JPH0433392Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a variable compression ratio mechanism for a four-cylinder internal combustion engine using an eccentric bearing, and in particular to a hydraulic passage structure for performing lock control of the eccentric bearing.

[Conventional technology]

One mechanism for making the compression ratio of an internal combustion engine variable is to use an eccentric bearing between the piston pin and the connecting rod, and angularly displace the eccentric bearing to raise or lower the relative position of the piston to the connecting rod. There are variable compression ratio mechanisms that allow variable settings (for example, Japanese Patent Application Laid-Open No. 172431/1982 and Japanese Utility Model Application No. 40537/1983).

In the compression ratio variable device using the eccentric bearing, as shown in FIGS. 5 and 6, the eccentric bearing 1 is provided with a lock pin engagement hole 2, and the connecting rod 3 is provided with a lock pin storage hole 4. The lock pin 5 is stored in the lock pin storage hole 4, and by applying hydraulic pressure to the lock pin 5, the lock pin 5 is driven to move forward and backward in the direction of the lock pin engagement hole 2, and the lock pin 5 is engaged with the lock pin engagement hole 2. It is designed so that it can be engaged or disengaged. Then, when the eccentric bearing 1 rotates to a position where the piston 6 is placed high relative to the connecting rod 3 under light load, the lock pin 5 is engaged with the lock pin engagement hole 2 to lock the rotation of the eccentric bearing 1. When the load is medium or high, the lock pin 5 is removed from the lock pin engagement hole 2 to allow the eccentric bearing 1 to rotate freely, and at the compression top dead center position, it receives compressed gas pressure and explosive force. Then, the eccentric bearing 1 is automatically rotated to a position that lowers the piston 6 relative to the connecting rod 3, thereby maintaining a low compression ratio state.

In the conventional device described above, the hydraulic pressure actuated by the pressure difference between the two ends of the lock pin 5 is applied through two mutually independent hydraulic passages 7 and 8 formed in the connecting rod 3. Passage 7, 8
Pressure oil from the compression ratio switching hydraulic passage provided on the cylinder block side flows to the crankshaft 9.
The oil was alternately fed through one oil hole 10 formed therein in accordance with the rotation of the crankshaft 9.

FIG. 4 shows the configuration of a conventional compression ratio switching hydraulic passage provided on the cylinder block side. In the figure, 11 indicates a hydraulic passage that locks the eccentric bearing 1, that is, a high compression ratio hydraulic passage that switches from a low compression ratio to a high compression ratio, and 12 indicates a hydraulic passage that releases the lock of the eccentric bearing 1, that is, a high compression ratio hydraulic passage that switches from a low compression ratio to a high compression ratio. A low compression ratio hydraulic passage for switching from a compression ratio to a low compression ratio is shown.

The low compression ratio hydraulic passage 12 is constituted by a main gear rally provided on the side surface of the cylinder block 13. Further, the high compression ratio hydraulic passage 11 is constituted by a pipe extending in the same direction as the axial direction of the crankshaft 9, and this high compression ratio hydraulic passage 11 is connected to a bearing cap 22 that supports the crankshaft 9. It is connected to the oil hole 10 of the crankshaft via.

In addition to the above-mentioned structure, there is also a structure in which two main gear rallies are provided on both sides of the cylinder block, with passages for high compression ratio and low compression ratio, respectively.

Oil supply ports 14 and 15 of the high compression ratio hydraulic passage 11 and the low compression ratio hydraulic passage 12 are provided on the longitudinal end surface 13a of the cylinder block 13, respectively. Each oil supply port 14, 15 is connected to a compression ratio switching valve 16, and the compression ratio switching valve 16 is connected to an oil pan 17 from an oil pump 1.
The oil pumped up by filter 8 passes through filter 1.
9.

Note that 20 and 21 in FIG. 4 indicate each crank journal bearing portion 23 of the cylinder block 13.
This is an oil groove formed in the crankshaft 9 for pumping oil to an oil hole 10 in the crankshaft 9. The oil groove 20 is connected to the high compression ratio hydraulic passage 11, and the oil groove 21 is connected to the low compression ratio hydraulic passage 12.

[Problem that the invention attempts to solve]

However, with the above-mentioned configuration of the hydraulic passage, the length of the passage from the compression ratio switching valve to the oil groove formed in each crank journal bearing becomes uneven, the distance becomes long, and the lock pin in each cylinder becomes uneven. There is a problem in that there is significant variation in the timing of hydraulic operation.

