The present application claims priority to Japanese Patent Application No. 2015-100295 filed on May 15, 2015, which is incorporated herein by reference in its entirety.
The present invention relates to an internal combustion engine.
Known in the past has been an internal combustion engine wherein operating members (stopper pins) provided at connecting rods are made to operate by supplying hydraulic oil from an oil feed device through a main gallery, crank journals, and crankpins to the operating members (for example, PLT 1). In such an internal combustion engine, the hydraulic oil path supplying oil for making the operating members operate is made a single path and the load of the oil feed device is reduced by supplying the hydraulic oil path with hydraulic oil only when making the operating members operate.
However, in such an internal combustion engine, during the period when not making the operating members operate, oil is not supplied to the crank journals at which the hydraulic oil path is formed. For this reason, during operation of the internal combustion engine, the crank journals are liable to end up seizing.
Therefore, to suppress seizing of the crank journals, it may be considered to supply hydraulic oil of a low oil pressure to the crank journals even while not making the operating members operate. However, the oil pressure of hydraulic oil fluctuates according to the engine speed or temperature of the hydraulic oil, so the operating members are liable to mistakenly operate due to fluctuation of the oil pressure.
Therefore, in consideration of the above problem, an object of the present invention is to provide an internal combustion engine able to suppress seizing of all of the crank journals without causing mistaken operation of the operating members to which hydraulic oil is supplied through the crank journals.
In order to solve the above problem, in a first invention, there is provided an internal combustion engine comprising operating members provided at a connecting rod and operating by a predetermined pressure or more of oil pressure, a hydraulic oil path supplying hydraulic oil from an oil feed device to the operating members through part of crank journals among a plurality of crank journals, and a lubricating oil path supplying lubricating oil from the oil feed device to crankpins through the remaining crank journals among the plurality of crank journals, characterized in that the internal combustion engine further comprises a hydraulic control valve provided in the hydraulic oil path and linearly controlling an oil pressure supplied to the operating members due to change of that opening degree, and a control device controlling the opening degree of the hydraulic control valve, and that the control device controls the opening degree of the hydraulic control valve so that when operating the operating members, the predetermined pressure or more of oil pressure is supplied to the operating members, and controls the opening degree of the hydraulic control valve so that when not operating the operating members, less than the predetermined pressure of oil pressure is supplied to the operating members.
In a second invention, if the control device does not operate the operating members, the control device makes the opening degree of the hydraulic control valve smaller when a temperature of the hydraulic oil is relatively low compared with when the temperature of the hydraulic oil is relatively high, and makes the opening degree of the hydraulic control valve smaller when an engine speed is relatively high compared with when the engine speed is relatively small, in the first invention.
In a third invention, the engine further comprises a hydraulic sensor provided in the hydraulic oil path at the operating members side from the hydraulic control valve and detecting an oil pressure supplied to the operating members, and the control device controls the opening degree of the hydraulic control valve based on an output of the hydraulic sensor, in the first or second invention.
In a fourth invention, the hydraulic oil path is communicated with the lubricating oil path at a position at an upstream side from the part of crank journals in a direction of oil flow and at a downstream side of the hydraulic control valve in the direction of oil flow so that an oil pressure of less than the predetermined pressure is supplied from the lubricating oil path to the part of crank journals when the lubricating oil path is supplied with the lubricating oil, in any one of the first to third inventions.
In a fifth invention, a main gallery formed in a cylinder block is formed with two passages, these passages respectively form parts of the hydraulic oil path and lubricating oil path, the hydraulic oil is supplied from the main gallery to the part of crank journals, and the lubricating oil is supplied from the main gallery to the remaining crank journals, in any one of the first to fourth inventions.
In a sixth invention, one of the remaining crank journals is a crank journal closest to a timing belt, in any one of the first to fifth inventions.
According to the present invention, there is provided an internal combustion engine able to suppress seizing of all of the crank journals without causing mistaken operation of the operating members to which hydraulic oil is supplied through the crank journals.
