulic pressure to the outer end surface of the connection pin 14 is provided from the journal support wall 2 to the second connection recess 16. When the elements of the first connecting oil passage 20 are cited from the upstream side, an annular groove 20a provided in the inner peripheral surfaces of the journal support wall 2 and the bearing cap 6 and a small hole 20b in the radial direction in the annular groove 20a are provided. And an annular groove 20c provided on the inner peripheral surface of the metal bearing 7 so as to communicate with each other.
0 and hole 20d provided on the crank journal 5 _J so as to communicate with the, the through hole 20e extending obliquely towards this hole 20d in the crank pin 5 _P, the crank pin 5 _P to communicate with the through hole 20e Through hole 20f provided in
An annular groove 20g provided on the inner peripheral surface of the eccentric ring 11 so as to communicate with the through hole 20f, a radial small hole 20h communicating with the annular groove 20g, and the small hole 20h formed in the pin hole 13 An axial groove 20j is provided on the outer peripheral surface of the eccentric ring 11 so as to communicate with the second coupling recess 16 (or the second guide groove 18) via the outer end portion. Eccentric wheel 1
1 is provided with a radial small hole 20i for lubrication which communicates with the annular groove 20g on the side opposite to the small hole 20h.

Further, as shown in FIGS. 3, 4 and 7,
In order to obtain the second connection state of the mandrel 11, a connection pin
The second connecting oil passage 21 that applies hydraulic pressure to the inner end surface of 14
It is provided from the journal support wall 2 to the first connection concave portion 15.
Be done. The elements of this second connecting oil passage 21 are listed from the upstream side.
Then, the journal support wall 2 and the bearing cap 6
An annular groove 21a provided on the inner peripheral surface and the annular groove 21a
To the metal via the small hole 21b in the radial direction.
An annular groove 21c provided on the inner peripheral surface of the ring 7,
The crank journal 5 communicates with the annular groove 21c._JTo
The through hole 21d provided and the crank from the through hole 21d
Pin 5_PThrough hole 21e extending obliquely toward
21e is connected to the inner end of the first connection recess 15 by a clan.
Cupin 5 _PAnd a through hole 21f provided in the.

As shown in FIG. 3, the large end portion 8 _B of the connecting rod 8 is provided with a leak jet 22 (pressure reducing means) which opens from the second connecting recess 16 toward the piston 9.
Also on the left and right end faces of the big end 8 _B as shown in FIGS. 3 and 8, the oil groove 23 is provided which opens toward from the inner peripheral edge to the piston 9.

1 and 2, the first connecting oil passage 2
The annular groove 20a of 0 is connected to an oil gallery 24 provided in the cylinder block 1 via a communication oil passage 25,
The annular groove 21a of the second connecting oil passage 21 is connected to the oil gallery 24 via an inlet oil passage 26, a control valve 28 and an outlet oil passage 27.

In the oil gallery 24, an oil pump 29, which is originally driven by the crankshaft 5, pumps oil from the oil pan 4 and receives the oil to be pumped through the oil filter 30, and the oil is supplied to the lubricating oil passages (see FIG. In the present invention, the oil is also distributed to the communication oil passage 25 and the inlet oil passage 26 at the same time.

As shown in FIG. 2, the control valve 28 has a housing 31 joined to one side surface of the cylinder block 1, and the housing 31 opens toward the joint surface with the cylinder block 1. The inlet port 32, the outlet port 33, and the release port 34 are opened, and a leak jet 35 is provided between the inlet port 32 and the outlet port 33 in order to appropriately release the hydraulic pressure from the former to the latter. A filter 36 is attached to the inlet port 32.

The inlet oil passage 26 is provided at the inlet port 32,
Further, the outlet oil passage 27 is connected to the outlet port 33, and the return oil passage 37 for opening the end in the oil pan 4 is connected to the release port 34.

In the bottomed cylindrical valve hole 38 of the housing 31, the spool valve body 39 closes the inlet port 32 and opens between the output port 33 and the release port 34, and the release port 34 is closed. In and out ports 32, 33
A valve spring 40, which is mounted so as to move between a lower valve opening position that opens the space and biases the spool valve 39 toward the valve closing position, is housed.

A spool valve body 39 is provided at the open end of the valve hole 38.
The plug 41 for controlling the valve closing position of the
A pilot oil chamber 42 is defined between 1 and the upper end surface of the spool valve body 39.

