JP4760814B2 - Valve timing adjustment device - Google Patents

Description

  The present invention controls a valve timing adjustment device (hereinafter referred to as VVT) that controls the advance angle of a camshaft of an internal combustion engine (hereinafter referred to as an engine) by hydraulic control and varies the opening and closing timing of at least one of an intake valve and an exhaust valve. Name).

The background art will be described with reference to FIG. 5 (the reference numerals in the figure are common to the embodiments described later).
The VVT is attached to the camshaft of the engine and has a variable valve timing mechanism (hereinafter referred to as VCT) 2 that can continuously change the valve opening and closing timing, and a hydraulic control means 3 that hydraulically controls the operation of the VCT 2. And an ECU (abbreviation of engine control unit: control device) 4 for electrically controlling an oil flow control valve (hereinafter referred to as OCV) 22 provided in the hydraulic control means 3 ( For example, see Patent Documents 1 and 2).

  The VCT 2 includes an input side rotor 5 that is rotationally driven by the crankshaft of the engine and an output side rotor 6 that rotationally drives the camshaft of the engine, and the advance chamber A (the output side rotor 6 is displaced to the advance side). The output-side rotor 6 is rotated relative to the input-side rotor 5 by the hydraulic pressure applied to the hydraulic chamber) and the retarding chamber B (the hydraulic chamber that displaces the output-side rotor 6 to the retarding side). This adjusts the amount of advance of the camshaft.

Since the camshaft drives the intake valve or the exhaust valve to open and close, the camshaft generates torque fluctuations accompanying the opening and closing drive of the valve.
The torque fluctuation generated in the camshaft is transmitted to the output-side rotor 6, so that the output-side rotor 6 undergoes torque fluctuation to the retard side and the advance side with respect to the input side rotor 5.
When torque fluctuation toward the advance side is given to the output side rotor 6, an expansion force is generated in the advance chamber A, and the inside of the advance chamber A acts in the negative pressure direction.
On the other hand, when torque fluctuation toward the retard side is given to the output side rotor 6, an expansion force is generated in the retard chamber B, and the inside of the retard chamber B acts in the negative pressure direction.
That is, the expansion force is repeatedly applied to the advance chamber A and the retard chamber B by the torque fluctuation transmitted from the camshaft.

Here, when the discharge hydraulic pressure of the oil pump 21 is low (the oil temperature is high, the engine is rotating slowly and the amount of supplied oil is low), the hydraulic pressure applied from the OCV 22 to the advance chamber A and the retard chamber B is low. It becomes hydraulic.
In this state, if torque fluctuation toward the advance side is given to the output side rotor 6, the torque fluctuation cannot be suppressed by the hydraulic pressure in the retard chamber B, and the advance chamber A tries to expand. Since the oil flow resistance of the OCV 22 is large, the advance chamber A becomes a negative pressure unless the oil supplied from the oil pump 21 to the advance chamber A via the OCV 22 is in time.
Conversely, when torque fluctuation toward the retard angle side is given to the output side rotor 6, the torque fluctuation cannot be suppressed by the hydraulic pressure in the advance chamber A, and the retard chamber B tries to expand. Since the oil flow resistance of the OCV 22 is large, the retard chamber B becomes negative pressure if the oil supplied from the oil pump 21 to the retard chamber B via the OCV 22 is not in time.

When negative pressure is generated in the advance chamber A due to torque fluctuation, a force in the retard direction acts on the output-side rotor 6. For this reason, when the phase of the camshaft is changed from the retarded angle side to the advanced angle side, there arises a problem that the response time until reaching the target phase becomes longer.
Similarly, when a negative pressure is generated in the retard chamber B due to torque fluctuation, a force in the advance direction acts on the output side rotor 6. For this reason, when the phase of the camshaft is changed from the advance side to the retard side, there arises a problem that the response time until the target phase is reached becomes longer.
JP 2001-27107 A JP 2005-54797 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a VVT capable of preventing deterioration of responsiveness due to negative pressure generated in an advance chamber or a retard chamber.

[Means of Claim 1]
In the VVT employing the means of claim 1, when the expansion force is applied to the advance chamber due to the torque fluctuation of the camshaft and the advance chamber becomes negative pressure, the advance side oil passage opening / closing valve becomes the advance side high pressure. Open the bypass. Then, the hydraulic pressure generated by the oil pump bypasses the OCV having a large oil flow resistance and is given to the advance chamber, so that the hydraulic pressure in the advance chamber increases. When the hydraulic pressure in the advance chamber becomes positive, the advance side oil passage opening / closing valve closes the advance side high pressure bypass passage. As a result, only the hydraulic pressure regulated by the OCV is applied to the advance chamber and the retard chamber.
Thus, since the negative pressure in the advance chamber is prevented, the retarding force acting on the output-side rotor is suppressed. As a result, when the phase of the camshaft is changed from the retard side to the advance side, the response time until the target phase is reached can be shortened.