Below, referring to the drawings, an embodiment of the present invention will be explained in detail. Note that, in the following explanation, similar component elements are assigned the same reference notations.
<Internal Combustion Engine>
The variable length connecting rod 6 is connected at a small diameter end part thereof by a piston pin 21 to the piston 5, and is connected at a large diameter end part thereof to a crank pin 22 of the crankshaft. The variable length connecting rod 6, as explained later, can change the distance from the axis of the piston pin 21 to the axis of the crank pin 22, that is, the effective length.
If the effective length of the variable length connecting rod 6 becomes longer, the length from the crank pin 22 to the piston pin 21 is longer, and therefore as shown by the solid line in the figure, the volume of the combustion chamber 7 when the piston 5 is at top dead center is smaller. On the other hand, even if the effective length of the variable length connecting rod 6 changes, the stroke length of the piston 5 reciprocating in the cylinder does not change. Therefore, at this time, the mechanical compression ratio at the internal combustion engine 1 is larger.
On the other hand, if the effective length of the variable length connecting rod 6 is shorter, the length from the crank pin 22 to the piston pin 21 is shorter, and therefore as shown by the broken line in the figure, the volume of the combustion chamber when the piston 5 is at top dead center is larger. However, as explained above, the stroke length of the piston 5 is constant. Therefore, at this time, the mechanical compression ratio at the internal combustion engine 1 is smaller.
<Configuration of Variable Length Connecting Rod>
First, the connecting rod body 31 will be explained. The connecting rod body 31 has at one end a crank pin receiving opening 41 which receives the crank pin 22 of the crankshaft, and has at the other end a sleeve receiving opening 42 which receives a sleeve of the later explained eccentric member 32. The crank pin receiving opening 41 is larger than the sleeve receiving opening 42, and therefore the end of the connecting rod body 31 positioned at the side where the crank pin receiving opening 41 is provided (the crankshaft side), will be called a large diameter end part 31a, while the end of the connecting rod body 31 positioned at the side where the sleeve receiving opening 42 is provided (the piston side), will be called a small diameter end part 31b.
Note that, in this Description, an axis X extending between a center axis of the crank pin receiving opening 41 (that is, the axis of the crank pin 22 received in the crank pin receiving opening 41) and a center axis of the sleeve receiving opening 42 (that is, the axis of the sleeve received in the sleeve receiving opening 42) (
As will be understood from
Next, the eccentric member 32 will be explained.
Further, the sleeve 32a of the eccentric member 32 has a piston pin receiving opening 32d for receiving a piston pin 21. This piston pin receiving opening 32d is formed in a cylindrical shape. The cylindrical piston pin receiving opening 32d has an axis parallel to the center axis of the cylindrical shape of the sleeve 32a, but is formed so as not to become coaxial with it. Therefore, the axis of the piston pin receiving opening 32d is offset from the center axis of the cylindrical external shape of the sleeve 32a, i.e., the swiveling axis of the eccentric member 32.
In this way, in the present embodiment, the center axis of the piston pin receiving opening 32d of the sleeve 32a is offset from the swiveling axis of the eccentric member 32. Therefore, if the eccentric member 32 swivels, the position of the piston pin receiving opening 32d in the sleeve receiving opening 42 changes. When the position of the piston pin receiving opening 32d is at the large diameter end part 31a side in the sleeve receiving opening 42, the effective length of the connecting rod 6 becomes shorter. Conversely, when the position of the piston pin receiving opening 32d is at the opposite side to the large diameter end part 31a side in the sleeve receiving opening 42, i.e., the small diameter end part 31b side, the effective length of the connecting rod becomes longer. Therefore, according to the present embodiment, by swiveling the eccentric member, the effective length of the connecting rod 6 changes.
