JP2001027107A - Valve timing adjusting device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent inflow of air into an advance angle chamber and a lag angle chamber communicated with an oil exhausting port when a feeding oil pressure is low and to reduce occurrence of a phase shift in valve opening/ closing timing as much as possible. SOLUTION: This adjusting device arranges a rotor 2 connected with a cam shaft inside a housing 1 which is connected with a crankshaft of an internal combustion engine for rotating to form partitioningly an advance angle chamber 11 and a lag angle chamber 12 by a rotor 2. Oil is fed into one of the advance angle chamber 11 and the lag angle chamber 12 by an oil pressure control valve 3 and the oil is exhausted from the other of the advance angle chamber 11 and the lag angle chamber 12 for having the rotor 2 rotated reciprocally to change valving opening/closing timing of the internal combustion engine. In an oil exhausting passage 74 from the oil pressure control valve 3, an oil reservoir part 75 adapted to feed oil into the advance angle chamber 11 and the lag angle chamber 12 according to change in volume expansion of the advance angle chamber 11 and the lag angle chamber 12 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing adjusting device, and more particularly, to a valve timing adjusting device capable of preventing a flow of air into an advance chamber or a retard chamber to accurately adjust a valve opening / closing timing. About.

[0002]

2. Description of the Related Art A valve timing adjusting device is provided for optimally adjusting the opening / closing timing of an intake valve or an exhaust valve according to the operating state of an internal combustion engine, and is disclosed, for example, in Japanese Patent Application Laid-Open No. H10-176510. like,
A rotor connected to a camshaft is disposed in a housing that is connected to a crankshaft of an internal combustion engine and rotates. The rotor is used to advance and retard the chamber (hereinafter, both chambers are referred to as hydraulic chambers).
Are formed. Then, oil is supplied to one of the hydraulic chambers by a hydraulic control valve and the oil is discharged from the other of the hydraulic chambers, and the rotor is rotated forward and reverse in the housing to change the valve opening / closing timing of the internal combustion engine.

[0003]

By the way, the torque of the camshaft fluctuates with the opening and closing of the valve, and the pressure in the hydraulic chamber changes to match this torque, and the hydraulic chamber changes according to the bulk modulus of the oil. As a result, the rotational position of the rotor fluctuates, causing a shift in the valve opening / closing timing (phase shift). FIG. 6 shows a case where the valve timing is changed to the retard side by supplying the oil to the retard chamber and simultaneously discharging the oil from the advance chamber, and the advance chamber and the retard are changed according to the fluctuation of the camshaft torque. It can be seen that the hydraulic pressure of the chamber fluctuates and the volume of both chambers fluctuates, causing a phase shift in the valve opening / closing timing. Such a phase shift is usually within an allowable range. However, when the oil pressure supplied from the oil pump is reduced due to the driving state of the vehicle, the phase shift becomes considerably large as shown in FIG.

The cause of the phase shift due to a decrease in the bulk modulus of the oil in the hydraulic chamber is usually due to bubbles mixed in the oil, but a new cause may occur when the supply oil pressure is low. found. That is, in order to improve the responsiveness to change of the valve opening / closing timing, both the oil supply port and the oil discharge port of the hydraulic control valve are widely opened to supply or discharge a large amount of oil to the advance or retard chamber immediately. However, if the oil pressure supplied to the oil supply port is low, the hydraulic chamber (advanced chamber in the example of FIG. 7) communicating with the oil discharge port becomes a negative pressure when its volume expansion changes. If the oil discharge port is not filled with oil at this time, air flows into the hydraulic chamber (FIG. 7).
Broken line portion). As a result, the substantial bulk modulus of the oil in the hydraulic chamber is greatly reduced, and this, together with the reduction in the fluid frictional resistance when passing through the hydraulic control valve, causes the subsequent torque fluctuation of the camshaft. As a result, the volume of the hydraulic chamber fluctuates greatly, causing an excessive phase shift.

Accordingly, the present invention solves such a problem, and prevents a flow of air into a hydraulic chamber communicating with an oil discharge port when supply hydraulic pressure is low, thereby making it possible to generate a phase shift in valve opening / closing timing. It is an object of the present invention to provide a valve timing adjustment device that is as small as possible.

[0006]

According to the present invention, a rotor (2) connected to a camshaft is provided in a housing (1) which is connected to a crankshaft of an internal combustion engine and rotates. Then, the advance chamber (11) is rotated by the rotor (2).
And a retard chamber (12) are formed, and oil is supplied to one of the advance chamber (11) and the retard chamber (12) by the hydraulic control valve (3), and the advance chamber (11) and the retard chamber are formed. In the valve timing adjusting apparatus for an internal combustion engine, the oil is discharged from the other side of (12) and the opening and closing timing of the internal combustion engine is changed by rotating the rotor (2) forward and reverse in the housing (1). An advance chamber (11) or a retard chamber (1) is provided in an oil discharge passage (74) from the control valve (3).
Oil in an amount corresponding to the volume expansion fluctuation of 2) is supplied to the advance chamber (1).
1) or an oil reservoir (75, supplied to the retard chamber (12))
76) is provided.

