JPH03213629A - Variable compression ratio device of internal combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable compression ratio device for an internal combustion engine (hereinafter referred to as an "engine" as necessary).

[Conventional technology] Traditionally, while preventing knocking in a high load range or high engine speed range that is larger than the engine load range, it has been attempted to improve fuel efficiency by increasing thermal efficiency in operating ranges below medium load. To this end, various engines with variable compression ratios have been proposed.

Such a variable compression ratio mechanism is disclosed in Japanese Patent Publication No. 63-3297, for example.
It is disclosed in Publication No. 2. The variable compression ratio mechanism disclosed in this publication includes an eccentric bearing on one of the shaft supports at both ends of the connecting rod of the engine, which makes the bearing hole of the connecting rod and the support shaft inserted through the bearing hole eccentric to each other. The eccentric bearing is designed to rotate freely by the rotational force generated by the eccentric load and the reaction force from the support shaft, and furthermore, by driving a lock pin that is movable in the radial direction of the bearing, the eccentric bearing can be rotated freely. Provided with hydraulically actuated locking means for switching between fixed and
The pressure of the operating oil supplied to this locking means is determined by a signal from a computer that receives signals from the piston position detection means and the operating condition detection means, and hydraulic pressure is constantly applied to the locking means during locking, and during unlocking. The locking mechanism is controlled under conditions where no hydraulic pressure is applied to the locking means.

[Problems to be Solved by the Invention] However, in such conventional variable compression ratio mechanisms for internal combustion engines, the rotation of the eccentric bearing is switched between free and fixed by driving the lock pin in the radial direction of the bearing. Therefore, there is a risk that the operation of the lock pin may become uncertain due to the influence of inertia force generated due to the reciprocating movement of the connecting rod or the like.

The present invention aims to solve these problems, and provides a variable compression compression system for an internal combustion engine that prevents the locking/unlocking operation of the locking means from becoming uncertain due to centrifugal force or acceleration of the reciprocating motion of the connecting rod. The purpose is to provide a ratio device.

[Means for Solving the Problems] Therefore, the variable compression ratio device for an internal combustion engine of the present invention has one end pivotally supported by a piston that reciprocates within a cylinder of an internal combustion engine, and the other end supported by a crankshaft. A pivotally supported connecting rod is provided, and an eccentric sleeve is rotatably mounted on either one of the pivot parts at both ends of the connecting rod to make a bearing hole of the connecting rod and a support shaft inserted through the bearing hole eccentric with respect to each other. An eccentric sleeve capable of fixing rotation of the eccentric sleeve by actuating a pin member provided and movable in the axial direction of the eccentric sleeve to engage the pin member with an engaging portion formed on the eccentric sleeve. It is characterized by being provided with blocking means.

[Function] In the above-described variable compression ratio device for an internal combustion engine of the present invention, the bearing hole of the connecting rod and the support shaft passing through the bearing hole are eccentrically arranged in either one of the pivot parts at both ends of the connecting rod. An eccentric sleeve is rotatably provided, and the rotation of the eccentric sleeve causes the eccentric sleeve locking means to actuate a pin member movable in the axial direction of the eccentric sleeve to engage the engagement formed on the eccentric sleeve. It can be fixed by engaging a pin member with the portion.

[Examples] Examples of the present invention will be described below with reference to the drawings.
Figures 1 to 8 show a variable compression ratio device for an internal combustion engine as a first embodiment of the present invention. Figure 1 is an overall configuration diagram showing the situation when it is in a low compression ratio state, and Figure 2 is a Figure 3 is a front view of the connecting rod showing how it looks when it is in a low compression ratio state, Figure 3 is an overall configuration diagram showing how it looks when it is in a high compression ratio state, and Figure 4 shows how it looks when it is in a high compression ratio state. The front view of the connecting rod shown in Figure 5 is V in Figures 1 and 3.
FIG. 6 is a cross-sectional view of the hydraulic drive mechanism showing the state when it is in a low compression ratio state. FIG. 7 is a cross-sectional view of the hydraulic drive mechanism showing the state when it is in a high compression ratio state. Fig. 8 is a hydraulic circuit diagram thereof, and Figs. 9 to 13 show a variable compression ratio device for an internal combustion engine as a second embodiment of the present invention.
Figure 9 is an overall configuration diagram showing the situation when the compression ratio is low, Figure 10 is an overall configuration diagram showing the situation when the compression ratio is high, and Figure 11 is the overall configuration diagram showing the situation when the compression ratio is low. FIG. 12 is a cross-sectional view of the hydraulic drive mechanism showing the state when it is in a high compression ratio state, FIG. 13 is its hydraulic circuit diagram, and FIG. 14 is a diagram of the crankshaft. FIG. 15, which is a diagram illustrating the dimensions of each part, is a characteristic diagram of the hydraulic pressure applied to the hydraulic drive mechanism and its hydraulic pressure supply system. In each figure, the same reference numerals indicate substantially the same parts.