Next, referring to
The first piston 33b is connected with the first arm 32b of the eccentric member 32 by a first connecting member 45. The first piston 33b is connected by a pin to the first connecting member 45 to be able to rotate. As shown in
The first oil seal 33c has a ring shape and is attached to the circumference of the bottom end part of the first piston 33b. The first oil seal 33c contacts the inner surface of the first cylinder 33a. Frictional force is generated between the first oil seal 33c and the first cylinder 33a.
Next, the second piston mechanism 34 will be explained. The second piston mechanism 34 has a second cylinder 34a formed in the connecting rod body 31, a second piston 34b sliding in the second cylinder 34a, and a second oil seal 34c sealing the oil supplied into the second cylinder 34a. The second cylinder 34a is almost entirely or entirely arranged at the second arm 32c side with respect to the axis X of the connecting rod 6. Further, the second cylinder 34a is arranged slanted by a certain extent of angle with respect to the axis X so that it sticks out further in the width direction of the connecting rod body 31 the closer to the small diameter end part 31b. Further, the second cylinder 34a is communicated with the flow direction changing mechanism 35 through a second piston communicating fluid path 52.
The second piston 34b is connected by a second connecting member 46 to the second arm 32c of the eccentric member 32. The second piston 34b is connected by a pin to the second connecting member 46 to be able to rotate. As shown in the
The second oil seal 34c has a ring shape and is attached to the circumference of the bottom end part of the second piston 34b. The second oil seal 34c contacts the inner surface of the second cylinder 34a. Frictional force is generated between the second oil seal 43c and the second cylinder 34a.
<Operation of Variable Length Connecting Rod>
Next, referring to
In this regard, as explained later, the flow direction changing mechanism 35 can be switched between a first state where it prohibits the flow of oil from the first cylinder 33a to the second cylinder 34a and permits the flow of oil from the second cylinder 34a to the first cylinder 33a, and a second state where it permits the flow of oil from the first cylinder 33a to the second cylinder 34a and prohibits the flow of oil from the second cylinder 34a to the first cylinder 33a.
When the flow direction changing mechanism 35 is in the first state where it prohibits flow of oil from the first cylinder 33a to the second cylinder 34a and permits flow of oil from the second cylinder 34a to the first cylinder 33a, as shown in
On the other hand, if the flow direction changing mechanism 35 is in the second state where it permits the flow of oil from the first cylinder 33a to the second cylinder 34a and prohibits the flow of oil from the second cylinder 34a to the first cylinder 33a, as shown in
Therefore, in the connecting rod 6 according to the present embodiment, as explained above, the effective length of the connecting rod 6 can be switched between L1 and L2, by switching the flow direction changing mechanism 35 between the first state and the second state. As a result, in the internal combustion engine 1 using the connecting rod 6, it is possible to change the mechanical compression ratio.
Here, when the flow direction switching mechanism 35 is in the first state, basically, oil is not supplied from the outside. As explained below, the first piston 33b and the second piston 34b move to the positions shown in
On the other hand, even when the flow direction switching mechanism 35 is in the second state, basically oil is not supplied from the outside. As explained below, the eccentric member 32 swivels to the position shown by
Therefore, in the internal combustion engine 1, the mechanical compression ratio is switched by the inertial force from the low compression ratio to the high compression ratio and is switched by the inertial force and explosive force from the high compression ratio to the low compression ratio.
<Configuration of Flow Direction Switching Mechanism>
Next, referring to
The flow direction switching mechanism 35, as shown in
Furthermore, the two switching pins 61, 62 are provided at the both sides of the axis X of the connecting rod body 31 while the check valve 63 is provided on the axis X. Accordingly, it is possible to suppress a drop in the left and right balance of weight of the connecting rod body 31 due to provision of the switching pins 61, 62 and check valve 63 in the connecting rod body 31.
