JP5192454B2 - Valve timing adjustment device - Google Patents

Description

    The present invention relates to a valve timing adjusting device for an internal combustion engine.

Conventionally, a valve timing adjusting device is provided in a driving force transmission system that transmits a driving force from a driving shaft of an internal combustion engine to a driven shaft, and adjusts the opening / closing timing of at least one of an intake valve and an exhaust valve that the driven shaft opens and closes. Is known.
In Patent Document 1, the relative rotation phase between the housing and the vane rotor is controlled by switching the oil passage for supplying the hydraulic oil from the hydraulic pump to the advance chamber and the retard chamber using an oil control valve. In addition, a check valve is provided between the advance and retard chambers and the oil control valve to reduce hydraulic oil leakage from the advance or retard chamber to the oil control valve due to the cam torque reaction force. Yes.
In Patent Document 2, the relative rotation phase between the housing and the vane rotor is adjusted by controlling the rotation of the vane rotor by a brake using a magnetorheological fluid.

JP 2003-106115 A JP 2008-31905 A

However, an oil control valve that switches the oil passage for supplying hydraulic oil from the hydraulic pump of the internal combustion engine to the advance chamber and the retard chamber, a check valve that reduces leakage of hydraulic oil from the advance chamber and the retard chamber, etc. If provided, the configuration of the oil passage system of the valve timing adjusting device becomes complicated, and there is a concern that the size of the system will increase.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a valve timing adjusting device that can be reduced in size with a simple configuration.

According to the first aspect of the invention, the vane rotor that partitions the accommodation chamber formed in the housing that rotates together with one of the drive shaft and the driven shaft into the advance chamber and the retard chamber is provided so as to be relatively rotatable with respect to the housing. Rotates with the other of the drive shaft or driven shaft. Magnetorheological fluid is filled in the advance chamber, the retard chamber, and the communication path connecting the advance chamber and the retard chamber, and the magnetic field generating means applies a magnetic field to the magnetorheological fluid. The switching means corresponds to the state in which the cam torque reaction force acting on the driven shaft by opening and closing at least one of the intake valve and the exhaust valve acts in the forward rotation direction or the reverse rotation direction of the driven shaft. Switching between application and non-application of the magnetic field. Thereby, the viscosity of the magnetorheological fluid changes corresponding to the state in which the cam torque reaction force acts on the vane rotor. Thus, by controlling the flow of the magnetorheological fluid between the advance chamber and the retard chamber, the relative rotational phase of the vane rotor with respect to the housing can be controlled using the cam torque reaction force as a power source. Therefore, the invention according to claim 1 can reduce the physique with a simple configuration without providing an oil control valve, a check valve, or the like, as compared with the conventional hydraulic valve timing adjusting device.
In addition, since the power of the hydraulic pump of the internal combustion engine is not used, it is possible to hold the phase at the optimum position for starting the internal combustion engine without waiting for the hydraulic pressure to increase immediately after the internal combustion engine is started, thereby improving fuel efficiency immediately after the start. , Emission can be reduced.
Furthermore, the invention according to claim 1 can eliminate the motor and the drive unit that drives the motor, and can realize low cost and low power consumption, as compared with the conventional motor-driven valve timing adjusting device.

The magnetic field generating means applies a magnetic field to the magnetorheological fluid filled in the communication path formed by one or both of the housing and the vane rotor. As a result, the magnetorheological fluid flowing through the advance chamber and the retard chamber can be controlled in one place, phase control can be performed accurately, and the magnetic field generating means can be miniaturized. .

The communication path has an annular communication path provided coaxially with the annular magnetic field generating means. Thus, when a magnetic field is applied to the magnetorheological fluid in the annular communication path, the magnetic particles form clusters substantially perpendicular to the direction in which the annular communication path extends. For this reason, the responsiveness of the viscosity change of the magnetorheological fluid to the magnetic field applied by the magnetic field generating means is improved, and reliable phase control can be performed. The term “coaxial” is not limited to the case where the axial centers coincide with each other, but includes those that are substantially the same.

