JP3014819B2 - Valve timing control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control device for variably controlling the opening / closing timing of an intake valve or an exhaust valve of an engine, and more particularly to a valve timing control device which changes a valve timing in accordance with an intake charge amount.

[0002]

2. Description of the Related Art Conventionally, this type of valve timing control device is well known.
In the engine disclosed in Japanese Patent Application Laid-Open No. 11, the opening timing of the exhaust valve is retarded in the middle load region of the engine more than in the low load region and the high load region. In this engine, in the low-load and low-rotation region including the idling of the engine, the overlap between the intake / exhaust valves is reduced, the internal recirculation exhaust gas is reduced to improve the combustibility, and the engine is rotated at a stable rotation speed. be able to.

[0003]

In the case where the valve timing of the intake / exhaust valve is switched in accordance with the load of the engine as described above, when the intake charge is employed as the engine load, the intake charge switching line is switched. The overlap of the intake / exhaust valves is reduced in the low load range of the engine where the intake charge is lower than the switching line, and the overlap of the intake / exhaust valves is reduced in the high load range higher than the switching line. The valve timings are switched so as to increase.

[0004] The valve timing switching line is set so that the engine output torque is the same even when the valve timing is switched, in order to eliminate torque shock accompanying the switching.

[0005] However, when the engine is provided with a first idle mechanism for increasing the intake charge amount when the engine is cold as compared to when the engine is warmed up, the engine is more coldly cooled than when the engine is completely warmed up.
A fully closed intake air charge line indicating the intake air charge when the throttle valve is substantially fully closed is raised. Then, in a region where the switching line is lower than the fully closed intake air charge line along with the rise of the fully closed intake air charge line, the overlap of the intake / exhaust valve becomes large when the throttle valve is almost fully closed. This is switched and held at the valve timing, so that the combustibility of the engine deteriorates and torque shock occurs.

The present invention has been made in view of the above, and an object of the present invention is to provide a valve timing in which the overlap of the intake / exhaust valves becomes large when the fully closed intake charge line rises due to a first idle mechanism or the like. To prevent the torque shock.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, when the fully closed intake charge amount line rises, switching of valve timing in a switching line below the line is suppressed. And

Specifically, as shown in FIG. 1, the present invention comprises a valve timing varying means 26 for varying the opening / closing timing of an intake valve 24 or an exhaust valve 25 of the engine 1;
A switching line I for switching the valve timing varying means 26 in accordance with at least the amount of intake air of the engine 1 is provided.
In the valve timing control device provided with the control means 44 for controlling the overlap of the engine 5 so as to reduce the overlap, when the fully closed intake air charge line in the state where the throttle valve 15 of the engine 1 is substantially fully closed rises. The control means 44 is provided with a suppressing means 45 for suppressing the switching of the valve timing varying means 26 on the switching line I below the fully closed intake air charge line.

According to the second aspect of the present invention, a first idle mechanism is provided, and the first idle mechanism raises the fully closed intake air charge line.

That is, according to the present invention, there is provided a first idle mechanism 21 for increasing the amount of intake air to the engine 1 when the engine is cold compared to when the engine is warmed up. It is configured to be.

According to a third aspect of the present invention, as a specific example of the suppressing means 45, the suppressing means 45 is arranged such that, when the fully-closed intake air charging line rises, the intake air charging amount is larger than the fully closed intake air charging line. The switching line I is configured to be shifted by a predetermined amount.

According to the fourth aspect of the present invention, the suppressing means 45 is provided.
Is configured such that when the fully-closed intake air charge line rises, the switching time in the switching line is made longer than in the normal case.

[0013]

With the above construction, according to the first aspect of the present invention, when the fully-closed intake air charge line in the state in which the throttle valve 15 of the engine 1 is substantially fully closed rises, the line is not more than the fully-closed intake air charge line. The switching of the valve timing varying means 26 itself on the switching line I is suppressed by the suppressing means 45, so that the overlap between the intake / exhaust valves 24, 25 becomes large when the throttle valve 15 is substantially fully closed. It is not possible to switch to the valve timing, and it is possible to prevent torque shock due to deterioration of flammability.