The two switching pins 61, 62 are respectively held in the cylindrical pin holding spaces 64, 65. In the present embodiment, the pin holding spaces 64, 65 are formed so that their axes extend in parallel with the center axis of the crank pin receiving opening 41. The switching pins 61, 62 can slide in the pin holding spaces 64, 65 in the direction in which the pin holding space 64 extends. That is, the switching pins 61, 62 are arranged in the connecting rod body 31 so that their operating directions become parallel to the center axis of the crank pin receiving opening 41.
Further, among the two pin holding spaces 64, 65, the first pin holding space 64 which holds the first switching pin 61, as shown in
The first switching pin 61 has two circumferential grooves 61a, 61b which extend in the circumferential direction. These circumferential grooves 61a, 61b are communicated with each other by a communicating path 61c formed in the first switching pin 61. Further, in the first pin holding space 64. a first biasing spring 67 is held. Due to this first biasing spring 67, the first switching pin 61 is biased in a direction parallel to the center axis of the crank pin receiving opening 41. In particular, in the example shown in
Similarly, the second switching pin 62 also has two circumferential grooves 62a, 62b which extend in the circumferential direction. These circumferential groove 62a and 62b are communicated with each other by a communicating path 62c formed in the second switching pin 62. Further, in the second pin holding space 65, a second biasing spring 68 is held. Due to this second biasing spring 68, the second switching pin 62 is biased in a direction parallel to the center axis of the crank pin receiving opening 41. In particular, in the example shown in
In addition, the first switching pin 61 and the second switching pin 62 are arranged in opposite directions to each other in directions parallel to the center axis of the crankshaft receiving opening 41. In addition, the second switching pin 62 is biased in the opposite direction to the first switching pin 61. For this reason, in the present embodiment, the operating directions of these first switching pin 61 and second switching pin 62 when these first switching pin and second switching pin 62 are supplied with oil pressure become opposite to each other.
The check valve 63 is held in a cylindrical check valve holding space 66. In the present embodiment, the check valve holding space 66 is formed to extend in parallel with the center axis of the crank pin receiving opening 41. The check valve 63 can move in the check valve holding space 66 in the direction in which the check valve holding space 66 extends. Therefore, the check valve 63 is arranged in the connecting rod body so that its direction of operation is parallel with the center axis of the crank pin receiving opening 41. Further, the check valve holding space 66 is formed as a check valve holding hole which is opened to one side surface of the connecting rod body 31 and is closed to the other side surface of the connecting rod body 31.
The check valve 63 is configured to permit flow from a primary side (in
The first pin holding space 64 holding the first switching pin 61 is communicated with the first cylinder 33a through the first piston communicating oil path 51. As shown in
Note that, the first piston communicating oil path 51 and the second piston communicating oil path 52 are formed by cutting from the crankshaft receiving opening 41 by a drill etc. Therefore, at the crankshaft receiving opening 41 sides of the first piston communicating oil path 51 and the second piston communicating oil path 52, the first extended oil path 51a and the second extended oil path 52a coaxial with these piston communicating oil paths 51 and 52 are formed. In other words, the first piston communicating oil path 51 and the second piston communicating oil path 52 are formed so that the crankshaft receiving opening 41 is positioned on their extensions. These first extended oil path 51a and second extended oil path 52a are, for example, closed by bearing metal 71 provided inside the crankshaft receiving opening 41.
The first pin holding space 64 holding the first switching pin 61 is communicated with the check valve holding space 66 through two space communicating oil paths 53 and 54. Among these, the first space communicating oil path 53, as shown in
Further, the second pin holding space 65 holding the second switching pin 62 is communicated with the check valve holding space 66 through two space communicating oil paths 55 and 56. Among these, the third space communicating oil path 55, as shown in
These space communicating oil paths 53 to 56 are formed by cutting by a drill etc. from the crankshaft receiving opening 41. Therefore, at the crankshaft receiving opening 41 sides of these space communicating oil paths 53 to 56, extended oil paths 53a to 56a coaxial with these space communicating oil paths 53 to 56 are formed. In other words, the space communicating oil paths 53 to 56 are formed so that the crankshaft receiving opening 41 is positioned on their extensions. These extended oil paths 53a to 56a are, for example, closed by the bearing metal 71.