Changeover means, to retain the relative rotational phase between the housing and the vane rotor, by the state of the magnetic field generating means for applying a magnetic field to the magnetic fluid, to increase the viscosity of the magnetorheological fluid. In addition, when the vane rotor is controlled to advance with respect to the housing, the magnetic field generating means is configured to prevent the magnetic field from being applied to the magnetorheological fluid by the magnetic field generating means so as to correspond to the state in which the cam torque reaction force acts in the positive rotation direction of the driven shaft. By setting the state of application, the viscosity of the magnetorheological fluid is reduced. In addition, when the vane rotor is controlled to be retarded with respect to the housing, the magnetic field applied to the magnetorheological fluid by the magnetic field generating means is not applied so as to correspond to the state in which the cam torque reaction force acts in the reverse rotation direction of the driven shaft. This reduces the viscosity of the magnetorheological fluid.
When the viscosity of the magnetorheological fluid increases due to the magnetic field applied by the magnetic field generating means, the movement of the magnetorheological fluid between the advance chamber and the retard chamber is limited, and the relative rotational phase between the vane rotor and the housing is maintained.
If the viscosity of the magnetorheological fluid decreases when the cam torque reaction force acts in the reverse rotation direction of the driven shaft, the magnetorheological fluid moves from the advance chamber to the retard chamber via the communication path, and the vane rotor moves against the housing. Rotate in the retard direction. On the other hand, if the viscosity of the magnetorheological fluid decreases when the cam torque reaction force acts in the positive rotation direction of the driven shaft, the magnetorheological fluid moves from the retard chamber to the advance chamber via the communication path, and the vane rotor is moved to the housing. Rotate in the advance direction. In this way, the magnetic field generating means can control the relative rotational phase between the housing and the vane rotor.

Magnetic field generating means includes a constant magnetic field generating means for constantly applying a magnetic field to the magnetic fluid, the magnetic field cancellation means to be applied to the magnetorheological fluid a magnetic field that cancels the magnetic field at all times the magnetic field generating means.
The magnetic field canceling means applies the magnetic field canceling means so as to correspond to the state in which the cam torque reaction force acts in the positive rotation direction of the driven shaft when controlling the advance angle of the vane rotor with respect to the housing, and delays the vane rotor with respect to the housing. In the case of angle control, the magnetic field canceling means is applied so as to correspond to the state in which the cam torque reaction force acts in the reverse rotation direction of the driven shaft.
In general, the valve timing adjusting device has a longer phase holding period than the phase controlling period. For this reason, the electric power consumed by the magnetic field cancellation means can be reduced by always maintaining the phase by the magnetic field generation means.

According to the invention of claim 2 , the constant magnetic field generating means is provided coaxially with the magnetic field canceling means across the communication path. For this reason, the magnetic field canceling means can surely cancel the magnetic field formed by the magnetic field generating means at all times and accurately control the phase of the valve timing adjusting device.

According to the invention of claim 3 , the magnetorheological fluid is sealed inside the housing. For this reason, the structure of the oil passage system can be simplified and the physique can be reduced in size without providing a fluid passage outside the housing.

It is sectional drawing of the valve timing adjustment apparatus by 1st Embodiment of this invention. It is sectional drawing of the II-II line of FIG. 1 is a schematic diagram of an internal combustion engine to which a valve timing adjusting device according to a first embodiment of the present invention is applied. It is sectional drawing of the valve timing adjustment apparatus by 1st Embodiment of this invention. It is principal part sectional drawing of the valve timing adjustment apparatus by 1st Embodiment of this invention. It is a characteristic view of the valve timing adjustment apparatus by 1st Embodiment of this invention. It is sectional drawing of the valve timing adjustment apparatus by 2nd Embodiment of this invention. It is a characteristic view of the valve timing adjustment apparatus by 2nd Embodiment of this invention.

