JPH04224210A - Variable valve timing controller - Google Patents

Abstract

PURPOSE:To reduce energy loss in hydraulic pressure to improve responsiveness and controllability in a variable valve timing controller utilizing hydraulic pressure. CONSTITUTION:In a variable valve timing controller which varies a relative position between a cam shaft 1 and a pulley 2 by controlling an intermediate gear 3 by means of hydraulic pressure fed from a pressure feed pump 6, a valve means 100 for controlling the hydraulic pressure comprises an outer valve 110 for opening and closing communication to a lower pressure side, an inner valve 120 for opening and closing an inner path of the outer valve 110, an armature 130 connected to the outer valve 110 and an electromagnetic coil 150 for driving the armature 130.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing control device for variably controlling the opening and closing timing of intake and exhaust valves.

0002

BACKGROUND OF THE INVENTION Conventional variable valve timing control devices include shafts on the drive side and the driven side, as shown in, for example, Japanese Patent Laid-Open No. 62-191606 or Japanese Patent Laid-Open No. 62-191636. A helical spline is placed between the two shafts, and by shifting the rotational phase angle between the two shafts, the opening and closing timing of the intake and exhaust valves of the internal combustion engine is variably controlled. In this system, the shifter that rotates the helical spline is driven by engine oil pressure against the biasing force of a spring. This hydraulic pressure is controlled by a solenoid valve, and when the solenoid valve opens, the shifter is driven by the biasing force of the spring. The hydraulic pressure is returned to the low pressure side by the returned moving volume.

0003

However, in this case, engine oil pressure continues to be supplied in the same manner as when the solenoid valve is closed, so there is a problem that the return response speed of the shifter is slow and the pump driving loss is large. Further, since the response of the solenoid valve is slow, it is difficult to control the intermediate position of the shifter, and there is a problem in that the shifter movement stroke can only be controlled at two positions: 0 and the maximum position.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a variable valve timing control device that reduces hydraulic energy loss and has excellent responsiveness and controllability.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a cylindrical intermediate gear in which at least one of the teeth on the inner and outer peripheries is formed in a helical shape, an outer gear that meshes with the intermediate gear, and Three gears, including an inner gear, are interposed between the cam pulley and the camshaft, which are periodically driven by the engine, and the linear movement of the intermediate gear in the camshaft direction causes the camshaft and pulley to undergo relative rotational movement. a hydraulic actuator that drives the intermediate gear in the camshaft direction, and a pump that pumps hydraulic pressure;
In a variable valve timing control device for an engine, which includes a valve means for controlling hydraulic pressure fed from the pump to a hydraulic actuator, and a control means for controlling the valve means according to an operating state, the valve means is configured to move to a low pressure side. an outer valve that opens and closes communication with the inner valve and has an internal passage that communicates with the high pressure side; an inner valve that is slidably disposed within the outer valve and opens and closes the internal passage; and an outer valve that is integrated with the outer valve. The outer valve is provided with an armature made of a magnetic material and an electromagnetic actuator that electromagnetically drives the armature and the outer valve, and when the armature and the outer valve are electromagnetically driven by the electromagnetic actuator, the outer valve opens communication to the low pressure side. At the same time, the inner valve closes the internal passage of the outer valve, and when the armature and the outer valve are not electromagnetically driven by the electromagnetic actuator, the outer valve closes communication to the low pressure side, and the inner valve closes the internal passage of the outer valve. The internal passage is opened in response to hydraulic pressure sent from the pump.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below based on the drawings. In FIG. 1, a screw mechanism that relatively rotates the intake valve camshaft 1 and the cam pulley 2 is provided between a cam pulley 2 that transmits the rotation of a crankshaft (not shown) and the camshaft 1, and a hydraulic control mechanism that controls this screw mechanism. is provided.