First, a first example will be described.

Now, as shown in FIGS. 1 to 4, the connecting rod 6 has its small end pivotally supported by a piston pin 7 of a piston 8 that reciprocates within the cylinder of a gasoline engine (internal combustion engine), and its large end. The end portion is pivotally supported by a crank pin 2 of a crankshaft 1.

In addition, an eccentric sleeve 5 is rotatably provided at the pivot point at the large end of the connecting rod 6 to make the bearing hole of the connecting rod 6 and the crank pin 2, which is a support shaft inserted through the bearing hole, eccentric with respect to each other. It is being

That is, the eccentric sleeve 5 is eccentric between the center of its inner circumferential circle and the center of its outer circumferential circle, and the minimum eccentric position can be obtained by rotating the outer circumference of the crank pin 2 by 180° from the maximum eccentric position.

As shown in detail in FIG. 5, a metal bearing 9 with the inner circumferential surface of the eccentric sleeve 5 is interposed between the inner circumferential surface of the eccentric sleeve 5 and the outer circumferential surface of the crank pin 2. A metal bearing 10 with an inner circumferential surface of the bearing hole of the connecting rod 6 is interposed between the outer circumferential surface of the eccentric sleeve 5 and the inner circumferential surface of the bearing hole of the connecting rod 6. Thereby, it is possible to slide between the eccentric sleeve 5 and the crank pin 2, and also between the eccentric sleeve 5 and the bearing hole of the connecting rod 6.

Incidentally, an eccentric sleeve locking means 11 is provided, and this eccentric sleeve locking means 11 is provided with a stopper pin 12 as a pin member movable in the axial direction of the eccentric sleeve 5, that is, in the axial direction of the crankshaft 1. By operating this stopper pin 12 with a hydraulic drive mechanism 11A serving as a piston-type fluid pressure drive mechanism, two engaging portions 5a and 5b formed on the eccentric sleeve 5 are activated.
The stopper pin 12 is engaged with the eccentric sleeve 5.
can be fixed at two positions (the maximum eccentricity position and the minimum eccentricity position described above).

Furthermore, this eccentric sleeve locking means 11 will be explained in detail. As shown in Figures 6 and 7, first, stopper pin 1
A piston portion 12a is integrally provided in the intermediate portion of the piston 2 with an enlarged diameter in the form of a flange.

The stopper pin 12 with the piston portion 12a is fitted into a through hole formed in the large end of the connecting rod 6. This through hole passes through the large end of the connecting rod 6 in the crankshaft axial direction, and is configured as a three-step hole having three diameters, and the small diameter hole located at one end is for the stopper pin 12. The diameter of the piston 12a is approximately the same as that of the piston 12a, and the medium diameter hole located in the middle is approximately the same as the diameter of the piston 12a.

Therefore, when the stopper pin 12 with the piston portion 12a is inserted into this through hole, the stopper pin 12 is inserted into the small diameter hole of the through hole.
2 is fluid-tightly inserted thereinto, and the piston portion 12a is fluid-tightly inserted into the medium-diameter hole portion of the through hole. Then, insert the return spring 15, and then fit the cap 16, which has a through hole in the center that is approximately the same diameter as the large diameter part of the through hole and approximately the same diameter as the stopper pin 12, and connect this cap 16 to the connecting rod 6. When the stopper pin 12 is fixed with a bolt or the like, one end of the stopper pin 12 is fitted into the small diameter part of the through hole in a liquid-tight manner, and the other end is fitted into the through hole of the cap 16 in a liquid-tight manner. The middle diameter part is the piston part 12
It is divided into two chambers 13.14 at a. Hydraulic passages 17.1 and 17.1 are provided in these chambers 13.14, respectively.
8 are connected in series. Thereby, these two chambers are configured as hydraulic chambers (fluid pressure chambers) 13 and 14 formed on both sides of the piston portion 12a. Note that the return spring 15 is loaded into the hydraulic chamber 13 and urges the stopper pin 12 with the piston portion 12a toward the hydraulic chamber 14 side. Note that the pressure receiving areas on both sides of the piston portion 12a are set to be equal.

As a result, the piston portion 12a attached to this stopper pin 12, the hydraulic chambers 13, 14, . Return spring 15.
The stopper pin 1 is moved by moving the piston portion 12a connected to the stopper pin 12 using the cap 16 or the like.
A piston-type hydraulic drive mechanism 11A capable of driving 2 is constructed.