In addition, it is necessary to supply oil for lubrication to each crank journal bearing, and if a compression ratio hydraulic passage and a lubrication passage are provided, the structure of the hydraulic passage in the cylinder block becomes complicated. This is a concern.

The present invention has focused on the above-mentioned problems, and aims to eliminate the large variations in the timing of hydraulic operation for lock pin control in each cylinder, and to simplify the structure of the hydraulic passage in the cylinder block.

[Means to solve the problem]

The hydraulic passage of the variable compression ratio mechanism of the present invention, which meets this purpose, has an eccentric bearing rotatably interposed between the piston pin and the connecting rod, and the movement of the eccentric bearing is fixed and released by a hydraulically driven lock pin. a compression ratio switching hydraulic passage that makes the compression ratio variable and drives the lock pin;
In a variable compression ratio mechanism for a four-cylinder internal combustion engine, which is connected from the crank journal bearing portion of the cylinder block to the lock pin storage hole of the connecting rod through the oil hole of the crankshaft, among the plurality of crank journal bearing portions of the cylinder block, A pair of oil grooves for switching the compression ratio of the first and second cylinders are formed in the crank journal bearing located between the first and second cylinders, and a pair of oil grooves are located between the third and fourth cylinders. A pair of oil grooves for switching the compression ratios of the third and fourth cylinders are formed in the crank journal bearing portion of the cylinder block, and the lubricating oil is supplied only to the crank journal bearing portion in which the oil groove is not formed. At the same time, a high compression ratio hydraulic passage and a low compression ratio hydraulic passage are arranged to supply oil to the oil groove, and the oil supply ports of the high compression ratio hydraulic passage and the low compression ratio hydraulic passage are arranged. , located near the crank journal bearing part on the side surface of the cylinder block along the crankshaft axial direction and located between the two crank journal bearing parts in which the oil grooves are formed among all the crank journal bearing parts. Consists of.

[Effect]

In the hydraulic passage of the variable compression ratio mechanism configured in this way, the compression ratio switching hydraulic passages are arranged inside the cylinder blocks, and the oil supply ports of the compression ratio switching hydraulic passages are connected to the cylinder block of the four-cylinder engine. Because it is located near the crank journal bearing part, which is located on the side surface along the axial direction of the crankshaft and between the two crank journal bearing parts where the oil groove for compression ratio is formed among all the crank journal bearing parts. It is possible to make the distance from the oil supply port to each crank journal bearing portion where the oil groove for changing the compression ratio is formed approximately equal.

Therefore, the conditions such as the flow path resistance of the hydraulic passages between the cylinders become almost constant, the large variations in the lock pin hydraulic actuation timing are eliminated, and the compression ratio is smoothly switched.

In addition, the compression ratio of the first and second cylinders is varied by the oil groove in the crank journal bearing located between the first and second cylinders, and the compression ratio of the first and second cylinders is varied by the oil groove of the crank journal bearing located between the third and fourth cylinders. The compression ratio of the 3rd and 4th cylinders is varied by the oil grooves in the crank journal bearings, so even in the case of a 4-cylinder engine, just provide oil grooves in the two crank journal bearings for switching the compression ratio. , and the structure of the hydraulic passage can be simplified.

Oil is supplied to each crank journal bearing part where an oil groove for changing the compression ratio is not formed through a lubricating oil passage, but the crank journal bearing part where an oil groove is formed is provided with a hydraulic passage for changing the compression ratio. lubricated by oil from Therefore, there is no need to particularly supply lubricating oil through a lubricating oil passage to the crank journal bearing portion in which the oil groove is formed, and the configuration of the hydraulic passage is simplified.

〔Example〕

Hereinafter, preferred embodiments of the hydraulic passage of the variable compression ratio mechanism according to the present invention will be described with reference to the drawings.

First Embodiment FIGS. 1 and 2 show a first embodiment of the present invention, and particularly show an example applied to an in-line four-cylinder engine. In FIG. 2, a piston 31 is slidably inserted into a cylinder 32, and the reciprocating movement of the piston 31 is controlled by a piston pin 33,
This is converted into a rotational movement of the crankshaft 35 via the connecting rod 34.