The screw mechanism is composed of external teeth 1a formed on the outer periphery of the camshaft 1, an intermediate gear 3, and internal teeth 2a formed on the inner periphery of the cam pulley 2. An annular intermediate gear 3 arranged to be sandwiched between an external tooth 1a and an internal tooth 2a has teeth 3a and 3b formed on the inner and outer peripheries, respectively, and teeth 3a and 3b on the inner and outer peripheries. One or both of them are formed in a helical shape, and the teeth 3a, 3b on the inner and outer peripheries mesh with the outer teeth 1a and the inner teeth 2a, respectively. The intermediate gear 3 can move linearly in the camshaft direction, whereas the camshaft 1 and cam pulley 2, on which external teeth 1a and internal teeth 2a are formed, are only allowed to rotate in the circumferential direction, and movement in the camshaft direction is restricted. ing. Therefore, when the intermediate gear is moved linearly in the camshaft direction, the torque generated by this movement attempts to move or rotate the camshaft 1 or cam pulley 2 in the camshaft direction via the screw mechanism, but these Since the cam shaft 1 and the cam pulley 2 are restricted from moving, only rotation is allowed, and as a result, the cam shaft 1 and the cam pulley 2 rotate relative to each other in accordance with the twist angle of the helical teeth.

The intermediate gear 3 is controlled by a hydraulic control mechanism. Hydraulic pressure is pumped from a tank 5 by a pressure pump 6 into a passage 7 in a hydraulic chamber 4 formed at one end of the intermediate gear.
, 8 sequentially. The intermediate gear 3 is driven by this oil pressure against the biasing force of the spring 9. A three-way solenoid valve 100 for controlling this oil pressure is arranged in the pressure feeding passages 7 and 8. This three-way solenoid valve 100
is an outer valve 110 that comes into contact with and separates from the conical seat surface 9.
an inner valve 120 slidably disposed within the outer valve 110; an armature 130 fixed to the outer valve 110; a spring 140 that biases the outer valve 110 in the closing direction; an electromagnetic coil 150 that is driven against the urging force of the inner valve 12;
A stopper 160 restricts the maximum movement position of 0. The outer valve 110 has a passage 7 and a passage 8.
An internal passage including a radial passage 111, an annular chamber 112, and an axial passage 113 is formed for connecting the inner valve 1 and the inner valve 1.
It is opened and closed by 20 conical tips. Note that the seat diameter dA of the outer valve 110 and the inner diameter d of the axial passage
B, and the guide diameter dC of the inner valve is dC
>dA >dB. Further, an annular chamber 10 is continuously formed in the seat surface 9, and this chamber 10 is connected to the suction side of the pressure pump 6 via a passage 11.

[0009] The electromagnetic coil 150 is energized and controlled by the EDU 13, which is controlled by commands from the ECU 12 to which information such as the rotation speed, accelerator opening, and intake air amount is input. Next, the operation of this embodiment will be explained. When the engine is in a low load range or a low speed range, the electromagnetic coil 150 is energized from the EDU 13, and the armature 130 and the outer valve 110 are attracted to the electromagnetic coil 150. On the other hand, the inner valve 120 contacts the stopper 160, and the tip of the inner valve 120 closes the opening of the axial passage 112 of the outer valve 110. Therefore, the hydraulic pressure from the pressure pump 6 is not transferred to the hydraulic chamber 4, and the pressure in the hydraulic chamber 4 is low. Therefore, the intermediate gear 3 is biased by the spring 9 to the initial position, and the relationship between the camshaft 1 and the cam pulley 2 is set so that the closing timing of the intake valve is the latest. This reduces the valve overlap and prevents the residual gas ratio from increasing.

[0010] Also, when the engine is under high load or at high speeds, the ED
Power supply from U13 to electromagnetic coil 150 is stopped. Therefore, the outer valve 110 suddenly moves downward in the figure due to the biasing force of the spring 140 and the pressure inside the chamber 112, and is seated on the seat surface 9. The hydraulic pressure flowing into the chamber 112 from the radial passage 111 pushes the inner valve 120 upward in the figure, and as a result, the passage 7 and the passage 8 are connected via the radial passage 111, the chamber 112, and the axial passage 113. The hydraulic pressure is sent to the hydraulic chamber 4 through communication. The intermediate gear 3 moves under the pressure of this hydraulic chamber 4. Here, since the movement of the camshaft 1 and the cam pulley 2 in the axial direction is restricted, only rotational movement in the circumferential direction is allowed, and the camshaft 1 and the cam pulley 2 move according to the torsional angle of the teeth formed in a helical shape. 2 rotates relative to each other. Therefore, the closing timing of the intake valve becomes earlier, thereby increasing the valve overlap, increasing the intake efficiency, and improving the engine output.

