Patent Application
20110073055
This application is based on and claims priority under 35 U.S.C. ยง119 to Japanese Patent Application 2009-220652, filed on Sep. 25, 2009, the entire content of which is incorporated herein by reference.
This disclosure relates to a valve opening/closing timing control device including a driving side rotational member synchronously rotatable with a crankshaft of an internal combustion engine, a driven side rotational member arranged coaxially with the driving side rotational member and synchronously rotatable with a camshaft that opens and closes at least any one of intake and exhaust valves of the internal combustion engine, and a phase converting mechanism displacing a relative phase between the driving side rotational member and the driven side rotational member by distributing an operating fluid to each of two kinds of pressure chambers, the volume of which is complementarily varied by a movable partition.
JP-A-2009-074384 (Patent Document 1; paragraphs 0009 and 0029, FIGS. 1, 2 and 3) is provided as literature information of the related art concerning a valve opening/closing timing control device. The valve opening/closing timing control device disclosed in Patent Document 1 includes a lock mechanism capable of locking a relative phase to an intermediate phase which is suitable for starting of an internal combustion engine, if necessary. The lock mechanism has a lock groove formed in the driven side rotational member, and a lock pin movably supported by the driving side rotational member so as to be fitted into the lock groove. The lock pin is biased by a spring in a direction of fitting the lock pin into the lock groove. If the relative phase of both rotational members reaches the intermediate phase, the lock pin automatically enters the lock groove by a biasing force of the spring. After the starting of the internal combustion engine is completed, the locking state of the lock mechanism is generally released by a pressure of oil supplied from an oil pump or the like, and, simultaneously, a displacement operation from the intermediate phase to an advanced angle side is performed by the pressure of the oil.
In general, there are many cases in which the valve opening/closing timing control device is provided with a biasing mechanism, such as a torsion spring, for biasing the relative phase in a direction of the intermediate phase, as a means for suppressing a tendency in which the driven side rotational member is retarded with respect to the driving side rotational member by a reaction force of a cam received from a valve spring of the intake valve or the exhaust valve. In particular, according to the torsion spring of the valve opening/closing timing control device disclosed in Patent Document 1, since its biasing function is defined between an intermediate control phase which is positioned at a retarded angle phase direction side than the intermediate phase, and a most retarded angle phase, and the biasing function is not effective in a region between an advanced angle phase and the intermediate phase, a displacement operation from the advanced angle phase to the intermediate phase or the intermediate control phase is quickly performed by the reaction force of the cam and an oil pressure of the pump.
However, in the valve opening/closing timing control device disclosed in Patent Document 1, since the lock operation to the intermediate phase depends upon entry operation of the lock pin when it reaches the intermediate phase, for example, if the movement of the lock pin is interfered with by foreign substances existing in the oil, the lock pin is not reliably fitted into the lock groove. Therefore, the lock may not be sufficiently displaced to the intermediate phase.
After the starting of the internal combustion engine is completed at the intermediate phase, in order to displace the relative phase from the intermediate phase to the advanced angle phase, there is a need for an oil supply mechanism or the like to push the lock pin out from the lock groove. Therefore, the valve opening/closing timing control device has a tendency to become larger and be complicated.
A need thus exists for a valve opening/closing timing control device which is not susceptible to the drawback mentioned above.
According to a first aspect of this disclosure, a valve opening/closing timing control device includes a driving side rotational member synchronously rotatable with a crankshaft of an internal combustion engine, a driven side rotational member arranged coaxially with the driving side rotational member and synchronously rotatable with a camshaft that opens and closes any one of intake and exhaust valves of the internal combustion engine, a phase converting mechanism displacing a relative phase between the driving side rotational member and the driven side rotational member toward an advanced angle phase side or a retarded angle phase side by distributing an operating fluid to each of two kinds of pressure chambers, the volume of which is complementarily varied by a movable partition, and a biasing member biasing the relative phase toward a predetermined phase suitable for a start-up of the internal combustion engine except for a most advanced angle phase and a most retarded angle phase.
The foregoing and additional features and characteristics of this disclosure will become more apparent from the following detailed description considered with the reference to the accompanying drawings, wherein:
Embodiments disclosed here will now be described with reference to the accompanying drawings.