Connecting rod 34 and piston pin 33
An eccentric bearing 36 whose inner and outer circumferences are mutually eccentric is interposed between the eccentric bearing 3 and
The compression ratio is changed according to the amount of rotation of 6. A lock pin engagement hole 37 extending in the radial direction is bored in the eccentric bearing 36, and a lock pin 38 is disposed on the connecting rod 34 side. The lock pin 38 is slidably housed in a lock pin housing hole 39, and is moved by the differential pressure between two hydraulic passages 40 and 41 formed in the connecting rod 34 for driving the lock pin. One hydraulic passage 40 is a lock pin locking hydraulic passage that drives the lock pin 38 toward the eccentric bearing 36, and the other passage 41 is a lock pin unlocking hydraulic passage that drives the lock pin 38 away from the eccentric bearing 36.

The lock pin locking hydraulic passage 40 and the lock pin unlocking hydraulic passage 41 communicate with a pair of oil grooves 42 and 43 formed in the large end of the connecting rod, respectively. The oil grooves 42 and 43 are a pair of oil grooves 45 and 43 formed in a crank journal bearing 47 that supports the crankshaft 35 through an oil hole 44 formed in the crankshaft 35, respectively.
46. The oil grooves 45 and 46 are the first
#2 crank journal bearing portion 47 located between cylinder A and second cylinder B, third cylinder C and fourth cylinder
It is provided only in the #4 crank journal bearing portion 47 located between the cylinders D.

The oil hole 44 communicates one oil groove 42 of the oil grooves 42, 43 with one oil groove 45 of the oil grooves 45, 46 in a half rotation range of the crankshaft 35, and connects one oil groove 42 of the oil grooves 42, 43 with one oil groove 45 of the oil grooves 45, 46 in a half rotation range of the crankshaft 35. In the rotation range, the other oil groove 43 of the oil grooves 42 and 43
The other oil groove 46 of the oil grooves 45 and 46 communicates with each other.

As shown in FIG. 1, a high compression ratio hydraulic passage 51 and a low compression ratio hydraulic passage 52 are provided in the cylinder block 48 as hydraulic passages for switching compression ratios. The oil groove 45 formed in the crank journal bearing part 47 is connected to a high compression ratio hydraulic passage 51.
The oil groove 46 is connected to a low compression ratio hydraulic passage 52. The oil supply ports 53 and 54 of the high compression ratio hydraulic passage 51 and the low compression ratio hydraulic passage 52 are provided in one side surface 55 of the cylinder block 48 along the crankshaft axial direction, and are located in all crank journal bearings. 47
It is arranged near the #3 crank journal bearing section 47 located in the center of the two. The high compression ratio hydraulic passage 51 and the low compression ratio hydraulic passage 52 extend parallel to the side surface 55, and are perpendicular to each other at the positions of the #2 crank journal bearing portion 47 and the #4 crank journal bearing portion 47. The grooves 45 and 46 are respectively connected to the oil grooves 45 and 46 as described above.

The oil grooves 45 and 46 formed in the #2 crank journal bearing part 47 are oil grooves for controlling the lock pins 38 of the first cylinder A and the second cylinder B. The oil grooves 45 and 46 that are formed are oil grooves that control the lock pins 38 of the third cylinder C and the fourth cylinder D. The #2 and #4 oil grooves 45 and 46 also function as lubricating oil grooves.

A lubrication hydraulic passage 56 provided in the cylinder block 48 is connected to the oil groove 65 of the #1, #3, and #5 crank journal bearing portions 47, and the lubrication hydraulic passage 56 is also connected to the cylinder block 48.
It extends parallel to the side surface portion 55 of. The oil supply port 57 of the lubricating hydraulic passage 56 is provided on one end surface 59 of the cylinder block 48 in the longitudinal direction. Therefore, in this embodiment, three hydraulic passages pass through the #2 and #4 journal bearing portions 47 of the cylinder block 48.

The oil supply port 53 of the high compression ratio hydraulic passage 51 and the oil supply port 54 of the low compression ratio hydraulic passage 52 are
It is connected to a compression ratio switching valve 60 attached to the side surface 55 of the cylinder block 48. The high compression ratio hydraulic passage 51 and the low compression ratio hydraulic passage 52 include
Oil pumped up from an oil pan 61 by an oil pump 62 is switched and fed under pressure via a filter 63 and the above-mentioned compression ratio switching valve 60. Further, the oil supply port 57 of the lubricating hydraulic passage 56 is connected to a hydraulic passage between the filter 63 and the compression ratio switching valve 60 .