Hereinafter, a plurality of embodiments according to the present invention will be described with reference to the drawings.
(First embodiment)
The valve timing adjusting device according to the first embodiment of the present invention is used for a driving force transmission system of an internal combustion engine, and adjusts the opening / closing timing of an intake valve. In the driving force transmission system used in the valve timing adjusting device, as shown in FIG. 3, it is fixed to a gear 2 fixed to a crankshaft 1 as a driving shaft of an internal combustion engine and camshafts 3 and 4 as driven shafts. The chain 7 is wound around the gears 5 and 6, and torque is transmitted from the crankshaft 1 to the camshafts 3 and 4. One camshaft 3 drives the intake valve 8 to open and close, and the other camshaft 4 drives the exhaust valve 9 to open and close. The valve timing adjusting device 10 connects the sprocket gear 5 to the chain 7, connects the vane rotor to the camshaft 3, and rotates the crankshaft 1 and the camshaft 3 with a predetermined phase difference. Adjust the opening and closing timing. The valve timing adjusting device 10 rotates clockwise in FIG. Hereinafter, this rotation direction is referred to as an advance direction, and the reverse rotation direction is referred to as a retard direction.

As shown in FIGS. 1 and 2, the valve timing adjusting device 10 includes a housing 11, a vane rotor 19, a magnetorheological fluid 50, a coil 60, and the like.
The housing 11 includes a sprocket 12, a shoe housing 13, a front plate 14, and the like. The sprocket 12 is formed in a substantially disk shape, and has a gear 5 at an end portion in the radial direction. The sprocket 12 has an axial hole 121 through which the camshaft 3 passes in the axial direction.
The shoe housing 13 and the front plate 14 are integrally formed and fixed coaxially with the sprocket 12. The shoe housing 13 is formed integrally with an annular peripheral wall 130 and shoes 131 to 133 extending radially inward from the peripheral wall 130. The shoes 131 to 133 are provided at substantially equal intervals in the rotation direction, and a storage chamber 30 having a fan-like cross section is formed in a gap between shoes adjacent in the rotation direction. The front plate 14 is formed in a substantially disc shape and has a circular hole 140 through which the center bolt 15 passes in the axial direction. The front plate has a cover 141 that covers the center bolt 15 in a liquid-tight manner.

The vane rotor 19 is accommodated in the housing 11 so as to be relatively rotatable. The vane rotor 19 includes a cylindrical rotor 20 and vanes 21 to 23 that protrude radially outward from the rotor 20 and are installed at substantially equal intervals in the rotation direction. The outer diameters of the vanes 21 to 23 are formed smaller than the inner diameter of the peripheral wall 130 of the shoe housing 13. Further, the outer diameter of the rotor 20 is formed smaller than the inner diameters of the shoes 131 to 133.
The rotor 20 has a bolt hole 201 through which the center bolt 15 passes in the axial direction. The center bolt 15 is fastened to the screw hole 151 of the camshaft 3 through the bolt hole 201 from the front plate 14 side, and fixes the camshaft 3 and the vane rotor 19.

  The vanes 21 to 23 partition the storage chamber 30 into a retard chamber and an advance chamber as a pressure chamber. An advance chamber 31 is formed between the shoe 131 and the vane 21, an advance chamber 32 is formed between the shoe 132 and the vane 22, and an advance chamber 33 is formed between the shoe 133 and the vane 23. Yes. Further, a retardation chamber 34 is formed between the shoe 132 and the vane 21, a retardation chamber 35 is formed between the shoe 133 and the vane 22, and a retardation chamber 36 is formed between the shoe 131 and the vane 23. Is formed. 1 represent the advance direction and the retard direction of the vane rotor 19 with respect to the housing 11.

