JPH04232344A - Valve timing control device - Google Patents

Abstract

PURPOSE:To reduce noise at the time of deceleration and to improve durability of a variable valve timing system by preventing unnecessary changeover of valve timing at the time of deceleration of a car. CONSTITUTION:This valve timing control device has a variable valve timing system to change over valve timing in accordance with engine speed. Additionally, changeover of the valve timing by the aforementioned variable valve timing system is restricted by a control means 52 at the time of deceleration of a car detected by a deceleration detection means 51 to detect the time of deceleration of the car.

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 engine valve timing in accordance with engine speed.

0002

2. Description of the Related Art Conventionally, various types of engine valve timings have been proposed in which the valve timing of an engine is made variable in accordance with the engine speed. One technique is to provide a pair of relatively rotatable sleeves on the camshaft side and the crankshaft side, for example, as disclosed in Japanese Patent Application Laid-Open No. 185914/1983.
It is known that the relative rotation of these sleeves is caused to create a rotational phase difference between the camshaft and the crankshaft, thereby changing the valve timing.

The reason why the valve timing is made variable as described above is that the opening/closing timing of the intake and exhaust valves, that is, the valve timing, which improves the volumetric efficiency of intake air and obtains maximum torque, differs mainly depending on the engine speed.

0004

[Problems to be Solved by the Invention] By the way, in a vehicle equipped with an engine equipped with a variable valve timing mechanism that switches valve timing according to the engine speed as described above, when the vehicle decelerates, the engine speed changes as the vehicle speed decreases. The number also decreases, and when the valve timing switching rotation speed is passed, the valve timing is switched. Then, when the vehicle speed further decreases and the driver performs a downshift operation on the transmission, the engine speed increases, and when the engine speed passes through the valve timing switching speed, the valve timing is switched again. In particular, in the case of a vehicle equipped with an automatic transmission that determines the gear ratio depending on the driving condition, this automatic transmission automatically downshifts sequentially from a high gear to a low gear as the vehicle speed decreases. The engine speed repeatedly fluctuates up and down as described above every time the engine is downshifted, and at this time, when the above-mentioned switching speed is passed, the valve timing is frequently switched each time.

However, when the vehicle is decelerating,
In terms of engine output, switching of valve timing is not particularly required, and on the contrary, the problem is the occurrence of torque shock due to switching of valve timing and abnormal noise such as mechanical noise and changes in intake and exhaust noise due to switching operation. . Furthermore, there is concern that the durability of the valve timing mechanism will deteriorate due to an increase in the frequency of switching operations.

[0006] The present invention has been made in view of the above points, and its purpose is to reduce the speed when decelerating a vehicle equipped with an engine equipped with a variable valve timing mechanism that switches valve timing according to the engine speed. The object of the present invention is to prevent unnecessary switching of valve timing, thereby reducing noise during deceleration and improving the durability of a variable valve timing mechanism.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention restricts switching of valve timing when the vehicle is decelerated.

Specifically, as shown in FIG. 1, the solution taken by the invention of claim 1 includes a variable valve timing mechanism 20 that changes the valve timing of the engine according to the engine speed, and a variable valve timing mechanism 20 that changes the valve timing of the engine according to the engine speed, Deceleration detection means 5 for detecting
1, and a control means 52 which receives the output of the deceleration detecting means 51 and limits switching of valve timing by the variable valve timing mechanism 20 when the vehicle is decelerating.

[0009] Furthermore, in the invention of claim 2, the variable valve timing mechanism 20 of claim 1 is of an electrically driven type that is turned ON in a energized state and turned OFF in a de-energized state to switch the valve timing. The means 52 controls the OF of the variable valve timing mechanism 20 during deceleration of the vehicle.
The configuration is such that switching from F to ON operation is prohibited.

0010

[Operation] With the above structure, in the invention of claim 1, when the deceleration detecting means 51 detects that the vehicle is decelerating, the switching of valve timing by the variable valve timing mechanism 20 is restricted by the control means. Even if the engine speed fluctuates up and down due to a downshift operation of the transmission during deceleration and frequently passes the switching speed, valve timing switching is restricted, reducing the frequency of unnecessary valve timing switching.

In particular, in the invention according to claim 2, the variable valve timing mechanism 20 is electrically driven, and when the vehicle is decelerated, the control means 52 changes the variable valve timing mechanism 20 from an OFF operation, which is a non-energized state, to an energized state. Since switching to the ON operation is prohibited, in addition to the same effects as in the case of claim 1, the energization state that consumes power is reduced, and power consumption is reduced.

0012

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

FIGS. 2 and 3 schematically show the structure of an engine equipped with a valve timing control device according to an embodiment of the present invention. This engine is connected to an automatic transmission. In these figures, 1 is an engine, 2 is its cylinder block, and 3 is a cylinder head joined to the upper surface of the cylinder block 2.
An intake cam shaft 5 integrally formed with intake cams 5a, 5a, . . . for driving intake valves to open and close at predetermined timing;
An exhaust camshaft 6 integrally formed with exhaust cams 6a, 6a, . . . for driving the exhaust valves to open and close at predetermined timings is arranged parallel to each other and parallel to the crankshaft 4. Reference numeral 7 denotes a crank pulley that is rotatably provided at the end of the crankshaft 4, and 8 is a cam pulley that is provided on the camshaft at the end of the exhaust camshaft 6 so as to be relatively rotatable but immovable in the axial direction. , 9 are idle pulleys provided on the cylinder head 3, and the three pulleys 7, 8, 9 are drivingly connected via a timing belt 10, so that the rotational driving force of the crankshaft 4 is applied to the crank pulley 7. The signal is transmitted from the cam pulley 8 to the cam pulley 8. A sprocket 11 is rotatably provided on the shaft end of the intake camshaft 5, and a sprocket 12 is rotatably provided on the exhaust camshaft 6 closer to the engine body than the cam pulley 8. , 12 are drivingly connected via a chain 13, so that rotational driving force is transmitted from the exhaust camshaft 6 to the intake camshaft 5. The rotational driving force of the crankshaft 4 is transmitted from the cam pulley 8 to the exhaust camshaft 6, and the cam pulley 8 is connected between the exhaust camshaft 6 and a cam pulley 8 provided at the end of the shaft.
a variable valve timing mechanism 2 that operates to generate a rotational phase difference by a predetermined phase angle between the exhaust camshaft 6 and the exhaust camshaft 6;
0 is set.