Further, as shown in FIGS. 1 to 4, the eccentric sleeve 5 has flange portions spaced apart in the axial direction so as to sandwich the large end portion of the connecting rod 6.

A notch-shaped engaging portion 5a is formed in a portion of one flange portion where the eccentric sleeve 5 takes the minimum eccentric position, and a portion where the eccentric sleeve 5 of the other flange portion takes the maximum eccentric position. A cutout-like engagement portion 5b is formed in the portion, and the stopper pin 12 is connected to the third
, 7, the stopper pin 12 and the engaging portion 5b engage with each other as shown in FIGS. 3 and 4, and the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the maximum eccentric position, and the stopper pin 12 is moved to the left to take the second position as shown in FIGS. , 2, the stopper pin 12 and the engaging portion 5a engage with each other, so that the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the minimum eccentric position.

When the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the maximum eccentric position, the connecting rod 6 appears to be in the most extended state, and a high compression ratio state can be achieved. When the eccentric sleeve 5 is fixed to the big end of the connecting rod 6 in the minimum eccentric position,
The connecting rod 6 appears to be in the most compressed state, thereby realizing a low compression ratio state.

Note that the compression ratio in this low compression ratio state is selected to a value that does not cause the engine to knock, and this value is approximately the same as the value set in a normal engine. Therefore, the compression ratio in the high compression ratio state is set to a higher value than the value set for a normal engine.

Furthermore, means for previously applying a required hydraulic pressure (standard hydraulic pressure) to both hydraulic chambers 13 and 14 through hydraulic passages 17 and 18, and a means for applying a required hydraulic pressure (standard hydraulic pressure) to both hydraulic chambers 13 and 14 in advance, and a means for applying a required hydraulic pressure (standard hydraulic pressure) to both hydraulic chambers 13 and 14 in advance, and a stopper pin 12 with a piston portion 12a are provided to apply hydraulic pressure against the biasing force of the return spring 15. In order to move the oil to the chamber 13 side, a hydraulic pressure higher than the standard oil pressure (
Means for applying standard oil pressure +α) is provided.

That is, as shown in FIGS. 1 and 3, the hydraulic passages 17, 18 extend from the crank journal 3 of the crankshaft 1, through the crank arm 4, and from the crank pin 2 to the metal bearing 9. Eccentric sleeve5. The metal bearing 10 and the large end of the connecting rod 6 are connected to hydraulic chambers 13 and 14, respectively.

Since the metal bearing 9 and the crank pin 2 and the metal bearing 10 and the eccentric sleeve 5 slide, as shown in FIG.
Two endless grooves are formed around this inner peripheral surface and connected to hydraulic passages 17 and 18, respectively, and the hydraulic passages 17 and 17 formed in the eccentric sleeve 5 are located in the grooves formed in the metal bearing 9.
．． A through hole is formed that matches the section 18, and
A through hole is also formed in the groove formed in the metal bearing 10 and is aligned with the hydraulic passage 17 and 18 formed in the large end of the connecting rod 6.

Further, as shown in FIG. 8, the part of the hydraulic passage 17 outside the crankshaft is connected to the main gear rally 23 side, and the part of the hydraulic passage 18 outside the crankshaft is connected to the sub oil pump 24 or the main gear rally 23 side. There is. That is, oil (lubricating oil) from the oil tank or oil pan 20 is supplied to the main gear rally 23 via the oil filter 22 as oil at the required oil pressure (hydraulic pressure that supplies standard oil pressure) by the oil pump 19 with the relief valve 21. , this main gear rally 2
3 supplies standard oil pressure oil through a hydraulic passage 17. Furthermore, the oil from the main gear rally 23 is supplied to a sub-oil pump 24 and discharged as an even higher oil pressure (standard oil pressure + α), but the oil pressure from this sub-oil pump 24 is supplied to the switching valve 24.
5, the oil pressure from the main gear rally 23 and selectively are supplied to the oil pressure passage 18. That is,
When the switching valve 25 is placed in position a as shown in FIG. High oil pressure (standard oil pressure + α) is supplied from

Therefore, when the switching valve 25 is placed in the b position, the high oil pressure (standard oil pressure + α) is supplied from the sub-oil pump 24 to the hydraulic passage 18, and this high oil pressure is supplied to the hydraulic chamber 14. At this time, the standard hydraulic pressure from the main gear rally 23 is supplied into the hydraulic chamber 13 through the hydraulic passage 17, so the stopper pin 12 with the piston portion 12a moves against the biasing force of the return spring 15.
When it moves to the right as shown in Fig. 7 and assumes the first position, the stopper pin 12 and the engaging portion 5b engage with each other as shown in Figs. 3 and 4, and the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the maximum eccentric position. As a result, the connecting rod 6 appears to be in the most extended state, and a high compression ratio state can be achieved.