Inside the rotor 20, there is provided a communication passage 40 that communicates the advance chambers 31 to 33 and the retard chambers 34 to 36. The communication passage 40 includes a first shaft passage 41, a second shaft passage 42, advance communication passages 43 to 45, retard communication passages 46 to 48, and an annular communication passage 49.
The first shaft passage 41 and the second shaft passage 42 sandwich the bolt hole 201 in the radial direction and extend from the front plate 14 side to the middle of the rotor 20.
The advance communication passages 43 to 45 communicate the advance chambers 31 to 33 with the first shaft passage 41. The retard communication passages 46 to 48 are displaced in the axial direction so as not to overlap the advance communication passages 43 to 45, and communicate with the retard chambers 34 to 36 and the second shaft passage 42.
The annular communication passage 49 is provided in an annular shape around the bolt hole 201, and communicates the first shaft passage 41 and the second shaft passage 42.

The magnetorheological fluid 50 is sealed in the advance chambers 31 to 33, the retard chambers 34 to 36 and the communication passage 40 in a filled state. A seal member (not shown) is provided between the inner wall of the shaft hole 121 of the sprocket 12 and the outer wall of the camshaft 3 to prevent leakage of the magnetorheological fluid 50. Further, the cover 141 of the front plate 14 prevents the magnetic viscous fluid 50 from leaking out.
The magnetorheological fluid 50 is a kind of functional fluid, in which magnetic particles are suspended in a liquid base material. A liquid non-magnetic material such as oil is used as the base material of the magnetorheological fluid 50, and a powdery magnetic material such as carbonyl iron is used as the magnetic particles. The magnetorheological fluid 50 increases in apparent viscosity following the strength of the applied magnetic field, is proportional to the viscosity, and is inversely proportional to the size of the space in which the magnetorheological fluid 50 exists, and the shear stress is increased. Has the property of increasing.

The coil 60 is formed in an annular shape and is provided coaxially with the annular communication passage 49 at a position facing the annular communication passage 49 in the axial direction. In the present embodiment, the coil 60 corresponds to the magnetic field generating means described in the claims. The coil 60 is fixed to the internal combustion engine by a stay (not shown). When the coil 60 is energized from an electronic control unit (hereinafter referred to as “ECU”) 70 as switching means, a magnetic flux flows as shown by a broken line 61 in FIG. 4 to generate a magnetic field. The ECU 70 is provided integrally with the coil 60 or separately.
In a state where the coil 60 is not energized, the magnetic viscous fluid 50 in the annular communication passage 49 is in a state where the magnetic particles are diffused into the liquid base material as shown in FIG. At this time, the magnetorheological fluid 50 has a low viscosity and can move between the advance chambers 31 to 33 and the retard chambers 34 to 36 via the communication path 40.
On the other hand, when the coil 60 is energized from the ECU 70, the magnetic viscous fluid 50 in the annular communication path 49 is caused to extend in the direction in which the annular communication path 49 extends, as shown in FIG. When the magnetic particles form clusters almost vertically, the fluid resistance increases and the apparent viscosity increases. For this reason, the movement of the magnetorheological fluid 50 between the advance chambers 31 to 33 and the retard chambers 34 to 36 is restricted by the flow in the annular communication passage 49 being suppressed.

Here, when the camshaft 3 is rotated by torque transmission from the crankshaft 1 and the cam 18 of the camshaft 3 shown in FIG. 3 opens the intake valve 8, the camshaft 3 is moved by the elastic force of the valve spring 17. A cam torque reaction force acts in the reverse rotation direction. On the other hand, when the cam 18 of the camshaft 3 closes the intake valve 8, a cam torque reaction force acts in the positive rotation direction of the camshaft 3 due to the elastic force of the valve spring 17.
The ECU 70 energizes the coil 60 in response to a state in which the cam torque reaction force acting on the camshaft acts in the forward rotation direction or the reverse rotation direction of the camshaft. Thereby, the flow of the magnetorheological fluid 50 between the advance chamber and the retard chamber is controlled, and the phase control of the valve timing adjusting device 10 using the cam torque reaction force as a power source becomes possible.