According to the second aspect of the present invention, when the first idle mechanism 21 raises the fully closed intake air charge line when the engine 1 is cold, the valve timing on the switching line I below the full closed intake air charge line is reduced. Switching of the variable means 26 is suppressed. For this reason, similarly to the first aspect of the present invention, when the throttle valve 15 is substantially fully closed, the valve timing cannot be switched to the valve timing at which the overlap between the intake / exhaust valves 24 and 25 becomes large, and torque shock can be prevented.

According to the third aspect of the present invention, when the fully-closed intake air charge line rises, the valve timing switching line I is shifted by a predetermined amount to a side where the amount of air is increased more than the fully-closed intake air charge line. Therefore, the switching line I does not fall below the fully-closed intake charging amount line, and does not immediately reach the switching line even if the intake charging amount increases from the fully-closed intake charging line at the time of slow acceleration of the engine 1. Thus, torque shock due to switching of the valve timing can be prevented.

According to the fourth aspect of the present invention, when the fully closed intake air charge line rises, the switching time on the switching line becomes longer than usual, so that the valve timing can be switched slowly even when the engine 1 is slowly accelerated. In other words, torque shock associated with switching can be prevented.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. FIG. 2 shows an overall configuration of an engine and an intake system thereof according to an embodiment of the present invention. Reference numeral 1 denotes a V-type six-cylinder engine mounted on a vehicle body. This engine 1 has a pair of banks B, B facing left and right. Having. The engine 1 includes a cylinder block 2 having a substantially V-shaped cross section that supports a crankshaft 1 a, a pair of left and right cylinder heads 3, 3 mounted on the upper surface of the cylinder block 2, and mounted on the upper surface of each cylinder head 3. And an oil pan 5 attached to the lower surface of the cylinder block 2. The right bank B has first, third and fifth three cylinders 6, 6,... (Only one is shown), and the left bank B has second, fourth and sixth cylinders.
(Only one is shown) is formed, and a combustion chamber 8 surrounded by a piston 7 and a cylinder head 3 fitted therein is provided in each of the cylinders 6. .

Reference numeral 9 denotes an exhaust passage for discharging exhaust gas from the combustion chamber 8 in each of the cylinders 6.
An exhaust gas purification device 10 for purifying exhaust gas by oxidizing and reducing O, HC, NOx and the like is provided.

Reference numeral 11 denotes an intake passage for supplying intake air (air) to the combustion chamber 8 in each cylinder 6, and an upstream end of the intake passage 11 is connected to an air cleaner 12. An air flow meter 13 for detecting the amount of intake air is disposed in the intake passage 11. The intake passage 11 downstream of the air flow meter 13 is branched into two branch intake passages 11 a by a partition wall 14. Are provided with throttle valves 15, 15 for narrowing the intake passage in synchronization with each other. The downstream ends of both branch intake passages 11a, 11a are assembled and connected to the right surge tank 16 above the right bank B. Above left bank B, left surge tank 1
The three independent intake passages 11 b, 1 independent for each cylinder 6 are provided downstream of the surge tanks 16, 17.
1b,... Both surge tanks 16, 17
Are communicated with each other by a communication passage 11c, and the configuration of the intake passage achieves a resonance supercharging effect of intake air. Reference numerals 18 and 19 denote on-off valves which are opened and closed in accordance with the engine speed to switch the tuning speed of the resonance supercharging effect, and 20 denotes an injector for injecting fuel into each of the independent intake passages 11b.