[0011] Then, the electromagnetic coil 1 is connected again from the EDU 13.
50 is energized, the armature 130 is attracted by the electromagnetic coil 150 against the hydraulic pressure in the chamber 111 and the biasing force of the spring 140. Therefore,
The tip of the inner valve 120 is seated at the opening of the axial passage 112 of the outer valve 110 to block communication between the passage 7 and the passage 8, and the passage 8 is connected to the chamber 10 and the passage 1.
1 to the suction side of the pressure pump 6. As a result, the oil pressure in the hydraulic chamber 7 is rapidly reduced by the suction force of the pressure pump 6, and the intermediate gear 3 quickly returns to its initial position, thereby delaying the closing timing of the intake valve. At this time, regarding the hydraulic pressure fed from the pressure pump 6, the tip of the inner valve 120 is seated at the opening of the axial passage 113 of the outer valve 110, and communication to the low pressure side is cut off, so there is no energy loss. does not occur.

As described above, according to this embodiment, the three-way solenoid valve 100 can control the hydraulic pressure fed from the pressure pump 6 with excellent responsiveness, and reduce energy loss associated with the control. be able to. Therefore, the closing timing of the intake valve can be quickly controlled. In addition, in the above-mentioned operation, control of two positions (initial position and drive position) of the intermediate gear 3 was explained, but the three-way solenoid valve 10
0 enables quick hydraulic control, so EDU1
By controlling the duty of the three-way solenoid valve 100 using the three-way solenoid valve 3, it is also possible to control the position of the intermediate gear 3 with high precision.

Next, another embodiment of the present invention will be explained. 2, in this embodiment, in addition to the configuration shown in FIG.
4 is used as a second hydraulic chamber to introduce the hydraulic pressure sent from the pressure pump 6, and this hydraulic pressure is transferred to the three-way solenoid valve 1 in FIG.
It is controlled by a three-way solenoid valve 200 having a structure similar to that of 00.

According to this configuration, since the intermediate gear 3 is controlled by the pressure balance between the hydraulic chambers 4 and 5, the position of the intermediate gear 3 can be controlled with high accuracy without performing duty control. I can do it. In addition, spring 9
It is not necessary to set the biasing force as strongly as in the embodiment of FIG. 1, and it is sufficient to have a biasing force that can drive the intermediate gear 3 to the left in the figure in the event of a failure.

[0015]

[Effects of the Invention] As explained above, in the present invention, the hydraulic pressure fed from the pump to the hydraulic actuator can be quickly controlled without energy loss by the valve means composed of the outer valve, the inner valve, the armature, and the electromagnetic actuator. This makes it possible to control the intermediate gear not only in two positions but also in a predetermined position with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing the overall configuration of another embodiment of the present invention.

[Explanation of symbols]

1 Camshaft 2 Cam pulley 3 Intermediate gear 4 Hydraulic chamber 6 Pressure pump 100 Three-way solenoid valve 110 Outer valve 120 Inner valve 130 Armature 150 Electromagnetic coil

Claims (2)

[Claims] Claim 1: A cylindrical intermediate gear in which at least one of the teeth on the inner and outer peripheries is formed in a helical shape, and three gears, an outer gear and an inner gear that mesh with the intermediate gear, respectively, are driven periodically by an engine. a screw mechanism that is interposed between a cam pulley and a camshaft, and that causes the camshaft and pulley to undergo relative rotational movement by linear movement of the intermediate gear in the camshaft direction; and a screw mechanism that drives the intermediate gear in the camshaft direction. Variable valve timing control for an engine that includes a hydraulic actuator, a pump that pumps hydraulic pressure, a valve means that controls the hydraulic pressure that is pumped from the pump to the hydraulic actuator, and a control means that controls the valve means according to the operating state. In the device, the valve means includes an outer valve that opens and closes communication to the low pressure side and has an internal passage that communicates with the high pressure side, and an inner valve that is slidably disposed within the outer valve and opens and closes the internal passage. and an armature formed integrally with the outer valve and formed of a magnetic material, and an electromagnetic actuator that electromagnetically drives the armature and the outer valve, and in a state where the armature and the outer valve are electromagnetically driven by the electromagnetic actuator. , the outer valve opens communication to the low pressure side, and the inner valve closes the internal passage of the outer valve, and when the armature and the outer valve are not electromagnetically driven by the electromagnetic actuator, the outer valve communicates with the low pressure side. A variable valve timing control device, characterized in that the inner valve receives hydraulic pressure sent from the pump and opens the internal passage. 2. The variable valve timing control device according to claim 1, wherein the low pressure passage through which the outer valve opens and closes is connected to the suction side of the pump.