Hereinafter, the operation of the valve timing adjusting device 10 will be described in detail.
<When starting internal combustion engine>
When the ignition power is turned on, the ECU 70 starts energizing the coil 60. Due to the magnetic field generated by the coil 60, the viscosity of the magnetorheological fluid 50 in the annular communication passage 49 increases, and the magnetorheological fluid 50 is restricted from moving between the advance chambers 31 to 33 and the retard chambers 34 to 36. Is done. For this reason, the valve timing adjusting device 10 is held at an optimum position for starting, and the occurrence of a hitting sound caused by the collision between the housing 11 and the vane rotor 19 due to the cam torque reaction force is suppressed. Here, the optimal position for starting is not limited to the most retarded position, and in a valve timing adjusting device having a wide operating range, a predetermined intermediate phase may be the optimal position for starting.

<After starting internal combustion engine>
When the internal combustion engine starts, in the four-cylinder engine of the present embodiment, as shown in FIG. 6, while the crankshaft 1 rotates 720 °, the four intake valves provided on the camshaft are driven to open and close, Positive and negative cam torque reaction forces act on the camshaft 3 four times. In FIG. 6, the cam torque reaction force acting in the reverse rotation direction of the camshaft 3 is shown on the positive side, and the cam torque reaction force acting in the positive rotation direction of the camshaft 3 is shown on the negative side.

<Advance angle operation>
When the valve timing adjusting device 10 is advanced, the ECU 70 corresponds to a state in which the cam torque reaction force is on the negative side, and turns off or reduces the energization to the coil 60. As a result, the magnetic field generated by the coil 60 disappears or weakens, and the magnetorheological fluid 50 moves from the retard chambers 34 to 36 to the retard communication passages 46 to 48, the second shaft passage 42, the annular communication passage 49, and the first shaft. It moves to the advance chambers 31 to 33 via the passage 41 and the advance communication passages 43 to 45 in this order. For this reason, the vane rotor 19 rotates in the advance direction with respect to the housing 11.

<At retarded angle operation>
When the valve timing adjusting device 10 is retarded, the ECU 70 corresponds to a state where the cam torque reaction force is on the positive side, and turns off or reduces the energization to the coil 60. As a result, the magnetic field generated by the coil 60 disappears or weakens, and the magnetorheological fluid 50 moves from the advance chambers 31 to 33 to the advance communication passages 43 to 45, the first shaft passage 41, the annular communication passage 49, and the second shaft. It passes through the passage 42 and the retard communication passages 46 to 48 in this order, and moves to the retard chambers 34 to 36. For this reason, the vane rotor 19 rotates in the retard direction with respect to the housing 11.
Here, the ECU 70 changes the magnitude of the viscosity of the magnetorheological fluid 50 in the annular communication passage 49 by adjusting the magnitude of the voltage applied to the coil 60 or the energization stop time, so that the vane rotor 19 moves relative to the housing 11. Accurate phase control can be performed by adjusting the rotation speed in the advance direction or the retard direction.

<Intermediate holding operation>
When the cam angle sensor (not shown) provided on the camshaft 3 detects that the vane rotor 19 has reached the target phase, the ECU 70 keeps the coil 60 energized. Due to the magnetic field generated by the coil 60, the viscosity of the magnetorheological fluid 50 in the annular communication passage 49 increases, and the magnetorheological fluid 50 cannot move between the advance chambers 31 to 33 and the retard chambers 34 to 36. Become. For this reason, the vane rotor 19 is held at the target phase.
Here, when it is detected by a cam angle sensor (not shown) that the vane rotor 19 has deviated from the target phase, the ECU 70 supplies power to the coil 60 in response to a state where the cam torque reaction force is on the positive side or the negative side. Turn off or reduce for a predetermined period. By this feedback control, the ECU 70 can correct the phase of the vane rotor 19 to the target phase.

