US20130000576A1

US20130000576A1 - Valve characteristics control apparatus

Info

Publication number: US20130000576A1
Application number: US13/539,663
Authority: US
Inventors: Takehiro Tanaka; Takashi Yamaguchi
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2011-07-03
Filing date: 2012-07-02
Publication date: 2013-01-03
Also published as: JP2013015057A

Abstract

A control valve part switches a flowing direction of working fluid between a first advance chamber and a first retard chamber in a timing adjustment mode, and restricts working fluid from flowing between the first advance chamber and the first retard chamber in a working angle adjustment mode. A check valve part allows working fluid to flow from a second retard chamber through a check passage to a second advance chamber, and restricts working fluid from flowing from the second advance chamber through the check passage to the second retard chamber. A switch valve part allows a communication between the second advance chamber and the second retard chamber through a switch passage in the working angle adjustment mode, and prohibits the communication between the second advance chamber and the second retard chamber through the switch passage in the timing adjustment mode.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2011-147821 filed on Jul. 3, 2011, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a valve characteristics control apparatus.

BACKGROUND

JP-A-2004-183612 (U.S. Pat. No. 7,047,922) describes a valve characteristics control apparatus that controls a valve timing and a valve working angle as valve characteristics of a valve of an internal combustion engine.
In the valve characteristics control apparatus, a motor is engaged with a camshaft through a gear train. The motor controls the valve timing and the valve working angle by varying the rotating speed of the camshaft from a basic velocity that is set as a half of a rotating speed of a crankshaft.
The valve characteristics control apparatus is required to electrically accurately control the rotating speed of the motor, which determines the rotating speed of the camshaft, while the rotating speed of the crankshaft of the combustion engine is varied every moment. However, an acting direction of a variation torque applied to the camshaft from a spring reaction force of the valve is alternately changed in accordance with the rotation of the crankshaft. Therefore, it is difficult to accurately control the rotating speed of the motor, while the variation torque is absorbed by a torque generated by the motor, so that the accuracy of controlling the valve characteristics may become low.

SUMMARY

According to a first example of the present disclosure, a valve characteristics control apparatus that controls valve characteristics of a valve opened and closed by a rotation of a camshaft in accordance with a rotation of a crankshaft in an internal combustion engine includes a housing rotating with the crankshaft; a first vane rotor; a control valve part; a second vane rotor; a check valve part; and a switch valve part. The first vane rotor has a first vane rotatably received in the housing, and a first advance chamber and a first retard chamber are defined by partitioning a space between the housing and the first vane in a rotation direction. The first vane rotor has a relative rotation with respect to the housing in an advance direction when working fluid is introduced into the first advance chamber and when working fluid is discharged from the first retard chamber. The first vane rotor has a relative rotation with respect to the housing in a retard direction when working fluid is discharged from the first advance chamber and when working fluid is introduced into the first retard chamber. The control valve part switches a flowing direction of working fluid between the first advance chamber and the first retard chamber in a timing adjustment mode adjusting valve timing as the valve characteristics, and restricts working fluid from flowing between the first advance chamber and the first retard chamber in a working angle adjustment mode adjusting a valve working angle as the valve characteristics. The second vane rotor has a second vane rotating with the camshaft in a state that the second vane is projected into the first vane in the housing, and a second advance chamber and a second retard chamber are defined by partitioning a space between the first vane and the second vane in the rotation direction. The second vane rotor has a relative rotation with respect to the first vane rotor in the advance direction when working fluid is introduced into the second advance chamber and when working fluid is discharged from the second retard chamber. The second vane rotor has a relative rotation with respect to the first vane rotor in the retard direction when working fluid is discharged from the second advance chamber and when working fluid is introduced into the second retard chamber. The check valve part has a check passage connecting the second advance chamber and the second retard chamber with each other. The check valve part allows working fluid to flow from the second retard chamber through the check passage to the second advance chamber, and restricts working fluid from flowing from the second advance chamber through the check passage to the second retard chamber. The switch valve part has a switch passage connecting the second advance chamber and the second retard chamber with each other. The switch valve part allows a communication between the second advance chamber and the second retard chamber through the switch passage in the working angle adjustment mode, and prohibits the communication between the second advance chamber and the second retard chamber through the switch passage in the timing adjustment mode.
According to a second example of the present disclosure, a valve characteristics control apparatus that controls valve characteristics of a valve opened and closed by a rotation of a camshaft in accordance with a rotation of a crankshaft in an internal combustion engine includes a housing rotating with the crankshaft; a first vane rotor; a control valve part; a second vane rotor; a check valve part; and a switch valve part. The first vane rotor has a first vane rotatably received in the housing, and a first advance chamber and a first retard chamber are defined by partitioning a space between the housing and the first vane in a rotation direction. The first vane rotor has a relative rotation with respect to the housing in an advance direction when working fluid is introduced into the first advance chamber and when working fluid is discharged from the first retard chamber. The first vane rotor has a relative rotation with respect to the housing in a retard direction when working fluid is discharged from the first advance chamber and when working fluid is introduced into the first retard chamber. The control valve part switches a flowing direction of working fluid between the first advance chamber and the first retard chamber in a timing adjustment mode adjusting valve timing as the valve characteristics, and restricts working fluid from flowing between the first advance chamber and the first retard chamber in a working angle adjustment mode adjusting a valve working angle as the valve characteristics. The second vane rotor has a second vane rotating with the camshaft in a state that the second vane is projected into the first vane in the housing, and a second advance chamber and a second retard chamber are defined by partitioning a space between the first vane and the second vane in the rotation direction. The second vane rotor has a relative rotation with respect to the first vane rotor in the advance direction when working fluid is introduced into the second advance chamber and when working fluid is discharged from the second retard chamber. The second vane rotor has a relative rotation with respect to the first vane rotor in the retard direction when working fluid is discharged from the second advance chamber and when working fluid is introduced into the second retard chamber. The check valve part has a check passage connecting the second advance chamber and the second retard chamber with each other. The check valve part allows working fluid to flow from the second advance chamber through the check passage to the second retard chamber, and restricts working fluid from flowing from the second retard chamber through the check passage to the second advance chamber. The switch valve part has a switch passage connecting the second advance chamber and the second retard chamber with each other. The switch valve part allows a communication between the second advance chamber and the second retard chamber through the switch passage in the working angle adjustment mode, and prohibits the communication between the second advance chamber and the second retard chamber through the switch passage in the timing adjustment mode.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

FIG. 1 is a schematic view illustrating a valve characteristics control apparatus according to a first embodiment;

FIG. 2 is a cross-sectional view taken along a line II-II of FIG. 1;

FIG. 3 is a schematic view illustrating the valve characteristics control apparatus of the first embodiment in an operation state different from FIG. 1;

FIG. 4 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the first embodiment where a spool is located at an advance position in a timing adjustment mode;

FIG. 5 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the first embodiment where the spool is located at a retard position in the timing adjustment mode;

FIG. 6 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the first embodiment where the spool is located at a hold position in the timing adjustment mode;

FIG. 7 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the first embodiment in an operation state of a working angle adjustment mode;

FIG. 8 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the first embodiment in an operation state of the working angle adjustment mode different from FIG. 7;

FIG. 9 is a graph illustrating a relationship between a crank angle and a variation in torque applied to the valve characteristics control apparatus;

FIG. 10 is a characteristics view illustrating characteristics of the valve characteristics control apparatus of the first embodiment;

FIG. 11 is a view illustrating advantage of the valve characteristics control apparatus;

FIG. 12 is a schematic cross-sectional view illustrating a valve characteristics control apparatus according to a second embodiment where a spool is located at an advance position in a working angle adjustment mode;

FIG. 13 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the second embodiment in an operation state of the working angle adjustment mode;

FIG. 14 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the second embodiment in an operation state of the working angle adjustment mode different from FIG. 13;

FIG. 15 is a characteristics view illustrating characteristics of the valve characteristics control apparatus of the second embodiment;

FIG. 16 is a characteristics view illustrating characteristics of the valve characteristics control apparatus of the second embodiment;

FIG. 17 is a view illustrating advantage of the valve characteristics control apparatus;

FIG. 18 is a schematic cross-sectional view illustrating a valve characteristics control apparatus according to a third embodiment where a spool is located at an advance position in a timing adjustment mode;

FIG. 19 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the third embodiment where the spool is located at a retard position in the timing adjustment mode;

FIG. 20 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the third embodiment where the spool is located at a hold position in the timing adjustment mode;

FIG. 21 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the third embodiment in an operation state of a working angle adjustment mode;

FIG. 22 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the third embodiment in an operation state of the working angle adjustment mode different from FIG. 21;

FIG. 23 is a characteristics view illustrating characteristics of the valve characteristics control apparatus of the third embodiment;

FIG. 24 is a schematic cross-sectional view illustrating a valve characteristics control apparatus according to a fourth embodiment where a spool is located at a retard position in a working angle adjustment mode;

FIG. 25 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the fourth embodiment in an operation state of the working angle adjustment mode;

FIG. 26 is a schematic cross-sectional view illustrating the valve characteristics control apparatus of the fourth embodiment in an operation state of the working angle adjustment mode different from FIG. 25;

FIG. 27 is a characteristics view illustrating characteristics of the valve characteristics control apparatus of the fourth embodiment; and

FIG. 28 is a characteristics view illustrating characteristics of the valve characteristics control apparatus of the fourth embodiment.