Further, when the switching valve 25 is set to the a position, the standard hydraulic pressure is supplied from the main gear rally 23 to the hydraulic passage 18, and this standard hydraulic pressure is also supplied to the hydraulic chamber 14. At this time, standard hydraulic pressure is supplied from the main gear rally 23 into the hydraulic chamber 13 via the hydraulic passage 17, so the biasing force of the return spring 15 causes the piston portion 12 to
When the stopper pin 12 with a moves to the left as shown in FIGS. 2 and 6 and assumes the second position, the stopper pin 12 and the engaging portion 5a engage as shown in FIGS. is engaged,
An eccentric sleeve 5 is fixed to the big end of the connecting rod 6 in a minimum eccentric position. As a result, the connecting rod 6 appears to be in the most compressed state, and a low compression ratio state can be achieved.

In addition, oil pump 19. Both sub oil pumps 24 are driven by the engine.

Further, reference numeral 26 in FIG. 8 is a relief valve, and this relief valve 26 is used to adjust the differential pressure α between (standard oil pressure + α) and the standard oil pressure to be constant.

Furthermore, 27 is an oil control valve for switching control of the switching valve 25, and when this oil control valve 27 is set to the a position, the switching valve 25
The pilot oil pressure of the oil control valve 2 can be lowered and the switching valve 25 can be moved to the a position.
7 to the b position, the pilot oil pressure of the switching valve 25 increases and the switching valve 25 can be moved to the b position.

The oil control valve 278 is configured to receive a switching control signal from the controller 40, and the controller 40 is connected to the engine load sensor 4.
1 and the engine rotation speed sensor 42, and when it detects an engine high load range or engine high rotation range that is larger than the engine medium load range, it outputs a control signal to set the oil control valve 27 to position a. When detecting a region where the engine load is medium or lower, a control signal is issued to set the oil control valve 27 to position b.

With the above-mentioned configuration, when a region below the engine load is detected, a control signal is issued to set the oil control valve 27 to the b position, so the switching valve 25 is also set to the b position.
position, high hydraulic pressure from the oil pump 24 is supplied to the hydraulic passage 18, and this high hydraulic pressure (
Standard oil pressure +α) is supplied. At this time, the standard oil pressure from the main gear rally 23 is supplied into the oil pressure chamber 13 via the oil pressure passage 17, so that as a result, the differential pressure α between the above-mentioned high oil pressure (standard oil pressure + α) and the standard oil pressure is applied to the piston. 1
As a result, this differential pressure α moves the stopper pin 12 with the piston portion 12a to the right, as shown in FIGS. 3 and 7, against the biasing force of the return spring 15. As a result, the stopper pin 12 assumes the first position,
As shown in FIGS. 3 and 4, the stopper pin 12 and the engaging portion 5
b are engaged with each other, and the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the maximum eccentric position. As a result, the connecting rod 6 appears to be in the most extended state, resulting in a high compression ratio state. Setting the compression ratio to such a high state improves thermal efficiency and can be expected to improve fuel efficiency.

Furthermore, when a high engine load range or a high engine speed range that is larger than the engine medium load range is detected, a control signal is issued to set the oil control valve 27 to the a position, so the switching valve 25 also moves to the a position, and the oil pressure is Standard hydraulic pressure is supplied from the main gear rally 23 to both passages 17 and 18, and standard hydraulic pressure is supplied to the hydraulic chambers 13 and 14.

As a result, the stopper pin 12 with the piston portion 12a is moved by the urging force of the return spring 15.
If you move to the left and assume the second position as shown in the figure,
As shown in FIGS. 1 and 2, the stopper pin 12 and the engaging portion 5
a are engaged with each other, and the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the minimum eccentric position. the result,
The connecting rod 6 is in a state where the apparent volume of soil is also shrunk, resulting in a low compression ratio state. By creating a low compression ratio state in this way, knocking can be reliably avoided.

In this way, in this first embodiment, the control oil pressure of the standard oil pressure is applied to both oil pressure chambers 13 and 14 as a base, so that changes in the engine speed and crank angle can cause
The pressure difference between the two hydraulic chambers does not change, and as a result, centrifugal force, acceleration of the reciprocating movement of the connecting rod 6, etc.
The operation of the stopper pin 12 is not uncertain.

Further, since the stopper pin 12 is configured to be movable in the axial direction of the crankshaft 1, the stopper pin 12 can be operated reliably even under the influence of inertia generated due to reciprocating movement of the connecting rod, etc. I can do it.