<When the internal combustion engine is stopped>
When the stop of the internal combustion engine is instructed during the operation of the valve timing adjusting device 10, the vane rotor 19 is phase-controlled at the optimum position for starting by the same operation as the advance angle operation or the retard angle operation. In this state, when the rotation of the internal combustion engine stops, the ECU 70 stops energization of the coil 60.

In the present embodiment, the advance chambers 31 to 33, the retard chambers 34 to 36 and the communication passage 40 are sealed with the magnetorheological fluid 50, and the cam torque reaction force in the forward rotation direction or the reverse rotation direction of the camshaft 3 is sealed. The ECU 70 turns off or reduces the energization of the coil 60 that applies a magnetic field to the magnetorheological fluid 50 in the annular communication passage 49. By changing the viscosity of the magnetorheological fluid 50 in the annular communication passage 49 by the magnetic field generated by the coil 60, the flow of the magnetorheological fluid 50 between the advance chambers 31 to 33 and the retard chambers 34 to 36 is controlled. be able to. Thereby, the phase control of the vane rotor 19 with respect to the housing 11 can be performed using the cam torque reaction force as a power source. Therefore, the valve timing adjusting device 10 can simplify the oil passage configuration and reduce the size of the body by eliminating the conventional oil control valve and check valve.
In the present embodiment, the moving speed of the vane rotor 19 can be adjusted by controlling the voltage applied to the coil 60 and the energization stop time. For this reason, the valve timing adjusting device 10 can perform accurate phase control.
Furthermore, in this embodiment, since it is possible to maintain the phase at an optimal position for starting the internal combustion engine immediately after starting the internal combustion engine, it is possible to improve fuel consumption immediately after the start and reduce emissions.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure substantially the same as 1st Embodiment, and description is abbreviate | omitted.
In the valve timing adjusting device 100 of this embodiment, a concave portion 24 that is recessed in the axial direction is provided on the sprocket side of the rotor 20, and an annular permanent magnet 62 is fitted in the concave portion 24. The permanent magnet 62 is provided coaxially with the coil 60 across the communication path 40. The permanent magnet 62 has opposite magnetic poles at both ends in the axial direction, and a magnetic flux flows as shown by a broken line 63 in FIG. 7 to form a magnetic field.

On the other hand, when the coil 60 is energized from the ECU 70, a magnetic flux flows as shown by a broken line 61 in FIG. 7 and generates a magnetic field opposite to the permanent magnet 62. For this reason, the magnetic field generated by the coil 60 cancels at least a part of the magnetic field formed by the permanent magnet 62. Therefore, the combined magnetic field formed by the permanent magnet 62 and the coil 60 disappears or weakens according to the energization state from the ECU 70 to the coil 60.
In a state where the coil 60 is not energized, the magnetic viscous fluid 50 in the communication path 40 maintains a high viscosity state by the magnetic field formed by the permanent magnet 62. For this reason, the movement of the magnetorheological fluid 50 between the advance chambers 31 to 33 and the retard chambers 34 to 36 is restricted.
On the other hand, when the coil 70 is energized from the ECU 70, the combined magnetic field formed by the permanent magnet 62 and the coil 60 disappears or weakens, and the viscosity of the magnetorheological fluid 50 in the communication path 40 decreases. For this reason, the magnetorheological fluid 50 can move between the advance chambers 31 to 33 and the retard chambers 34 to 36.
In the present embodiment, the coil 60 corresponds to a magnetic field canceling unit, and the permanent magnet 62 corresponds to a constant magnetic field generating unit that constantly applies a magnetic field to the magnetorheological fluid.

