JP2000186514A - Variable compression ratio device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable compression ratio device for an internal combustion engine that is simple in construction, excellent in durability, and capable of changing the compression ratio with high reliability. SOLUTION: A cylinder block 12 of an engine 16 is provided with an intake side valve supporting hole 30 and an exhaust side valve supporting hole 40 both extending in the direction perpendicular to the directin of reciprocating motion of a piston 16. An intake rotary valve 34 having an intake port 36 and an exhaust rotary valve 44 having an exhaust port 46 are inserted into the valve supporting holes 30, 40, respectively, and supported rotatably. Four pair of recessed parts 60 capable of exposing themselves to a combustion chamber 22 are formed in the exhaust rotary valve 44, corresponding to respective cylinders. During the combustion stroke, by moving the exhaust rotary valve 44 in its axial direction, switching its position in the axial direction, a state in which the recessed part 60 is exposed to the combustion chamber 22 can be switched to the state in which the recessed part 60 is not exposed, and vice versa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compression ratio variable device capable of changing a compression ratio of an internal combustion engine, and more particularly to an internal combustion engine having an intake rotary valve and an exhaust rotary valve rotatably provided in the internal combustion engine. The present invention relates to a variable compression ratio device for an internal combustion engine applied to an engine.

[0002]

2. Description of the Related Art As a variable compression ratio device for an internal combustion engine, there is a device described in Japanese Patent Application Laid-Open No. 7-83081. In this device, a mechanism for changing the eccentric position of an eccentric piston pin connecting the piston of the engine and the connecting rod is provided in the connecting portion, and the compression is performed by substantially changing the length of the connecting rod based on the operation of this mechanism. The ratio is switched. By switching the compression ratio in this manner, the compression ratio can be more accurately adapted to the operating state of the engine, and the output can be increased and the fuel efficiency can be improved.

[0003]

However, the device described in the above publication is not only limited to the connection portion between the piston and the connecting rod, that is, the combustion pressure generated during the combustion stroke,
A mechanism for changing the compression ratio is provided in a portion where an extremely large external force acts due to an external load transmitted to the engine through the crankshaft and the connecting rod. For this reason, there is a problem in practical durability, and since the positions of a plurality of members are changed to change the eccentric position of the eccentric piston pin, complication of the configuration cannot be avoided. Was. As a result, the above-mentioned conventional apparatus is not necessarily sufficient in terms of reliability due to such a decrease in durability and a complicated configuration.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an internal combustion engine having a simple and highly durable structure and capable of changing the compression ratio with high reliability. To provide a compression ratio variable device.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, at least one surface of an intake rotary valve and an exhaust rotary valve rotatably provided in an internal combustion engine is provided with the rotation thereof. In synchronization with the engine combustion chamber, the one rotary valve is moved in the direction of its rotational axis to change the manner in which the concave portion is exposed during the combustion stroke of the internal combustion engine, thereby causing engine combustion. A change means for changing the volume of the chamber is provided.

According to the above configuration, the volume of the engine combustion chamber can be changed only by moving the rotary valve having the concave portion in the axial direction, so that the compression ratio can be changed based on a very simple configuration. It can be realized. Further, since an extremely large external force does not act on the rotary valve having such a position change due to an external load of the engine, it is possible to avoid a decrease in durability.

[0007] Further, as a more specific configuration for switching the manner of exposing the concave portion, claims 2 to 4 are provided.
Can be adopted. That is,
As described in claim 2, the plurality of recesses are formed. The changing means sets a state in which a predetermined number of recesses are exposed as a mode of exposure and a state in which a number of recesses different from the predetermined number are exposed. By adopting such a configuration as described above, by changing the number of recesses exposed to the engine combustion chamber during the combustion stroke, the volume of the engine combustion chamber can be changed to change the compression ratio. Become like

[0008] Alternatively, as in the invention according to claim 3, a plurality of recesses are formed with different volumes, and the changing means is a state in which a recess having a predetermined volume is exposed as an exposure mode. And a state in which a concave portion having a volume different from the predetermined volume is exposed.By adopting such a configuration, by switching the volume of the concave portion exposed to the engine combustion chamber during the combustion stroke, Thus, the compression ratio can be changed by changing the volume of the engine combustion chamber.