The plug body 41 is provided with an introduction hole 43 connected to the pilot oil chamber 42, and an oil passage 44 which is always connected to the inlet port 32 is opened at the upper end of the housing 31. A normally-closed solenoid valve 45 that can open between the introduction holes 43 at appropriate times is attached to the upper end of the housing 31.

The pilot oil chamber 42 and the open port 3
A leak jet 46 that releases the hydraulic pressure in the pilot oil chamber 42 when the solenoid valve 45 is closed is provided between the four.

Next, the operation of this embodiment will be described.

First, the operation of the control valve 28 will be described. If the solenoid valve 45 is in the closed state as shown in FIG.
Since the oil pressure in the pilot oil chamber 42 is released to the release port 34, the spool valve body 39 is held at the valve closing position shown in the figure by the urging force of the valve spring 40. Therefore, since the inlet port 32 is closed and the outlet port 33 and the release port 34 are opened, the oil in the oil gallery 24 is not supplied to the second connecting passage 21, and the oil passage 21 is not connected to the outlet oil passage. It is released into the oil van 4 through 27 and the return oil passage 37.

When the solenoid valve 45 is excited to open the valve,
The oil in the oil gallery 24 waiting in the oil passage 44 is introduced into the pilot oil chamber 42 via the solenoid valve 45 and the introduction hole 43, and the hydraulic pressure thereof pushes the spool valve element 39 to the lower valve opening position. Therefore, the release port 34 is closed, and the inlet / outlet ports 32, 33 are opened, so that the oil in the oil gallery 24 is supplied to the second connecting oil passage 21 through the inlet oil passage 26 and the outlet oil passage 27. Like

On the other hand, the first connecting oil passage 20 is connected to the control valve 28.
Since the oil gallery 24 is connected to the oil gallery 24 via the communication passage 25 regardless of the above, the oil is constantly supplied from the oil gallery 24.

Now, the operation of changing the compression ratio of the eccentric wheel 11 will be described.

First, when the spool valve element 39 of the control valve 28 occupies the valve closing position so that the oil in the oil gallery 24 is supplied only to the first connecting oil passage 20, the oil is supplied to the oil passage. It is supplied to the second connecting concave portion 16 via 29, and its hydraulic pressure acts on the outer end surface of the connecting pin 14. As a result, it is assumed that the connecting pin 14 is now kept fitted in the first connecting recess 15 as shown in FIG.

In this state, the eccentric wheel 11 is connected to the crank pin 5 _P with the thickest part of the eccentric wheel 11 facing the rotation center O of the crank shaft 5. As a result, as shown in FIG. 11, the eccentric wheel 11 rotates together with the crank pin 5 _P around the rotation center O of the crank shaft 5 as the crank shaft 5 rotates, and the large end portion 8 _{B of the} connecting rod 8 is rotated. The piston 9 is moved up and down by giving a circular motion to. This is the low compression ratio operation state, and the stroke L _S of the piston 9 at this time can be expressed by the following equation.

L _S = 2 (r−ε) ……………………………… (1) where r: Revolution radius of crank pin 5 _P ε: Inner and outer peripheral surfaces of eccentric ring 11 Eccentricity between 11 _I and 11 _O Next, the spool valve element 39 of the control valve 28 is switched to the lower valve opening position, so that the oil in the oil gallery 24 is transferred to the first and second connecting oil passages 20 and 21. When supplied at the same time, the oil is supplied to the first and second connecting recesses 1
5 and 16 are supplied simultaneously. Therefore, the connecting pin 1
No. 4 receives hydraulic pressure on its inner and outer end surfaces,
Since the leak jet 22 communicates with the second connection recess 16, the oil pressure of the second connection recess 16 is lower than the oil pressure of the first connection recess 15 by the amount of oil leaking from the leak jet 22. As a result of the pressure difference between them, the connecting pin 14 moves outward in the radial direction as shown in FIG. Try to fit into.

At this time, if the positions of the connecting pin 14 and the second connecting concave portion 16 do not coincide with each other, the connecting pin 14
While brought into sliding contact with the outer end to the inner peripheral surface of the large end 8 _B, together with the eccentric 11, and rotate relative to the big end 8 _B, it comes to a position before approximately 90 ° in the second coupling recess 16 And the second guide groove 1
8 and is guided to a fitting position with the second coupling recess 16.

In this way, when the eccentric wheel 11 is connected to the large end portion 8 _B with its thickest portion directed toward the rotation center O of the crankshaft 5, this time, as shown in FIG. Along with the rotation, the eccentric wheel 11 and the large end portion 8 _B are integrally provided with a circular motion from the crank pin 5 _P to move the piston 9 up and down. This is the high compression ratio operation state, and the stroke L _L of the piston 9 at this time can be expressed by the following equation.

[0047] _L L = 2r ................................................... (2) where, r: radius of revolution in the high compression ratio operation of the crankpin 5 _P, the crank pin 5 _P and Large end 8 _B
The relative rotation of the connecting pin 14 causes the connecting pin 14 to receive the thrust inward in the radial direction from the slope 19 of the second connecting recess 16, and this thrust again switches the connecting pin 14 to the mating position with the first connecting recess 15. It will be a helper in the case and contribute to the improvement of the switchability.

To return from the high compression ratio operating state to the low compression ratio operating state, as described above, the spool valve element 39 of the control valve 28 is used.
By returning to the valve closed position again, only the hydraulic pressure in the second connecting oil passage 21 is released. As a result, the connecting pin 14
As shown in FIG. 14, the hydraulic pressure of the second connecting concave portion 16 moves inward in the radial direction, and first, the outer end of the second connecting concave portion 1 is moved.
6 and then try to fit the inner end into the first connection recess 15.

At this time, if the positions of the connecting pin 14 and the first connecting concave portion 15 do not coincide with each other, the connecting pin 14
When together with the eccentric 11 while sliding the inner end to the crank pin 5 _P peripheral surface, and rotate relative to the crank pin 5 _P, it comes to a position before approximately 270 ° of the first connecting recess 15, the first
The guide groove 17 is engaged with the guide groove 17, and the guide groove 17 is guided to a position where the first connecting recess 15 is fitted.

[0050] As apparent from the above, the high, in any case of low compression ratio operation state, the bottom dead center of the crank pin 5 _P, the connecting pin 14 of the rotation center O and the crank pin 5 _P of the crankshaft 5 Since it is located on the straight line connecting the center, the orientation of the eccentric ring 11 does not change, and therefore the bottom dead center position of the piston 9 is always constant. In addition, according to the above equations (1) and (2), the stroke L _S of the piston 9 in the low compression ratio operating state is greater than that in the high compression ratio operating state.
Of these, the amount of eccentricity between the outer peripheral surfaces 11 _I and 11 _O corresponding to twice the eccentricity decreases, so that the amount of eccentricity is maximally utilized for changing the low compression ratio.

By the way, since the length A of the connecting pin 14 is set to be slightly shorter than the length B of the pin hole 13 of the eccentric wheel 11, the first and second connecting concave portions 15, 1 of the connecting pin 14 are formed.
In the process of switching between 6, there is a neutral position in which neither of the connecting recesses 15 and 16 fits, so there is a locking phenomenon in which the crank pin 5 _P and the large end 8 _B are fixed to each other by the connecting pin 14. Avoided.

Further, since oil is constantly supplied to the first connecting oil passage 20 from the oil gallery 24 in both high and low compression ratio operating states, one of the inner peripheral surfaces of the metal bearing 7 is located around the crank journal 8 _J. The other annular groove 2 on the inner peripheral surface of the metal bearing 7 is constantly lubricated by the oil constantly flowing through the annular groove 20c and is operated at a high compression ratio.
The oil flowing through 1c adds to the lubrication.

On the other hand, between the crank pin 5 _P and the large end portion 8 _B , oil is constantly lubricated by the oil flowing through the annular groove 20 g and the small holes 20 i, 20 h of the eccentric wheel 11 regardless of whether the compression ratio is high or low. part 8 _B of the leak jet 22
The oil ejected from the oil groove 23 goes to the piston 9 and contributes to its lubrication and cooling. And at the time of the high compression ratio operation, the oil supplied to the first coupling recess 15 and the first guide groove 17 is applied to the lubrication around the crankpin 5 _P.

In each of the above embodiments, various design changes can be made without departing from the gist of the present invention. For example, it is also possible to provide a switching stage of the connecting pin 14 to set the top dead center of the crank pin 5 _P, the pin hole 13 of the eccentric 11 to the thinnest portion.

[0055]

As described above, according to the first aspect of the present invention, the inner and outer peripheral surfaces are decentered from each other by a predetermined amount between the outer peripheral surface of the crank pin and the inner peripheral surface of the large end of the connecting rod surrounding the crank pin. The eccentric wheel is rotatably fitted, and the eccentric wheel is connected to one of the crank pin and the large end of the connecting rod so that the piston stroke is minimized and the eccentric wheel is connected to the other. A variable compression ratio device for an internal combustion engine, comprising: a connection switching means that can selectively establish a high compression ratio state that maximizes a piston stroke. Pin hole penetrating in the direction, a connecting pin slidably supported by the pin hole so that the inner and outer ends can alternately project from the pin hole, and an inner end of the connecting pin provided on the outer peripheral surface of the crank pin. First mating
The connecting recess and the second connecting recess provided on the inner peripheral surface of the large end of the connecting rod, into which the outer end of the connecting pin fits, and the connecting pin for obtaining a low compression ratio state. The first connecting oil passage for supplying oil for hydraulically urging toward the fitting position with the connecting pin for obtaining a high compression ratio state,
It is connected to a second connecting oil passage for supplying oil for hydraulically urging the same toward a predetermined fitting position with the other connecting recess, and upstream of these first and second connecting oil passages. An oil gallery for engine lubrication, a control valve provided to open and close between the oil gallery and the second connecting oil passage, and a first
Since the pressure reducing means provided in the first oil passage is provided to control the hydraulic pressure of the connecting oil passage to be lower than that of the second connecting oil passage,
By using the oil in the oil gallery and operating the connecting pin with a simple structure, it is possible to accurately switch between the low and high compression ratio states. Therefore, a dedicated hydraulic source is not required, and the oil around the eccentric ring can be lubricated by the oil flowing through the first and second connecting oil passages. Particularly, in the low compression ratio state, the oil is supplied to the first connecting oil passage, and in the high compression ratio state, the oil is supplied to both the first and second connecting oil passages, so that suitable lubrication according to the output state of the engine is performed. It can be carried out.

Further, according to the second aspect of the present invention, since the pressure reducing means is constituted by a leak jet for leaking the oil in the first connecting oil passage, the oil in the first connecting oil passage is removed from the leak jet. The depressurization control of the oil passage can be performed with an extremely simple configuration of leaking.

Further, according to the third aspect of the present invention, since the leak jet is provided at the connecting rod large end so as to open toward the piston connected to the connecting rod small end, the leak jet is leaked from the leak jet. Oil can lubricate and cool the piston.

Further, according to the fourth feature of the present invention,
Since an oil groove that opens from the inner peripheral edge toward the piston is provided on the end surface of the connecting rod large end, the oil leaking from the first and second connecting oil passages is passed through the oil groove at the connecting rod large end to the piston. It can be supplied and lubricated and cooled.

Furthermore, according to the fifth feature of the present invention,
Since the length of the connecting pin is set shorter than the length of the pin hole of the eccentric wheel, in the connecting pin switching process, there is a neutral position where the connecting pin does not fit into the first and second connecting recesses. The locking phenomenon in which the crank pin and the large end of the connecting rod are fixed to each other by the connecting pin is avoided.

Further, according to the sixth feature of the present invention,
Since the side surface of the second connecting recess on the rotation direction side of the crank pin is formed as an inclined surface that descends toward the eccentric ring, when the connecting pin is fitted in the second connecting recess, the large end of the crank pin and the connecting rod is formed. With the relative rotation, the inclined surface imparts thrust to the connecting pin in the direction of the first connecting recess, and this can be used as a switching force to improve the switchability.

[Brief description of drawings]

1 is a cross-sectional view of a part of an internal combustion engine equipped with the device of the present invention.

FIG. 2 is an enlarged sectional view of a control valve portion in FIG.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1 showing the engine in a low compression ratio operation state.

4 is a sectional view taken along line 4-4 of FIG.

5 is a sectional view taken along line 5-5 of FIG.

6 is a sectional view taken along line 6-6 of FIG.

7 is a sectional view taken along line 7-7 of FIG.

8 is a sectional view taken along line 8-8 of FIG.

9 is a cross-sectional view corresponding to FIG. 3, showing a high compression ratio operation state of the engine.

10 is a sectional view taken along line 10-10 of FIG.

FIG. 11 is an operation explanatory view of the engine in a low compression ratio operation state.

FIG. 12 is an operation explanatory view of the engine in a high compression ratio operation state.

FIG. 13 is an explanatory view of the switching operation of the engine from the low compression ratio operating state to the high compression ratio operating state.

FIG. 14 is an explanatory view of the switching operation of the engine from the high compression ratio operating state to the low compression ratio operating state.

[Explanation of symbols]

5 ... Crank shaft 5 _P ... Crank pin 8 ... Connecting rod 8 _B ... Large end 8 _S ... Small end 9 Piston 11 .... Eccentric wheel 12 ... Connection switching means 14 ... Connection pin 15 ... First connection recess 16 ... Second connection recess 20 ... First connection oil passage 21 ... Second oil passage for connection 22 ... Leak jet (pressure reducing means) 24 ... Oil gallery 28 ... Control valve

Claims (6)

[Claims] 1. The inner and outer peripheral surfaces (11 _I , 11 _O ) are separated from each other by a predetermined amount (ε) between the outer peripheral surface of the crank pin (5 _P ) and the inner peripheral surface of the connecting rod large end (8 _B ) surrounding the crank pin (5 _P ). ) An eccentric wheel (11) that is eccentric is rotatably fitted, and this eccentric wheel (11) is connected to one of the crank pin (5 _P ) and the connecting rod large end (8 _B ) to minimize the piston stroke ( L _S ) and a low compression ratio state and this eccentric ring (11) is connected to the other of them to maximize the piston stroke (L
A variable compression ratio device for an internal combustion engine, comprising connection switching means capable of selectively establishing a high compression ratio state of _L ), wherein the connection switching means (12) is one of the eccentric wheels (11). A pin hole (13) penetrating the side wall in the radial direction and the pin hole (1
3) is slidably supported by the pin hole (13) so that the inner and outer ends thereof can alternately project, and the crank pin (5 _P ) is provided on the outer peripheral surface thereof. 1
4) is provided on the inner peripheral surface of the connecting rod large end portion (8 _B ) with the first connecting concave portion (15) into which the inner end of the connecting pin (1) is fitted.
The second connecting concave portion (16) to which the outer end of 4) is fitted, and the connecting pin (14) for obtaining a low compression ratio state are provided with hydraulic pressure toward the fitting position of one predetermined connecting concave portion. A first connecting oil passage (20) for supplying oil for urging, and a connecting pin (14) for obtaining a high compression ratio state, are hydraulically moved toward a predetermined fitting position with the other connecting recess. A second connecting oil passage (21) for supplying oil for urging, and an engine lubricating oil gallery (24) connected upstream of these first and second connecting oil passages (20, 21). , A control valve (28) provided to open and close between the oil gallery (24) and the second connecting oil passage (20), and the first connecting oil passage (2).
Pressure reducing means (2) provided in the first oil passage (20) so as to control the oil pressure of (0) lower than that of the second connecting oil passage (21).
2) A variable compression ratio device for an internal combustion engine, comprising: 2. The variable internal combustion engine according to claim 1, wherein the pressure reducing means is constituted by a leak jet (22) that leaks oil in the first connecting oil passage (20). Compression ratio device. 3. The connecting rod large end (8) according to claim 2, wherein the leak jet (22) opens towards a piston (9) which is connected to the connecting rod small end (8 _S ). A variable compression ratio device for an internal combustion engine, characterized in that it is provided in _B ). 4. The oil groove (23) according to claim 1, 2 or 3, wherein the end surface of the connecting rod large end (8 _B ) is provided with an opening from the inner peripheral edge thereof toward the piston (9). A variable compression ratio device for an internal combustion engine, characterized in that 5. The eccentric ring (11) according to claim 1, 2, 3 or 4, wherein the length (A) of the connecting pin (14) is set to the eccentric ring (11).
A variable compression ratio device for an internal combustion engine, characterized in that it is set shorter than the length (B) of the pin hole (13). 6. The eccentric ring (11) according to claim 1, 2, 3, 4 or 5, wherein a side surface of the second coupling recess (16) on the rotation direction side of the crank pin (5 _P ) is formed on the eccentric ring (11). A variable compression ratio device for an internal combustion engine, characterized in that it is formed on a slope (19) which descends.