Further, when the stopper pin 12 assumes the first position, the eccentric sleeve 5 can be fixed to the large end of the connecting rod 6 at the maximum eccentric position, and the stopper pin 12 moves in the opposite direction to the second position. Once in this position, the eccentric sleeve 5 can be fixed to the large end of the connecting rod 6 at the minimum eccentric position, so there is no need to consider the drive timing of the stopper pin 12, and this allows control for changing the compression ratio. can be simplified.

On the other hand, in the device described in Japanese Patent Publication No. 63-32972, it is necessary to detect the piston position and control the lock pin protrusion timing, making the control complicated.

As mentioned above, the control oil pressure supplied to the hydraulic chambers 13 and 14 is supplied through the path of cylinder block journal → crank pin 2 of crankshaft 1 → connecting rod 6, so this control oil pressure is caused by the crankshaft centrifugal force. It fluctuates greatly due to the centrifugal force of the connecting rod.

That is, as shown in FIG. 14, the crankshaft angular velocity is ω, the crank radius is R, and the crank journal radius is r.
j, the crank pin radius is rp, the oil path length from the crank pin center to the stopper pin center is Q, and the oil pressure of the journal portion is PA, then the oil pressure PPC at the crank pin center at an angular velocity ω is as follows.

PPC”PA+ (1/A)/Aura”:PA+
(1/2) #m” (R”-rj”)...(1)
Here, A is the cross-sectional area of the oil passage, Δm is the mass of oil between minute distances, and ρ is the density of oil.

Furthermore, the connecting rod supply oil pressure PCR is as follows.

Pci”Ppc+(1/A)/Amrs”:PA+(1
/2) $4” (R”-rj”)+P@” ・R-r
p-cosIIt...(2) Similarly, connecting rod stopper pin hydraulic pressure P
SP becomes as follows.

Psp=PA+(1/2)4Il"(R"-rj")+
#m”R(rp+j)cos41t”PA+u” ((
1/2)(R"-rj")+R(rp+1)cos@t
)...(3) Here, PB=(1/2)u"(R"-rj")"(4)Pc=
−@”R(rp+1)cosIIt・1(5), then PA is a function of engine speed and oil viscosity coefficient,
Since PB is a function of the engine speed and crank phase, the control oil pressure of the stopper pin built into the connecting rod 6 varies greatly as shown in FIG. 17.

In FIG. 15, the connecting rod supply oil pressure PCR is the crank bin part oil pressure (max, m1n) (characteristics B, C), and the connecting rod/stopper pin part oil pressure psp is the stopper pin part oil pressure (max.

m1n) (characteristic, E).

However, if the differential pressure α is made to act between the two hydraulic chambers 13 and 14 as in this embodiment, the pressure that fluctuates due to the crankshaft centrifugal force and the connecting rod centrifugal force is canceled out. Therefore, it is possible to form a hydraulic pressure supply system that is not affected by engine speed or crank phase.

Next, a second embodiment will be described using FIGS. 9 to 13.

Now, in this second embodiment, as shown in FIGS. 9 and 10,
An eccentric sleeve 5 is attached to a pivot portion at the large end of the connecting rod 6 to make the bearing hole of the connecting rod 6 and the crank pin 2, which serves as a support shaft inserted through the bearing hole, eccentric from each other. It is rotatable so that it can be adjusted.

Further, eccentric sleeve locking means 11 is also provided,
This eccentric sleeve locking means 11 also operates a stopper pin 12 as a pin member movable in the axial direction of the eccentric sleeve 5, that is, in the axial direction of the crankshaft 1, by a hydraulic movement mechanism 11A as a piston-type fluid pressure drive mechanism. By this, two engaging portions 5a are formed on the eccentric sleeve 5.

5b is engaged with the stopper pin 12, rotation of the eccentric sleeve 5 can be fixed at two positions (the above-mentioned maximum eccentric position and minimum eccentric position).

In this embodiment as well, the eccentric sleeve 5 has flanges spaced apart in the axial direction so as to sandwich the large end of the connecting rod 6, and the eccentric sleeve 5 in one flange portion is located at the minimum eccentricity position. For the parts that need to be taken,
A notch-like engaging portion 5a is formed, and a notch-like engaging portion 5b- is formed in a portion of the other flange portion where the eccentric sleeve 5 takes the maximum eccentric position. With the pin 12 moving to the right and assuming the first position as shown in Fig. 10.12, the stopper pin 12 and the engaging portion 5b engage with each other as shown in Fig. 10. , the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the maximum eccentric position, and the stopper pin 1
2 moves to the left and assumes the second position as shown in FIGS. 9 and 11, the stopper pin 12 and the engaging portion 5a engage with each other as shown in FIG. The eccentric sleeve 5 is adapted to be fixed to the large end of the connecting rod 6 in the minimum eccentric position, and furthermore, when the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 in the maximum eccentric position,
The connecting rod 6 appears to be in the most extended state to achieve a high compression ratio state, and when the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the minimum eccentric position, the connecting rod No. 6 appears to be in the most compressed state, making it possible to realize a low compression ratio state.