[Means of claim 2]
The advance side oil passage opening / closing valve of the VVT employing the means of claim 2 adopts a structure such as a spool valve operated by negative pressure or a switching valve using a diaphragm, and the advance side high pressure bypass passage. A valve body that opens and closes the valve body, a valve closing force applying means that urges the valve body toward the closing side of the advance side high-pressure bypass path, and a differential pressure that drives the valve body by a differential pressure between atmospheric pressure and the hydraulic pressure of the advance chamber Operating means.

[Means of claim 3]
In the VVT employing the means of claim 3, when the expansion force is applied to the retard chamber due to the torque fluctuation of the camshaft and the retard chamber becomes negative pressure, the retard side oil passage opening / closing valve is set to the retard side high pressure. Open the bypass. Then, the hydraulic pressure generated by the oil pump bypasses the OCV having a large oil flow resistance and is given to the retard chamber, and the retard chamber hydraulic pressure increases. When the hydraulic pressure in the retard chamber becomes positive, the retard side oil passage opening / closing valve closes the retard side high pressure bypass passage. As a result, only the hydraulic pressure regulated by the OCV is applied to the advance chamber and the retard chamber.
In this way, the negative pressure in the retard chamber is prevented, so that the advance force acting on the output-side rotor is suppressed. As a result, when the phase of the camshaft is changed from the advance side to the retard side, the response time until the target phase is reached can be shortened.

[Means of claim 4]
The VVT retarded side oil passage opening / closing valve employing the means of claim 4 employs a structure such as a spool valve operated by negative pressure or a switching valve using a diaphragm, and the retarded side high pressure bypass passage. A valve body that opens and closes the valve body, a valve closing force applying means that urges the valve body toward the closing side of the retard-side high-pressure bypass, and a differential pressure that drives the valve body by the differential pressure between the atmospheric pressure and the hydraulic pressure of the retard chamber Operating means.

  The VVT outputs an output side rotor for rotationally driving an engine camshaft with respect to an input side rotor that is rotationally driven by an engine crankshaft, and an output to an advance side chamber for hydraulically driving the output side rotor. VCT having a retarding chamber for driving the side rotor to the retarding angle side by hydraulic pressure, and hydraulic control means having an OCV for supplying and discharging hydraulic pressure to and from the advance chamber and the retarding chamber.

  The VVT hydraulic pressure control means of the best mode 1 is driven by an advance side high-pressure bypass passage that bypasses the OCV and supplies the hydraulic pressure generated by the oil pump to the advance chamber, and is driven by the negative pressure of the advance chamber. And an advance-side oil passage opening / closing valve that opens the advance-side high-pressure bypass when the negative pressure is negative and closes the advance-side high-pressure bypass when the advance chamber is positive.

  The hydraulic control means for the VVT of the best mode 2 is driven by a retarded-side high-pressure bypass passage that bypasses the OCV and supplies the retarded chamber with the hydraulic pressure generated by the oil pump, and is driven by the negative pressure of the retarded chamber. And a retarding-side oil passage opening / closing valve that opens the retarding-side high-pressure bypass when the negative pressure is negative, and closes the retarding-side high-pressure bypass when the retarding chamber is positive.

  The VVT hydraulic control means of the best mode 3 is a combination of the best modes 1 and 2, and an advance side high-pressure bypass passage that bypasses the OCV and supplies the oil pressure generated by the oil pump to the advance chamber; An advance side oil passage opening / closing valve that is driven by the negative pressure of the advance chamber, opens the advance side high pressure bypass passage when the advance chamber pressure is negative, and closes the advance side high pressure bypass passage when the advance chamber pressure is positive; A retarded-side high-pressure bypass that bypasses the OCV and supplies the oil pressure generated by the oil pump to the retarded chamber, and is driven by the negative pressure in the retarded chamber, and opens the retarded-side high-pressure bypass when negative pressure is in the retarded chamber And a retard-side oil passage opening / closing valve that closes the retard-side high-pressure bypass when the retard chamber has a positive pressure.