When the engine 1 is cold, the throttle valve 1
A first idle mechanism 21 is provided for controlling the amount of air taken into the combustion chamber 8 of each cylinder 6 to be greater than when warming up when the cylinder 5 is in a substantially fully closed state. That is, one end of a bypass passage 11d for bypassing the throttle valve 15 is branched and connected to the intake passage 11 on the upstream side of the throttle valve 15, and the other end of the bypass passage 11d is connected to the right surge tank 16. This bypass passage 1
An air valve 22 that controls the opening of the bypass passage 11d by a bimetal that operates according to the temperature of the cooling water of the engine 1 is provided in the middle of 1d. The opening of the bypass passage 11d is adjusted by the air valve 22. This controls the amount of intake air to be charged into the combustion chamber 8 when the throttle valve 15 is substantially fully closed, and as shown in FIG. It is configured to increase the fully closed intake charge amount line.

Reference numeral 24 denotes an intake valve for opening and closing the opening of the intake passage 11 to the combustion chamber 8, and reference numeral 25 denotes an exhaust valve for opening and closing the opening of the exhaust passage 9 to the combustion chamber 8.
4 and 25 are each driven by a valve operating mechanism (not shown).
The valve timing mechanism of the intake valve 24 includes a variable valve timing mechanism 2.
6 are provided. This variable valve timing mechanism 2
6 are cylinder heads 3 as shown in enlarged detail in FIG.
A phase angle between the intake side camshaft 27 and a timing pulley 28 connected to the crankshaft 1a of the engine 1 is provided at one end of an intake side camshaft 27 supported on the upper surface of the intake valve 24, respectively. Engine 1 for valve timing
It is an electromagnetically actuated type that changes according to the operating state of the device.

That is, the variable valve timing mechanism 26 is a hub 2 that is rotatably attached to a camshaft 27.
The hub 29 has a plurality of engaging pieces 29b, 29b,... Extending obliquely in the circumferential direction toward the axial direction from a plurality of locations on the outer periphery of the disk portion 29a (only one is shown).
Are formed. On the other hand, the pulley 28 is arranged concentrically with the camshaft 27 and is supported so as to be rotatable relative to the camshaft 27 via a needle bearing 30. On the inner periphery of the pulley 28, longitudinal grooves 31, 31,.
(Only one is shown) is formed, and a ring-shaped advancing plate 32 is slidable in each vertical groove 31 by engaging projections 32a, 32a,. Is engaged. A recess 32b is formed on the outer periphery of the advancing plate 32 between the adjacent engaging projections 32a, 32a.
9, and is adapted to transmit the rotational force of the pulley 28 to the camshaft 27 via the advancing plate 32 and the hub 29.

The inner periphery of the advancing plate 32 is screwed to a thread 33a on the outer periphery of a drum 33 which is rotatably supported by the cam shaft 27. The advancing plate 32 is axially moved by the relative rotation of the drum 33. By moving the hub 29 and changing the engagement position of the hub 29 with the engagement piece 29b, the pulley 28 is rotated relative to the hub 29, that is, the cam shaft 27, and the valve timing of the intake valve is changed.

The drum 33 is urged to rotate in one direction (a direction in which the valve timing of the intake valve 24 is retarded) by a spiral spring 34 disposed on the shaft end side.
An electromagnetic coil 35 controlled by a signal from the control unit 40 is disposed inside the drum 33, and the electromagnetic coil 35 is non-rotatably attached to the cylinder head 3 by a bracket 36. A brake plate 37 that can contact the drum 33 is disposed on the shaft end side of the electromagnetic coil 35.
By pressing the drum 7 against the drum 33, the drum 33 is rotated in the other direction (a direction in which the valve timing of the intake valve 24 advances) against the urging force of the spiral spring 34.

The variable valve timing mechanism 2
6, the valve timing of the intake valve 24 is changed.
As shown in FIG. 5, when the energization of the electromagnetic coil 35 is stopped, the valve timing of the intake valve 24 is retarded,
While reducing the overlap with the exhaust valve 25 to ensure combustion stability, when the electromagnetic coil 35 is energized,
The valve timing of the intake valve 24 is advanced by a predetermined angle as compared with the non-energized state, so that the overlap with the exhaust valve 25 is increased.