Hereinafter, the operation of the valve timing adjusting device 10 will be described in detail.
<When starting internal combustion engine>
When the internal combustion engine is started, the coil 60 is not energized, and the viscosity of the magnetorheological fluid 50 in the communication path 40 is increased by the magnetic field formed by the permanent magnet 62. For this reason, the magnetic viscous fluid 50 cannot move between the advance chambers 31 to 33 and the retard chambers 34 to 36. As a result, the valve timing adjusting device 10 is held at an optimum position for starting, and the occurrence of a hitting sound caused by the collision between the housing 11 and the vane rotor 19 due to the cam torque reaction force is suppressed.

<Advance angle operation>
When the valve timing adjusting device 10 is advanced after the internal combustion engine is started, the ECU 70 turns on the energization of the coil 60 in response to the state where the cam torque reaction force is on the negative side, as shown in FIG. As a result, the combined magnetic field formed by the permanent magnet 62 and the coil 60 disappears or weakens, and the magnetorheological fluid 50 moves from the retard chambers 34 to 36 to the retard communication passages 46 to 48, the second shaft passage 42, and the annular shape. The communication passage 49, the first shaft passage 41, and the advance communication passages 43 to 45 travel in this order to the advance chambers 31 to 33. For this reason, the vane rotor 19 rotates in the advance direction with respect to the housing 11.

<At retarded angle operation>
When the valve timing adjusting device 10 is retarded, the ECU 70 turns on the energization of the coil 60 in response to a state where the cam torque reaction force is on the positive side. Thereby, the synthetic magnetic field formed by the permanent magnet 62 and the coil 60 disappears or weakens, and the magnetorheological fluid 50 moves from the advance chambers 31 to 33 to the advance communication passages 43 to 45, the first shaft passage 41, the annular shape. It moves to the retardation chambers 34 to 36 through the communication passage 49, the second shaft passage 42, and the retard communication passages 46 to 48 in this order. For this reason, the vane rotor 19 rotates in the retard direction with respect to the housing 11.
Here, the ECU 70 changes the viscosity of the magnetorheological fluid 50 in the communication path 40 by adjusting the voltage or energization time for energizing the coil 60, so that the vane rotor 19 is advanced or retarded with respect to the housing 11. The rotational speed in the angular direction can be adjusted.

<Intermediate holding operation>
When the cam angle sensor (not shown) provided on the camshaft 3 detects that the vane rotor 19 has reached the target phase, the ECU 70 turns off the energization of the coil 60. Due to the magnetic field formed by the permanent magnet 62, the viscosity of the magnetorheological fluid 50 in the communication path 40 increases, and the magnetorheological fluid 50 cannot move between the advance chambers 31 to 33 and the retard chambers 34 to 36. Become. For this reason, the vane rotor 19 is held at the target phase.
Here, when it is detected by a cam angle sensor (not shown) that the vane rotor 19 has deviated from the target phase, the ECU 70 supplies power to the coil 60 in response to a state where the cam torque reaction force is on the positive side or the negative side. Turn on for a predetermined period. Thereby, the phase of the vane rotor 19 can be corrected to the target phase.

<When the internal combustion engine is stopped>
When the stop of the internal combustion engine is instructed during the operation of the valve timing adjusting device 10, the vane rotor 19 is phase-controlled at the optimum position for starting by the same operation as the advance angle operation or the retard angle operation. In this state, the ECU 70 stops energization of the coil 60.

  In the present embodiment, an annular permanent magnet 62 is provided on the rotor 20, and the permanent magnet 62 always maintains a phase by applying a magnetic field to the magnetorheological fluid 50 in the communication path 40. When the phase is advanced or retarded, the coil 60 generates a magnetic field opposite to the permanent magnet 62 by energization from the ECU 70 and cancels at least a part of the magnetic field formed by the permanent magnet. In general, the valve timing adjusting device has a longer period for maintaining the phase than a period for controlling the phase. For this reason, the electric power consumed to energize the coil 60 can be reduced by holding the phase with the permanent magnet 62.