A first embodiment to which the present invention is applied will be described with reference to FIGS.
(Explanation of VVT)
First, the structure of the VVT will be described with reference to FIGS.
The VVT is attached to the engine camshaft (intake valve, exhaust valve, intake / exhaust combined camshaft) 1 and can continuously change the opening / closing timing of at least one of the intake valve and the exhaust valve. VCT 2, hydraulic control means 3 for controlling the operation of VCT 2 by hydraulic pressure, and ECU 4 for electrically controlling hydraulic control means 3.

(Explanation of VCT2)
The VCT 2 is provided with an input side rotor (housing rotor) 5 that is driven to rotate in synchronization with the crankshaft of the engine, and an output side that is provided so as to be rotatable relative to the input side rotor 5 and rotates integrally with the camshaft 1. The rotor (vane rotor) 6 is provided, and the output side rotor 6 is driven to rotate relative to the input side rotor 5 by a hydraulic actuator configured in the input side rotor 5 to advance the camshaft 1. It changes to the side or retarded side.

The input-side rotor 5 is sandwiched in the axial direction between a sprocket 7 that is rotationally driven by a crankshaft of an engine via a timing belt, a timing chain, or the like, a substantially ring disk-shaped front plate 8, and the sprocket 7 and the front plate 8. The three parts with the shoe housing 9 are coupled by a plurality of bolts 10 and rotate integrally with the sprocket 7. Note that the front plate 8 and the shoe housing 9 may be formed of a single component.
As shown in FIG. 4, the shoe housing 9 has a plurality of (three in this embodiment) shoes 9a as partition members in the inner diameter direction, and a substantially fan-shaped recess is formed between the shoes 9a. In addition, the input side rotor 5 rotates clockwise in FIG. 4, and this rotation direction is an advance angle direction.

The output-side rotor 6 is positioned at the end of the camshaft 1 so as to rotate integrally with the knock pin 11, and then fixed to the end of the camshaft 1 by the center bolt 12. Rotate.
The output-side rotor 6 includes a plurality of (three in this embodiment) vanes 6a that divide a substantially fan-shaped recess formed between the shoes 9a into an advance chamber A and a retard chamber B. The side rotor 6 is provided to be rotatable within a predetermined angle with respect to the input side rotor 5.
The advance chamber A is a hydraulic chamber for driving the vane 6a to the advance side by hydraulic pressure, and is formed in a substantially fan-shaped recess on the side opposite to the rotation direction of the vane 6a. Conversely, the retard chamber B is a hydraulic chamber for driving the vane 6a to the retard side by hydraulic pressure. A seal member 13 that slides on the inner peripheral surface of the shoe housing 9 is provided on the outer peripheral surface of each vane 6a to block communication between the advance chamber A and the retard chamber B.

The VCT 2 includes a stopper pin 14 for engaging the output side rotor 6 with the input side rotor 5 at the most retarded position.
The stopper pin 14 has a substantially cylindrical rod shape, and is slidably inserted in the axial direction into a substantially circular stopper insertion hole 15 formed through one of the three vanes 6a in the axial direction. Yes. The stopper pin 14 is biased toward the sprocket 7 by a spring 16 and is provided so as to be fitted in a stopper bush 17 press-fitted and fixed to the sprocket 7 at the most retarded position. A tapered portion is formed in the fitting portion between the stopper pin 14 and the stopper bush 17 so that the stopper pin 14 can be smoothly fitted into the stopper bush 17.

A first stopper releasing oil chamber 18 formed between the tip of the stopper pin 14 on the right side in FIG. 3 and the sprocket 7 communicates with the advance chamber A, and the stopper pin 14 is driven by the hydraulic pressure applied to the advance chamber A. 3 is pushed back to the left side in FIG. 3 to release the fitting between the stopper pin 14 and the stopper bush 17.
Further, the stopper pin 14 is provided with a large diameter on the left side in FIG. 3, and the second stopper release oil chamber 19 formed between the step portion of the stopper pin 14 and the stopper insertion hole 15 is a retard chamber. The stopper pin 14 is pushed back to the left side in FIG. 3 by the hydraulic pressure applied to the retard chamber B, and the fitting between the stopper pin 14 and the stopper bush 17 is released.

(Description of hydraulic control means 3)
Next, the hydraulic control means 3 will be described with reference to FIGS.
The hydraulic pressure control means 3 supplies and discharges oil from the advance chamber A and the retard chamber B, generates a hydraulic pressure difference between the advance chamber A and the retard chamber B, and connects the output side rotor 6 to the input side rotor 5. OCV 22 is a means for relatively rotating the oil, and supplies oil (hydraulic pressure) pumped from an oil pump (hydraulic pressure generating source) 21 driven by a crankshaft or the like to the advance chamber A or the retard chamber B. Prepare. The bypass path of the OCV 22 will be described later.