As explained above, the extended oil paths 51a to 56a are both sealed by bearing metal 71. For this reason, only by using bearing metal 71 to assemble the connecting rod 6 to the crankpin 22, it is possible to close these extended oil paths 51a to 56a without separately performing processing for closing these extended oil paths 51a to 56a.
Further, inside the connecting rod body 31, a first control-use oil path 57 for supplying oil pressure to the first switching pin 61 and a second control-use oil path 58 for supplying oil pressure to the second switching pin 62 are formed. The first control-use oil path 57 is communicated with the first pin holding space 64 at the end part at the opposite side to the end part at which the first biasing spring 67 is provided. The second control-use oil path 58 is communicated with the second pin holding space 65 at the end part at the opposite side to the end part at which the second biasing spring 68 is provided. These control-use oil paths 57 and 58 are formed so as to communicate with the crankshaft receiving opening 41 and are communicated with an oil feed device at the outside of the connecting rod 6 through oil paths formed inside the crankpin 22. The oil feed device is, for example, an oil pump driven by rotation of the crankshaft. The oil pump also supplies oil to the intake camshaft 10, exhaust camshaft 13, crankpins 22 of the crankshaft and crank journals, and other lubricated parts. The path from the oil feed device to the crankpins 22 will be explained later.
Therefore, when oil pressure is not being supplied from the oil feed device, the first switching pin 61 and the second switching pin 62 are respectively biased by the first biasing spring 67 and the second biasing spring 68 and, as shown in
Furthermore, inside the connecting rod body 31, a refill-use oil path 59 is formed for refilling oil at the primary side of the check valve 63 in the check valve holding space 66 in which the check valve 63 is held. One end part of the refill-use oil path 59 is communicated with the check valve holding space 66 at the primary side of the check valve 63. The other end part of the refill-use oil path 59 is communicated with the crankshaft receiving opening 41. Further, the bearing metal 71 is formed with a through hole 71a matched with the refill-use oil path 59. The refill-use oil path 59 is communicated with the oil feed device through this through hole 71a and an oil path (not shown) formed inside the crankpin 22. Therefore, due to the refill-use oil path 59, the primary side of the check valve 63 is communicated with the oil feed device constantly or periodically matched with the rotation of the crankshaft.
<Operation of Flow Direction Switching Mechanism>
Next, referring to
As shown in
Here, the check valve 63 is configured to permit the flow of oil from the primary side where the second space communicating oil path 54 and fourth space communicating oil path 56 communicate to the secondary side where the first space communicating oil path 53 and third space communicating oil path 55 communicate, and to prohibit the reverse flow. Therefore, in the state shown in
As a result of this, in the state shown in
On the other hand, as shown in
Due to the action of the above-mentioned check valve 63, in the state shown in
Further, in the present embodiment, as explained above, oil travels back and forth between the first cylinder 33a of the first piston mechanism 33 and the second cylinder 34a of the second piston mechanism 34. For this reason, basically, oil does not have to be supplied from the outside of the first piston mechanism 33, second piston mechanism 34, and flow direction switching mechanism 35. However, oil may leak to the outside from the oil seals 33c, 34c, etc. provided at these mechanisms 33, 34, and 35. If oil leaks in this way, it has to be refilled from the outside.
In the present embodiment, there is the refill-use oil path 59 at the primary side of the check valve 63. Due to this, the primary side of the check valve 63 is constantly or periodically communicated with the oil feed device 75. Therefore, even if oil leaks from the mechanisms 33, 34, 35, etc., the oil can be refilled.