DETAILED DESCRIPTION

Embodiments of the present invention will be described hereafter referring to drawings. In the embodiments, a part that corresponds to a matter described in a preceding embodiment may be assigned with the same reference numeral, and redundant explanation for the part may be omitted. When only a part of a configuration is described in an embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined even if it is not explicitly described that the parts can be combined. The embodiments may be partially combined even if it is not explicitly described that the embodiments can be combined, provided there is no harm in the combination.

First Embodiment

FIG. 1 illustrates a valve characteristics control apparatus 1 according to a first embodiment which is applied to an internal combustion engine of a vehicle. The apparatus 1 adjusts valve timing and valve working angle for plural exhaust valves having different opening/closing timings, as valve characteristic of a valve which is opened and closed by rotation of a camshaft 2 according to rotation of a crankshaft (not shown) in the engine. The apparatus 1 is constructed by combining a rotation drive system 3 and a rotation control system 4. The drive system 3 is arranged in a transmission path through which the engine torque is transmitted from the crankshaft to the camshaft 2, and the control system 4 controls the drive system 3.

(Rotation Drive System)

The drive system 3 will be described with reference to FIGS. 1 and 2. The rotation drive system 3 coaxially has a housing 10, a first vane rotor 20, and a second vane rotor 30 which are integrally rotatable. The housing 10 and the vane rotors 20 and 30 have common rotation (circumference) direction, common axis direction, and common radial direction. Hereinafter, description is made using the rotation (circumference) direction, the axis direction, and the radial direction.
The metal housing 10 is constructed by joining a pair of accommodation plates 13, 14 to axial ends of a main part 12, respectively, and has a hollow shape as a whole. The main part 12 has an accommodation wall 120 and plural shoes 122.
As shown in FIG. 1, the cylindrical accommodation wall 120 has plural sprocket teeth (not shown) projected outward in the radial direction and located with regular intervals in the rotation direction. A timing chain (not shown) is arranged between the sprocket teeth and teeth of the crankshaft, so that the accommodation wall 120 is linked with the crankshaft. When the engine is rotated, the engine torque output from the crankshaft is transmitted to the housing 10 through the timing chain, and the housing 10 is rotated in response to the rotation of the crankshaft in a counterclockwise direction of FIG. 1.
Each of the convex shoes 122 is projected inward in the radial direction from the wall 120, and the shoes 122 are located with regular intervals in the rotation direction. A first accommodation chamber 16 is defined between the shoes 122 located adjacent with each other in the rotation direction.
The first vane rotor 20 is accommodated between the accommodation plates 13 and 14 in the axis direction in the housing 10, and is slidably fitted with each of the plates 13 and 14. The first vane rotor 20 has plural rotation walls 200 and plural first vanes 202.
The rotation wall 200 partially has a cylindrical shape, and is located on the inner side of the corresponding shoe 122 in the radial direction. The rotation wall 200 is slidably fitted to a projection-side end portion of the corresponding shoe 122. The fitting structure allows the first vane rotor 20 to rotate in the counterclockwise direction and to have relative rotation with respect to the housing 10.
The concave first vane 202 defines a second chamber 26 opening to the inner side in the radial direction by recessing outward in the radial direction from a position between the rotation walls 200 in the rotation direction. The first vane 202 is accommodated in the corresponding first accommodation chamber 16 so as to partition the chamber 16 in the rotation direction, so that the first vane 202 defines a first advance chamber 16 a and a first retard chamber 16 r. That is, the first advance chamber 16 a and the first retard chamber 16 r are formed through the first vane 202 in the rotation direction, and are located between the shoes 122 of the housing 10 defining the first chamber 16.
A volume of the chamber 16 a, 16 r is varied by a flow of working liquid such as oil, and the first vane rotor 20 has relative rotation with respect to the housing 10. Specifically, the volume of the retard chamber 16 r is reduced when working oil is discharged, and the volume of the advance chamber 16 a is increased when working oil is introduced, so that the first vane rotor 20 has relative rotation with respect to the housing 10 in the advance direction. As a result, the first vane 202 is pressed against the shoe 122 in the advance direction, and the relative rotation phase of the first vane rotor 20 is restricted from being varied in the advance direction relative to the housing 10.
In contrast, the volume of the advance chamber 16 a is reduced when working oil is discharged, and the volume of the retard chamber 16 r is increased when working oil is introduced, so that the first vane rotor 20 has relative rotation with respect to the housing 10 in the retard direction. As a result, the first vane 202 is pressed against the shoe 122 in the retard direction, and the relative rotation phase of the first vane rotor 20 is restricted from being varied in the retard direction relative to the housing 10.
The second vane rotor 30 made of metal is accommodated between the accommodation plates 13 and 14 in the axis direction in the housing 10, and is slidably fitted with each of the plates 13 and 14. The second vane rotor 30 has a rotation shaft 300 and plural second vanes 302.
The cylindrical rotation shaft 300 is arranged on the inner side of the rotation wall 200 of the first vane rotor 20 in the radial direction, and is coaxially linked with the camshaft 2 in a state where the shaft 300 is slidably fitted with the wall 200. Therefore, the second vane rotor 30 rotates in the counterclockwise direction together with the camshaft 2 and is able to have relative rotation with respect to the first vane rotor 20 and the housing 10.
Each of the convex second vanes 302 is projected outward in the radial direction from the shaft 300, and the second vanes 302 are located with regular intervals in the rotation direction. The second vane 302 is accommodated and projected into the corresponding second accommodation chamber 26 so as to partition the chamber 26 in the rotation direction, so that the second vane 302 defines a second advance chamber 26 a and a second retard chamber 26 r. That is, the second advance chamber 26 a and the second retard chamber 26 r are formed through the second vane 302 in the rotation direction, and are located in the first vane 202 defining the second chamber 26.
A volume of the chamber 26 a, 26 r is varied by a flow of working oil, and the second vane rotor 30 has relative rotation with respect to the first vane rotor 20. Specifically, the volume of the retard chamber 26 r is reduced when working oil is discharged, and the volume of the advance chamber 26 a is increased when working oil is introduced, so that the second vane rotor 30 has relative rotation with respect to the first vane rotor 20 in the advance direction. As a result, the second vane 302 is pressed against an inner surface 202 a of the first vane 202 in the advance direction, and the relative rotation phase of the second vane rotor 30 is restricted from being varied in the advance direction relative to the first vane rotor 20.
In contrast, the volume of the advance chamber 26 a is reduced when working oil is discharged, and the volume of the retard chamber 26 r is increased when working oil is introduced, so that the second vane rotor 30 has relative rotation with respect to the first vane rotor 20 in the retard direction. As a result, the second vane 302 is pressed against an inner surface 202 r of the first vane 202 in the retard direction, and the relative rotation phase of the second vane rotor 30 is restricted from being varied in the retard direction relative to the first vane rotor 20.