The OCV 22 is a well-known electromagnetic spool valve formed by coupling a spool valve and an electromagnetic actuator that drives the spool valve.
The spool valve includes an input port 23 communicating with the oil pump 21, an advance side output port 25 communicating with the advance chamber A via the advance oil passage 24, and a retard oil passage 26 with the retard chamber B. A retarded angle side output port 27 communicating therewith, an advance angle side drain port 28 for draining oil from the advance angle chamber A, and a retard angle side drain port 29 for draining oil from the retard angle chamber B. The advance side discharge port 28 and the retard side discharge port 29 may be made common.
Then, the communication state of each port is controlled by displacing the spool in the spool valve by the operation of the electromagnetic actuator, and the hydraulic pressure generated by the advance side output port 25 (hydraulic pressure of the advance chamber A) and the retard side output It controls the hydraulic pressure generated by the port 27 (hydraulic pressure in the retard chamber B).

  As shown in FIG. 3, the advance oil passage 24 leading from the advance angle side output port 25 of the OCV 22 to the advance angle chamber A and the retard angle oil passage 26 leading from the retard angle side output port 27 to the retard angle chamber B are as shown in FIG. The engine side fixed oil passage → the cam journal 30 that rotatably supports the camshaft 1 → the internal oil passage of the camshaft 1 → the internal oil passage of the output side rotor 6 is provided.

(Description of ECU 4)
The ECU 4 is a known computer. The ECU 4 performs duty ratio control on the energization amount (supply current amount) of the OCV 22 based on the engine operation state (including the occupant operation state) read by various sensors and the program stored in the memory. It has a function, and the hydraulic pressure of the advance chamber A and the retard chamber B is controlled by controlling the energization amount of the OCV 22, and the advance phase (advance amount) of the camshaft 1 is set according to the engine operating state. Control to advance phase.

[Feature 1 of Example 1]
As shown in FIG. 2A, the hydraulic pressure control means 3 of the first embodiment is provided with an advance side high pressure bypass passage 41 that bypasses the OCV 22 and supplies the hydraulic pressure generated by the oil pump 21 to the advance chamber A. It has been. The advance side high pressure bypass passage 41 is a fixed oil passage on the engine side, and is formed, for example, in a cylinder head or a cam cover to which the OCV 22 is attached.
The advance side high pressure bypass passage 41 is driven by the negative pressure of the advance chamber A, opens the advance side high pressure bypass passage 41 when the advance chamber A has a negative pressure, and advances on the advance side when the advance chamber A has a positive pressure. An advance side oil passage opening / closing valve 42 for closing the high pressure bypass passage 41 is provided.

The advance side oil passage opening / closing valve 42 is a switching valve that opens and closes the advance side high pressure bypass passage 41 according to the pressure difference between the atmospheric pressure and the advance chamber A, and is provided in a small size in order to improve responsiveness. The advance side oil passage opening / closing valve 42 includes a valve body 43 for opening and closing the advance side high pressure bypass passage 41 and a valve closing force applying means 44 for biasing the valve body 43 toward the side where the advance side high pressure bypass passage 41 is closed. And differential pressure operating means for driving the valve body 43 with a differential pressure between the atmospheric pressure and the hydraulic pressure of the advance chamber A.
The advance side oil passage opening / closing valve 42 of the first embodiment employs a spool valve structure as shown in FIG. The differential pressure actuating means of the first embodiment is configured by a valve body 43 and a space on both sides in the axial direction of the valve body 43 (a space communicating with the atmosphere and a space communicating with the advance chamber A). The valve body 43 is provided so as to be displaced by the pressure difference between the spaces on both sides of the valve 43. The advance side oil passage opening / closing valve 42 may be provided so that the diaphragm is displaced by the differential pressure and the valve body 43 is driven by the displacement of the diaphragm.

Here, the structure of the advance side oil passage opening / closing valve 42 will be specifically described with reference to FIG.
The advance side oil passage opening / closing valve 42 is slidable in the axial direction inside a shaft hole 45 (a shaft hole of a cylindrical sleeve attached to the cylinder head or cam cover) formed in the cylinder head or cam cover to which the OCV 22 is attached. A valve body 43 (spool) to be supported is provided. One space (left space in the figure) of the shaft hole 45 defined by the valve body 43 is an atmospheric chamber that communicates with the atmosphere through the opening. Further, the other space (right space in the figure) of the shaft hole 45 defined by the valve body 43 is a back pressure chamber (advance chamber) that communicates with the advance chamber A side of the advance side high pressure bypass passage 41 via an oil passage. A space having substantially the same pressure as A).