By the way, in this second embodiment, the structure of the eccentric sleeve locking means 11 is different from that of the above-mentioned second embodiment.

That is, the stopper pin 12 with the piston portion 12a is
By fitting into the through hole formed at the large end of the connecting rod 6 and fixing the cap 16 to the connecting rod 6 with bolts or the like, the medium diameter portion of the through hole is connected to the piston portion 12a to form two chambers. 13.14, which is configured as a hydraulic chamber, each chamber 13.1
The fact that the hydraulic passages 17 and 18 are connected to the hydraulic passages 17 and 18 is the same as in the first embodiment described above, but in this second embodiment,
None of the hydraulic chambers 13, 14 are loaded with return springs.

Instead, the differential pressure α' (α
'〈α) occurs, and hydraulic pressure is applied to both hydraulic chambers 13 and 14 so that the required hydraulic pressure (standard hydraulic pressure) is maintained even on the low pressure side, and the hydraulic pressure in one hydraulic chamber 13 is higher (Ijl semi-hydraulic + α). ') and the state where the oil pressure in the other hydraulic chamber 14 is higher (
It has means that can switch between standard oil pressure +α').

Such means will be explained in further detail.

That is, as shown in FIGS. 9 and 10, the hydraulic passages 17, 18 extend from the crank journal 3 of the crankshaft 1, through the crank arm 4, and from the crank pin 2 to the metal bearing 9. Eccentric sleeve5. The metal bearing 10 and the large end of the connecting rod 6 are connected to hydraulic chambers 13 and 14, respectively, but as shown in FIG. 13, the parts of the hydraulic passages 17 and 18 outside the crankshaft are It is connected to the oil pump 24 or main gear rally 23 side. That is, oil tank 2o
The oil (lubricating oil) is supplied to the main gear rally 23 via an oil filter 22 as oil at the required oil pressure (standard oil pressure) by an oil pump 19 with a relief valve 21.
The oil from this main gear rally 23 is supplied to
The oil pressure from the sub oil pump 24 is supplied to the sub oil pump 24 and discharged as a higher oil pressure (standard oil pressure + α'), but the oil pressure from the sub oil pump 24 is supplied to the main gear rally 23 via a switching valve 25'. The hydraulic pressure is selectively supplied to hydraulic passages 17 and 18. That is, when the switching valve 25' is set to the a position as shown in FIG. (standard oil pressure + α') is supplied, while switching valve 2
5 to position b, the standard hydraulic pressure from the main gear rally 23 is supplied to the hydraulic passage 18, and the hydraulic passage 1
7 is supplied with high oil pressure (standard oil pressure + α') from the sub-oil pump 24. As a result, a differential pressure α' is constantly generated between the two hydraulic chambers 13 and 14.

Therefore, when the switching valve 25' is set to the a position, the standard hydraulic pressure from the main gear rally 23 is supplied to the hydraulic passage 17, and the high hydraulic pressure (standard hydraulic pressure + α') from the sub oil pump 24 is supplied to the hydraulic passage 18. standard hydraulic pressure is supplied to the hydraulic chamber 13, and the standard hydraulic pressure is supplied to the hydraulic chamber 14.
(Standard oil pressure + α') is supplied to . As a result, the stopper pin 12 with the piston portion 12a moves to the right as shown in FIG. 10.12, assumes the first position, and
As shown in FIG. 0, the stopper pin 12 and the engaging portion 5b engage with each other, and the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the maximum eccentric position. As a result, the connecting rod 6 appears to be in a state where the amount of soil is expanded, and a high compression ratio state can be achieved.

Furthermore, when the switching valve 25' is set to the b position, the standard oil pressure from the main gear rally 23 is supplied to the oil pressure passage 18, and the high oil pressure (standard oil pressure + α') from the sub oil pump 24 is supplied to the oil pressure passage 17. Since the stopper pin 12 with the piston portion 128 is supplied, the stopper pin 12 with the piston portion 128
Move to the left and assume the second position as shown in Figure 1.
As shown in FIG. 9, the stopper pin 12 and the engaging portion 5a engage, and the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the minimum eccentric position. As a result, the connecting rod 6 appears to be in a state where the earth volume is also reduced, and a low compression ratio state can be realized.

It is assumed that the pressure receiving areas on both sides of the piston part 12a are set equal, and the sliding friction of the piston part 12a is negligibly small. In addition, the reference numeral 26' in FIG. 13 is a relief valve. ' is adjusted so that the differential pressure α' between (standard oil pressure + α') and the standard oil pressure is constant.