Furthermore, in the present embodiment, the flow direction switching mechanism 35 is configured to become a first state where the effective length of the connecting rod 6 becomes long when a predetermined pressure or more of oil pressure is supplied from the oil feed device 75 to the switching pins 61 and 62 and to become a second state where the effective length of the connecting rod 6 becomes short when oil pressure is not supplied from the oil feed device 75 to the switching pins 61 and 62. Due to this, for example, when a breakdown at the oil feed device 75 etc. makes it no longer possible to supply oil pressure, it is possible to leave the effective length of the connecting rod 6 short and therefore possible to maintain the mechanical compression ratio low.
<Hydraulic Oil Path and Lubricating Oil Path>
As explained above, the operating members provided at the connecting rod 6, that is, the switching pins 61 and 62, operate by a predetermined pressure or more of oil pressure. Further, in the internal combustion engine 1, to reduce the friction between metals and seizing, lubricating oil is supplied to the intake camshaft 10, exhaust camshaft 13, crankpins 22 of the crankshaft and crank journals, and other lubricated parts. Below, referring to
In the present embodiment, the internal combustion engine 1 is an in-line internal combustion four-cylinder engine. For this reason, the crankshaft 76 comprises five crank journals 70a to 70e. As shown in
Further, at the end part of the crankshaft 76 at the first crank journal 70a side, a crankshaft pulley 101 is fastened. At the crankshaft pulley, a timing belt 102 is attached. Therefore, the first crank journal 70a is the crank journal closest to the timing belt among the plurality of crank journals.
As shown in
As explained above, in the present embodiment, the first crank journal 70a, third crank journal 70c, and fifth crank journal 70e are formed with the first lubricating oil path 72. In the second crank journal 70b, the balance weights 78a and 78b at the two ends extend in opposite directions from the axis of the crankshaft 76, so the inertial forces generated by the balance weights 78a and 78b due to rotation of the crankshaft 76 are cancelled out. Therefore, during rotation of the crankshaft 76, the load which the second crank journal 70b receives is small. The fourth crank journal 70d is also similar to the second crank journal 70b. On the other hand, at the third crank journal 70c, the balance weights 78b and 78c of the two ends extend in the same direction, so the inertial forces generated by the balance weights 78b and 78c due to rotation of the crankshaft 76 are amplified. Therefore, during rotation of the crankshaft 76, the load which the third crank journal 70c receives is the greatest. Further, at the first crank journal 70a and fifth crank journal 70e, the balance weights 78a and 78d extend to only one side, so the inertial forces generated by the balance weights 78a and 78d due to rotation of the crankshaft 76 are not cancelled out. Therefore, during rotation of the crankshaft 76, the loads which the first crank journal 70a and fifth crank journal 70e receive are relatively large. Further, the first crank journal 70a is the crank journal closest to the timing belt, so a load from the timing belt is also received.
Therefore, the loads which the first crank journal 70a, third crank journal 70c, and fifth crank journal 70e receive are larger than the loads which the second crank journal 70b and fourth crank journal 70d receive. For this reason, in the first crank journal 70a, third crank journal 70c, and fifth crank journal 70e, the lubrication request is relatively high. In the present embodiment, by forming the first lubricating oil path 72 at the first crank journal 70a, third crank journal 70c, and fifth crank journal 70e, it is possible to effectively suppress seizing of the crank journals with a large load.
On the other hand, as shown by the broken line arrows in
Further, as shown in
The hydraulic control valve 79 is arranged at the switching pin 61 and 62 side (oil flow direction downstream side) from the oil feed device 75. Further, the hydraulic control valve 79 has a discharged oil path 80 connected to it. If the opening degree of the hydraulic control valve 79 is not wide open, part of the hydraulic oil supplied to the hydraulic control valve 79 is returned through the discharged oil path 80 to the oil pan 2a.
The hydraulic oil path 74 is further provided with a hydraulic sensor 81. The hydraulic sensor 81 can detect the oil pressure controlled by the hydraulic control valve 79, that is, the oil pressure supplied to the switching pins 61 and 62. The hydraulic sensor 81 is arranged at the switching pin 61 and 62 side from the oil feed device 75 and hydraulic control valve 79.