The valve body 43 is provided so as to close the advance side high pressure bypass passage 41 when displaced toward the atmosphere chamber side and open the advance side high pressure bypass passage 41 when displaced toward the back pressure chamber side.
Inside the back pressure chamber, there is provided a valve closing force applying means 44 for biasing the valve body 43 toward the atmosphere chamber, that is, the side of closing the advance side high pressure bypass passage 41 (the valve closing direction). The valve closing force applying means 44 is a spring (for example, a compression coil spring or the like) that urges the valve body 43 toward the atmosphere chamber side (valve closing side). The valve closing force applying means 44 sets the valve opening pressure of the advance side oil passage opening / closing valve 42, and the valve closing force applying means 44 improves the responsiveness when the valve opening force is applied. The biasing force is set to be weak.

[Feature 2 of Example 1]
Further, in the hydraulic pressure control means 3 of the first embodiment, as shown in FIG. 2A, the retard side high pressure bypass passage 51 that bypasses the OCV 22 and supplies the hydraulic pressure generated by the oil pump 21 to the retard chamber B. Is provided. The retard side high pressure bypass passage 51 is a fixed oil passage on the engine side, similar to the advance side high pressure bypass passage 41 described above, and is formed, for example, in a cylinder head or a cam cover to which the OCV 22 is attached.
The retard side high pressure bypass 51 is driven by the negative pressure of the retard chamber B, opens the retard side high pressure bypass 51 when the retard chamber B has a negative pressure, and retards when the retard chamber B has a positive pressure. A retarded-side oil passage opening / closing valve 52 that closes the high-pressure bypass passage 51 is provided.

The retarding-side oil passage opening / closing valve 52 is a switching valve that opens and closes the retarding-side high-pressure bypass passage 51 according to the pressure difference between the atmospheric pressure and the retarding chamber B, and is provided in a small size in order to improve responsiveness. The retard side oil passage opening / closing valve 52 includes a valve body 53 that opens and closes the retard side high pressure bypass passage 51 and a valve closing force applying means 54 that biases the valve body 53 toward the side where the retard side high pressure bypass passage 51 is closed. And differential pressure operating means for driving the valve body 53 with a differential pressure between the atmospheric pressure and the hydraulic pressure of the retarded chamber B.
The retard angle side oil passage opening / closing valve 52 of the first embodiment employs the same configuration as the advance angle side oil passage opening / closing valve 42. That is, a spool valve structure is adopted, and the differential pressure operating means is constituted by a valve body 53 and spaces on both axial sides of the valve body 53 (a space communicating with the atmosphere and a space communicating with the retarded angle chamber B). In addition, the valve body 53 is provided so as to be displaced by the pressure difference between the spaces on both sides of the valve body 53. Note that the retard side oil passage opening / closing valve 52 may be provided so that the diaphragm is displaced by the differential pressure and the valve body 53 is driven by the displacement of the diaphragm.
The specific structure of the retard side oil passage opening / closing valve 52 of the first embodiment employs the same structure as that of the aforementioned advance side oil passage opening / closing valve 42 (see FIG. 2B), and the description thereof is omitted. To do.

(Explanation of VVT operation)
When the engine is stopped, the stopper pin 14 is fitted to the stopper bush 17. Immediately after the engine is started, oil pressure is not sufficiently supplied from the oil pump 21 to each hydraulic chamber, so that the stopper pin 14 remains fitted to the stopper bush 17 and the camshaft 1 is held at the most retarded position. ing. Thus, there is no problem that the input-side rotor 5 and the output-side rotor 6 swing and collide with each other due to the torque fluctuation received by the camshaft 1 until the hydraulic pressure is supplied to each hydraulic chamber.

After the engine is started, if the hydraulic pressure is sufficiently supplied from the oil pump 21 to each hydraulic chamber, the stopper pin 14 comes out of the stopper bush 17 by the hydraulic pressure supplied to the first and second stopper release oil chambers 18 and 19. The output-side rotor 6 can rotate relative to the input-side rotor 5. Then, by making the hydraulic pressure in the advance chamber A greater than the hydraulic pressure in the retard chamber B, the output side rotor 6 is displaced toward the advance side relative to the input side rotor 5, and the camshaft 1 is advanced. Conversely, by making the hydraulic pressure in the retard chamber B greater than the hydraulic pressure in the advance chamber A, the output side rotor 6 is displaced to the retard side relative to the input side rotor 5 and the camshaft 1 is retarded.
When the output side rotor 6 reaches the target phase, the ECU 4 controls the duty ratio of the energization amount of the OCV 22, maintains the drive hydraulic pressure of the advance chamber A and the retard chamber B, and holds the output side rotor 6 at the target phase. .