Further, as in the invention as set forth in claim 4, the configuration is adopted in which the changing means selectively switches between a state in which the recess is exposed to the engine combustion chamber and a state in which the recess is not exposed. By switching between a state in which the recess is exposed to the engine combustion chamber and a state in which the recess is not exposed during the combustion stroke, the volume of the engine combustion chamber can be changed by the volume of the recess. Further, the number of concave portions formed in the rotary valve can be minimized.

[0010] Further, as in the invention described in claim 5,
The invention according to any one of claims 1 to 4, further comprising: detecting means for detecting an engine operating state; and changing means based on the detected engine operating state. Is moved in the direction of the rotation axis to switch the exposure mode. According to such a configuration, the compression ratio can be changed so as to be suitable for the engine operating state.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a cross-sectional structure of an in-line four-cylinder engine 10 for a vehicle to which the variable compression ratio device of the present embodiment is applied. As shown in the figure, a cylinder block 12 is formed with four cylinders 14 (only one of them is shown in the figure), and in each of these cylinders 14, a piston 16 is provided so as to be able to reciprocate. ing. The piston 16 is connected to a crankshaft (not shown) via a connecting rod 18.

A cylinder head 20 is provided on the cylinder block 12, and a combustion chamber 22 is defined by a bottom surface of the cylinder head 20, an inner wall surface of the cylinder 14, a top surface of the piston 16, and the like. The cylinder block 12 is formed with an intake-side valve support hole 30 and an exhaust-side valve support hole 40 extending in a direction perpendicular to the reciprocating direction of the piston 16 (vertical direction in FIG. 1).

An intake port 32 and an exhaust port 42 are formed in the cylinder head 20, respectively.
2 is a combustion chamber 2 through exhaust side valve support holes 40, respectively.
2 are connected. An intake rotary valve 34 and an exhaust rotary valve 44 are inserted through the respective valve support holes 30 and 40 and rotatably supported. Each of these rotary valves 34 and 44 has a columnar shape, and a part thereof is exposed to the combustion chamber 22.

FIG. 2 shows each of these rotary valves 34, 44.
3 shows a perspective structure of the exhaust rotary valve 44, and FIG. 3 shows a sectional structure taken along line 3-3 in FIG.

As shown in FIG. 2, the exhaust rotary valve 4
A timing pulley 45 is provided on one end side of 4. The timing pulley 45 is connected to the exhaust rotary valve 4.
4 is splined to one end of
While the relative rotation of the exhaust rotary valve 44 is restricted, the relative movement of the exhaust rotary valve 44 in the axial direction is allowed. A timing pulley (not shown) having a substantially similar shape is fixedly provided on one end side of the intake rotary valve 34.

A timing belt 50 is mounted on each of the timing pulleys and a crank pulley (not shown) of the crankshaft. By transmitting torque from the crankshaft via the timing belt 50, the rotary valves 34 and 44 rotate in synchronization with the rotation of the crankshaft. By the way, while the crankshaft makes one rotation, each rotary valve 34, 44
The number of teeth of each pulley is set so as to make four rotations. Therefore, while the series of strokes of the engine 10 such as intake, compression, combustion, and exhaust are repeated twice, each rotary valve 3
4, 44 will make one rotation.

As shown in FIGS. 1 and 2, exhaust holes 46 are formed in the exhaust rotary valve 44 at positions that can be exposed to the combustion chambers 22 of the respective cylinders so as to penetrate in a direction perpendicular to the axial direction. Have been. These exhaust holes 46 allow the exhaust gas to be discharged from the combustion chamber 22 by communicating the exhaust port 42 with the combustion chamber 22 with the rotation of the exhaust rotary valve 44 during the exhaust stroke of the corresponding cylinder.

Four intake holes 36 are similarly formed in the intake rotary valve 34, and the intake holes 36 communicate with the intake port 32 and the combustion chamber 22 during the intake stroke of the corresponding cylinder. The intake air is introduced into the combustion chamber 22 together with the injected fuel.

As shown in FIGS. 1 and 3, the exhaust rotary valve 44 is formed with four pairs of concave portions 60 so as to correspond to each cylinder. Each of these recesses 60 is formed on the surface of the exhaust rotary valve 44 at a position 180 degrees opposite to the axis of the exhaust rotary valve 44, and is formed at a predetermined interval in the axial direction of the exhaust rotary valve 44 from each exhaust hole 46. ing.