As shown in
The valve opening/closing timing control device includes a configuration in which the inner rotor 2 (driven side rotational member) is inserted in the outer rotor 1 (driving side rotational member). Consequently, the outer rotor 1 and the inner rotor 2 can be relatively rotated around a core X of a rotational shaft in the range of a desired relative rotational phase. A fluid pressure chamber is formed between the outer rotor 1 and the inner rotor 2, and as shown in
The vane 5 is inserted into a vane groove formed in the outer circumference of the inner rotor 2, and is biased in a protruding direction by a leaf spring or the like. Consequently, irrespective of a relative phase of the outer rotor 1 and the inner rotor 2, an outer end portion of the vane 5 is always slidably held on an inner surface of the outer rotor in the fluid pressure chamber.
The camshaft 3 is coaxially arranged with the core X of the rotational shaft. The camshaft 3 is connected to the inner rotor 2 by means of a connecting bolt 4. A front plate 6 is placed on one surface of the outer rotor 1, and a rear plate 7 is placed on the other surface of the outer rotor 1. The front plate 6 and the rear plate 7 are fixed to the outer rotor 1 by means of a plurality of fixing bolts 8. The inner rotor 2 is interposed between the front plate 6 and the rear plate 7.
A timing sprocket 7S is integrally installed on the outer periphery of the rear plate 7. Between the timing sprocket 7S and a gear attached to the crankshaft of the engine, there is provided a power transmission member (not shown) such as a timing chain or a timing belt.
In the configuration, upon start-up of the engine, a rotational driving force of the crankshaft is transmitted to the timing sprocket 7S through the power transmission member, and the outer rotor 1 rotates in a rotational direction T shown in
When the engine operates, if the advanced angle chamber 12 is supplied with operating oil, the volume of the advanced angle chamber 12 is enlarged by the pressure acting on the vane 5, and thus the inner rotor 2 is moved in a direction denoted by an arrow Ti with respect to the outer rotor 1. Consequently, the relative rotational phase of the outer rotor 1 and the inner rotor 2 is shifted in an advanced angle direction. In contrast, if the retarded angle chamber 11 is supplied with the operating oil, the volume of the retarded angle chamber 11 is enlarged by the pressure acting on the vane 5 in an adverse direction, and thus the inner rotor 2 is moved in a direction denoted by an arrow T2 with respect to the outer rotor 1. Consequently, the relative rotational phase of the outer rotor 1 and the inner rotor 2 is shifted in a retarded angle direction. The opening and closing timing of the intake vale or exhaust valve is controlled by changing a rotational phase of the camshaft 3 with respect to the rotational phase of the crankshaft.
Engine oil is used as the operating oil, and the valve opening/closing timing control device includes a maintenance mechanism M to maintain the relative rotational phase between the outer rotor 1 and the inner rotor 2 at a start-up optimum phase (referred to as an intermediate phase, and one example of the predetermined phase) suitable for the start-up of the engine. The maintenance mechanism M maintains the outer rotor 1 and the inner rotor 2 at the set relative rotational phase in circumstances in which the pressure of the operating oil is very low immediately after the start-up of the engine. Therefore, the rotational phase of the camshaft 3 with respect to the rotational phase of the crankshaft is maintained at the start-up optimum phase, thereby providing the stable start-up of the engine.
A general maintenance mechanism in the valve opening/closing timing control device of a related art is constituted of a lock groove formed in the inner rotor, and a lock pin supported on the outer rotor to be extendable and retractable to each of the lock groove.
However, the maintenance mechanism M disclosed here includes two spiral springs S1 and S2 applying the biasing force between the outer rotor 1 (driving side rotational member) and the inner rotor 2 (driven side rotational member) in mutually reverse directions. The first spiral spring S1 biases the relative phase toward the advanced angle side, and the second spiral spring S2 biases the relative phase toward the retarded angle side. The two spiral springs S1 and S2 are kept in a concave portion 6a formed in the front plate 6, and a disc spacer 15 is interposed between the spiral springs S1 and S2. The concave portion 6a is covered by a disc cover 9. The operation of the spiral springs S1 and S2 will be described in detail.
As shown in
As shown in
Further, the operating oil supplied to the cylindrical space 2S is supplied to the retarded angle chamber side passage 11a and the advanced angle chamber side passage 12a described above through the fluid control valve mechanism V which is relatively rotatably supported with respect to the outer rotor 1 and the inner rotor 2, and is discharged from the retarded angle chamber side passage 11a and the advanced angle chamber side passage 12a.
The fluid control valve mechanism V includes, as shown in
A main oil passage 23 penetrates into the center portion of the operating oil supply/discharge portion Vb to receive the operating oil from the above-described inner oil passage 2a, and a check valve C is provided in the main oil passage 23 to block flow of the fluid toward the cylindrical space 2S. The spool valve 22 has a bottomed cylindrical shape.
The housing 28 is fixed to a front cover or the like of the engine, and the inner rotor 2 is rotatably supported by the operating oil supply/discharge part Vb.
In the outer circumference of the operating oil supply/discharge part Vb, two ports 24 and 25 are formed in a groove, in which the distribution of the operating oil is controlled by the spool valve 22. An oil seal 27 is formed on the outer circumference of the operating oil supply/discharge portion Vb to suppress leakage of the operating oil from the first port 24 and the second port 25. The first port 24 is always in communication with the retarded angle chamber side passage 11a, and the second port 25 is always in communication with the advanced angle chamber side passage 12a.
A compression spring 29 is installed between the spool valve 22 and the bottom surface of the housing 28 to bias the spool valve 22 in an upward direction on the figure. If the solenoid 21 is energized in the state of
In the outer circumferential surface of the spool valve 22, ring-shaped discharge grooves 22a and 22b and a ring-shaped supply groove 22c are formed. The discharge grooves 22a and 22b are respectively provided with through-holes 23a and 23b penetrating an inner hollow portion.
A position relationship between the discharge grooves 22a and the 22b and the supply groove 22c is set in such a manner that the supply groove 22c is in communication with the main oil passage 23 and the advanced angle chamber communication hole 12a and the discharge groove 22b is in communication with the retarded angle chamber side passage 11a, as shown in
In the valve opening/closing timing control device, a gap is formed between the inner rotor 2 and the front plate 6 and between the inner rotor 2 and the rear plate 7, through which the operating oil slightly leaks. The operating oil slightly leaks through the other movable portion. The leaked operating oil is collected by an oil pan 36.
As shown in
On the other hand, in the case where the relative rotational phase is displaced in the retarded angle direction T2, the solenoid 21 is energized during the operation of the oil pressure pump P. The spool valve 22 is pushed into the rod 22 of the solenoid 21 and then is positioned at the downward position. The operating oil supplied to the main oil passage 23 of the camshaft 8 from the fluid pump P is fed to each retarded angle chamber 11 through the cylindrical space 2S, the main oil passage 23, the supply groove 22c, the retarded angle chamber side passage 11a and the first port 24. The vane 5 is moved in the retarded angle direction T2 by the feeding, so that the operating oil of each advanced angle chamber 12 is discharged. The operating oil discharged from the advanced angle chamber 12 is discharged to the oil pan 36 through the second port 25, the advanced angle chamber side passage 12a, the discharge groove 22a and the drain passage 35.
Although not shown in the figures, the control system of the valve opening/closing timing control device includes a crank angle sensor detecting the rotational angle of the crankshaft of the engine, a camshaft angle sensor detecting the rotational angle of the camshaft 3, and an ECU (not shown) controlling the fluid control valve mechanism V.
The ECU is provided with a signal system acquiring ON/OFF information of an ignition key, information from an oil temperature sensor detecting the temperature of the engine oil, or the like, and control information of the optimum relative rotational phase according to the driving state of the engine is stored in a nonvolatile memory.
The ECU detects the relative phase of the outer rotor 1 and the inner rotor 2 from the detected result of the above-described crank angle sensor and camshaft angle sensor. The distribution of the operating oil to each of the retarded angle chamber 11 and the advanced angle chamber 12 is performed by operating the fluid control valve mechanism V based on the information of the relative phase and the information of the driving state (e.g., revolutions of engine, temperature of cooling water or the like), thereby controlling the relative rotational phase of the outer rotor 1 and the inner rotor 2. Consequently, the phase control is achieved between the most retarded angle phase (relative rotational phase in which the volume of the retarded angle chamber 11 is maximized) and the most advanced angle phase (relative rotational phase in which the volume of the advanced angle chamber 12 is maximized).
If the operation is performed to stop the engine, the ECU stops the distribution of the operating oil to the retarded angle chamber 11 and the advanced angle chamber 12 by the fluid control valve mechanism V, so that the vane 5 is not applied with the operating oil of any direction. Consequently, the engine stops in the state in which the relative phase of the outer rotor 1 and the inner rotor 2 is displaced at the start-up optimum phase suitable for next start-up by the above-described biasing operation of the spiral springs S1 and S2. When the engine starts up after the stop, the engine starts up reliably.
In this instance, when the inner rotor 2 is positioned in the area in the retarded angle side than the start-up optimum phase with respect to the outer rotor 1, the above-described spiral springs S1 and S2 have a function of applying the biasing force to the inner rotor 2 in a direction of the start-up optimum phase against the reaction force received from the valve spring of the intake valve or exhaust valve in cooperation with each other. More specifically, the biasing force of the spiral spring S1 biasing the relative phase to the advanced angle side is set to be higher than that of the spiral spring S2 biasing the relative phase to the retarded angle side. Consequently, a problem that the relative phase of the inner rotor 2 integrally rotating with the camshaft 3 tends to be retarded with respect to the rotation of the outer rotor 1 due to the reaction force received from the valve spring of the intake valve or exhaust valve, or the tendency that the relative phase is maintained at the retarded angle side rather than the start-up optimum phase when the operating oil is discharged from the retarded angle chamber 11 and the advanced angle chamber 12 are suppressed.
After the start-up of the engine, the ECU performs the distribution of the operating oil to each of the retarded angle chamber 11 and the advanced angle chamber 12 by the fluid control valve mechanism V to change the relative phase of the outer rotor 1 and the inner rotor 2, so that the control of the opening and closing timing of the intake valve and the exhaust valve is performed by the ECU.
In a case where the engine is in the stop state, since excessive load is applied to the engine, the inner rotor 2 may reach the most retarded angle phase with respect to the outer rotor 1. When the engine starts up in this situation, in order to perform stable engine starting, the ECU controls the phase of the inner rotor 2 with respect to the outer rotor 1 to move at the start-up optimum phase early.
As a detailed control mode, the fluid control valve mechanism V discharges the operating oil from the retarded angle chamber 11 and supplies the operating oil to advanced angle chamber 12 by the control of the ECU, the inner rotor 2 with respect to the outer rotor 1 is moved in the direction of the start-up optimum phase. In this instance, the rotational phase of the most retarded angle phase, in which the inner rotor 2 is disposed at the most retarded angle side, is referred to as the most retarded angle phase.
However, according to the above-described control, in a case in which the engine starts up in the state in which the inner rotor 2 is at the most retarded angle phase, the time is needed until the relative rotational phase reaches the start-up optimum phase, so that the start-up of the engine is not smoothly performed. In particular, the operating oil is cold at the time of stopping the engine in cold climates, the viscosity of the operating oil is high, and thus the distribution of the operating oil to each of the retarded angle chamber 11 and the advanced angle chamber 12 is not smoothly performed. For this reason, the start-up of the engine is not smoothly performed. In order to address the above problem, it is aimed to shorten the time required to reach the start-up optimum phase by assisting the relative movement of the outer rotor 1 and the inner rotor 2 in the direction of the start-up optimum phase by means of the above-described difference in the intensity of the spiral springs S1 and S2.
As shown in
As shown in
As shown in
The outer circumference of an axial portion 10 of the inner rotor 2 is provided on one portion thereof with an engaging concave portion 10G which may be engaged to the inner engaging portion 31, so as to correspond to the shape of the spiral springs S1 and S2. The inner surface of the front plate 6 connected to the outer rotor 1 is provided on one portion thereof with an engaging concave portion 6T which may be engaged to the outer engaging portion 32.
When the spiral springs S1 and S2 are set, first, after the engaging concave portion 6T of the outer rotor 1 is engaged and fixed to the outer engaging portion 32, the inner engaging portion 31 is turned by predetermined turns against the biasing force of the spiral springs S1 and S2 which tend to be returned in a straight direction, in other words, in a direction of the spring body 30 which is curled in an inner diameter direction around the axis X, the inner engaging portion 31 is engaged and fixed to the engaging concave portion 10G. The rotation operating direction of the inner engaging portion 31 at the time of performing the setting corresponds to a counterclockwise direction in the first spring S1, and corresponds to a clockwise direction in the second spiral spring S2, in
By setting the springs in the above manner, both ends of the spiral springs S1 and S2 are reliably fixed to each of the outer rotor 1 and the inner rotor 2 so as to prevent the relative movement therebetween, thereby achieving the configuration in which the inner engaging portion 31 of the first spiral spring S1 biases the inner rotor 2 toward the advanced angle side (clockwise direction in
In this instance, only one of the two spiral springs S1 and S2 may be disposed in the concave portion 6a formed in the front plate 6, and the other may be disposed in the concave portion formed in the rear plate 7. In this instance, the disc spacer 15 is not required.
As described above, since the distribution of the operating oil to each of the retarded angle chamber 11 and advanced angle chamber 12 is stopped at the general start-up of the engine, as shown in
After the start-up of the engine, since the operating oil is generally supplied to the retarded angle chamber 11 by the fluid control valve mechanism V in accordance with the control of the ECU, the relative rotational phase is displaced to the intermediate control phase slightly closer to the retarded angle phase side rather than the start-up optimum phase. The intermediate control phase is a phase suitable for improvement of the emission or torque-up at cold temperatures, and this phase is generally maintained during warm air driving. In this instance,
Since the displacement operation from the start-up optimum phase to the retarded angle phase side such as the intermediate control phase by the supply of the operating oil to the retarded angle chamber 11 is followed by the relative rotation operation of the inner rotor 2 in a counterclockwise direction in
When the displacement operation is performed to the advanced angle side rather than the start-up optimum phase in the general driving control, it is followed by the relative rotation operation of the inner rotor 2 in a clockwise direction in
A second embodiment disclosed here will now be described with reference to the accompanying drawings.
The second embodiment includes two spiral springs S1 and S2 to bias a biasing force in a mutually reverse direction, as the maintenance mechanism M for maintaining the relative rotational phase of the outer rotor 1 and the inner rotor 2 at the start-up optimum phase suitable for the start-up of the engine, similar to the first embodiment.
The first feature of the configuration according to the second embodiment is that the width of the engaging concave portion 10G of the inner rotor 2 in a circumferential direction is sufficiently larger than the thickness of the inner engaging portion 31 of the spiral springs S1 and S2, as shown in
The second feature of the configuration according to the second embodiment is that the front plate 6 is provided with first restriction piece 33A in a standing manner which can abut against the inner engaging portion 31 of the first spiral spring S1, and the front plate 6 is provided with second restriction piece 33B in a standing manner which can abut against the inner engaging portion 31 of the second spiral spring S2. The first restriction piece 33A restricts the displacement of the inner engaging portion 31 of the first spiral spring S1 in the direction of the advanced angle region B, and the second restriction piece 33B restricts the displacement of the inner engaging portion 31 of the second spiral spring S2 in the direction of the retarded angle region A.
As a result, as shown in
As shown in
In contrast, as shown in
As a result, since the biasing operation position to the inner rotor 2 by the inner engaging portion 31 of the respective spiral springs S1 and S2 is limited to each position of the first and second restriction pieces 33A and 33B, if the distribution of the operating oil to each of the retarded angle chamber 11 and the advanced angle chamber 12 is stopped, as shown in
A third embodiment employs not the spiral spring, but two torsion springs S1 and S2 as a biasing member for maintaining the relative phase at the start-up optimum phase, as shown in
The outer engaging portions 32 of the torsion springs S1 and S2 are engaged to the engaging concave portion 6T in a relatively non-movable manner in the inner surface of the front plate 6 which is connected to the outer rotor 1. However, the inner engaging portions 31 of the torsion springs S1 and S2 are engaged to the engaging concave portion 10G with a wide width in a relatively movable manner, the width of the engaging concave portion being cut sufficiently rather than an outer diameter of the inner engaging portion 31.
The restriction pieces 33A and 33B engaging to the inner engaging portions 31 of the torsion springs S1 and S2 protrude from the bottom portion of the front plate 6.
The same working effect as the second embodiment is achieved by the engaging concave portion 10G with the wide width and the restriction pieces 33A and 33B.
As will be understood from
In contrast, as will be understood from
As a result, since the biasing operation position to the inner rotor 2 by the inner engaging portion 31 of the respective torsion springs S1 and S2 is limited to each position of the first and second restriction pieces 33A and 33B, if the distribution of the operating oil to each of the retarded angle chamber 11 and the advanced angle chamber 12 is stopped, in a case where the balance of the biasing force of the respective torsion springs S1 and S2 is lost from an original state due to long-term use, the rotational phase is not deviated by the collapse in the balance, and can be maintained at the start-up optimum phase with high accuracy. The position of the first restriction piece 33A corresponds to the first predetermined phase, and the position of the second restriction piece 33B corresponds to the second predetermined phase.
A fourth embodiment employs single torsion spring S having an inner engaging portion 31 which is engaged to the engaging concave portion 10G of the inner rotor 2 and an outer engaging portion 32 which is engaged to the engaging concave portion 6T of the outer rotor 1, as a biasing member for maintaining the relative phase at the start-up optimum phase, as shown in
In this embodiment, if the distribution of the operating oil to each of the retarded angle chamber 11 and the advanced angle chamber 12 is stopped, the relative phase is displaced at the start-up optimum phase by the biasing force of the torsion spring S, and is maintained at this phase. The displacement operation from the start-up optimum phase to the retarded angle side by the operating oil is performed, with being accompanied by deformation in which the inner engaging portion 31 of the torsion spring S relatively rotates in a counterclockwise direction with respect to the outer engaging portion 32, when seen at plane view in
A fifth embodiment employs the engaging concave portion 10 of the inner rotor 2 extended long in a circumferential direction and single torsion spring S fitted to the cylindrical operating oil supply/discharge portion Vb, as a biasing member for maintaining the relative phase at the start-up optimum phase. Both ends 31a and 31b of the torsion spring S are extended outwardly in a radial direction, and the torsion spring S is fitted into the engaging concave portion 10 in a state in which both ends 31a and 31b are close to each other against the biasing force of the torsion spring S.
The front plate 6 is provided with a pair of restriction pieces 34A and 34B in a standing manner which abut against or are adjacent to the outside of the torsion spring S in the vicinity of both ends 31a and 31b. In a state in which the distribution of the operating oil to each of the retarded angle chamber 11 and the advanced angle chamber 12 is stopped, as shown in
If the relative phase is displaced toward the retarded angle side by the operation of the operating oil, as shown in
The embodiments disclosed here can be used in the whole valve opening/closing timing control devices capable of setting the opening and closing timing of anyone of an intake valve and an exhaust valve of an engine.
According to a first aspect of this disclosure, a valve opening/closing timing control device includes a driving side rotational member synchronously rotatable with a crankshaft of an internal combustion engine, a driven side rotational member arranged coaxially with the driving side rotational member and synchronously rotatable with a camshaft that opens and closes any one of intake and exhaust valves of the internal combustion engine, a phase converting mechanism displacing a relative phase between the driving side rotational member and the driven side rotational member toward an advanced angle phase side or a retarded angle phase side by distributing an operating fluid to each of two kinds of pressure chambers, the volume of which is complementarily varied by a movable partition, and a biasing member biasing the relative phase toward a predetermined phase suitable for a start-up of the internal combustion engine except for a most advanced angle phase and a most retarded angle phase.
The valve opening/closing timing control device according to the first aspect of this disclosure does not require a lock mechanism constituted of a lock groove formed on one rotational member and a lock pin supported by the other rotational member, but includes the biasing member biasing the relative phase toward a predetermined phase (start-up optimum phase) suitable for a start-up of the internal combustion engine except for a most advanced angle phase and a most retarded angle phase. Consequently, in a state in which it is free of the force of operating oil, the relative phase is shifted to the start-up optimum phase by the movement of the biasing member. Accordingly, since there is no problem in that the movement of the lock pin is interfered with by foreign substances contained in the oil, the maintenance of the relative phase in the start-up optimum phase is carried out reliably by the biasing member.
Further, since the lock mechanism is not constituted of a lock groove formed on one rotational member and a lock pin supported by the other rotational member, but constituted of a biasing member interposed between the driving side rotational member and the driven side rotational member, it is mechanistically simple, and thus the valve opening/closing timing control device which is not susceptible to failure is obtained. In addition, it is possible to downsize the valve opening/closing timing control device.
Furthermore, since it does not require a lock mechanism with a lock pin which alternatively performs fitting and leaving to each of a lock groove, noise is not generated by the lock mechanism when the internal combustion engine starts up.
According to a second aspect of this disclosure, the biasing member includes a first biasing member to bias the relative phase in a direction of the advanced angle phase and a second biasing member to bias the relative phase in a direction of the retarded angle phase, and the biasing member further includes a first restricting portion to define the biasing force of the first biasing member between the predetermined phase and the most retarded angle phase, and a second restricting portion to define the biasing force of the second biasing member between the predetermined phase and the most advanced angle phase.
The biasing member biasing the relative phase toward the predetermined phase in a range from the most advanced angle phase side to the most retarded angle phase side may be constituted by one torsion spring (biasing member) to bias the relative phase toward the predetermined phase under circumstances in which an external force does not act. However, since the biasing force of the biasing member is most small near the predetermined phase, it is difficult to maintain the relative phase reliably at the predetermined phase. Further, as it is deviated from the predetermined phase to the most advanced angle phase side or the most retarded angle phase side, a restoring force of the biasing member is increased. As a result, high oil pressure is needed to displace the relative phase against the biasing force of the biasing member, which tends to increase energy loss.
However, as the configuration, if it is constituted of two biasing members, in which a biasing direction thereof is opposite to each other, and the relative phase is biased to the predetermined phase in cooperation with an acting force from two biasing members, the relative phase can be maintained reliably at the predetermined phase, for example, as compared with the above configuration in which one torsion spring (biasing member) is installed.
In the configuration, when the relative phase is operated from the predetermined phase to the retarded angle phase side or the advanced angle phase side by operation of the oil pressure or the like, for example, when the relative phase is operated toward the retarded angle phase side, only the biasing force of one biasing member acts in a state in which the biasing force of the second biasing member is defined between the predetermined phase and the most advanced angle phase by the second restriction portion. Therefore, the relative phase can be displaced by relatively small oil pressure.
In addition, in the configuration, according to the respective restriction portions, the biasing force by the first biasing member is defined between the predetermined phase and the most retarded angle phase and the biasing force by the second biasing member is defined between the predetermined phase and the most advanced angle phase. Therefore, in a state in which there is no oil pressure or the like for performing the displacement operation of the relative phase, the predetermined phase is achieved in a state in which the biasing force by the first biasing member toward the advanced angle phase rather than the predetermined phase is restricted by the first restriction portion, and the biasing force by the second biasing member toward the retarded angle phase rather than the predetermined phase is restricted by the second restriction portion. As a result, in a case where two biasing forces are not equal to each other through error in manufacturing precision of the biasing members or the like, the relative phase can be easily controlled at the original desired phase without deviating to the retarded phase side or the advanced angle phase side through the error.
According to a third aspect of this disclosure, the biasing member has the biasing force against a displacing force acting on the driven side rotational member based on torque fluctuation of the camshaft.
With the configuration, since the biasing force of the biasing member tends to offset the displacing force acting on the driven side rotational member based on the torque fluctuation of the camshaft, it is possible to increase the maintaining accuracy of the relative phase by the biasing member in the predetermined phase, and control accuracy of the relative phase by oil pressure is enhanced.
According to a fourth aspect of this disclosure, the biasing member is a spring placed between the driving side rotational member and the driven side rotational member.
With the configuration, since the aspect of this disclosure can be implemented by the biasing member of a simple configuration in which a spring such as a torsion spring or a spiral spring is disposed between the driving side rotational member and the driven side rotational member which are placed adjacent to each other, an assembling operation of the valve opening/closing timing control device is easily performed, and miniaturization can be easily performed.
According to a fifth aspect of this disclosure, a valve opening/closing timing control device includes a driving side rotational member synchronously rotatable with a crankshaft of an internal combustion engine, a driven side rotational member arranged coaxially with the driving side rotational member and synchronously rotatable with a camshaft that opens and closes any one of intake and exhaust valves of the internal combustion engine, a retarded angle chamber and an advanced angle chamber formed by the driving side rotational member and the driven side rotational member, in which the retarded angle chamber moves a relative phase of the driven side rotational member to the driving side rotational member in a retarded angle direction as a volume thereof is enlarged, and the advanced angle chamber moves the relative phase in an advanced angle direction as a volume thereof is enlarged, and a biasing member biasing the relative phase toward a predetermined phase except for a most advanced angle phase and a most retarded angle phase.
That is, the valve opening/closing timing control device according to the fifth aspect of this disclosure does not require a lock mechanism constituted of a lock groove formed on one rotational member and a lock pin supported by the other rotational member, but includes the biasing member biasing the relative phase toward a predetermined phase except for the most advanced angle phase and the most retarded angle phase. Consequently, in a state in which it is free of the force of the operating oil, the relative phase is shifted to the predetermined phase by the movement of the biasing member. Accordingly, since there is no problem in that the movement of the lock pin is interfered with by foreign substances contained in the oil, the maintenance of the relative phase in the predetermined phase (e.g., start-up optimum phase) is carried out reliably by the biasing member.
According to a sixth aspect of this disclosure, the biasing member includes a first biasing member to bias the relative phase to a first predetermined phase which is positioned in a direction of the advanced angle phase rather than the most retarded angle phase, and a second biasing member to bias the relative phase to a second predetermined phase which is positioned in a direction of the retarded angle phase rather than the most advanced angle phase. The first biasing member biases the relative phase from the most retarded angle phase to the first predetermined phase and does not bias the relative phase from the first predetermined phase to the most advanced angle phase. The second biasing member biases the relative phase from the most advanced angle phase to the second predetermined phase and does not bias the relative phase from the second predetermined phase to the most retarded angle phase.
The biasing member biasing the relative phase toward the predetermined phase in a range from the most advanced angle phase side to the most retarded angle phase side may be constituted by, for example, one torsion spring. However, since the biasing force of the biasing member is most small near the predetermined phase, it is difficult to maintain the relative phase reliably at the predetermined phase. Further, as it is deviated from the predetermined phase to the most advanced angle phase side or the most retarded angle phase side, a restoring force of the biasing member is increased. As a result, high oil pressure is needed to displace the relative phase against the biasing force of the biasing member, which tends to increase energy loss.
In the configuration, if it is constituted of two biasing members, in which a biasing direction thereof is opposite to each other, and the relative phase is biased to the predetermined phase in cooperation with an acting force from two biasing members, the relative phase can be maintained reliably at the predetermined phase, for example, as compared with the above configuration in which one torsion spring is installed.
In the configuration, when the relative phase is operated from the predetermined phase to the retarded angle phase side or the advanced angle phase side by operation of the oil pressure or the like, for example, when the relative phase is operated toward the retarded angle phase side, only the biasing force of one biasing member acts in a state in which the biasing force of the second biasing member is defined between the predetermined phase and the most advanced angle phase by the second restriction portion. Therefore, the relative phase can be displaced by relatively small oil pressure.
In addition, in the configuration, in a state in which there is no oil pressure or the like for performing displacement operation of the relative phase, the first biasing portion does not bias the predetermined phase from the first predetermined phase to the most advanced angle phase, and the second biasing portion does not bias the predetermined phase from the second predetermined phase to the most retarded angle phase. As a result, in a case where two biasing forces are not equal to each other through error in manufacturing precision of the biasing members or the like, the relative phase can be easily controlled at the original desired phase without deviating to the retarded phase side or the advanced angle phase side through the error.
The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-220652 | Sep 2009 | JP | national |