(Effect 1 of Example 1)
Referring to FIG. 1A, in the engine operating state where the oil pump 21 has a low discharge hydraulic pressure (the oil temperature is high, the engine is rotating low and the amount of oil supplied is low), the OCV 22 and the advance chamber A and the slow oil pressure are retarded. The “advanced angle operation” of the VVT when the hydraulic pressure applied to the corner chamber B is low will be described. In this state, if torque fluctuation of the camshaft 1 toward the advance side is given to the output side rotor 6, the torque fluctuation cannot be suppressed by the hydraulic pressure of the retard chamber B, and the advance chamber A tries to expand. . At this time, if the supply of oil supplied from the oil pump 21 to the advance chamber A via the OCV 22 is not in time, the advance chamber A becomes negative pressure. Then, the back pressure chamber of the advance side oil passage opening / closing valve 42 communicating with the advance angle chamber A also becomes negative pressure, and the valve body 43 of the advance side oil passage opening / closing valve 42 is displaced to the valve opening side, so that the advance angle is increased. The side oil passage opening / closing valve 42 opens the advance side high pressure bypass passage 41. As a result, the hydraulic pressure generated by the oil pump 21 bypasses the OCV 22 having a large oil flow resistance and is given to the advance chamber A, so that the hydraulic pressure in the advance chamber A increases.

When the hydraulic pressure in the advance chamber A rises to a positive pressure due to the opening operation of the advance side oil passage opening / closing valve 42, the back pressure chamber of the advance side oil passage opening / closing valve 42 communicating with the advance chamber A is also positive pressure. Thus, the valve element 43 of the advance side oil passage opening / closing valve 42 is displaced toward the valve closing side, and the advance side oil passage opening / closing valve 42 closes the advance side high pressure bypass passage 41. As a result, only the hydraulic pressure regulated by the OCV 22 is applied to the advance chamber A and the retard chamber B.
Since the negative pressure in the advance chamber A is prevented by the above operation, the retard force acting on the output side rotor 6 is suppressed, and the phase of the camshaft 1 is changed from the retard side to the advance side. The time to reach the target phase can be shortened. That is, the responsiveness at the time of advance can be improved.

(Effect 2 of Example 1)
Referring to FIG. 1B, in the engine operating state where the discharge hydraulic pressure of the oil pump 21 is low (the oil temperature is high, the engine is low and the supply oil amount is low), the OCV 22 and the advance angle chamber A and the slow chamber The “retarding operation” of the VVT in the case where the working oil pressure applied to the corner chamber B is a low oil pressure will be described. In this state, when the torque fluctuation of the camshaft 1 toward the retard side is given to the output side rotor 6, the torque fluctuation cannot be suppressed by the hydraulic pressure of the advance chamber A, and the retard chamber B tries to expand. . At this time, if the supply of oil supplied from the oil pump 21 to the retardation chamber B via the OCV 22 is not in time, the retardation chamber B becomes negative pressure. Then, the back pressure chamber of the retard side oil passage opening / closing valve 52 communicating with the retardation chamber B also becomes negative pressure, and the valve body 53 of the retard side oil passage opening / closing valve 52 is displaced to the valve opening side, thereby retarding the retard angle. The side oil passage opening / closing valve 52 opens the retard side high pressure bypass passage 51. As a result, the hydraulic pressure generated by the oil pump 21 bypasses the OCV 22 having a large oil flow resistance and is given to the retarded chamber B, so that the hydraulic pressure in the retarded chamber B increases.

When the hydraulic pressure in the retarding chamber B rises to a positive pressure due to the opening operation of the retarding-side oil passage opening / closing valve 52, the back pressure chamber of the retarding-side oil passage opening / closing valve 52 communicating with the retarding chamber B is also positive pressure. Thus, the valve body 53 of the retarded-side oil passage opening / closing valve 52 is displaced toward the valve closing side, and the retarding-side oil passage on-off valve 52 closes the retarding-side high-pressure bypass passage 51. As a result, only the hydraulic pressure regulated by the OCV 22 is applied to the advance chamber A and the retard chamber B.
Since the negative pressure in the retard chamber B is prevented by the above operation, the force in the advance direction acting on the output side rotor 6 is suppressed, and the phase of the camshaft 1 is changed from the advance side to the retard side. The time to reach the target phase can be shortened. That is, the responsiveness at the time of retardation can be improved.