(Rotation Control System)

The rotation control system 4 will be described with reference to FIGS. 1-8. As shown in FIG. 4, the control system 4 has a control valve part 40, a first check valve part 50, a second check valve part 60, a switch valve part 70, and a control circuit 80.
The control valve part 40 has an advance passage 42 a, a retard passage 42 r, a main supply passage 42 ms, a drain passage 42 d and a solenoid valve 44. A first end of the advance passage 42 a is branched and communicates with each of the first advance chambers 16 a. A first end of the retard passage 42 r is branched and communicates with each of the first retard chambers 16 r. The main supply passage 42 ms communicates with a pump 6 which is a supply source of working oil. The pump 6 is a mechanical pump driven by the internal combustion engine through the crankshaft. While the engine is operated, the pump 6 pumps up working oil from a drain pan 7 and supplies the working oil to the main supply passage 42 ms. The drain passage 42 d is open to atmospheric air with the drain pan 7 as a drain collecting section, and is arranged to discharge working oil to the drain pan 7.
The solenoid valve 44 is a spool valve that reciprocates a spool 443 in a sleeve 442 using a driving force generated by energizing a solenoid 440 and a recovery force generated by elastic deformation of a coil spring 441 in a direction opposite from the driving force. The sleeve 442 of the solenoid valve 44 has an advance port 442 a, a retard port 442 r, a main supply port 442 ms, a sub supply port 442 ss, and a drain port 442 d.
The advance port 442 a communicates with the advance passage 42 a. The retard port 442 r communicates with the retard passage 42 r. The main supply port 442 ms communicates with the main supply passage 42 ms. The sub supply port 442 ss communicates with the second check valve part 60. The drain port 442 d communicates with the drain passage 42 d. The solenoid valve 44 allows or prohibits the communication among the ports 442 a, 442 r, 442 ms, 442 ss and 442 d in accordance with the position of the spool 443 that is driven by controlling the solenoid 440.
Specifically, the advance port 442 a communicates with the main supply port 442 ms in the state where the spool 443 has moved to an advance position Pa of FIG. 4, so that working oil supplied from the pump 6 is introduced into each first advance chamber 16 a through the main supply passage 42 ms and the advance passage 42 a. Further, the retard port 442 r communicates with the drain port 442 d through the inside of the spool 443 in the state where the spool 443 is located at the advance position Pa, so that working oil of each first retard chamber 16 r is discharged to the drain pan 7 through the retard passage 42 r and the drain passage 42 d. Furthermore, the sub supply port 442 ss communicates with the main supply port 442 ms in the state where the spool 443 is located at the advance position Pa, so that working oil supplied from the pump 6 is introduced into the second check valve part 60 through the main supply passage 42 ms.
In contrast, the retard port 442 r communicates with the main supply port 442 ms in the state where the spool 443 has moved to a retard position Pr of FIG. 5, so that the working oil supplied from the pump 6 is introduced into each first retard chamber 16 r through the main supply passage 42 ms and the retard passage 42 r. Further, the advance port 442 a communicates with the drain port 442 d through the inside of the spool 443 in the state where the spool 443 is located at the retard position Pr, so that working oil of each first advance chamber 16 a is discharged to the drain pan 7 through the advance passage 42 a and the drain passage 42 d. Furthermore, the sub supply port 442 ss communicates with the main supply port 442 ms in the state where the spool 443 is located at the retard position Pr, so that working oil supplied from the pump 6 is introduced into the second check valve part 60 through the main supply passage 42 ms.
Further in contrast, when the spool 443 is moved to a hold position Ph of FIGS. 6-8, the advance port 442 a and the retard port 442 r are prohibited from communicating with the other ports, so that working oil is prohibited from flowing into or out of each first advance chamber 16 a and each first retard chamber 16 r. Furthermore, the sub supply port 442 ss communicates with the main supply port 442 ms in the state where the spool 443 is located at the hold position Ph, so that working oil supplied from the pump 6 is introduced into the second check valve part 60 through the main supply passage 42 ms.
As shown in FIG. 4, the first check valve part 50 has plural check passages 52 and plural check valves 54. The check passage 52 is defined to penetrate the corresponding second vane 302 so as to connect the second advance chamber 26 a and the second retard chamber 26 r with each other through the second vane 302. The check valve 54 is arranged in the middle of the check passage 52 in the corresponding second vane 302. When the check valve 54 is opened, working oil flows from the second retard chamber 26 r to the second advance chamber 26 a. Thereby, each check valve 54 permits the forward feed of working oil which goes to the second advance chamber 26 a from the second retard chamber 26 r. On the other hand, the backward flow of working oil which goes to the second retard chamber 26 r from the second advance chamber 26 a is regulated by the check valve 54. Thus, the check passage 52 and the check valve 54 construct the first check valve part 50, which is disposed in each of the second vanes 302.
As shown in FIG. 4, the second check valve part 60 has a sub supply passage 62 ss and a check valve 64. The sub supply passage 62 ss communicates with the sub supply port 442 ss of the solenoid valve 44 and the first switch valve part 70. Thereby, even when the spool 443 is located at any one of the positions Pa, Pr, and Ph, the sub supply passage 62 ss supplies working oil from the pump 6 to the first switch valve part 70 through the main supply passage 42 ms.
The check valve 64 is arranged in the middle of the sub supply passage 62 ss. When the check valve 64 is opened, working oil flows from the sub supply port 442 ss to the first switch valve part 70 through the sub supply passage 62 ss. Thereby, each check valve 64 permits the forward feed of working oil which goes to the first switch valve part 70 from the sub supply port 442 ss. On the other hand, the backward flow of working oil which goes to the sub supply port 442 ss from the first switch valve part 70 is regulated by the check valve 64. Thereby, when the spool 443 is located at one of the positions Pa, Pr, and Ph, the check valve 64 permits the forward feed of working oil which goes to a supply point 720 of the first switch valve part 70 from the pump 6, and restricts the backward flow having the opposite flowing direction.
The switch valve part 70 has a switch passage 72 and a solenoid valve 74. A first end of the switch passage 72 is branched and communicates with each of the second advance chambers 26 a. A second end of the switch passage 72 is branched and communicates with each of the second retard chambers 26 r. The switch passage 72 connects the second advance chamber 26 a and the second retard chamber 26 r with each other. The supply point 720 of the first switch valve part 70 is arranged in the switch passage 72, and receives working oil from the sub supply passage 62 ss by communicating with the sub supply passage 62 ss of the second check valve part 60.
The solenoid valve 74 is arranged in the switch passage 72 at a position adjacent to the second end of the switch passage 72 rather than the supply point 720. In other words, the solenoid valve 74 is located adjacent to the second retard chamber 26 r rather than the supply point 720. The solenoid valve 74 is driven by energizing the solenoid 740. Accordingly, the valve 74 allows the communication between the second advance chamber 26 a and the second retard chamber 26 r, as shown in FIGS. 7 and 8, or prohibits the communication, as shown in FIGS. 4-6.
As shown in FIG. 4, the control circuit 80 is an electronic circuit constructed by, for example, a microcomputer. The control circuit 80 is electrically connected to the solenoid 440, 740 of the solenoid valve 44, 74 of the valve part 40, 70, and various electronic components (not shown) of the combustion engine. The control circuit 80 controls the operational status of the combustion engine which includes energizing of the solenoid 440, 740 according to a computer program memorized in an internal memory.

(Variation Torque Applied to the Vane Rotor)

Next, the variation torque which acts on the second vane rotor 30 of the rotation drive system 3 of the apparatus 1 is explained with reference to FIG. 9. During rotation of the combustion engine, the variation torque generated by the spring reaction force from each exhaust valve that is opened and closed by the camshaft 2 is transmitted to the second vane rotor 30. As shown in FIG. 9, the torque is alternately varied between a positive torque Tr and a negative torque Ta. The positive torque Tr acts to the first vane rotor 20 in the retard direction, and the negative torque Ta acts to the first vane rotor 20 in the advance direction. The positive torque Tr is generated by the spring reaction force which resists the valve opening action of each exhaust valve. On the other hand, the negative torque Ta is generated by the spring reaction force which assists the valve closing action of each exhaust valve.
Characteristic operation of the apparatus 1 will be described. The control circuit 80 switches a mode of adjusting the valve characteristics according to the operational status of the combustion engine between a timing adjustment mode and a working angle adjustment mode. In the timing adjustment mode, the valve timing is adjusted by maintaining the valve working angle. In the working angle adjustment mode, the valve working angle is adjusted by maintaining the valve timing such as valve-closing-operation finishing timing “tec” (see FIG. 10).

(Timing Adjustment Mode)

When the apparatus 1 is set to have the timing adjustment mode, the circuit 80 controls the energizing of the solenoid 740 of the solenoid valve 74, thereby switching the switch passage 72 to prohibit the communication between the second advance chamber 26 a and the second retard chamber 26 r, as shown in FIGS. 4-6. Further, the control circuit 80 controls the energizing of the solenoid 440 of the solenoid valve 44, thereby switching the position of the spool 443 to one of the positions Pa, Pr and Ph. Therefore, the flow of working oil is switched, based on the position of the spool 443, relative to each first advance chamber 16 a and each first retard chamber 16 r.
In the timing adjustment mode, when the negative torque Ta acts on the second vane rotor 30 in the advance direction from the camshaft 2, working oil of the second retard chamber 26 r is pressurized by the second vane 302 in the first vane 202. At this time, the working oil of the second retard chamber 26 r is restricted from flowing into the second advance chamber 26 a through the switch passage 72 but is allowed to flow into the second advance chamber 26 a through the check passage 52.
On the other hand, when the positive torque Tr acts on the second vane rotor 30 in the retard direction from the camshaft 2, the working oil of the second advance chamber 26 a is pressurized by the second vane 302 in the first vane 202. At this time, the working oil of the second advance chamber 26 a is restricted from flowing into the second retard chamber 26 r through the switch passage 72 and is restricted from flowing into the second retard chamber 26 r through the check passage 52.
As a result, working oil can be introduced into each second advance chamber 26 a, and can be discharged from each second retard chamber 26 r, respectively. Thereby, the second vane 302 of the second vane rotor 30 that has relative rotation in the advance direction relative to the first vane rotor 20 presses the internal surface 202 a of the first vane 202 through the second retard chamber 26 r from which the working oil is discharged, as shown in FIGS. 4-6.
Therefore, in the timing adjustment mode where the spool 443 is moved to one of the positions Pa, Pr, and Ph, the vane rotors 20 and 30 operate in the state where the second vane 302 is pressed to the first vane 202 in the advance direction. That is, at the advance position Pa of FIG. 4, as shown in a blank arrow direction of FIG. 4, the second vane rotor 30 and the first vane rotor 20 integrally have relative rotation in the advance direction, relative to the housing 10. Further, at the retard position Pr of FIG. 5, as shown in a blank arrow direction of FIG. 5, the second vane rotor 30 and the first vane rotor 20 integrally have relative rotation in the retard direction, relative to the housing 10. Further, at the hold position Ph of FIG. 6, the second vane rotor 30 and the first vane rotor 20 integrally rotate at the same speed as the housing 10.
Thus, in the timing adjustment mode, in response to the switchover control of working oil relative to each first advance chamber 16 a and each first retard chamber 16 r, the housing 10 and the second vane rotor 30 can be controlled to have a relative rotation phase, and a valve timing corresponding to the relative rotation phase can be realized. Accordingly, the valve timing can be mechanically accurately adjusted in the timing adjustment mode using the variation torque.
Furthermore in the timing adjustment mode, the check valve 64 restricts the working oil pressurized in the second advance chamber 26 a by the positive torque Tr from flowing backward. That is, the working oil is restricted from flowing from the supply point 720 to the pump 6 through the switch passage 72. In contrast, when the negative torque Ta is applied, working oil can be supplied to the switch passage 72 through the supply point 720 from the pump 6 because the forward flow is permitted by the check valve 64.
At this time, the solenoid valve 74 intercepts the communication in a part of the switch passage 72 between the supply point 720 and the second retard chamber 26 r. In contrast, working oil supplied to the supply point 720 can flow to the second advance chamber 26 a in the other part of the switch passage 72 between the supply point 720 and the second advance chamber 26 a. Therefore, even if the working oil introduced to the second advance chamber 26 a is leaked out from a slide clearance between the vane rotors 20 and 30, working oil supplied to the supply point 720 can be supplied to the second advance chamber 26 a from the switch passage 72.
Thus, the state where the second vane 302 is pressed to the first vane 202 can be maintained in the advance direction as a result of the backflow regulation and the supply function, so that reliability can be raised for the accurate valve timing adjustment that is mechanically realized in the state where the second vane 302 is pressed to the first vane 202.
In addition, at the timing adjustment mode, because the second vane 302 is disposed between the second advance chamber 26 a and the second retard chamber 26 r, the length of the check passage 52 can be made short, so that the pressure loss can be decreased. Therefore, time period necessary for pressing the second vane 302 to the first vane 202 can be made short, so that the accurate valve timing adjustment can be quickly started in the timing adjustment mode.

(Working Angle Adjustment Mode)

When the apparatus 1 is set to have the working angle adjustment mode, the control circuit 80 controls the energizing of the solenoid 740 of the solenoid valve 74, thereby switching the switch passage 72 to allow the communication between the second advance chamber 26 a and the second retard chamber 26 r, as shown in FIGS. 7 and 8. Further, the control circuit 80 controls the energizing of the solenoid 440 of the solenoid valve 44, thereby switching the position of the spool 443 to the hold position Ph, as shown in FIGS. 7 and 8. Therefore, the flow of working oil is regulated relative to the first advance chamber 16 a and the first retard chamber 16 r, and the regulation is continued from the start to the end of the working angle adjustment mode.
The working angle adjustment mode is started from the state where the second vane 302 is pressed to the first vane 202 in the advance direction in the previous timing adjustment mode. Specifically, when the positive torque Tr acts on the second vane rotor 30 in the retard direction from the camshaft 2, working oil of the second advance chamber 26 a is pressurized by the second vane 302. At this time, the working oil of the second advance chamber 26 a is restricted from flowing into the second retard chamber 26 r through the check passage 52, but is allowed to flow into the second retard chamber 26 r through the switch passage 72, as shown in FIG. 8.
Thus, the working oil is discharged from the second advance chamber 26 a, and is introduced into the second retard chamber 26 r. Thereby, as shown in a blank arrow direction of FIG. 8, the second vane rotor 30 that receives the positive torque Tr has relative rotation in the retard direction relative to the first vane rotor 20, until the second vane 302 is pressed to the internal surface 202 r of the first vane 202 through the second advance chamber 26 a from which the working oil is discharged. At this time, the flow of working oil is regulated relative to the first advance chamber 16 a and the first retard chamber 16 r, so that the relative rotation of the first vane rotor 20 is regulated relative to the housing 10. Therefore, the second vane rotor 30 has relative rotation relative to the first vane rotor 20.
Thus, the positive torque Tr is consumed by the relative rotation of the second vane rotor 30 in a direction restricting the rotation of the camshaft 2 until the second vane 302 is pressed to the first vane 202. In contrast, after the second vane 302 is pressed to the first vane 202, a force resisting to the positive torque Tr comes to act on the second vane rotor 30 and the camshaft 2 from the first vane rotor 20.
Accordingly, as shown in FIG. 10, the valve-opening-operation that generates the positive torque Tr is delayed in each exhaust valve that is opened and closed by the camshaft 2 by a relative rotation angle “θer” until the second vane rotor 30 presses the second vane 302 to the first vane 202 in the retard direction. In an upper graph of FIG. 10, a valve lift amount represents a lift amount of the exhaust valve relative to a crank angle that represents a rotation angle of the crankshaft. In addition, a solid line represents the valve lift amount according to the first embodiment, and a double-chain line represent a valve lift amount before having the valve characteristics control of the first embodiment, and the solid line and the double-chain line are shown in the overlap state in a single graph of FIG. 10. In a lower graph of FIG. 10, the rotation angle of the first vane rotor 20 and the rotation angle of the second vane rotor 30 according to the first embodiment are shown relative to the crank angle.
Moreover, from the state of FIG. 8 in which the second vane 302 is pressed to the first vane 202 in the retard direction by the action of the positive torque Tr in the working angle adjustment mode, when the negative torque Ta acts in the advance direction, working oil of the second retard chamber 26 r is pressurized by the second vane 302. At this time, the working oil of the second retard chamber 26 r is permitted to flow into the second advance chamber 26 a through at least one of the switch passage 72 and the check passage 52, as shown in FIG. 7.
Thus, working oil can be introduced into the second advance chamber 26 a, and can be discharged from the second retard chamber 26 r. Thereby, as shown in a blank arrow direction of FIG. 7, the second vane rotor 30 that receives the negative torque Ta has relative rotation in the advance direction relative to the first vane rotor 20, until the second vane 302 is pressed to the internal surface 202 a of the first vane 202 through the second retard chamber 26 r from which the working oil is discharged. At this time, the flow of working oil is regulated relative to the first advance chamber 16 a and the first retard chamber 16 r, so that the relative rotation of the first vane rotor 20 is regulated relative to the housing 10. Therefore, the second vane rotor 30 has relative rotation relative to the first vane rotor 20.
Therefore, the negative torque Ta is consumed by the relative rotation of the second vane rotor 30 in a direction assisting the rotation of the camshaft 2 until the second vane 302 is pressed to the first vane 202. In contrast, after the second vane 302 is pressed to the first vane 202, a force resisting to the negative torque Ta comes to act on the second vane rotor 30 and the camshaft 2 from the first vane rotor 20.
Accordingly, as shown in FIG. 10, the valve-closing-operation that generates the negative torque Ta is advanced in the exhaust valve that is opened and closed by the camshaft 2 by a relative rotation angle “θea” until the second vane rotor 30 presses the second vane 302 to the first vane 202 in the advance direction.
Accordingly, from the start to the end of the working angle adjustment mode, while the valve-closing-operation finishing timing “tec” is maintained as shown in FIG. 10 by regulating the relative rotation between the housing 10 and rotor 20, a valve working angle “φe” can be reduced by the delay “θer” in the valve-opening-operation and the advance “θea” in the valve-closing-operation. Thus, when the valve-closing-operation finishing timing “tec” is maintained and when the valve working angle “φe” is reduced, as shown in FIG. 11, a blow-down pressure represented by a dashed line of FIG. 11 is restricted from overlapping between the exhaust valve shown in the upper graph of FIG. 11 and the exhaust valve shown in the lower graph of FIG. 11. In FIG. 11, the valve-opening-timing of the exhaust valve shown in the upper graph is earlier than that of the exhaust valve shown in the lower graph.
If the blow-down pressure overlaps between the exhaust valve shown in the upper graph of FIG. 11 and the exhaust valve shown in the lower graph of FIG. 11, residual gas is increased. However, according to the first embodiment, the residual gas can be restricted from increasing by restricting the overlapping in the flow-down pressure, so that the combustion is restricted from getting worse. Moreover, according to the working angle adjustment mode using the variation torque, the valve working angle “φe” can be mechanically accurately adjusted. Furthermore in the working angle adjustment mode, the working oil pressurized by the positive torque Tr or the negative torque Ta in the second advance chamber 26 a or the retard chamber 26 r can be restricted from flowing backward. Specifically, the check valve 64 restricts the working oil from flowing from the supply point 720 to the pump 6 through the switch passage 72. Even if the working oil introduced to the second retard chamber 26 r or the second advance chamber 26 a is leaked out from the slide clearance of the vane rotors 20 and 30, working oil can be supplied to the supply point 720 from the pump 6 through the switch passage 72. Thus, the relative rotation of the second vane rotor 30 with respect to the first vane rotor 20 can be realized alternately between the retard direction and the advance direction until the second vane 302 is pressed to the first vane 202, so that reliability can be raised in the accurate control adjusting the valve working angle.

Second Embodiment

A valve characteristics control apparatus 2001 according to a second embodiment is a modification example of the first embodiment, and controls valve timing and valve working angle for plural intake valves having different opening/closing timings, as valve characteristics of a valve. The second vane rotor 30 rotating with the camshaft 2 that opens and closes the intake valve receives variation torque that is alternately varied between the positive torque Tr and the negative torque Ta, similarly to the first embodiment shown in FIG. 9.

(Working Angle Adjustment Mode)

When the apparatus 2001 is set to have the working angle adjustment mode, the control circuit 2080 controls the energizing of the solenoid 440 of the solenoid valve 44, thereby switching the position of the spool 443 to the advance position Pa, as shown in FIG. 12, and then switching the position of the spool 443 to the hold position Ph, as shown in FIGS. 13 and 14. Therefore, working oil is introduced into the first advance chamber 16 a and is discharged from the first retard chamber 16 r, in accordance with the start of the working angle adjustment mode, and the regulation of working oil relative to the first advance chamber 16 a and the first retard chamber 16 r is continued to the end of the working angle adjustment mode. In addition, from the start to the end of the working angle adjustment mode, the control circuit 2080 controls the energizing of the solenoid 740 of the solenoid valve 74, thereby switching the switch passage 72 to allow the communication between the second advance chamber 26 a and the second retard chamber 26 r, as shown in FIGS. 12-14, similarly to the first embodiment.
The working angle adjustment mode is started from the state where the second vane 302 is pressed to the first vane 202 in the advance direction in the previous timing adjustment mode. In accordance with the start of the working angle adjustment mode, the spool 443 is moved to the advance position Pa of FIG. 12, thereby, as shown in a blank arrow direction of FIG. 12, the second vane rotor 30 and the first vane rotor 20 integrally have rotation in the advance direction relative to the housing 10. As a result, as shown in FIG. 15, the valve-opening-operation starting timing “tic” and the valve-closing-operation finishing timing “tic” are advanced by a predetermined advance amount “Δia” as a valve timing corresponding to the relative rotation phase between the housing 10 and the second vane rotor 30.
In FIG. 15, a valve lift amount represents a lift amount of the intake valve relative to a crank angle that represents a rotation angle of the crankshaft. In addition, a solid line represents the valve lift amount of the intake valve having the advance in the valve-opening-operation starting timing “tio” and the valve-closing-operation finishing timing “tic”, and a double-chain line represent a valve lift amount before having the advance in the valve-opening-operation starting timing “tio” and the valve-closing-operation finishing timing “tic”. The solid line and the double-chain line are shown in the overlap state in a single graph of FIG. 15.
After the advance operation of FIG. 15 is finished, when the spool 443 is moved to the hold position Ph of FIGS. 13 and 14 in the state where the second vane 302 is pressed to the first vane 202 in the advance direction, the valve-opening-operation is delayed and the valve-closing-operation is advanced, similarly to the first embodiment. That is, as shown in FIG. 14, working oil is discharged from the second advance chamber 26 a and is introduced into the second retard chamber 26 r, when the positive torque Tr is applied in the retard direction from the state shown in FIG. 13.
Accordingly, as shown in FIG. 16, the valve-opening-operation that generates the positive torque Tr is delayed in the intake valve that is opened and closed by the camshaft 2 by a relative rotation angle “θir” until the second vane rotor 30 presses the second vane 302 to the first vane 202 in the retard direction as shown in a blank arrow direction of FIG. 14. According to the second embodiment, the apparatus 2001 is constructed in a manner that the relative rotation angle “θir” becomes approximately equal to the predetermined advance amount “Δia”.
In an upper graph of FIG. 16, a valve lift amount represents a lift amount of the intake valve relative to a crank angle that represents a rotation angle of the crankshaft. In addition, a solid line represents the valve lift amount according to the second embodiment, and a double-chain line represent a valve lift amount before having the valve characteristics control of the second embodiment. The solid line and the double-chain line are shown in the overlap state in a single graph of FIG. 16. In a lower graph of FIG. 16, the rotation angle of the first vane rotor 20 and the rotation angle of the second vane rotor 30 according to the second embodiment are shown relative to the crank angle.
In contrast, as shown in FIG. 13, working oil is introduced into the second advance chamber 26 a and is discharged from the second retard chamber 26 r when the negative torque Ta is applied in the advance direction from the state of FIG. 14. Accordingly, as shown in FIG. 16, the valve-closing-operation that generates the negative torque Ta is advanced in the intake valve that is opened and closed by the camshaft 2 by a relative rotation angle “θia” until the second vane rotor 30 presses the second vane 302 to the first vane 202 in the advance direction as shown in a blank arrow direction of FIG. 13.
From the complete of the advance operation shown in FIG. 15 to the end of the working angle adjustment mode, the valve-closing-operation finishing timing “tic” is maintained in the advance state by regulating the relative rotation between the housing 10 and rotor 20, as shown in FIG. 16. Further, a valve working angle “φi” can be reduced by the delay “θir” in the valve-opening-operation and the advance “θia” in the valve-closing-operation.
Thus, as shown in FIG. 17, the valve working angle “φi” of the intake valve is restricted from overlapping with the valve working angle “φe” of the exhaust valve when the valve-closing-operation finishing timing “tic” is maintained and when the valve working angle “φi” is reduced. Therefore, at a low-load time of the combustion engine, residual gas can be restricted from increasing by restricting the overlapping in the valve working angle, so that the combustion is restricted from getting worse. Moreover, according to the working angle adjustment mode using the variation torque, the valve working angle “φi” can be mechanically accurately adjusted, similarly to the first embodiment, due to the backflow regulation and the supply function.

Third Embodiment

A valve characteristics control apparatus 3001 according to a third embodiment is a modification example of the first embodiment, and controls valve timing and valve working angle for plural intake valves having different opening/closing timings, as valve characteristics of a valve. The second vane rotor 30 rotating with the camshaft 2 that opens and closes the intake valve receives variation torque that is alternately varied between the positive torque Tr and the negative torque Ta, similarly to the first embodiment shown in FIG. 9.

(Rotation Control System)

As shown in FIG. 18, the first check valve part 3050 has plural check passages 52 and plural check valves 3054. The check passage 52 is defined to penetrate the corresponding second vane 302 so as to connect the second advance chamber 26 a and the second retard chamber 26 r with each other through the second vane 302. The check valve 3054 is arranged in the middle of the check passage 52 in the corresponding second vane 302. When the check valve 3054 is opened, working oil flows from the second advance chamber 26 a to the second retard chamber 26 r. Thereby, each check valve 3054 permits the forward feed of working oil which goes to the second retard chamber 26 r from the second advance chamber 26 a. On the other hand, the backward flow of working oil which goes to the second advance chamber 26 a from the second retard chamber 26 r is regulated by the check valve 3054. Thus, the check passage 52 and the check valve 3054 construct the first check valve part 3050, which is disposed in each of the second vanes 302.

(Timing Adjustment Mode)

When the apparatus 3001 is set to have the timing adjustment mode, similarly to the first embodiment, the control circuit 80 controls the energizing of the solenoid 740, 440, thereby switching the switch passage 72 to prohibit the communication between the second advance chamber 26 a and the second retard chamber 26 r, as shown in FIGS. 18-20. Further, the control circuit 80 switches the position of the spool 443 to one of the positions Pa, Pr and Ph. Therefore, the flow of working oil is switched, based on the position of the spool 443, relative to each first advance chamber 16 a and each first retard chamber 16 r.
In the timing adjustment mode, when the positive torque Tr acts on the second vane rotor 30 in the retard direction from the camshaft 2, working oil of the second advance chamber 26 a is pressurized by the second vane 302 in the first vane 202. At this time, the working oil of the second advance chamber 26 a is restricted from flowing into the second retard chamber 26 r through the switch passage 72 but is allowed to flow into the second retard chamber 26 r through the check passage 52.
On the other hand, when the negative torque Ta acts on the second vane rotor 30 in the advanced direction from the camshaft 2, the working oil of the second retard chamber 26 r is pressurized by the second vane 302 in the first vane 202. At this time, the working oil of the second retard chamber 26 r is restricted from flowing into the second advance chamber 26 a through the switch passage 72 and is restricted from flowing into the second advance chamber 26 a through the check passage 52.
As a result, working oil can be discharged from each second advance chamber 26 a, and can be introduced into each second retard chamber 26 r, respectively. Thereby, the second vane 302 of the second vane rotor 30 that has relative rotation in the retard direction relative to the first vane rotor 20 presses the internal surface 202 r of the first vane 202 through the second advance chamber 26 a from which the working oil is discharged, as shown in FIGS. 18-20.
Therefore, in the timing adjustment mode where the spool 443 is moved to one of the positions Pa, Pr, and Ph, the vane rotors 20 and 30 operate in the state where the second vane 302 is pressed to the first vane 202 in the retard direction. That is, at the advance position Pa of FIG. 18, as shown in a blank arrow direction of FIG. 18, the second vane rotor 30 and the first vane rotor 20 integrally have relative rotation in the advance direction, relative to the housing 10. Further, at the retard position Pr of FIG. 19, as shown in a blank arrow direction of FIG. 19, the second vane rotor 30 and the first vane rotor 20 integrally have relative rotation in the retard direction, relative to the housing 10. Further, at the hold position Ph of FIG. 20, the second vane rotor 30 and the first vane rotor 20 integrally rotate at the same speed as the housing 10.
Thus, in the timing adjustment mode, in response to the switchover control of working oil relative to each first advance chamber 16 a and each first retard chamber 16 r, the housing 10 and the second vane rotor 30 can be controlled to have a relative rotation phase, and a valve timing corresponding to the relative rotation phase can be realized. Accordingly, the valve timing can be mechanically accurately adjusted in the timing adjustment mode using the variation torque.
Furthermore in the timing adjustment mode, the check valve 64 restricts the working oil pressurized in the second retard chamber 26 r by the negative torque Ta from flowing backward. That is, the working oil is restricted from flowing from the supply point 720 to the pump 6 through the switch passage 72. In contrast, when the positive torque Tr is applied, working oil can be supplied to the switch passage 72 through the supply point 720 from the pump 6 because the forward flow is permitted by the check valve 64.
At this time, the solenoid valve 74 intercepts the communication in a part of the switch passage 72 between the supply point 720 and the second advance chamber 26 a. In contrast, working oil supplied to the supply point 720 can flow to the second retard chamber 26 r in the other part of the switch passage 72 between the supply point 720 and the second retard chamber 26 r. Therefore, even if the working oil introduced to the second retard chamber 26 r is leaked out from the slide clearance between the vane rotors 20 and 30, working oil supplied to the supply point 720 can be supplied to the second retard chamber 26 r from the switch passage 72.
Thus, the state where the second vane 302 is pressed to the first vane 202 can be maintained in the retard direction as a result of the backflow regulation and the supply function, so that reliability can be raised for the accurate valve timing adjustment that is mechanically realized in the state where the second vane 302 is pressed to the first vane 202.
In addition, at the timing adjustment mode, because the second vane 302 is disposed between the second advance chamber 26 a and the second retard chamber 26 r, the length of the check passage 52 can be made short, so that the pressure loss can be decreased. Therefore, the accurate valve timing adjustment can be quickly started in the timing adjustment mode.

(Working Angle Adjustment Mode)

When the apparatus 3001 is set to have the working angle adjustment mode, similarly to the first embodiment, the control circuit 80 controls the energizing of the solenoid 740, 440, thereby switching the switch passage 72 to allow the communication between the second advance chamber 26 a and the second retard chamber 26 r, as shown in FIGS. 21 and 22. Further, the control circuit 80 switches the position of the spool 443 to the hold position Ph, as shown in FIGS. 21 and 22. Therefore, the flow of working oil is regulated relative to the first advance chamber 16 a and the first retard chamber 16 r, and the regulation is continued from the start to the end of the working angle adjustment mode.
The working angle adjustment mode is started from the state where the second vane 302 is pressed to the first vane 202 in the retard direction in the previous timing adjustment mode. Specifically, when the negative torque Ta acts on the second vane rotor 30 in the advance direction from the camshaft 2, working oil of the second retard chamber 26 r is pressurized by the second vane 302. At this time, the working oil of the second retard chamber 26 r is restricted from flowing into the second advance chamber 26 a through the check passage 52, but is allowed to flow into the second advance chamber 26 a through the switch passage 72, as shown in FIG. 22.
Thus, the working oil is introduced into the second advance chamber 26 a, and is discharged from the second retard chamber 26 r. Thereby, as shown in a blank arrow direction of FIG. 22, the second vane rotor 30 that receives the negative torque Ta has relative rotation in the advance direction relative to the first vane rotor 20, until the second vane 302 is pressed to the internal surface 202 a of the first vane 202 through the second retard chamber 26 r from which the working oil is discharged. At this time, the flow of working oil is regulated relative to the first advance chamber 16 a and the first retard chamber 16 r, so that the relative rotation of the first vane rotor 20 is regulated relative to the housing 10. Therefore, the second vane rotor 30 has relative rotation relative to the first vane rotor 20.
Thus, the negative torque Ta is consumed by the relative rotation of the second vane rotor 30 in a direction assisting the rotation of the camshaft 2 until the second vane 302 is pressed to the first vane 202. In contrast, after the second vane 302 is pressed to the first vane 202, a force resisting to the negative torque Ta comes to act on the second vane rotor 30 and the camshaft 2 from the first vane rotor 20.
Accordingly, as shown in FIG. 23, the valve-closing-operation that generates the negative torque Ta is advanced in each intake valve that is opened and closed by the camshaft 2 by a relative rotation angle “θia” until the second vane rotor 30 presses the second vane 302 to the first vane 202 in the advance direction. In an upper graph of FIG. 23, a valve lift amount represents a lift amount of the intake valve relative to a crank angle that represents a rotation angle of the crankshaft. In addition, a solid line represents the valve lift amount according to the third embodiment, and a double-chain line represent a valve lift amount before having the valve characteristics control of the third embodiment, and the solid line and the double-chain line are shown in the overlap state in a single graph of FIG. 23. In a lower graph of FIG. 23, the rotation angle of the first vane rotor 20 and the rotation angle of the second vane rotor 30 according to the third embodiment are shown relative to the crank angle.
Moreover, from the state of FIG. 22 in which the second vane 302 is pressed to the first vane 202 in the advance direction by the action of the negative torque Ta in the working angle adjustment mode, when the positive torque Tr acts in the retard direction, working oil of the second advance chamber 26 a is pressurized by the second vane 302. At this time, the working oil of the second advance chamber 26 a is permitted to flow into the second retard chamber 26 r through at least one of the switch passage 72 and the check passage 52, as shown in FIG. 21.
Thus, working oil can be discharged from the second advance chamber 26 a, and can be introduced into the second retard chamber 26 r. Thereby, as shown in a blank arrow direction of FIG. 21, the second vane rotor 30 that receives the positive torque Tr has relative rotation in the retard direction relative to the first vane rotor 20, until the second vane 302 is pressed to the internal surface 202 r of the first vane 202 through the second advance chamber 26 a from which the working oil is discharged. At this time, the flow of working oil is regulated relative to the first advance chamber 16 a and the first retard chamber 16 r, so that the relative rotation of the first vane rotor 20 is regulated relative to the housing 10. Therefore, the second vane rotor 30 has relative rotation relative to the first vane rotor 20.
Therefore, the positive torque Tr is consumed by the relative rotation of the second vane rotor 30 in a direction restricting the rotation of the camshaft 2 until the second vane 302 is pressed to the first vane 202. In contrast, after the second vane 302 is pressed to the first vane 202, a force resisting to the positive torque Tr comes to act on the second vane rotor 30 and the camshaft 2 from the first vane rotor 20.
Accordingly, as shown in FIG. 23, the valve-opening-operation that generates the positive torque Tr is delayed in the intake valve that is opened and closed by the camshaft 2 by a relative rotation angle “θir” until the second vane rotor 30 presses the second vane 302 to the first vane 202 in the retard direction.
Accordingly, from the start to the end of the working angle adjustment mode, while the valve-opening-operation starting timing “tio” is maintained as shown in FIG. 23 by regulating the relative rotation between the housing 10 and rotor 20, a valve working angle “φi” can be reduced by the advance “θia” in the valve-closing-operation and the delay “θir” in the valve-opening-operation.
Thus, similarly to the second embodiment shown in FIG. 17, the valve working angle “φi” of the intake valve is restricted from overlapping with the valve working angle “φe” of the exhaust valve when the valve-opening-operation starting timing “tio” is maintained and when the valve working angle “φi” is reduced. Therefore, at a low-load time of the combustion engine, residual gas can be restricted from increasing by restricting the overlapping in the valve working angle, so that the combustion is restricted from getting worse. Moreover, according to the working angle adjustment mode using the variation torque, the valve working angle “φi” can be mechanically accurately adjusted, similarly to the first embodiment, due to the backflow regulation and the supply function.

Fourth Embodiment

A valve characteristics control apparatus 4001 according to a fourth embodiment is a modification example of the third embodiment, and controls valve timing and valve working angle for plural exhaust valves having different opening/closing timings, as valve characteristics of a valve. The second vane rotor 30 rotating with the camshaft 2 that opens and closes the intake valve receives variation torque that is alternately varied between the positive torque Tr and the negative torque Ta, similarly to the first embodiment shown in FIG. 9.

(Working Angle Adjustment Mode)

When the apparatus 4001 is set to have the working angle adjustment mode, the control circuit 4080 controls the energizing of the solenoid 440 of the solenoid valve 44, thereby switching the position of the spool 443 to the retard position Pr, as shown in FIG. 24, and then switching the position of the spool 443 to the hold position Ph, as shown in FIGS. 25 and 26. Therefore, working oil is discharged from the first advance chamber 16 a and is introduced into the first retard chamber 16 r, in accordance with the start of the working angle adjustment mode, and the regulation of working oil relative to the first advance chamber 16 a and the first retard chamber 16 r is continued to the end of the working angle adjustment mode. In addition, from the start to the end of the working angle adjustment mode, the control circuit 4080 controls the energizing of the solenoid 740 of the solenoid valve 74, thereby switching the switch passage 72 to allow the communication between the second advance chamber 26 a and the second retard chamber 26 r, as shown in FIGS. 24-26, similarly to the first embodiment.
The working angle adjustment mode is started from the state where the second vane 302 is pressed to the first vane 202 in the retard direction in the previous timing adjustment mode that is realized similarly to the third embodiment. In accordance with the start of the working angle adjustment mode, the spool 443 is moved to the retard position Pr of FIG. 24, thereby, as shown in a blank arrow direction of FIG. 24, the second vane rotor 30 and the first vane rotor 20 integrally have rotation in the retard direction relative to the housing 10. As a result, as shown in FIG. 27, the valve-opening-operation starting timing “teo” and the valve-closing-operation finishing timing “tec” are retarded by a predetermined retard amount “Δer” as a valve timing corresponding to the relative rotation phase between the housing 10 and the second vane rotor 30.
In FIG. 27, a valve lift amount represents a lift amount of the exhaust valve relative to a crank angle that represents a rotation angle of the crankshaft. In addition, a solid line represents the valve lift amount of the exhaust valve having the delay in the valve-opening-operation starting timing “teo” and the valve-closing-operation finishing timing “tec”, and a double-chain line represent a valve lift amount before having the delay in the valve-opening-operation starting timing “teo” and the valve-closing-operation finishing timing “tec”. The solid line and the double-chain line are shown in the overlap state in a single graph of FIG. 27.
After the retard operation of FIG. 27 is finished, when the spool 443 is moved to the hold position Ph of FIGS. 25 and 26 in the state where the second vane 302 is pressed to the first vane 202 in the retard direction, the valve-closing-operation is advanced and the valve-opening-operation is delayed, similarly to the third embodiment. That is, as shown in FIG. 26, working oil is introduced into the second advance chamber 26 a and is discharged from the second retard chamber 26 r, when the negative torque Ta is applied in the advance direction from the state shown in FIG. 25.
Accordingly, as shown in FIG. 28, the valve-closing-operation that generates the negative torque Ta is advanced in the exhaust valve that is opened and closed by the camshaft 2 by a relative rotation angle “θea” until the second vane rotor 30 presses the second vane 302 to the first vane 202 in the advance direction as shown in a blank arrow direction of FIG. 26. According to the fourth embodiment, the apparatus 4001 is constructed in a manner that the relative rotation angle “θea” becomes approximately equal to the predetermined retard amount “Δer”.
In an upper graph of FIG. 28, a valve lift amount represents a lift amount of the exhaust valve relative to a crank angle that represents a rotation angle of the crankshaft. In addition, a solid line represents the valve lift amount according to the fourth embodiment, and a double-chain line represent a valve lift amount before having the valve characteristics control of the fourth embodiment. The solid line and the double-chain line are shown in the overlap state in a single graph of FIG. 28. In a lower graph of FIG. 28, the rotation angle of the first vane rotor 20 and the rotation angle of the second vane rotor 30 according to the fourth embodiment are shown relative to the crank angle.
In contrast, as shown in FIG. 25, working oil is discharged from the second advance chamber 26 a and is introduced into the second retard chamber 26 r when the positive torque Tr is applied in the retard direction from the state of FIG. 26. Accordingly, as shown in FIG. 28, the valve-opening-operation that generates the positive torque Tr is retarded in the exhaust valve that is opened and closed by the camshaft 2 by a relative rotation angle “θer” until the second vane rotor 30 presses the second vane 302 to the first vane 202 in the retard direction as shown in a blank arrow direction of FIG. 25.
From the complete of the retard operation of FIG. 27 to the end of the working angle adjustment mode, while the valve-opening-operation starting timing “teo” is maintained in the retard state by regulating the relative rotation between the housing 10 and rotor 20, as shown in FIG. 28. Further, a valve working angle “φe” can be reduced by the delay “θer” in the valve-opening-operation and the advance “θea” in the valve-closing-operation.
Thus, when the valve-opening-operation starting timing “teo” is maintained and when the valve working angle “φe” is reduced, similarly to the first embodiment shown in FIG. 11, a blow-down pressure represented by a dashed line of FIG. 11 is restricted from overlapping between the exhaust valve shown in the upper graph of FIG. 11 and the exhaust valve shown in the lower graph of FIG. 11.
If the blow-down pressure overlaps between the exhaust valve shown in the upper graph of FIG. 11 and the exhaust valve shown in the lower graph of FIG. 11, residual gas is increased. However, according to the fourth embodiment, the residual gas can be restricted from increasing by restricting the overlapping in the flow-down pressure, so that the combustion is restricted from getting worse. Moreover, according to the working angle adjustment mode using the variation torque, the valve working angle “φe” can be mechanically accurately adjusted.

Other Embodiments

While the present disclosure has been described with reference to preferred embodiments thereof, it is to be understood that the disclosure is not limited to the preferred embodiments and constructions. The present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various combinations and configurations, which are preferred, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.
Specifically, the valve characteristics control apparatus 1, 4001 of the first and fourth embodiment may be applied to only one exhaust valve or at least one intake valve. Further, the valve characteristics control apparatus 2001, 3001 of the second and third embodiment may be applied to only one intake valve or at least one exhaust valve.
Further, in the working angle adjustment mode of the apparatus 2001, 4001 of the second and fourth embodiment, the communication between the second advance chamber 26 a and the second retard chamber 26 r through the switch passage 72 may be intercepted when the position of the spool 443 is switched to the advance position Pa or the retard position Pr before the position of the spool 443 is switched to the hold position Ph.
Furthermore, the above operation and advantage can be obtained if the first check valve part 50, 3050 is disposed in at least one second vane 302 in the first to fourth embodiments. Otherwise, the first check valve part 50, 3050 may be disposed in other part of the second vane rotor 30 other than the second vane 302, or may be disposed outside of the second vane rotor 30.
In addition, the main supply passage 42 ms and the sub supply passage 62 ss may be made to communicate with each other not through the port 442 ms, 442 ss in the first to fourth embodiments.
Such changes and modifications are to be understood as being within the scope of the present disclosure as defined by the appended claims.

Claims

1. A valve characteristics control apparatus that controls valve characteristics of a valve opened and closed by a rotation of a camshaft in accordance with a rotation of a crankshaft in an internal combustion engine, the apparatus comprising:

a housing rotating with the crankshaft;

a first vane rotor having a first vane rotatably received in the housing, a first advance chamber and a first retard chamber being defined by partitioning a space between the housing and the first vane in a rotation direction, the first vane rotor having a relative rotation with respect to the housing in an advance direction when working fluid is introduced into the first advance chamber and when working fluid is discharged from the first retard chamber, the first vane rotor having a relative rotation with respect to the housing in a retard direction when working fluid is discharged from the first advance chamber and when working fluid is introduced into the first retard chamber;

a control valve part that switches a flowing direction of working fluid between the first advance chamber and the first retard chamber in a timing adjustment mode adjusting valve timing as the valve characteristics, the control valve part restricting working fluid from flowing between the first advance chamber and the first retard chamber in a working angle adjustment mode adjusting a valve working angle as the valve characteristics;

a second vane rotor having a second vane rotating with the camshaft in a state that the second vane is projected into the first vane in the housing, a second advance chamber and a second retard chamber being defined by partitioning a space between the first vane and the second vane in the rotation direction, the second vane rotor having a relative rotation with respect to the first vane rotor in the advance direction when working fluid is introduced into the second advance chamber and when working fluid is discharged from the second retard chamber, the second vane rotor having a relative rotation with respect to the first vane rotor in the retard direction when working fluid is discharged from the second advance chamber and when working fluid is introduced into the second retard chamber;

a first check valve part having a check passage connecting the second advance chamber and the second retard chamber with each other, the check valve part allowing working fluid to flow from the second retard chamber through the check passage to the second advance chamber, the check valve part restricting working fluid from flowing from the second advance chamber through the check passage to the second retard chamber; and

a switch valve part having a switch passage connecting the second advance chamber and the second retard chamber with each other, the switch valve part allowing a communication between the second advance chamber and the second retard chamber through the switch passage in the working angle adjustment mode, the switch valve part prohibiting the communication between the second advance chamber and the second retard chamber through the switch passage in the timing adjustment mode.

2. The valve characteristics control apparatus according to claim 1, wherein

the control valve part restricts working fluid from flowing between the first advance chamber and the first retard chamber continuously from a start of the working angle adjustment mode to an end of the working angle adjustment mode.

3. The valve characteristics control apparatus according to claim 2, wherein

the valve is a plurality of exhaust valves having different valve opening timings.

4. The valve characteristics control apparatus according to claim 1, wherein

the control valve part restricts working fluid from flowing between the first advance chamber and the first retard chamber continuously to an end of the working angle adjustment mode, after working fluid is introduced into the first advance chamber and is discharged from the first retard chamber in response to a start of the working angle adjustment mode.

5. The valve characteristics control apparatus according to claim 4, wherein

the valve is an intake valve of the engine.

6. The valve characteristics control apparatus according to claim 1, wherein

the switch passage has a supply point to which working fluid is supplied, and

the switch valve part is located at a position adjacent to the second retard chamber rather than the supply point of the switch passage.

7. The valve characteristics control apparatus according to claim 6, further comprising:

a second check valve part having a supply passage that communicates with the supply point of the switch passage and a supply source of working fluid, wherein

the second check valve part allows working fluid to flow from the supply source to the supply point, and

the second check valve part prohibits working fluid from flowing from the supply point to the supply source.

8. A valve characteristics control apparatus that controls valve characteristics of a valve opened and closed by a rotation of a camshaft in accordance with a rotation of a crankshaft in an internal combustion engine, the apparatus comprising:

a housing rotating with the crankshaft;

a first check valve part having a check passage connecting the second advance chamber and the second retard chamber with each other, the check valve part allowing working fluid to flow from the second advance chamber through the check passage to the second retard chamber, the check valve part restricting working fluid from flowing from the second retard chamber through the check passage to the second advance chamber; and

9. The valve characteristics control apparatus according to claim 8, wherein

10. The valve characteristics control apparatus according to claim 9, wherein

the valve is an intake valve of the engine.

11. The valve characteristics control apparatus according to claim 8, wherein

the control valve part restricts working fluid from flowing between the first advance chamber and the first retard chamber continuously to an end of the working angle adjustment mode, after working fluid is discharged from the first advance chamber and is introduced into the first retard chamber in response to a start of the working angle adjustment mode.

12. The valve characteristics control apparatus according to claim 11, wherein

13. The valve characteristics control apparatus according to claim 8, wherein

the switch passage has a supply point to which working fluid is supplied, and

the switch valve part is located at a position adjacent to the second advance chamber rather than the supply point of the switch passage.

14. The valve characteristics control apparatus according to claim 13, further comprising:

15. The valve characteristics control apparatus according to claim 1, wherein

the first check valve part is located inside the second vane.