In the present invention, when the valve opening / closing timing is changed, the rotational position of the rotor periodically fluctuates due to the fluctuation of the camshaft torque. When the volume of the angular chamber or the retard chamber expands and fluctuates, the chamber pressure becomes a negative pressure and the oil is sucked from the oil discharge port. Here, in the present invention, since an oil storage portion having a sufficient volume is provided in the oil discharge path, all the oil required as the volume of the advance chamber or the retard chamber is increased is supplied from the oil storage portion, There is no problem that the oil in the oil discharge port runs short and air flows into the advance or retard chamber. Thus, due to the presence of the oil reservoir,
Since the inflow of air into the advance chamber or the retard chamber is prevented, the bulk elastic modulus of the oil in each of these chambers can be prevented from drastically lowering. It is possible to prevent the volume from greatly fluctuating and causing an excessive phase shift.

[0008] The reference numerals in parentheses indicate the correspondence with specific means described in the embodiments described later.

[0009]

(First Embodiment) FIG. 1 shows the structure of a valve timing adjusting device. In FIG. 1, a circular housing 1 has a chain extending from a crankshaft suspended by a sprocket (not shown) provided on the outer periphery thereof, and is rotated in the direction of the arrow. A rotor 2 is provided in the housing 1, and the rotor 2 is connected to a cam shaft (not shown) by a bolt 22 penetrating the center of the circular portion 21. In the circular portion 21 of the rotor 2, partition portions 23 projecting outward at three locations in the circumferential direction are formed.
3, the space formed at three places in the circumferential direction in the housing 1 is further partitioned in the circumferential direction.
The other is a retard chamber 12.

A hydraulic control valve 3 is fixed to an appropriate position of the internal combustion engine, and a spool valve 4 is inserted into a horizontally long casing 31 through a cylinder body 32.
One end of the spool valve 4 is supported by the coil spring 33, and the other end reaches the inside of the electromagnetic actuator 5 connected to the end face of the casing 3, and is moved by a predetermined amount from the neutral position to the left and right by the electromagnetic actuator 5.

An oil discharge port 61, an oil supply port 62, and an oil discharge port 63 are formed on one side of the cylinder body 32 around the spool valve 4 at three locations in the longitudinal direction, respectively. A corner port 64 and a retard port 65 are formed at two locations in the longitudinal direction, respectively. The oil supply port 62 is provided with an oil supply passage 71 (FIG. 2) that opens therethrough.
The oil discharge ports 61 and 63 are connected to an oil discharge path 74 formed in the casing 31 through flow paths 72 and 73 opened to these oil pumps. . The oil discharge passage 74 rises upward in the casing 31, and the rising portion has a large diameter and forms an oil storage portion 75 having a desired volume at a position higher than the oil discharge ports 61 and 63. The oil discharge path 74 that has exited from the oil storage section 75 is bent horizontally again in the casing 31 (FIG. 2), and reaches the oil pan outside the casing 31. One end of a flow path 81 is opened in the advance port 64, and communicates with each advance chamber 11 in the housing 1 through a cylinder head or a camshaft of the internal combustion engine.
One end of a flow path 82 is opened at the retard port, and communicates with each retard chamber 12 in the housing 1 through a cylinder head or a camshaft of the internal combustion engine.

In the valve timing adjusting device having such a structure, when the spool valve 4 is in the neutral position,
Large-diameter portions 41, 42 formed at the left and right positions of the spool valve 4
As a result, both the advance port 64 and the retard port 65 are closed and are blocked from the other ports 61 to 63.
When the valve opening / closing timing is changed to the retard side, the spool valve 4 is moved to the right from the neutral position as shown in FIG. 1, and the oil supply port 62 communicates with the retard port 65 to allow the oil to flow. It is supplied to the retard chamber 12 via 82. At this time,
Since the advance port 64 communicates with the oil discharge port 61, the oil in the advance chamber 11 is discharged to the oil discharge path 74 via the flow path 81. As a result, the rotor 2 is rotated in a direction opposite to the rotation direction of the housing 1, and as a result, the valve opening / closing timing is changed to the retard side.

When the valve opening / closing timing is changed, as described above, the torque of the camshaft causes the rotor 2 to change.
The rotational position periodically changes. At this time, if the oil pressure supplied from the oil pump is low depending on the operation state of the vehicle, the advance chamber 1 communicated with the oil discharge port 61 via the advance port 64.
When the volume of 1 expands and fluctuates, the chamber pressure becomes negative pressure and oil is sucked from the oil discharge port 61. Here, in the present embodiment, since the oil discharge section 74 is provided with the oil storage section 75 having a sufficient volume, all the oil required as the volume of the advance chamber 11 is increased is supplied from the oil storage section 75. As a result, the problem that the oil in the oil discharge port 61 runs short and air flows into the advance chamber 11 does not occur.