In addition, in FIG. 1, the compression ratio switching valve 60 is
Although shown as being disposed at a position remote from the cylinder block 48, it is actually disposed on a side surface 55 of the cylinder block 48. The oil supply port 64 of the compression ratio switching valve 60 is also connected to a lubricating hydraulic passage 56 formed inside the cylinder block, and the actual configuration of the hydraulic passage is is significantly simplified.

Further, in FIG. 1, one oil pump is used for lubrication and for switching the compression ratio, but it is also possible to supply oil with separate oil pumps.

Next, the operation of the first embodiment configured as described above will be explained.

When the internal combustion engine is in a light load state, the amount of intake air entering the combustion chamber is small and the degree of compression due to the piston rising is substantially small, so knocking is less likely to occur and a high compression ratio can be set. When the sensor detects a light load, the switching valve 60 switches. In this state, there is an oil groove 4 in the lock pin lock hydraulic passage 40.
5. Pressure oil is sent through the oil hole 44, and the pressure oil in the lock pin unlocking hydraulic passage 41 is drained through the oil groove 43, oil hole 44, and oil groove 46. At this time, the lock pin lock hydraulic passage 4
The passage including the lock pin unlocking hydraulic passage 41 becomes the pressure reduction passage.

The lock pin 38 moves in the direction of the eccentric bearing 36, and when the lock pin engagement hole 37 of the rotating eccentric bearing 36 comes to a position corresponding to the lock pin 38, it enters the lock pin engagement hole 37 and stops the rotation of the eccentric bearing 36. Lock. Since the lock pin engagement hole 37 is located at the thickest portion of the eccentric bearing 36, the piston 31 is maintained at a higher position relative to the connecting rod 34, creating a high compression ratio condition.

Next, when the internal combustion engine is in a medium or high load state, the amount of intake air entering the combustion chamber is large and knocking is likely to occur, so the eccentric bearing 36 must be in a low compression ratio state. When the medium or high load state is detected by the sensor, the changeover valve 60 is switched to send pressurized oil to the lock pin unlock hydraulic passage 41 and cut off or drain the supply of pressurized oil to the lock pin lock hydraulic passage 40. At this time, the passage including the lock pin unlock hydraulic passage 41 becomes a pressurized passage, and the lock pin 38 moves in a direction away from the eccentric bearing 36.

When the lock pin 38 moves away from the eccentric bearing 36, it comes out of the lock pin engagement hole 37, and the eccentric bearing 36 becomes free to rotate. Therefore, the eccentric bearing 36 automatically rotates upon receiving the compressive load and explosive load from the piston, and appears in a low compression ratio state.

The oil supply port 53 of the high compression ratio hydraulic passage 51 connected to the compression ratio switching valve 60 and the oil supply port 54 of the low compression ratio hydraulic passage 52 are connected to the total number (#1 to #5) of the cylinder block 48. Since it is located in the center of the crank journal bearing part 47,
The length of the passage from the oil supply port 53 to the oil groove 45 of the #2 crank journal bearing 47 is approximately the same as the length of the passage from the oil supply port 53 to the oil groove 45 of the #4 crank journal bearing 47. It becomes possible to

Similarly, the length of the passage from the oil supply port 54 to the oil groove 46 of the #2 crank journal bearing 47, and the length of the passage from the oil supply port 54 to the oil groove 46 of the #4 crank journal bearing 47. It is possible to make the values almost the same. Therefore, conditions such as flow path resistance in the hydraulic passages of cylinders A, B, C, and D can be set to almost the same values.
This eliminates large variations in lock pin hydraulic activation timing between cylinders.

Second Embodiment FIG. 3 shows a hydraulic passage of a variable compression ratio mechanism according to a second embodiment of the present invention. The second embodiment differs from the first embodiment in the configuration of the high compression ratio hydraulic passage, and other parts are similar to the first embodiment, so similar parts are given the same reference numerals as the first embodiment. The explanation of the parts that are the same will be omitted, and only the different parts will be explained. The same applies to the embodiments described later.