(Effect 3 of Example 1)
In the effects 1 and 2 of the first embodiment, the effects at the time of the advance operation and the operation at the retard angle have been described. Even when the output-side rotor 6 reaches the target phase and maintains the state, An effect can be obtained.
The operating hydraulic pressure applied from the OCV 22 to the advance chamber A and the retard chamber B is low in an engine operating state in which the discharge hydraulic pressure of the oil pump 21 is low (the oil temperature is high, the engine is rotating slowly and the amount of supplied oil is low). The “target phase holding operation” of VVT in the case of hydraulic pressure will be described.
When the torque fluctuation of the camshaft 1 is received in this state, the advance chamber A and the retard chamber B are alternately repeated to become negative pressure. When the advance chamber A becomes negative pressure, the advance side oil passage opening / closing valve 42 is opened and the negative pressure in the advance chamber A is eliminated as described in the effect 1 of the first embodiment. Similarly, when the retarding chamber B becomes negative pressure, the retarding-side oil passage opening / closing valve 52 is opened and the negative pressure in the retarding chamber B is eliminated as described in the effect 2 of the first embodiment.
As a result, the output side rotor 6 swings once in the left-right rotation direction with respect to the input side rotor 5, and the hydraulic pressure in the advance chamber A and the retard chamber B is increased and the negative pressure is eliminated. The swing of the rotor 6 is suppressed.

(Effect 4 of Example 1)
Here, in the prior art, when the advance chamber A and the retard chamber B become negative pressure due to torque fluctuation, the advance oil passage 24 and the retard oil passage 26 are moved from the sliding portion of the camshaft 1 and the cam journal 30 to each other. There was concern about inhaling air. Therefore, in the prior art, as shown in Patent Documents 1 and 2, it has been proposed to provide means for preventing air inhalation.
On the other hand, in the first embodiment, when the advance chamber A and the retard chamber B become negative pressure, the advance side oil passage opening / closing valve 42 and the retard side oil passage opening / closing valve 52 are opened to advance the advance angle. Since it is provided to eliminate the negative pressure in the chamber A and the retarded angle chamber B, it is not necessary to use the “air suction prevention means” in the prior art. That is, it is possible to prevent an increase in the vibration of the camshaft 1 caused by air mixed into the hydraulic fluid in the advance chamber A and the retard chamber B, and to control the advance amount of the camshaft 1 due to the air mixture. Can be prevented, and high reliability can be obtained.

[Modification]
In the above embodiment, the hydraulic pressure control means 3 is provided with both “advance side high pressure bypass passage 41 + advance side oil passage on / off valve 42” and “retard side high pressure bypass passage 51 + retard side oil passage on / off valve 52”. Although an example is shown, only one of “advance side high pressure bypass passage 41 + advance side oil passage on / off valve 42” or “retard side high pressure bypass passage 51 + retard side oil passage on / off valve 52” is used. There may be.

In addition to the above embodiment, a means for increasing the fixing holding force of the output side rotor 6 may be provided. As a specific example, an advance check valve for preventing the backflow of oil from the advance chamber A to the OCV 22 side is provided in the advance oil passage 24, and the retard chamber B to the OCV 22 side in the retard oil passage 26. A means for increasing the fixing holding force of the output-side rotor 6 when fixing the advance amount may be added by providing a retarded check valve for preventing the oil backflow. The advance check valve and the retard check valve shown in this means include check valve release means for releasing the function of each check valve when the advance amount is variable (for example, the bypass valve of the check valve). Open / close means) is provided.
Thus, by adopting a means for increasing the fixing holding force of the output side rotor 6, the oscillation of the output side rotor 6 due to the torque fluctuation of the camshaft 1 can be suppressed, so that the reliability can be further improved.

In the above embodiment, the spool valve is exemplified as an example of the valve structure of the OCV 22, but other valve structures (such as a rotary valve) may be adopted.
In the above-described embodiment, the OCV 22 is driven by an electromagnetic actuator (linear solenoid). However, there are other actuators such as an electric actuator that drives the OCV 22 by converting the rotation of the electric motor into an axial force, and a piezoelectric actuator. An electric actuator having a structure may be used. Alternatively, the OCV 22 may be driven by pilot hydraulic pressure.