To change the valve opening / closing timing to the advance side, the spool valve 4 is moved to the left in FIG. 1, the oil supply port 62 is communicated with the advance port 64, and the retard port 65 is drained. The communication with the port 63 is made. Thereby, the rotor 2 is rotated in the same direction as the rotation direction of the housing 1 and the valve opening / closing timing is changed to the advance side. Also at this time, if the oil pressure supplied from the oil pump is low, when the volume of the retard chamber 12 communicating with the oil discharge port 63 expands and fluctuates, the chamber pressure becomes negative and the oil discharge port 6
Although the oil is sucked from the oil discharge passage 3, the oil discharge path 74 is provided with an oil reservoir 75 having a sufficient volume. All the air is supplied to prevent the air from flowing into the retard chamber 12. The volume of the oil storage section 75 is set to the advance chamber 11 and the retard chamber 1.
2 (hereinafter referred to as a hydraulic chamber), which exceeds the maximum value of the volume expansion fluctuation amount.
c.

As described above, in the present embodiment, the oil storage 75
, The air flow into the hydraulic chambers 11 and 12 is prevented, so that the bulk modulus of the oil in the hydraulic chambers 11 and 12 is prevented from being significantly reduced. As a result, torque fluctuation of the camshaft is reduced. Accordingly, it is possible to prevent the volumes of the hydraulic chambers 11 and 12 from greatly fluctuating and causing an excessive phase shift. This is shown in FIG.
In this embodiment, the phase shift of the valve opening / closing timing is reduced over a wide engine speed range, as compared with the conventional device (line Y in the figure) which is not provided with an oil reservoir (see FIG. Middle line X).

(Second Embodiment) As shown in the first embodiment, the oil storage section does not necessarily need to be formed with a part of the oil discharge passage 74 having a large diameter, as shown in FIGS. To
By securing the length L of the oil discharge passage 74, the oil storage portion 76 having a required volume can be formed. Further, the oil storage section does not necessarily need to be provided in the hydraulic control valve, but can be provided at an appropriate position in the oil discharge path of the cylinder head section or the cam journal section that reaches the oil pan.

[0017]

As described above, according to the valve timing adjusting apparatus of the present invention, when the supply hydraulic pressure is low, air is prevented from flowing into the hydraulic chamber communicating with the oil discharge port, and the phase shift of the valve opening / closing timing is prevented. Can be reduced as much as possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a valve timing adjusting device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II of FIG.

FIG. 3 is a graph comparing the magnitude of a phase shift with a conventional example.

FIG. 4 is a cross-sectional view of a valve timing adjusting device showing another embodiment of the present invention.

FIG. 5 is a sectional view taken along line VV of FIG.

FIG. 6 is a graph showing a change in magnitude of a phase shift of valve opening / closing timing with respect to a cam angle.

FIG. 7 is a graph showing a change in magnitude of a phase shift of valve opening / closing timing with respect to a cam angle.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Housing, 11 ... Advance chamber, 12 ... Delay chamber, 2 ... Rotor, 3 ... Hydraulic control valve, 4 ... Spool valve, 5 ... Electromagnetic actuator, 61, 63 ... Oil discharge port, 62 ... Oil supply port, 64: advance port, 65: retard port, 74 ...
Oil discharge path, 75, 76 ... oil storage section.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroharu 41, Chukumi Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. (72) Inventor Hirofumi Tani Hirofumi, Aichi-gun, Aichi-gun 41 Chugaku-ji Yokomichi 1 Toyota Central Research Laboratory Co., Ltd. (72) Inventor Ken Hori 1-1-1, Showa-cho, Kariya-shi, Aichi F-term (reference) 3D016 AA06 AA19 BA23 CA13 CA24 CA27 CA30 CA33 CA36 CA42 CA59 DA06 DA22 GA00

Claims (1)

[Claims] A rotor connected to a camshaft is provided in a housing connected to a crankshaft of an internal combustion engine and rotating, and an advance chamber and a retard chamber are defined by the rotor, and a hydraulic control valve is used to define an advance chamber and a retard chamber. The valve opening / closing timing of the internal combustion engine is changed by supplying oil to one of the advance chamber or the retard chamber and discharging the oil from the other of the advance chamber or the retard chamber and rotating the rotor forward and reverse in the housing. In the valve timing adjusting device for an internal combustion engine as described above, an amount of oil corresponding to the volume expansion fluctuation of the advance chamber or the retard chamber is supplied to the advance chamber or the retard chamber in the oil discharge path from the hydraulic control valve. A valve timing adjusting device for an internal combustion engine, comprising a supply oil storage unit.