Furthermore, 27' is an oil control valve for switching control of the switching valve 25', and when this oil control valve 27' is set to the a position, the pilot oil pressure of the switching valve 25' decreases, and the switching valve 25' is set to the a position. When the oil control valve 27' is placed in the b position, the pilot oil pressure of the switching valve 25' increases, allowing the switching valve 25' to be placed in the b position.

A switching control signal from the controller 4o is input to the oil control valve 27'.

When receiving detection signals from the engine load sensor 41 and engine speed sensor 42 and detecting an engine high load range or engine high speed range that is larger than the engine medium load range, the oil control valve 27' is moved to position b. A control signal is issued, and when a region below the engine load is detected, a control signal is issued to set the oil control valve 27' to position a.

With the above-described configuration, when a region of engine load or below is detected, a control signal is issued to set the oil control valve 27' to position a, so that the switching valve 25'
is also in position a, and the main gear rally 2 is connected to the hydraulic passage 17.
3 is supplied with standard hydraulic pressure, and the hydraulic pressure passage 18
The high oil pressure from the sub oil pump 24 (standard oil pressure +
α′) is supplied, and the oil pressure in the hydraulic chamber 14 becomes higher, resulting in the higher oil pressure (standard oil pressure +
α') and the standard oil pressure are applied to the piston part 12a, and this pressure difference α' moves the stopper bin 12 with the piston part 12a to the right as shown in FIGS. 10 and 12. , takes the first position. As a result, as shown in FIG. 10, the stopper pin 12 and the engaging portion 5b engage with each other, and the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the maximum eccentric position. As a result, the connecting rod 6 appears to be in the most extended state, resulting in a high compression ratio state. When the compression ratio is set to high like this,
Thermal efficiency is improved and fuel efficiency can be expected to improve.

Furthermore, when a high engine load range or a high engine speed range that is larger than the engine medium load range is detected, a control signal is issued to set the oil control valve 27' to position b, so that the switching valve 25' is also set to position b. ,
The standard oil pressure from the main gear rally 23 is supplied to the hydraulic passage 18, and the high oil pressure (standard oil pressure + α') from the sub-oil pump 24 is supplied to the hydraulic passage 17. Since the oil pressure is higher, the stopper pin 12 with the piston portion 12a is
As shown in FIG. 11, move to the left and take the second position, and as shown in FIG.
are engaged with each other, and the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the minimum eccentric position. As a result, the connecting rod 6 appears to be in the most compressed state, resulting in a low compression ratio state. By creating a low compression ratio state in this way, knocking can be reliably avoided.

As described above, in this second embodiment, hydraulic pressure is applied to both hydraulic chambers 13° 14 so that a differential pressure α' is generated between both hydraulic chambers 13° 14 and the required hydraulic pressure (standard hydraulic pressure) is maintained even on the low pressure side. In addition, a state in which the oil pressure in one hydraulic chamber 13 is higher (standard oil pressure + α') and a state in which the oil pressure in the other hydraulic chamber 14 is higher (i
Since it has a means that can switch between semi-hydraulic pressure + α'), the pressure difference between the two hydraulic chambers does not change due to changes in engine speed or crank angle, and this prevents centrifugal force and connecting rod 6. The operation of the stopper pin 12 does not become uncertain due to the acceleration of the reciprocating motion of the stopper pin 12, and
The differential pressure α' between the two hydraulic chambers 13 and 14 may be smaller than the differential pressure α in the first embodiment described above (this differential pressure α needs to be large enough to overcome the biasing force of the return spring 15). (Theoretically, it is sufficient to have any positive value.) Therefore, for example, when the sub oil pump 2
The stopper pin 12 can be reliably driven even when the discharge capacity of the stopper pin 4 is low.

Further, since the stopper pin 12 is configured to be movable in the axial direction of the crankshaft 1, the stopper pin 12 can be operated reliably even under the influence of inertia generated due to reciprocating movement of the connecting rod, etc. I can do it.

Further, when the stopper pin 12 assumes the first position, the eccentric sleeve 5 can be fixed to the large end of the connecting rod 6 at the maximum eccentric position, and the stopper pin 12 moves in the opposite direction to the second position. Once in this position, the eccentric sleeve 5 can be fixed to the large end of the connecting rod 6 at the minimum eccentric position, so there is no need to consider the drive timing of the stopper pin 12, and this allows control for changing the compression ratio. can be simplified.