The recess 60 is used to change the compression ratio by exposing the combustion chamber 22 during the combustion stroke to change the volume of the combustion chamber 22. Such a change in the compression ratio is performed by moving the exhaust rotary valve 44 in the axial direction to switch the position of the recess 60 in the axial direction to a position where the recess 60 can be exposed to the combustion chamber 22.

Hereinafter, the exhaust rotary valve 44 will be described.
Will be described with reference to the schematic configuration diagram of FIG. As shown in the drawing, a drive shaft 81 of a hydraulic actuator 80 is connected via a coupling 70 to an end of the exhaust rotary valve 44 opposite to a side where the timing pulley 45 is provided. The coupling 70 is an exhaust rotary valve 4
4 transmits only the force acting in the axial direction. Accordingly, no rotational force is transmitted through the coupling 70, and the drive shaft 81 does not rotate with the rotation of the exhaust rotary valve 44.

The hydraulic actuator 80 includes a housing 82 fixed to the cylinder head 20 and a housing 82
And a piston 83 that can reciprocate in the axial direction of the exhaust rotary valve 44. This piston 8
Reference numeral 3 is connected to the drive shaft 81 and moves integrally with the drive shaft 81 in the axial direction of the exhaust rotary valve 44.

In the housing 82, a first hydraulic chamber 84 and a second hydraulic chamber 85 are formed on both sides of the piston 83, respectively. These hydraulic chambers 84 and 85 are formed by a pair of oil chambers formed in the housing 82. It is connected to the hydraulic unit 90 via the holes 86, 87 and the like. First hydraulic chamber 8
A return spring 88 for biasing the piston 83 is provided in the side 4 on the side (the right side in FIG. 5) that reduces the amount of protrusion of the drive shaft 81 from the housing 82.

The hydraulic unit 90 supplies the oil pan 91 and the oil stored in the oil pan 91 to the hydraulic chambers 84 and 8.
5, a hydraulic pump 93 for selectively supplying a pressure to the hydraulic pump 5, the hydraulic pump 93, the oil pan 91, and the respective hydraulic chambers 84,
A direction switching valve 95 for switching a connection state with the valve 85 is provided. The hydraulic pump 93 also serves as a lubrication pump for supplying lubricating oil to the engine 10, and is driven based on the rotational force of a crankshaft.

As shown in FIG. 5, the hydraulic pump 93 and the first
Is connected to the hydraulic chamber 84 of the
And the second hydraulic chamber 85 so that the direction switching valve 9 is connected.
By switching 5, oil is supplied from the hydraulic pump 93 to the first hydraulic chamber 84, while oil in the second hydraulic chamber 85 is returned to the oil pan 91.
As a result, the piston 83 is urged by the hydraulic pressure in the first hydraulic chamber 84 and moves toward the second hydraulic chamber 85 until it comes into contact with the inner wall of the housing 82.

The movement of the piston 83 minimizes the amount of protrusion of the drive shaft 81, so that the exhaust rotary valve 44 moves the hydraulic actuator 8 in the axial direction most.
It is arranged at a position closer to zero (referred to as “first position” in this embodiment).

FIG. 4 shows the exhaust rotary valve 4
4 is located at the “first position”,
3 shows a positional relationship between a surface R of the exhaust rotary valve 44 and a region R exposed in the combustion chamber 22 (a region surrounded by a dashed line in the drawing).

As shown in FIG.
4 is located at the “first position”, the concave portion 60 enters the exposed region R even when the exhaust rotary valve 44 rotates and the positional relationship between the concave portion 60 and the exposed region R changes. There is nothing. Accordingly, the compression ratio does not change due to the recess 60 being exposed to the combustion chamber 22, and the engine 10 is operated based on the relatively high compression ratio.

On the other hand, as shown in FIG.
And the second hydraulic chamber 85 are connected to each other, and the direction switching valve 95 is switched so that the oil pan 91 and the first hydraulic chamber 84 are connected to each other.
5 is supplied with oil from a hydraulic pump 93, while the first
The oil in the hydraulic chamber 84 is returned to the oil pan 91. As a result, the piston 83 is urged by the hydraulic pressure in the second hydraulic chamber 85 and moves toward the first hydraulic chamber 84 until it contacts the inner wall of the housing 82.

The displacement of the piston 83 maximizes the amount of protrusion of the drive shaft 81, and the exhaust rotary valve 44 is disposed at a position closest to the timing pulley 45 in the axial direction (referred to as a "second position" in this embodiment). Will be done.

FIG. 7 shows the exhaust rotary valve 4
4 is located at the “second position”,
And a positional relationship between the exposure region R and the exposure region R. As shown in the figure, when the exhaust rotary valve 44 is located at this “second position”, the exhaust rotary valve 4
With the rotation of 4, the concave portion 60 comes into the exposure region R during the combustion stroke. When the recess 60 is exposed to the combustion chamber 22 in this manner, the volume of the combustion chamber 22 during the combustion stroke is increased by the volume of the recess 60, and the exhaust rotary valve 44 is moved to the “first position”. , The engine 10 is operated based on a relatively lower compression ratio than when the engine 10 is disposed.

In the present embodiment, the change of the compression ratio based on the change of the position of the exhaust rotary valve 44 is performed by an electronic control unit (hereinafter referred to as “E”) that executes various controls of the engine 10.
CU ”). Hereinafter, a configuration related to this control and a control procedure thereof will be described.

As shown in FIGS. 5 and 6, the engine 10
In order to detect the operating state, the engine speed NE
Speed sensor 102 that outputs a signal corresponding to the magnitude of
And the intake pressure introduced into the combustion chamber 22, that is, an intake pressure sensor 10 that outputs a signal corresponding to the magnitude of the intake pressure PM.
4 are provided, and each of these sensors 102,
The signal output from 104 is input to ECU 100. The ECU 100 detects the engine speed NE based on each of these signals, and changes the intake pressure PM into the engine 10.
Is detected as a load equivalent value.

The ECU 100 determines the switching position of the exhaust rotary valve 44 based on the detected engine speed NE and the intake pressure PM. A memory (not shown) of the ECU 100 stores function data that defines the relationship between the engine speed NE and the intake pressure PM and the switching position,
The ECU 100 refers to this function data when determining the switching position of the exhaust rotary valve 44.

FIG. 8 shows this function data as a function map. As shown in the figure, for example, in a low-load low-rotation region, the “first position” is selected as the switching position of the exhaust rotary valve 44. Therefore, the ECU 100
The direction switching valve 95 is controlled such that the exhaust rotary valve 44 is located at the “first position”, and the compression ratio is set relatively high.

On the other hand, in the high load / high rotation range, the "second position" is selected as the switching position of the exhaust rotary valve 44. Therefore, the direction switching valve 95 is controlled by the ECU 100 such that the exhaust rotary valve 44 is located at the “second position”, and the compression ratio is set relatively low.

As described above, by setting the compression ratio relatively high in the low-load low-rotation region, the combustion state can be improved, the fuel efficiency can be improved, and the engine output can be increased. By setting the compression ratio relatively low in the rotation region, knocking can be suppressed and a predetermined engine output can be secured.

As described above, according to the present embodiment, (1) the compression ratio of the engine 10 can be changed to suit the engine operating state such as the engine speed NE and the intake pressure PM, and the engine output increases. In addition, the fuel efficiency can be improved.

(2) The compression ratio can be changed by changing the volume of the combustion chamber 22 only by moving the exhaust rotary valve 44 in the axial direction, and the exhaust rotary valve 44 having such a position change. Therefore, no extremely large external force acts due to the load on the vehicle side. Therefore, the compression ratio can be changed with high reliability by a simple and highly durable configuration.

Further, in this embodiment, since the return spring 88 is provided in the hydraulic actuator 80, the rotation speed of the crankshaft is extremely low as in the start of the engine 10, and a predetermined discharge pressure is secured in the hydraulic pump 93. Even if it is not possible, the exhaust rotary valve 4
4 can be reliably held at the “first position”.

(3) As a result, even at the time of such starting, unnecessary fluctuation of the compression ratio caused by vibration of the exhaust rotary valve 44 in the axial direction can be suppressed,
Combustion can be stabilized.

[Second Embodiment] Hereinafter, a second embodiment of the present invention will be described with a focus on differences from the first embodiment. The description of the same configuration as that of the first embodiment will be omitted.

This embodiment is different from the first embodiment in that the compression ratio is switched between three stages according to the operating state of the engine 10. FIG. 9 schematically shows a mechanism for moving the exhaust rotary valve 44 in the axial direction, and FIG. 10 shows a cross-sectional structure taken along line 10-10 of FIG.

As shown in these figures, a first recess 61 is formed in the exhaust rotary valve 44 at the same position as the recess 60 in the first embodiment.
Further, a pair of second concave portions 62 are formed corresponding to the respective cylinders.

Like the first recess 61, the second recess 62 is formed on the surface of the exhaust rotary valve 44 at a position 180 ° opposite to the axial center of the exhaust rotary valve 44, and is in contact with the first recess 61. The first recess 61 is formed at a predetermined interval in the axial direction of the exhaust rotary valve 44 so as to sandwich the exposure region R therebetween.

Further, as shown in FIG.
2 is recessed deeper than the first recess 61, and its volume is set to be larger than that of the first recess 61. In the present embodiment, the direction switching valve 95 is configured as a three-way position switching valve, and in addition to the two switching positions described in the first embodiment, as shown in FIG.
It is also possible to switch to a neutral position where the supply and discharge of oil to the 4, 85 are stopped. The piston 83 can be stopped at an arbitrary position in the housing 82 by appropriately switching the direction switching valve 95 to change the supply / discharge state of the oil to and from the hydraulic chambers 84 and 85.

The hydraulic actuator 80 is provided with a position sensor 106 for detecting the position of the piston 83 in the housing 82.
The output signal 06 is input to the ECU 100.

In the second hydraulic chamber 85, there is provided a return spring 89 for urging the piston 83 toward the first hydraulic chamber 84. For example, when sufficient hydraulic pressure does not act in both hydraulic chambers 84 and 85 when the engine is started, the urging force of the return spring 89 and the first
Is balanced with the urging force of the return spring 88 in the hydraulic chamber 84, the piston 83 is held at the "third position" described later.

The ECU 100 controls the direction switching valve 95 to adjust the position of the piston 83, thereby switching the position of the exhaust rotary valve 44 in the axial direction. That is, the ECU 100 switches the direction switching valve 95 to supply the oil to the second hydraulic chamber 85 and the first hydraulic chamber 84
, The piston 83 is moved toward the first hydraulic chamber 84 by the oil pressure in the second hydraulic chamber 85 until the piston 83 comes into contact with the inner wall of the housing 82. As a result, the exhaust rotary valve 44 is arranged at a position closest to the timing pulley 45 in the axial direction (referred to as a “first position” in this embodiment). And
By arranging the exhaust rotary valve 44 at the “first position”, only the first recess 61 enters the exposure region R during the combustion stroke.

On the other hand, the ECU 100 switches the direction switching valve 95 to supply the oil to the first hydraulic chamber 84 and discharges the oil from the second hydraulic chamber 85, thereby causing the piston 83 to move to the first hydraulic chamber 84. Of the housing 82
Is moved toward the second hydraulic chamber 85 until it comes into contact with the inner wall. As a result, the exhaust rotary valve 44 is arranged at a position closest to the hydraulic actuator 80 in the axial direction (referred to as a “second position” in this embodiment). And, as described above, the exhaust rotary valve 44
Is arranged at the “second position”, so that only the second concave portion 62 enters the exposure region R during the combustion stroke.

Further, in the ECU 100, the exhaust rotary valve 44 is disposed at a position substantially intermediate between the "first position" and the "second position" (in this embodiment, referred to as a "third position"). As described above, by switching the direction switching valve 95 based on the signal from the position sensor 106, the supply / discharge state of the oil to and from the hydraulic chambers 84 and 85 is appropriately adjusted. By arranging the exhaust rotary valve 44 at the “third position” in this manner, as shown in FIG. 10, both the first concave portion 61 and the second concave portion 62 expose the exposed region R during the combustion stroke. Will not enter.

The ECU 100 controls the switching position of the exhaust rotary valve 44 as described above based on the detection signals from the rotational speed sensor 102 and the intake pressure sensor 104 to set the compression ratio to 3 based on the operating state of the engine 10.
Switch to the stage.

That is, when the ECU 100 determines that the operating state of the engine 10 is in the low-load and low-speed range, the ECU 100 sets the switching position of the exhaust rotary valve 44 to the "third position". Therefore, neither the first recess 61 nor the second recess 62 is exposed to the combustion chamber 22 during the combustion stroke, and the compression ratio is set to the relatively highest value.

On the other hand, when the ECU 100 determines that the operation state is in the medium load / medium rotation region, the exhaust rotary valve 44
Is set to the "first position". Therefore,
Only the first concave portion 61 is exposed to the combustion chamber 22 during the combustion stroke, and the compression ratio is determined by the value of the compression ratio when the exhaust rotary valve 44 is located at the “third position”. The compression ratio is set to an intermediate value with the value of the compression ratio when it is arranged at the “second position”.

Further, when the ECU 100 determines that the operation state is in the high load / high rotation range, the exhaust rotary valve 44
Is set to the "second position". Therefore,
Only the second concave portion 62 becomes exposed to the combustion chamber 22 during the combustion stroke, and the second concave portion 62 becomes the first concave portion.
The compression ratio in this case is further lower than when the exhaust rotary valve 44 is arranged at the “first position”, and is relatively the lowest. Will be set to the value.

As described above, also in the present embodiment, the compression ratio can be changed to suit the operating state of the engine only by moving the exhaust rotary valve 44 in the axial direction. Further, the rotation speed of the crankshaft is extremely low as in the start of the engine 10, and the hydraulic pump 9
3, even if the predetermined discharge pressure cannot be secured, the return springs 8
The exhaust rotary valve 44 can be reliably held at the “third position” based on the urging forces of 8, 89.

Therefore, this embodiment can also provide the same operation and effects as (1) to (3) described in the first embodiment. In particular, according to the present embodiment, (4) the compression ratio is adjusted in three stages based on the switching position of the exhaust rotary valve 44, so that the compression ratio is more accurate with respect to the operating state of the engine 10. Can be adapted.

[Other Embodiments] Each of the embodiments described above can be implemented by changing the configuration as follows.

In the second embodiment, the compression ratio when the exhaust rotary valve 44 is located at the “second position” is set to a value lower than the compression ratio when the exhaust rotary valve 44 is located at the “first position”. For this purpose, the second concave portion 62 is formed to be deeper than the first concave portion 61 so that the volumes of the two concave portions 61 and 62 are different from each other. On the other hand, for example, as shown in FIG.
Each recess 61 in the circumferential direction of the exhaust rotary valve 44,
By changing the length of the recesses 62 or as shown in FIG. 12, the volumes of the recesses 61 and 62 may be made different by changing the number thereof.

Further, as shown in FIG. 12, if a plurality of first concave portions 61 are formed along the circumferential direction of the exhaust rotary valve 44, the first concave portions 61 may be formed.
Are sequentially exposed to the combustion chamber 22 during the combustion stroke, so that the compression ratio can be further changed during one combustion stroke. In addition, by appropriately setting the individual volumes of the plurality of first recesses 61 thus formed, it is possible to arbitrarily set the manner in which the compression ratio changes during one combustion stroke.

In the second embodiment, the compression ratio is switched in three stages in accordance with the position of the exhaust rotary valve 44. For example, the switching positions of the exhaust rotary valve 44 are "first position" and "first position". Only the position 2 may be selected, and the compression ratio may be switched between two levels.

In the above embodiments, the rotation speed sensor 10
2 and the rotational speed N detected by the intake pressure sensor 104
The compression ratio is switched based on E and the intake pressure PM, but instead of these rotational speed NE and intake pressure PM,
Alternatively or additionally, for example, a configuration in which the compression ratio is switched based on a detection signal from a knocking sensor that detects knocking of the engine 10 may be employed.

In each of the above embodiments, the concave portions 60, 61, and 62 are formed in the exhaust rotary valve 44, and the compression ratio is changed by moving the exhaust rotary valve 44 in the axial direction. However, it is also possible to adopt a configuration in which a concave portion is formed in the intake rotary valve 34 and the compression ratio is changed by moving the intake rotary valve 34 in the axial direction. Further, a configuration for changing such a compression ratio is provided by each of the rotary valves 34 and 4.
4 can also be provided.

In each of the above embodiments, a hydraulic actuator is used as an actuator for moving the exhaust rotary valve 44 in the axial direction. However, in addition to such a hydraulic actuator, electromagnetic force or air pressure is used. An actuator can also be employed.

In each of the above embodiments, the engine 1
Although the compression ratio is reduced as the operation state of 0 becomes relatively high load and high rotation, the relationship between the operation state and the compression ratio can be arbitrarily set according to the specifications of the engine 10.

[0067]

According to the first to fifth aspects of the present invention, it is possible to change the compression ratio by changing the volume of the engine combustion chamber only by moving the rotary valve having the recess formed in the axial direction. Also, since a very large external force does not act on the rotary valve with such a position change due to the external load of the engine, the compression ratio can be improved with high reliability by a simple and durable configuration. Can be changed.

In particular, according to the invention described in claim 5,
The compression ratio can be changed so as to be suitable for the operating state of the engine, so that the engine output can be increased and the fuel efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a sectional structure of an engine.

FIG. 2 is a perspective view showing a perspective structure of an exhaust rotary valve.

FIG. 3 is a sectional view showing a sectional structure along line 3-3 in FIG. 2;

FIG. 4 is a front view of an exhaust rotary valve showing a positional relationship between a region exposed to a combustion chamber and a recess.

FIG. 5 is a schematic configuration diagram illustrating a drive mechanism of an exhaust rotary valve according to the first embodiment.

FIG. 6 is a schematic configuration diagram showing a drive mechanism of the exhaust rotary valve.

FIG. 7 is a front view of an exhaust rotary valve showing a positional relationship between a region exposed to a combustion chamber and a recess.

FIG. 8 is a graph showing a relationship between an intake pressure and a rotation speed and a switching position of an exhaust rotary valve.

FIG. 9 is a schematic configuration diagram showing a drive mechanism of an exhaust rotary valve according to a second embodiment.

FIG. 10 is a sectional view showing a sectional structure taken along line 10-10 of FIG. 9;

FIG. 11 is a front view of an exhaust rotary valve showing a shape of a concave portion according to another embodiment.

FIG. 12 is a front view of an exhaust rotary valve showing a shape of a concave portion according to another embodiment.

[Explanation of symbols]

Reference Signs List 10 engine, 12 cylinder block, 14 cylinder, 16 piston, 18 connecting rod, 20 cylinder head, 22 combustion chamber, 30 intake valve support hole, 32 intake port, 34 intake rotary valve, 3
6 ... intake hole, 40 ... exhaust side valve support hole, 42 ... exhaust port, 44 ... exhaust rotary valve, 45 ... timing pulley, 46 ... exhaust hole, 50 ... timing belt, 60 ...
Recess, 61 ... First recess, 62 ... Second recess, 70 ... Coupling, 80 ... Hydraulic actuator, 81 ... Drive shaft, 82 ... Housing, 83 ... Piston, 84 ... First hydraulic chamber, 85 ... First 2 hydraulic chambers, 88, 89 return spring, 90 hydraulic unit, 91 oil pan, 93 hydraulic pump, 95 directional switching valve, 100 E
CU, 102: rotational speed sensor, 104: intake pressure sensor, 106: position sensor.

Claims (5)

[Claims] 1. A concave portion which is exposed to an engine combustion chamber in synchronization with the rotation thereof is formed on at least one surface of an intake rotary valve and an exhaust rotary valve rotatably provided in an internal combustion engine. A compression means for moving the valve in the direction of its rotation axis to change the manner in which the recess is exposed during the combustion stroke of the internal combustion engine, thereby changing the volume of the engine combustion chamber. Variable ratio device. 2. The compression ratio variable device for an internal combustion engine according to claim 1, wherein the plurality of recesses are formed, and the changing unit determines a state in which a predetermined number of the recesses is exposed as the exposure mode. A variable compression ratio device for an internal combustion engine, wherein the device selectively switches between a state in which a predetermined number of concave portions are exposed. 3. The compression ratio variable device for an internal combustion engine according to claim 1, wherein the plurality of recesses are formed with different volumes, and the changing means has a predetermined volume as the exposure mode. A compression ratio variable device for an internal combustion engine, wherein a state in which the recess is exposed and a state in which the recess having a volume different from the predetermined volume is exposed are selectively switched. 4. The variable compression ratio apparatus for an internal combustion engine according to claim 1, wherein the changing means selectively switches between a state in which the recess is exposed to the engine combustion chamber and a state in which the recess is not exposed. A variable compression ratio device for an internal combustion engine. 5. The variable compression ratio apparatus for an internal combustion engine according to claim 1, further comprising a detection unit that detects an engine operation state, and wherein the change unit changes the detected engine operation state. A compression ratio variable device for an internal combustion engine, wherein the one of the rotary valves is moved in a direction of a rotation axis thereof to switch the exposure mode.