(Other embodiments)
In the above embodiments, the valve timing adjusting device for controlling the intake valve of the internal combustion engine has been described. On the other hand, the present invention may be applied to a valve timing adjusting device that controls an exhaust valve of an internal combustion engine.
In the above embodiments, the coil is fixed to the internal combustion engine. On the other hand, the coil may be fixed to the housing, and the coil may be energized via a slip ring or the like. Thereby, the distance of a coil and a communicating path can be made small, and the magnetic field applied to a communicating path can be strengthened.
In the above embodiments, the vane rotor is provided with a communication path. On the other hand, you may make it the structure which provides a communicating path in a housing, and you may make it the structure which provides a communicating path outside the housing.
In the said 2nd Embodiment, the coil was provided in the outer side of the housing and the permanent magnet was provided in the vane rotor. On the other hand, you may make it the structure which provides a permanent magnet in the outer side of a housing and provides a coil in a vane rotor.
As described above, the present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the spirit of the claims.

  1: crankshaft (drive shaft), 3, 4: camshaft (driven shaft), 8: intake valve, 9: exhaust valve, 10: valve timing adjusting device, 11: housing, 30: housing chamber, 31-33: Advance chamber, 34-35 retard chamber, 19: vane rotor, 40: communication path, 49: annular communication path, 50: magnetorheological fluid, 60: coil (magnetic field generating means), 70: ECU (switching means)

Claims (3)

A valve timing adjusting device that adjusts the opening / closing timing of at least one of an intake valve and an exhaust valve that opens and closes a driven shaft by torque transmission of a drive shaft of an internal combustion engine,
A housing that rotates with one of the drive shaft or the driven shaft;
A vane rotor that rotates together with the other of the drive shaft or the driven shaft, partitions a storage chamber formed in the housing into an advance chamber and a retard chamber, and is rotatable relative to the housing;
A communication path formed by one or both of the housing and the vane rotor, and communicating the advance chamber and the retard chamber;
A magnetorheological fluid that fills the advance chamber, the retard chamber, and the communication path, and whose viscosity changes according to the applied magnetic field;
Magnetic field generating means for applying a magnetic field to the magnetorheological fluid filled in the communication path ;
The magnetic viscosity generated by the magnetic field generating means corresponds to a state where a cam torque reaction force acting on the driven shaft by opening / closing at least one of the intake valve and the exhaust valve acts in the forward rotation direction or the reverse rotation direction of the driven shaft. e Bei and switching means for switching the state of the application and non-application of the magnetic field to the fluid, and
The communication path has an annular communication path provided coaxially with the magnetic field generating means formed in an annular shape,
The magnetic field generation means includes a constant magnetic field generation means for constantly applying a magnetic field to the magnetorheological fluid, and a magnetic field cancellation means for applying a magnetic field for canceling the magnetic field of the constant magnetic field generation means to the magnetorheological fluid,
The switching means is
When maintaining the relative rotational phase between the housing and the vane rotor, the magnetic field generating means applies a magnetic field to the magnetorheological fluid;
When the advance angle of the vane rotor is controlled with respect to the housing, the magnetic field canceling means is applied in response to a cam torque reaction force acting in the positive rotation direction of the driven shaft, and the magnetic field generating means applies the magnetic force. The magnetic field to the viscous fluid is not applied,
When the vane rotor is controlled to be retarded with respect to the housing, the magnetic field canceling means is applied in response to a cam torque reaction force acting in the reverse rotation direction of the driven shaft, and the magnetic field generating means applies the magnetic force. A valve timing adjusting device characterized in that a magnetic field to a viscous fluid is not applied. 2. The valve timing adjusting device according to claim 1 , wherein the constant magnetic field generating means is provided coaxially with the magnetic field canceling means across the communication path. The magneto-rheological fluid, the valve timing controller according to claim 1 or 2, characterized in that it is sealed inside the housing.

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