In addition, an eccentric sleeve is attached to the pivot portion at the small end of the connecting rod 6 to make the bearing hole of the connecting rod 6 and the piston pin 7, which serves as a support shaft inserted through the bearing hole, eccentric from each other. The two engagements formed in this eccentric sleeve are made rotatable so that the sleeve can be rotated, and a stopper pin as a pin member that can move in the axial direction of the piston pin 7 is actuated by a piston-type fluid pressure drive mechanism. By selectively engaging the stopper pin in the part, the rotation of this eccentric sleeve is increased by two degrees! (The maximum eccentricity position and the minimum eccentricity position described above) may be fixed.

Also in this case, the same piston-type fluid pressure drive mechanism as in the first and second embodiments described above is used.

That is, something similar to the first and second embodiments described above is arranged at the small end of the connecting rod 6, and a hydraulic passage (corresponding to the hydraulic passage 17, 18) leading to the small end of the connecting rod 6 is provided. A hydraulic circuit system as shown in FIGS. 8 and 13 is connected to a portion of each hydraulic passage outside the crankshaft 1.

Even in this case, substantially the same effects and advantages as those of the first and second embodiments described above can be obtained.

In each of the above embodiments, pressure oil was used as the drive means for the stopper pin 12.30 of the eccentric sleeve lock means 11.29, but other fluids (liquid or gas) at the required pressure may be used. You can use whatever you have.

Furthermore, as a mechanism for driving the stopper pin 12, in addition to the fluid pressure drive mechanism as described above, there are other drive mechanisms that use electromagnetic principles (for example, a mechanism that drives the stopper pin 12 using electromagnetic force). You can also use

[Effects of the Invention] As detailed above, according to the variable compression ratio device for an internal combustion engine of the present invention, one end is pivotally supported by the piston that reciprocates within the cylinder of the internal combustion engine, and the other end is supported by the crankshaft. A connecting rod is provided which is pivotally supported on a shaft, and an eccentric sleeve is rotated on either one of the pivot parts at both ends of the connecting rod to make a bearing hole of the connecting rod and a support shaft inserted through the bearing hole eccentric with respect to each other. Rotation of the eccentric sleeve can be fixed by actuating a pin member movable in the axial direction of the eccentric sleeve to engage the pin member with an engaging portion formed on the eccentric sleeve. With a simple structure in which an eccentric sleeve locking means is provided, the operation of the pin member does not become uncertain even due to the influence of inertia caused by the reciprocating movement of the connecting rod, etc., and the reliability of the locking operation of the eccentric sleeve is improved. The advantage is that it can be improved.

[Brief explanation of drawings]

Figures 1 to 8 show a variable compression ratio device for an internal combustion engine as a first embodiment of the present invention. Figure 1 is an overall configuration diagram showing the situation when it is in a low compression ratio state, and Figure 2 is a Figure 3 is a front view of the connecting rod showing how it looks when it is in a low compression ratio state, Figure 3 is an overall configuration diagram showing how it looks when it is in a high compression ratio state, and Figure 4 shows how it looks when it is in a high compression ratio state. A front view of the connecting rod shown in Fig. 5 is v in Figs. 1 and 3.
FIG. 6 is a cross-sectional view of the hydraulic drive mechanism showing the state when it is in a low compression ratio state. FIG. 7 is a cross-sectional view of the hydraulic drive mechanism showing the state when it is in a high compression ratio state. Fig. 8 is a hydraulic circuit diagram thereof, and Figs. 9 to 13 show a variable compression ratio device for an internal combustion engine as a second embodiment of the present invention.
Figure 9 is an overall configuration diagram showing the situation when the compression ratio is low, Figure 10 is an overall configuration diagram showing the situation when the compression ratio is high, and Figure 11 is the overall configuration diagram showing the situation when the compression ratio is low. FIG. 12 is a cross-sectional view of the hydraulic drive mechanism showing the state when it is in a high compression ratio state, FIG. 13 is its hydraulic circuit diagram, and FIG. 14 is a diagram of the crankshaft. FIG. 15, which is a diagram illustrating the dimensions of each part, is a characteristic diagram of the hydraulic pressure applied to the hydraulic drive mechanism and its hydraulic pressure supply system.

Claims (1)

[Claims] A connecting rod is provided, one end of which is pivotally supported by a piston that reciprocates within a cylinder of an internal combustion engine, and the other end of which is pivotally supported by a crankshaft. An eccentric sleeve is rotatably provided to make the bearing hole of the connecting rod and the support shaft inserted through the bearing hole eccentric with respect to each other,
Eccentric sleeve locking means capable of fixing rotation of the eccentric sleeve by actuating a pin member movable in the axial direction of the eccentric sleeve and engaging the pin member with an engaging portion formed on the eccentric sleeve. A variable compression ratio device for an internal combustion engine, characterized in that: