JPH0842368A - Variable compression ratio device of internal combustion engine - Google Patents

Abstract

PURPOSE:To enable an eccentric ring to be rotatably interposed between a crank pin and a connecting rod large end part to be smoothly switched from the first connecting state wherein the eccentric ring is connected to the crank pin to the second connecting state wherein it is connected to the connecting rod large end part. CONSTITUTION:An oil passage 15 capable of applying switching oil pressure on the inner end of a connecting pin 9 is provided on a crank pin 1p so that the second connecting state may be established by fitting the outer end of the connecting pin 9 supported by a pin hole 8 of an eccentric ring 6 into a second connecting hole 11 of a connecting rod large end part 2B, and an orifice 19 for applying oil pressure to an extruding member 12 is provided on the eccentric ring 6 so that the extruding member 12 in the second connecting hole 11 may be retreated prior to fitting to the second connecting hole 11 of the connecting pin 9 when oil pressure is supplied to this oil passage 15.

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.Although the above changes the piston stroke by changing the eccentric direction of the eccentric wheel, the piston stroke is increased 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 capable of smoothly changing the compression ratio by further improving the above-mentioned proposed device.

[0006]

In order to achieve the above object, the present invention provides a connection switching means that is slidably fitted in a pin hole that radially penetrates one side wall of an eccentric ring and the pin hole. A coupling pin which is provided on the outer peripheral surface of the crank pin and a coupling pin whose inner and outer ends can be alternately projected from the pin hole, and which fits the inner end of the coupling pin to establish a first coupled state. A second connecting hole which is provided on the inner peripheral surface of the connecting rod large end and which establishes a second connected state by fitting the outer end of the connecting pin, and slidably fitted in the second connecting hole. The push-out member which is always urged toward the eccentric ring side by the elastic force of the return spring and the outer end of the connecting pin are fitted to the second connection hole against the push-out force of the push-out member. Switching hydraulic pressure supply means for applying a switching hydraulic pressure to the pin, and a second connecting hole of the connecting pin when the switching hydraulic pressure supplying means is activated. Characterized in that the pusher member is constructed from a retracted hydraulic pressure supply means for applying hydraulic pressure to the pusher member to retract into the second connecting hole prior to fitting.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

First, the first aspect of the present invention shown in FIGS.
An example will be described. 1 and 2, a crank shaft 1 of an internal combustion engine has a crank journal 1 _J supported by a bearing portion of a crank case (not shown) and a crank pin 1 _P integrally connected to an end of the crank journal 1 _J. The large end 2 _B of the connecting rod 2 is supported by the pin 1 _P , and the small end 2 _S of the connecting rod 2 has the cylinder bore 3 of the cylinder block.
It is connected via a piston pin 5 to a piston 4 that slides inside.

An eccentric wheel 6 is fitted between the large end portion 2 _{B of the} connecting rod 2 and the crank pin 1 _P. This eccentric wheel 6
Has an inner peripheral surface 6 _I rotatably fitted to the outer peripheral surface of the crank pin 1 _{P and} an outer peripheral surface 6 _O relatively rotatably fitted to the inner peripheral surface of the large end portion 2 _B. The inner and outer peripheral surfaces 6 _I and 6 _O are offset from each other by a constant distance ε.

The eccentric wheel 6 is connected to the crank pin 1 _P in a first connected state (a state shown in FIG. 1) and a large end portion 2 _B of the connecting rod 2 is connected in a second connected state (see FIG. 2). (State of) and a connection switching means 7 for controlling the state, and the means 7 will be described in detail below.

A radial pin hole 8 is formed in the thickest portion of the eccentric ring 6, and a connecting pin 9 longer than the pin hole 8 is slidably fitted in the pin hole 8. Also crank pin 1 _P
On the outer peripheral surface of and the inner peripheral surface of the large end portion 2 _B , first and second connecting holes 10 and 11 into which the inner end portion and the outer end portion of the connecting pin 9 can be fitted and released, respectively, are provided. A pin-shaped push-out member 12 and a return spring 13 for biasing the push-out member 12 toward the eccentric ring 6 are provided in the second connection hole 11 on the side of the large end 2 _B.
And a stopper 14 that defines the retracted position of the pushing member 12 in the second connecting hole 11. Second connection hole 11
Communicate with the outer surface of the connecting rod 2 via the breathing hole 18.

Length of connecting pin 9, first and second connecting holes 1
The depths of 0 and 11 and the lengths of the push-out member 12 and the stopper 14 are such that when the connecting pin 9 is securely fitted in the first connecting hole 10, the outer end of the connecting pin 9 escapes from the second connecting hole 11 and the above-mentioned first and second connecting holes 11 are inserted. 1 and the connecting pin 9 is securely fitted into the second connecting hole 11 until the pushing member 12 is pressed against the stopper 14, the inner end of the connecting pin 9 is separated from the first connecting hole 10 and the second Are set to be in a connected state.

On the other hand, the crankpin 1 _P is provided with an oil passage 15 having a downstream end opened at the bottom of the first connecting hole 10, and the switching oil pressure can be supplied to the upstream side of the oil passage 15 in a timely manner. When a hydraulic pressure source (not shown) such as a hydraulic pump is connected and the switching hydraulic pressure is supplied to the oil passage 15, the hydraulic pressure is changed to the connecting pin 9
Is pressed outward in the radial direction.

[0014] On the outer peripheral surface of the crank pin 1 _P, the first guide groove inner end of the connecting pin 9 over a range of approximately 90 ° to the rotation direction of the crank pin 1 _P from the first connecting hole 10 can slide 1
6 is provided, and the groove depth thereof gradually increases from zero toward the first connecting hole 10. Further, on the inner peripheral surface of the large end portion 2 _B , approximately 90 ° from the second connecting hole 11 in the anti-rotational direction of the crank pin 1 _P.
The second guide groove 17 on which the outer end of the connecting pin 9 can slide is provided over the range of, and the groove depth gradually increases from zero toward the second connecting hole 11.

Further, the eccentric ring 6 is provided with an orifice 19 which communicates the first guide groove 16 with the outer peripheral surface of the eccentric ring 6 at a position close to the pin hole 8.

In the figure, arrow A indicates the direction of rotation of the crankshaft 1, and O indicates its center of rotation.

Next, the operation of the first embodiment will be described.

Assuming that the switching hydraulic pressure is released on the upstream side of the oil passage 15, as shown in FIG.
When the three of the second connecting holes 10 and 11 are coaxially arranged, the pushing member 12 pushes the connecting pin 9 inward in the radial direction by the elastic force of the return spring 13 and fits into the first connecting hole 10. Then, the first connection state is established. Therefore, the eccentric wheel 6
Is connected to the crank pin 1 _P with its thickest portion directed toward the rotation center O of the crank shaft 1. As a result,
As shown in, the eccentric wheel 6 rotates together with the crank pin 1 _P around the center O of the crank shaft 1 as the crank shaft 1 rotates, and imparts a circular motion to the large end 2 _B of the connecting rod 2. Raise and lower the piston 4. This is the low compression ratio operation state, and the stroke L _S of the piston 4 at this time can be expressed by the following equation.

L _L = 2r-2ε (1) where r is the revolution radius of the crank pin 1 _P ε is the amount of eccentricity between the outer peripheral surfaces 6 _I and 6 _{O of the} eccentric ring 6. When the switching hydraulic pressure is supplied to the oil passage 15 in the specific operation state, the hydraulic pressure acts on the inner end of the connecting pin 9 and presses it radially outward. However, the connecting pin 9 rotates together with the crank pin 1 _P and the eccentric wheel 6 while sliding the outer end in sliding contact with the inner peripheral surface of the large end portion 2 _B while the connecting pin 9 is not arranged coaxially with the second connecting hole 11. As shown in FIG. 3A, when it comes to a position of about 90 ° before the second connecting hole 11, the engagement with the second guide groove 17 starts. Then, the connecting pin 9 is displaced in the radial direction while being guided by the second guide groove 17 as it approaches the second connecting hole 11, and accordingly, as shown in FIG. 16,
Since the orifice 19 and the second guide groove 17 communicate with the inlet of the second connecting hole 11, the pushing member 12 is connected to the oil passage 15.
It receives the hydraulic pressure from and resists the force of the return spring 13 and retracts into the second connecting hole 11. Therefore, as shown in FIGS. 3C and 3D, it is necessary to prevent a violent collision between the connecting pin 9 and the pushing member 12 from the time when the connecting pin 9 approaches the second connecting hole 11 to the time when the connecting pin 9 is coaxially arranged. You can Then, as soon as the connecting pin 9 is lined up with the second connecting hole 11, the connecting pin 9 is fitted into the second connecting hole 11 while the push-out member 12 is further retracted by the hydraulic pressure of the oil passage 15, and the first connecting hole 10 is formed. The second connection state in which the eccentric wheel 6 is connected to the large end portion 2 _B is established as the second connection state is established.

In this second connected state, the eccentric ring 6 is connected to the large end 2 _B with the thickest part thereof facing the small end 2 _S side of the connecting rod 2, so that the eccentric ring 6 will now be connected. As shown in FIG. 5, the crankpin 1 _P causes the eccentric wheel 6 and the large end portion 2 _B to make a circular motion with the rotation of the crankshaft 1 to move the piston 4 up and down. This is the high compression ratio operation state, and the stroke L _L of the piston 4 at this time can be expressed by the following equation.

L _S = 2r (2) However, r: Revolution radius of the crank pin 1 _{P As} is apparent from the above, the bottom dead center of the piston 4 in both high and low compression ratio operating states. Then, since the connecting pin 9 is located on the straight line connecting the rotation center O of the crankshaft 1 and the center of the crankpin 1 _P , the direction of the eccentric ring 6 does not change, and therefore the bottom dead center position of the piston 4 is always constant. Is. Moreover, according to the above formulas (1) and (2), the stroke L _S of the piston 4 in the low compression ratio operating state is higher than that in the high compression ratio operating state, in the eccentric wheel 6, the outer peripheral surfaces 6 _I , 6 _O. Since the amount corresponding to twice the eccentricity amount ε is reduced, the eccentricity amount is maximally utilized for reducing the compression ratio.

When the oil pressure in the oil passage 15 is released again from the high compression ratio operation state, the connecting pin 9 which is urged radially inward by the pushing force of the pushing member 12 is not aligned with the first connecting hole 10. Has its inner end slidably contacting the outer peripheral surface of the crank pin 1 _P , but the first end of the first connecting hole 10 is approximately 90 ° from the first position.
Since it engages with the guide groove 16 and is guided thereby to the first connecting hole 10, it can be smoothly fitted into the first connecting hole 10 when it is lined up with the first connecting hole 10, and thereby the low compression ratio operation state can be obtained again. Begins.

In the above, the oil passage 15 is formed by the pushing member 1.
The outer end of the connecting pin 9 against the pushing force of the second connecting hole 1
1 corresponds to the switching hydraulic pressure supply means of the present invention capable of applying a switching hydraulic pressure to the inner end of the connecting pin 9, and the first and second guide grooves 16 and 17 and the orifice 19 are the above-mentioned switching pressurizing supply. When the means is operated, the reversing hydraulic pressure supply means of the present invention applies a hydraulic pressure to the pushing member 12 so as to retract the pushing member 12 into the second connecting hole 11 before fitting the connecting pin 9 into the second connecting hole 11. Equivalent to.

FIG. 6 shows a second embodiment of the present invention.
A high compression ratio operation state is obtained by the first connection state in which the eccentric wheel 6 is connected to the crankpin 1 _P , and a low compression ratio operation state is obtained by the second connection state in which the eccentric wheel 6 is connected to the connecting rod large end 2 _B. The configuration is the same as that of the previous embodiment except that the pin hole 8 for supporting the connecting pin 9 is formed in the thinnest portion of the eccentric wheel 6, and the configuration is the same as that of the previous embodiment. The parts corresponding to are given the same reference numerals.

In the case of this embodiment, the stroke L _L of the piston 4 when the connecting pin 9 is fitted in the first connecting hole 10 and the eccentric wheel 6 is connected to the crank pin 1 _P (high compression ratio operation state) It can be expressed by the following equation.

L _S = 2r + 2ε (3) where r is the revolution radius of the crank pin 1 _P ε is the eccentric amount between the outer peripheral surfaces 6 _I and 6 _{O of the} eccentric ring 6, and the connecting pin 9 is 2 Eccentric ring 6 that fits into the connecting hole 11
Is connected to the large end portion 2 _B (low compression ratio operation state), the stroke L _S of the piston 4 can be expressed by the following equation.

L _L = 2r (4) Even in this embodiment, the direction of the eccentric wheel 6 does not change at the bottom dead center of the piston 4 in the high and low compression ratio operating condition. The bottom dead center position of the piston 4 is immovable. Therefore, as is clear from the equations (3) and (4), the eccentricity ε of the eccentric ring 6 greatly contributes to the high compression ratio.

In each of the above-described embodiments, various design changes can be made without departing from the gist of the present invention. For example, in view of the mounting of the crank pin 1 _P eccentric 6, the eccentric 6 can also split configured to be able to diametrically, also can be constituted pusher member 12 in a steel ball. It is also possible to set the switching timing of the connecting pin 9 to the top dead center of the piston 4 and change the bottom dead center position of the piston 4 to change the compression ratio.

[0029]

As described above, according to the present invention, the connection switching means and the pin hole which penetrates one side wall of the eccentric wheel in the radial direction are slidably fitted in the pin hole and are fitted in the pin hole. Is provided on the outer peripheral surface of the crank pin, and the inner end of the connecting pin fits to the connecting pin
And a second connecting hole which is provided on the inner peripheral surface of the large end portion of the connecting rod and which is fitted with the outer end of the connecting pin to establish the second connecting state. 2 An extruding member that is slidably fitted in the connecting hole and is constantly urged toward the eccentric ring by the elastic force of the return spring, and an outer end of the connecting pin that resists the pushing force of the extruding member. A switching hydraulic pressure supply means capable of applying a switching hydraulic pressure to the connecting pin so as to fit the connecting hole, and a second connecting member for the push-out member prior to fitting the connecting pin into the second connecting hole when the switching hydraulic pressure supplying means is operated. Since the retraction hydraulic pressure supply means applies a hydraulic pressure to the pushing member to retract it into the hole, when the connecting pin is switched from the first connecting state to the second connecting state, a violent impact of the connecting pin with the pushing member is prevented. Then, the fitting of the connecting pin with the second connecting hole can be smoothly performed. , Thus switched to the second connection state becomes smooth, it may also contribute to the durability of the connection switching means.

[Brief description of drawings]

FIG. 1 is a transverse sectional view of an internal combustion engine equipped with a variable compression ratio device according to a first embodiment of the present invention in a low compression ratio state.

FIG. 2 is a transverse sectional view of the engine in a high compression ratio state.

FIG. 3 is an explanatory view of the switching operation of the engine from the low compression ratio state to the high compression ratio state.

FIG. 4 is an operation explanatory view of the engine in a low compression ratio operation state.

FIG. 5 is an operation explanatory view of the engine in a high compression ratio operation state.

FIG. 6 is a transverse sectional view of an engine showing a second embodiment of the present invention.

[Explanation of symbols]

1 crankshaft 1 _P crank pin 2 connecting rod 2 _B large end 2 _S small end 4 piston 6 eccentric ring 6 _I inner peripheral surface 6 _O outer peripheral surface 7 connection switching means 8 pin hole 9 connecting pin 10 first connecting hole 11 1st 2 connection hole 12 pushing member 13 return spring 15 switching hydraulic pressure supply means 16, 17, 19 reverse hydraulic pressure supply means ε eccentric amount

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[Procedure amendment]