As will be understood from
The main gallery 82 extends in parallel to the axial direction of the crankshaft 76, that is, the axial direction of the crank journals 70a to 70e. The main gallery 82 is connected through the first connecting oil path 85a to the first crank journal 70a, is connected through the second connecting oil path 85b to the second crank journal 70b, is connected through the third connecting oil path 85c to the third crank journal 70c, is connected through the fourth connecting oil path 85d to the fourth crank journal 70d, and is connected through the fifth connecting oil path 85e to the fifth crank journal 70e. Therefore, the hydraulic oil is supplied from the main gallery 82 to the second crank journal 70b and fourth crank journal 70d. On the other hand, the lubricating oil is supplied from the main gallery 82 to the first crank journal 70a, third crank journal 70c, and fifth crank journal 70e. Note that, the oil feed device 75, hydraulic control valve 79, and hydraulic sensor 81 are arranged at the upstream side from the main gallery 82 in the direction of oil flow.
The bore diameter of the main gallery 82 in the cross-section vertical to the direction of extension of the main gallery 82 (cross-section shown in
As shown in
As shown in
As shown in
Further, the recessed part 83b of the pipe member 83 is communicated with the gap 84. For this reason, the recessed part 83b of the pipe member 83 communicates through the gap 84 with the inside 83a of the pipe member 83. Therefore, the hydraulic oil path 74 communicates with the first lubricating oil path 72 at a position at the upstream side from the second crank journal 70b and fourth crank journal 70d in the direction of oil flow and at the downstream side from the hydraulic control valve 79 in the direction of oil flow. As a result of this, when the first lubricating oil path 72 is supplied with lubricating oil, lubricating oil is supplied from the first lubricating oil path 72 through the gap 84 and recessed part 83b of the pipe member 83 to the second crank journal 70b and fourth crank journal 70d.
The gap 84 is configured so that the oil pressure supplied from the first lubricating oil path 72 to the second crank journal 70b and fourth crank journal 70d becomes lower than the oil pressure of the switching pins 61 and 62. Due to this, even if the hydraulic control valve 79 breaks down and oil can no longer be supplied from the hydraulic oil path 74 to the second crank journal 70b and fourth crank journal 70d, it is possible to suppress seizing of the second crank journal 70b and fourth crank journal 70d by the oil supplied from the first lubricating oil path 72 without causing mistaken operation of the switching pins 61 and 62.
<Control of Hydraulic Control Valve>
The internal combustion engine 1 further comprises a control device 100 (see
When operating the switching pins 61 and 62, the control device controls the opening degree of the hydraulic control valve 79 so that oil pressures of the operating pressures of the switching pins 61 and 62 or more are supplied to the switching pins 61 and 62, while when not operating the switching pins 61 and 62, it controls the opening degree of the hydraulic control valve 79 so that oil pressures of less than the operating pressures of the switching pins 61 and 62 are supplied to the switching pins 61 and 62. Due to this, while the oil feed device 75 is operating, it is possible to constantly supply oil to the second crank journal 70b and fourth crank journal 70d without causing mistaken operation of the switching pins 61 and 62. Therefore, in the present embodiment, in addition to the first crank journal 70a, third crank journal 70c, and fifth crank journal 70e, it is possible to keep down seizing of the second crank journal 70b and fourth crank journal 70d.
Below, referring to
In the internal combustion engine 1, if a predetermined pressure Pbase or more of oil pressure is supplied from the oil feed device 75 to the switching pins 61 and 62, the switching pins 61 and 62 operate and the flow direction switching mechanism 35 changes from the second state to the first state. As a result of this, the flow of oil from the second cylinder 34a to the first cylinder 33a is permitted and the mechanical compression ratio εm is switched from the low compression ratio εmlow to the high compression ratio εmhigh.