The control unit 40 includes an output signal of a crank angle sensor 41 for detecting the rotation angle of the crankshaft 1a of the engine 1, a detection signal of the air flow meter 13, and a water temperature sensor 4 for detecting the temperature of the cooling water of the engine 1.
2 and a signal of an idle switch 43 that is turned ON when the throttle valve 15 is substantially fully closed. In the control unit 40, the electromagnetic coil 3 of the variable valve timing mechanism 26
The procedure for controlling the energization to 5 will be described with reference to FIG.

First, in the first step S1, the engine speed Ne based on the crank angle by the crank angle sensor 41 and the intake air charge Ce as the engine load (the intake air amount detected by the air flow meter 13 is used to determine the engine speed Ne) And the value divided by). Then, step S
In 2, the ON operation area of the variable valve timing mechanism 26 according to the operating state of the engine 1 is determined based on the control map up to the previous time. In the control map, as shown in FIG. 4, two switching lines I and II for switching ON / OFF the variable valve timing mechanism 26 are set on the basis of the engine speed Ne and the intake air amount Ce, and the switching line II Is shifted by a predetermined amount with respect to the switching line I to a side where the filling amount is larger than that of the fully closed intake filling amount line in the cold state. The variable valve timing mechanism 26 is turned off by the non-energization of the electromagnetic coil 35 on the side where the intake air filling amount Ce is smaller than the switching lines I and II, and the variable valve timing mechanism 26 is energized by the electromagnetic coil 35 on the side where the intake air amount Ce is high. ON operation.

If the determination is NO, step S3
Then, after the variable valve timing mechanism 26 is turned off, the process proceeds to step S4. In step S4, the cooling water temperature of the engine 1 detected by the water temperature sensor 42 is read, and it is determined whether or not this temperature is higher than the set value T1. The set temperature T1 is a temperature indicating that the engine 1 is sufficiently warmed up, for example, 80 °. If this determination is NO, step S1
When YES, the switching line is set to the switching line I in step S5, the operation pattern at the time of switching is set to the pattern I in step S6, and the process returns to step S1. In the above-mentioned operation pattern I, as shown in FIG.
The operation value at the time of switching is shortened by increasing the current value to 5 at once.

If YES is determined in the step S2, the process proceeds to a step S7, where the idle switch 43 is turned on.
It is determined whether it is in the state (whether the throttle valve 15 is substantially fully closed). This determination is based on the idle switch 43
If the answer is YES, the process proceeds to step S8, where the switching line is changed to the switching line II, then, in step S9, the switching operation pattern is changed to pattern II, and in step S10, the valve timing variable mechanism 2 is changed.
After turning off the switch 6, the process returns to step S1. In the operation pattern II, unlike the operation pattern I, FIG.
As shown in (b), by turning on / off the current supply to the electromagnetic coil 35 in a short time and then switching to the ON state, the switching time is long and the switching is performed slowly. In steps S7 and S8, if the throttle valve 15 is in a substantially fully closed state, the operation is switched to the switching line II.

Further, when it is determined in step S7 that the idle switch 43 is not OFF, it is determined in step S11 whether or not the current switching line is the switching line I. When the determination is YES, the valve is determined in step S12. When the variable timing mechanism 26
After N operation, the process proceeds to step S14. On the other hand, if the determination is NO
In step S13, after the variable valve timing mechanism 26 is turned ON in the operation pattern II in step S13, the process proceeds to the same step S14. In step S14, the magnitude of the cooling water temperature is determined to be greater than or equal to the set value T1 as in step S4. If the determination is NO, the process returns to step S1.
If YES, the switching line is returned to the switching line I in step S15, and the operation pattern at the time of switching is set to the pattern I in step S16, and then the process returns to step S1.

In this embodiment, the above steps S2 and S3
, S12, there is provided a switching line I which is set in accordance with the intake air filling amount Ce and the rotational speed Ne of the engine 1 and switches the variable valve timing mechanism 26. Inlet / exhaust valves 24, 25
Control means 4 for controlling to reduce the overlap of
4 are configured.

In steps S7 to S9, when the fully closed intake air charge line with the throttle valve 15 of the engine 1 almost fully closed is raised by the first idle mechanism when the engine 1 is cold, The control means 44 suppresses the switching of the variable valve timing mechanism 26 on the switching line I below the raised fully closed intake air charge line, so that the switching line I has a higher charge than the raised fully closed intake air charge line. Suppressing means 45 is provided which switches to the switching line II by shifting by a predetermined amount to the increasing side, and switches from the operation pattern I to the operation pattern II to make the switching time on the switching line II longer than usual.

Next, the operation of the above embodiment will be described. Basically, the engine speed Ne and the intake charge amount Ce
The variable valve timing mechanism 26 is turned on / off based on the switching lines I and II of the control map set according to
Switching is controlled. That is, when the intake air amount Ce is smaller than the switching lines I and II, the electromagnetic coil 35 is de-energized and the variable valve timing mechanism 26 is turned off.
As a result, the overlap between the intake / exhaust valves 24 and 25 is reduced, and the combustion stability of the engine 1 is ensured. On the other hand, when the intake air filling amount Ce is larger than the switching lines I and II, the electromagnetic coil 35 is energized, the variable valve timing mechanism 26 is turned on, and the intake / exhaust valve 24,
25 overlap increases.

When the engine 1 is sufficiently warmed up and its cooling water temperature is higher than the set value T1, a control map for switching ON / OFF of the variable valve timing mechanism 26 is set to the switching line I. At this time, since the fully-closed intake air charge line when the throttle valve 15 is substantially fully closed is lower than the switching line I, the throttle valve 15 opens when the engine 1 is slowly accelerated, and the intake air charge Ce becomes lower. When it slightly increases, the variable valve timing mechanism 2
6 does not switch, but switches from the OFF state to the ON state only when the intake air amount Ce increases. The operation pattern at the time of this switching is pattern I, and the switching is performed rapidly.

On the other hand, when the cooling water temperature is lower than or equal to the set value T1, the air valve 22 of the first idle mechanism 21 is opened and the intake air charge Ce increases more than when the engine is warmed up. When the switching line of the variable valve timing mechanism 26 is the switching line I, the throttle valve 15 is slightly opened at the time of slow acceleration of the engine 1 and the intake charging amount Ce is increased. Even if it increases, the variable valve timing mechanism 26 is switched to the ON state. However, in this embodiment, when the vehicle is cold, the switching line II is selected as the control map. Since the switching line II is shifted from the switching line I by a predetermined amount toward a side where the filling amount is larger than that of the fully closed intake charging line at the time of cold, the slow acceleration of the engine 1 is performed similarly to the warm-up. When the intake air amount Ce slightly increases in this state, the variable valve timing mechanism 26 is not switched, and switching of the valve timing is suppressed, so that torque shock accompanying the switching can be prevented.

Then, when the intake air charging amount Ce is greatly increased during rapid acceleration of the engine 1, the above-mentioned OFF state is changed to O.
Switch to N state. Since the operation pattern at the time of this switching is pattern II, the switching is performed gently, and the torque shock accompanying the switching can be prevented.

Further, in this embodiment, even if the fully-closed intake air charge line is raised by the first idle mechanism 21 when the engine 1 is cold, the switching line I does not become lower than the full-closed intake air charge line. Therefore, the flammability of the engine 1 does not deteriorate when the first idle mechanism 21 operates, and a shock due to the deterioration of the flammability can be prevented.

Although the opening / closing timing of the intake valve 24 is changed in the above-described embodiment, the same operation and effect can be obtained by switching the valve timing of the exhaust valve 25.