[Submission date] April 6, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

L _S = 2r−2ε (1) where r is the revolution radius of the crank pin 1 _P ε is the amount of eccentricity between the outer peripheral surfaces 6 _I and 6 _{O of the} eccentric ring 6. When the switching hydraulic pressure is supplied to the oil passage 15 in the specific operation state, the hydraulic pressure acts on the inner end of the connecting pin 9 and presses it radially outward. However, the connecting pin 9 rotates together with the crank pin 1 _P and the eccentric wheel 6 while sliding the outer end in sliding contact with the inner peripheral surface of the large end portion 2 _B while the connecting pin 9 is not arranged coaxially with the second connecting hole 11. As shown in FIG. 3A, when it comes to a position of about 90 ° before the second connecting hole 11, the engagement with the second guide groove 17 starts. Then, the connecting pin 9 is displaced in the radial direction while being guided by the second guide groove 17 as it approaches the second connecting hole 11, and accordingly, as shown in FIG. 16,
Since that pass with the inlet of the second connecting hole 11 through the orifice 19 and the second guide groove 17, the pushing member 12 is an oil passage 1
The hydraulic pressure from 5 causes the return spring 13 to resist the force of the second
It retreats into the connecting hole 11. Therefore, as shown in FIGS. 3C and 3D, it is necessary to prevent a violent collision between the connecting pin 9 and the pushing member 12 from the time when the connecting pin 9 approaches the second connecting hole 11 to the time when the connecting pin 9 is coaxially arranged. You can Then, as soon as the connecting pin 9 is lined up with the second connecting hole 11, the connecting pin 9 is fitted into the second connecting hole 11 while the push-out member 12 is further retracted by the hydraulic pressure of the oil passage 15, and the first connecting hole 10 is formed. The second connection state in which the eccentric wheel 6 is connected to the large end portion 2 _B is established as the second connection state is established.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

L _L = 2r (2) However, r: Revolution radius of the crank pin 1 _{P As} is apparent from the above, the bottom dead center of the piston 4 in both high and low compression ratio operating states. Then, since the connecting pin 9 is located on the straight line connecting the rotation center O of the crankshaft 1 and the center of the crankpin 1 _P , the direction of the eccentric ring 6 does not change, and therefore the bottom dead center position of the piston 4 is always constant. Is. Moreover, according to the above formulas (1) and (2), the stroke L _S of the piston 4 in the low compression ratio operating state is higher than that in the high compression ratio operating state, in the eccentric wheel 6, the outer peripheral surfaces 6 _I , 6 _O. Since the amount corresponding to twice the eccentricity amount ε is reduced, the eccentricity amount is maximally utilized for reducing the compression ratio.

Claims (1)

[Claims] 1. Between the outer peripheral surface of the crank pin (1 _P ) and the inner peripheral surface of the connecting rod large end portion (2 _B ) surrounding the crank pin (1 _P ),
An eccentric ring (6) in which the inner and outer peripheral surfaces (6 _I , 6 _O ) are eccentric to each other by a predetermined amount (ε) is rotatably fitted, and the eccentric ring (6) is connected to the crank pin (1 _P ). Internal combustion comprising a connection switching means (7) capable of selectively establishing a first connection state and a second connection state for connecting the eccentric wheel (6) to the connecting rod large end (2 _B ). A variable compression ratio device for an engine, wherein a connection switching means (17) is slidable in a pin hole (8) penetrating one side wall of an eccentric wheel (6) in a radial direction and the pin hole (8). The connecting pin (9) is fitted to the pin hole (8) so that the inner and outer ends thereof can alternately project, and the crank pin (1 _P ) is provided on the outer peripheral surface, and the inner end of the connecting pin (9) is A first connecting hole (1) which is fitted to establish the first connected state.
0) and a second connecting hole (11) which is provided on the inner peripheral surface of the connecting rod large end (2 _B ) and which is fitted with the outer end of the connecting pin (9) to establish the second connected state. , The second connection hole (11) is slidably fitted, and the return spring (1
3) The pushing member (12) which is constantly urged toward the eccentric ring (6) by the elastic force of the pushing member (3) and the second end of the connecting pin (9) against the pushing force of the pushing member (12). A switching hydraulic pressure supply means (15) for applying a switching hydraulic pressure to the connecting pin so as to fit the connecting hole (11), and a second connecting hole () of the connecting pin (9) when the switching hydraulic pressure supplying means (15) is operated. Prior to fitting into the second connecting hole (11) prior to fitting into the second connecting hole (11), and a reversing hydraulic pressure supply means (16, 17, 19) for applying hydraulic pressure to the pushing member (12). A variable compression ratio device for an internal combustion engine, characterized in that