In the above-described embodiment, the example in which the VCT 2 is provided on the camshaft 1 has been described. However, the VCT 2 may be provided on another part such as an engine crankshaft.
In the above embodiment, the input side rotor 5 is divided into three substantially fan-shaped concave portions by the three shoes 9a, and the three vanes 6a are provided on the outer peripheral portion of the output side rotor 6. The number and the number of vanes 6a may be any number as long as it is one or more in terms of configuration, and the number of shoes 9a and vanes 6a may be other numbers.
In the above embodiment, the input-side rotor 5 rotates synchronously with the crankshaft, and the output-side rotor 6 rotates integrally with the camshaft 1. Conversely, the output-side rotor 6 rotates synchronously with the crankshaft, The input side rotor 5 may be configured to rotate integrally with the camshaft 1.

(Example 1) which is the operation | movement explanatory drawing at the time of the advance angle of VVT, and a retard angle. (Example 1) which is the schematic of VVT and an advance angle side oil-path on-off valve. (Example 1) which is the schematic of VVT using the axial direction cross section of VCT. (Example 1) which is explanatory drawing of VCT seen from the axial direction. It is the schematic of VVT (conventional example).

Explanation of symbols

1 Camshaft 2 VCT (Variable valve timing mechanism)
3 Hydraulic control means 5 Input side rotor 6 Output side rotor 21 Oil pump 22 OCV (oil flow control valve)
41 Advance angle side high pressure bypass passage 42 Advance angle side oil passage opening / closing valve 43 Valve body 44 of advance angle side oil passage opening / closing valve Valve closing force applying means 51 of advance angle side oil passage opening / closing valve Delay angle side high pressure bypass passage 52 Delay angle Side oil passage opening / closing valve 53 Valve element 54 of the retarding side oil passage opening / closing valve A means for closing the retarding side oil passage opening / closing valve A Advance angle chamber B Delay angle chamber

Claims (4)

With respect to an input side rotor that is rotationally driven by a crankshaft of the internal combustion engine, an advance angle chamber that drives an output side rotor that rotationally drives the camshaft of the internal combustion engine to an advance side by hydraulic pressure, and the input side rotor A variable valve timing mechanism including a retard chamber that drives the output-side rotor to the retard side by hydraulic pressure;
In a valve timing adjustment device comprising: an oil flow control valve that includes an oil flow control valve that supplies and discharges hydraulic pressure to and from the advance chamber and the retard chamber.
The hydraulic pressure control means bypasses the oil flow control valve, and provides an advance side high-pressure bypass path that supplies the hydraulic pressure generated by the oil pump to the advance chamber;
Advancing oil that is driven by the negative pressure of the advance chamber, opens the advance-side high-pressure bypass when the advance chamber is negative, and closes the advance-side high-pressure bypass when the advance chamber is positive A valve timing adjusting device comprising: a road opening / closing valve. In the valve timing adjustment device according to claim 1,
The advance side oil passage opening / closing valve includes a valve body that opens and closes the advance side high pressure bypass passage, a valve closing force applying means that biases the valve body toward a side where the advance side high pressure bypass passage is closed, A valve timing adjusting device comprising: a differential pressure operating means for driving the valve body by a differential pressure between an atmospheric pressure and a hydraulic pressure of the advance chamber. With respect to an input side rotor that is rotationally driven by a crankshaft of the internal combustion engine, an advance angle chamber that drives an output side rotor that rotationally drives the camshaft of the internal combustion engine to an advance side by hydraulic pressure, and the input side rotor A variable valve timing mechanism including a retard chamber that drives the output-side rotor to the retard side by hydraulic pressure;
In a valve timing adjustment device comprising: an oil flow control valve that includes an oil flow control valve that supplies and discharges hydraulic pressure to and from the advance chamber and the retard chamber.
The hydraulic pressure control means bypasses the oil flow control valve and provides a retarded-side high-pressure bypass path that supplies the hydraulic pressure generated by the oil pump to the retarded chamber;
Retarded side oil that is driven by the negative pressure of the retarded chamber, opens the retarded high pressure bypass when the retarded chamber is negative, and closes the retarded high pressure bypass when the retarded chamber is positive A valve timing adjusting device comprising: a road opening / closing valve. In the valve timing adjusting device according to claim 3,
The retard angle side oil passage on-off valve includes a valve body that opens and closes the retard side high pressure bypass passage, a valve closing force applying means that biases the valve body toward a side where the retard angle high pressure bypass passage is closed, A valve timing adjusting device comprising: a differential pressure operating means for driving the valve body by a differential pressure between an atmospheric pressure and a hydraulic pressure of the retard chamber.

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