In the above embodiment, the throttle valve 15
The first idle mechanism 21 has been described as a cause of the rise of the fully closed intake charge amount line of the substantially fully closed state.
Similarly, when the bypass passage in the idle speed control mechanism is fixed at the open state, the fully-closed intake air charge line similarly rises.

[0040]

As described above, according to the first aspect of the present invention, the switching line of the variable valve timing means of the engine is set at least by the intake charge, and the intake / exhaust valve of the intake / exhaust valve is set on the low load side of the switching line. In a valve timing control device that can be switched to reduce the overlap, when the line of the fully closed intake air charge in the substantially fully closed state of the throttle valve rises, the switching of the valve timing on the switching line below that line is suppressed. Therefore, when the throttle valve is almost fully closed, the valve timing is not switched to the valve timing where the overlap between the intake / exhaust valves becomes large, and the combustion of the engine can be ensured and the accompanying shock can be effectively prevented. it can.

According to the second aspect of the present invention, the fully-closed intake air charge line is raised by the first idle mechanism when the engine is cold. Shock during line rise can be prevented.

According to the third aspect of the present invention, when the fully closed intake charge line rises, the switching line is shifted by a predetermined amount to the side where the charge is larger than the fully closed intake charge line. It is difficult to reach the switching line when the intake air charge increases at the time of slow acceleration, and it is possible to suppress switching of valve timing and prevent torque shock.

According to the fourth aspect of the present invention, when the fully closed intake air charge line rises, the switching time in the switching line is made longer than usual, so that the valve timing is gently switched when the engine is slowly accelerated. To prevent torque shock.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of an engine and an intake / exhaust system in an embodiment.

FIG. 3 is an enlarged sectional view of a variable valve timing mechanism.

FIG. 4 is a characteristic diagram showing a valve timing switching line and a fully closed intake air charge line.

FIG. 5 is a timing chart showing a switching operation pattern of valve timing.

FIG. 6 is a characteristic diagram showing a valve timing switching characteristic of an intake / exhaust valve.

FIG. 7 is a flowchart illustrating a control procedure in the control unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 6 ... Cylinder 11 ... Intake passage 11d ... Bypass passage 15 ... Throttle valve 21 ... Fast idle mechanism 22 ... Air valve 24 ... Intake valve 26 ... Variable valve timing mechanism 40 ... Control unit 44 ... Control means 45 ... Suppression means Ne ... Engine speed Ce: intake air charge

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsumi Nakamura 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP-A-58-158335 (JP, A) JP-A-59 -113221 (JP, A) JP-A-2-248608 (JP, A) JP-A-4-269341 (JP, A) JP-A-4-284138 (JP, A) JP-A-3-138443 (JP, A) ) Hikaru 4-137205 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 13/02

Claims (4)

(57) [Claims] A valve timing varying means for varying an opening / closing timing of an intake valve or an exhaust valve of the engine; and a switching line for switching the valve timing varying means at least in accordance with the intake air charge of the engine. ,
In a valve timing control device provided with control means for controlling an overlap between intake / exhaust valves on a low load side of the switching line, a fully-closed intake valve in a state in which an engine throttle valve is substantially fully closed. A valve timing control device, characterized in that the control means is provided with suppression means for suppressing switching of the valve timing variable means on a switching line below the fully closed intake charge amount line when the filling amount line rises. 2. A system according to claim 1, further comprising a first idle mechanism for increasing an amount of intake air to be charged into the engine in a cold state as compared with a time of warm-up, wherein the first idle mechanism raises a fully closed intake air charge line. The valve timing control device according to claim 1, wherein: 3. The suppression means is configured to shift the switching line by a predetermined amount to a side where the intake air charge increases from the fully closed intake air charge line when the fully closed intake air charge line rises. The valve timing control device according to claim 1 or 2, wherein 4. The control device according to claim 1, wherein the suppression means is configured to make the switching time in the switching line longer when the fully-closed intake air charge line rises than in the normal case.
A valve timing control device as described.