In FIG. 3, reference numeral 53 indicates an oil supply port, and reference numeral 51a indicates a high compression ratio hydraulic passage formed within the cylinder block 48. The high compression ratio hydraulic passage 51a extends from the oil supply port 53 in a direction perpendicular to the side surface 55 of the cylinder block 48, passes through the #3 crank journal bearing section 47, and is located near the other side surface 70 on the left and right sides. branched in directions. The branched high compression ratio hydraulic passage 51a communicates with the #2 and #4 crank journal bearings 47 45.

Note that the operation of this embodiment is similar to that of the first embodiment.

[Effect of idea]

According to the hydraulic passage of the variable compression ratio mechanism of the present invention,
The following effects can be obtained.

(1) It is possible to make the length of the hydraulic passage from the oil supply port to each crank journal bearing part where the oil groove for changing the compression ratio is formed almost uniform. Therefore, variations in the lock pin hydraulic actuation timing between cylinders in a four-cylinder engine can be suppressed to a small extent, and the compression ratio can be smoothly switched.

(2) The compression ratio of the first and second cylinders is varied by the oil groove in the crank journal bearing located between the first and second cylinders, and the oil groove is located between the third and fourth cylinders. Since the compression ratio of the 3rd and 4th cylinders is varied by the oil grooves in the crank journal bearings, even in the case of a 4-cylinder engine, oil grooves for changing the compression ratio are provided in the two crank journal bearings. The structure of the hydraulic passage can be simplified.

(3) Each crank journal bearing, where the oil groove for changing the compression ratio is formed, is lubricated by oil from the hydraulic passage for changing the compression ratio, so this crank journal bearing has a special oil groove for lubricating oil. Eliminates the need to supply oil through passages,
The configuration of the hydraulic passage can be simplified.

(4) By providing the oil supply port of the hydraulic passage for compression ratio switching on the side of the cylinder block,
For example, it becomes possible to attach the compression ratio switching valve directly to the side surface of the cylinder block. Therefore, the corresponding piping becomes unnecessary, and the hydraulic piping configuration of the variable compression ratio mechanism can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a transparent perspective view showing the overall configuration of a hydraulic passage of a variable compression ratio mechanism according to a first embodiment of the present invention;
2 is a perspective view of the hydraulic passage near the crankshaft of FIG. 1; FIG. 3 is a transparent perspective view showing the overall configuration of the hydraulic passage of the variable compression ratio mechanism according to the second embodiment of the present invention; 5 is a sectional view of the conventional variable compression ratio mechanism; FIG. 6 is a sectional view taken along the line - in FIG. 5; It is. 33...Piston pin, 34...Connecting rod, 35...Crankshaft, 36...
Eccentric bearing, 37...Lock pin engagement hole, 3
8...Lock pin, 39...Lock pin storage hole,
44... Oil hole, 45, 46... Oil groove, 47... Crank journal bearing section, 51, 51a... Hydraulic passage for high compression ratio, 52... Hydraulic passage for low compression ratio,
53, 54... Oil supply port, 56... Hydraulic passage for lubrication, 60... Compression ratio switching valve.

Claims (1)

[Claims for Utility Model Registration] An eccentric bearing is rotatably interposed between a piston pin and a connecting rod, and the movement of the eccentric bearing is fixed and released by a hydraulically driven lock pin to make the compression ratio variable. In a variable compression ratio mechanism for a four-cylinder internal combustion engine, a compression ratio switching hydraulic passage for driving the lock pin is connected from a crank journal bearing of a cylinder block to a lock pin storage hole of a connecting rod through an oil hole of a crankshaft. A pair of oil grooves for switching the compression ratios of the first cylinder and the second cylinder are formed in the crank journal bearing part located between the first cylinder and the second cylinder among the plurality of crank journal bearing parts of the cylinder block. A pair of oil grooves for switching the compression ratios of the third and fourth cylinders are formed in a crank journal bearing located between the third and fourth cylinders, and the oil grooves are formed in the cylinder block. A lubricating oil passage is provided to supply oil only to the crank journal bearings that are not in use, and a high compression ratio hydraulic passage and a low compression ratio hydraulic passage are arranged to supply oil to the oil groove. The oil supply ports of the passages and the low compression ratio hydraulic passages are connected to the side surfaces of the cylinder block along the crankshaft axial direction, and of the two crank journal bearing parts in which the oil grooves are formed among all the crank journal bearing parts. A hydraulic passage of a variable compression ratio mechanism, characterized in that it is arranged near a crank journal bearing part located between.