In the example of
Even if the opening degree of the hydraulic control valve 79 is constant, the oil pressure OP fluctuates according to the engine speed or the temperature of the hydraulic oil. Specifically, the oil pressure OP becomes higher the higher the engine speed when the oil feed device 75 is driven by rotation of the crankshaft 76. Further, the oil pressure OP becomes higher the lower the temperature of the hydraulic oil, since the viscosity of the hydraulic oil becomes higher the lower the temperature of the hydraulic oil. In the present embodiment, the hydraulic control valve 79 can linearly control the pressure of the hydraulic oil based on the output of the hydraulic sensor 81, so can control the oil pressure OP to a predetermined value. Due to this, while the mechanical compression ratio εm is set to the low compression ratio εmlow, it is possible to supply a suitable amount of lubricating oil to the second crank journal 70b and fourth crank journal 70d without causing mistaken operation of the switching pins 61 and 62. Therefore, in the present embodiment, seizing of the second crank journal 70b and the fourth crank journal 70d is inhibited.
Note that, to make the oil pressure supplied to the switching pins 61 and 62 become a predetermined value, in addition to the output of the hydraulic sensor 81 or instead of the output of the hydraulic sensor 81, the opening degree of the hydraulic control valve 79 may be controlled based on the temperature of the hydraulic oil and engine speed. Specifically, when not making the switching pins 61 and 62 operate, the control device makes the opening degree of the hydraulic control valve 79 smaller when the oil temperature of the hydraulic oil is relatively low compared with when the oil temperature of the hydraulic oil is relatively high, and makes the opening degree of the hydraulic control valve 79 smaller when the engine speed is relatively high compared with when the engine speed is relatively low so that the oil pressure supplied to the switching pins 61 and 62 becomes the lubrication-use oil pressure Plow. In other words, when not making the switching pins 61 and 62 operate, the control device makes the opening degree of the hydraulic control valve 79 smaller in steps or linearly as the oil temperature of the hydraulic oil becomes lower, and makes the opening degree of the hydraulic control valve 79 smaller in steps or linearly as the engine speed becomes higher. Due to this, while the mechanical compression ratio εm is set to the low compression ratio εmlow, a suitable amount of lubricating oil can be supplied to the second crank journal 70b and fourth crank journal 70d without causing mistaken operation of the switching pins 61 and 62. Note that, the temperature of the hydraulic oil can, for example, be detected by an oil temperature sensor 92 provided at the internal combustion engine 1. Further, the engine speed is calculated by a crank angle sensor 91 provided at the internal combustion engine 1.
Further, in the example of
In the example of
After the time t1, the oil pressure OP rises to the working-use oil pressure Phigh and is maintained at the working-use oil pressure Phigh until the time t2. If the oil pressure OP becomes a predetermined pressure Pbase or more, the switching pins 61 and 62 operate and the mechanical compression ratio εm starts to change from the low compression ratio εmlow toward the high compression ratio εmhigh. The mechanical compression ratio εm is maintained at the high compression ratio εmhigh after that.
In the example of
Above, suitable embodiments according to the present invention were explained, but the present invention is not limited to these embodiments and can be modified and changes in various ways within the language of the claims. For example, as long as an operating member operated by the hydraulic oil is provided at the connecting rod 6, it may be an operating member other than the switching pins 61 and 62.
1. internal combustion engine
5. piston
6. connecting rod
15. cylinder
21. piston pin
22. crankpin
35. flow direction switching mechanism
61. first switching pin
62. second switching pin
75. oil feed device
70
a. first crank journal
70
b. second crank journal
70
c. third crank journal
70
d. fourth crank journal
70
e. fifth crank journal
72. first lubricating oil path
74. hydraulic oil path
75. oil feed device
79. hydraulic control valve
81. hydraulic sensor
Number | Date | Country | Kind |
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2015-100295 | May 2015 | JP | national |
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