The variable valve timing mechanism 20 is equipped with a brake device 21 driven by an electromagnetic type actuator as a drive device, and is turned on and off depending on the state of energization to the brake device 21, and although not shown, the above-mentioned An advancing plate that engages both a hub and a cam pulley 8 that are rotatably provided on the exhaust camshaft 6 and transmits rotational driving force from the cam pulley 8 to the hub, that is, the exhaust camshaft 6, is moved in the axial direction. According to the amount of axial movement of this advancing plate, the cam pulley 8
That is, a rotational phase difference occurs between the crankshaft 4 and the hub, that is, the exhaust camshaft 6, and as a result, the opening/closing timing, that is, the valve timing, of the exhaust valves that are driven to open and close by the exhaust camshaft 6 is changed. At this time, since the intake camshaft 5 is drivingly connected to the exhaust camshaft 6 via a chain, the opening/closing timing of the intake valves that are driven to open and close by the intake camshaft 5, that is, the valve timing, is also changed. The variable valve timing mechanism 20 operates at a predetermined engine speed No.
In the following, the brake device 21 is in a de-energized state, that is, the variable valve timing mechanism 20 is in a de-energized state.
The FF is activated, the brake device 21 is not driven, and the advancing plate is held at the initial position in the axial direction. In this state, the intake and exhaust valves are set to have low speed valve timing. Further, when the predetermined engine speed No. is exceeded, the variable valve timing mechanism 20 becomes energized and operates to turn on the brake device 21.
is driven, the advancing plate is moved in the axial direction by a predetermined amount and held at that position, and in this state, the intake and exhaust valves are set to have high-speed valve timing. Therefore, the output characteristics of the engine 1 are as shown in FIG.
With this as the boundary, the output characteristic range can be switched to two stages: an output characteristic range at low-speed valve timing during OFF operation, and an output characteristic range at high-speed valve timing during ON operation. Further, 40 is an automatic transmission connected to the engine 1, and this automatic transmission 40 is a 4-speed transmission type.
Among the shift schedules, the shift schedule for deceleration is as shown in the schedule map of FIG. 5. Of the two-stage output characteristic range shown in FIG. 4 of the engine 1, the ON operation range of the variable valve timing mechanism 20 in which high-speed valve timing is used is based on the schedule shown in FIG. 5 of the automatic transmission 40. On the map, the area is surrounded by diagonal lines.

[0015]The variable valve timing mechanism 2
The energization state of the brake device 21 of 0, that is, the ON/OFF operation of the variable valve timing mechanism 20, is controlled by a control unit 50 containing a CPU.

Furthermore, in FIG. 3, 30 is a rotation speed sensor that detects the engine rotation speed, 31 is a throttle position sensor that detects the opening of a throttle valve that adjusts the amount of intake air, and 32 is a sensor that detects the running speed of the vehicle. vehicle speed sensor,
33 is a gear shift position sensor that detects the gear position of the automatic transmission 40. And each of the above sensors 30
The output signals of 33 are input to the control unit 50.

Next, operation control of the variable valve timing mechanism 20 in the control unit 50 will be explained based on the flowchart shown in FIG. In the figure, after a start, the engine speed N, vehicle speed V, and throttle opening θ are read in step S1. Then, in step S2, it is determined whether the vehicle is in a deceleration state. This determination is made when the engine rotation speed N is a predetermined rotation speed (for example, 1000
rpm) or more and the throttle opening θ is less than or equal to a predetermined opening (for example, ⅛ opening) as deceleration. This step S2, the rotational speed sensor 30, and the throttle position sensor 31 constitute a deceleration detecting means 51 that detects when the vehicle is decelerating. Here, NO when decelerating
In this case, the process ends immediately. On the other hand, if the answer is YES during deceleration, the process advances to the next step S3. And step S3
Then, it is determined whether the vehicle speed V is less than or equal to a predetermined vehicle speed V1 (approximately 27 km/h). Here, if NO, the process ends, and if YES, the process advances to the next step S4. In step S4, the operation of the variable valve timing mechanism 20 is turned to O.
Fixed to FF operation, that is, variable valve timing mechanism 2
The energized state of 0 is fixed to the non-energized state, and switching of the valve timing is prohibited, and the process ends. The control means 52 receives the output of the deceleration detection means 51 in steps S2 to S4 and limits the switching of valve timing by the variable valve timing mechanism 20 when the vehicle is decelerated.

Therefore, in the above embodiment, it is detected that the vehicle is decelerating, and the vehicle speed is set to the predetermined vehicle speed V1 (approximately 27 km/h).
) or below, the variable valve timing mechanism 20
The operation is fixed to the OFF operation, which is a non-energized state. In this case, when decelerating, the throttle opening is usually 1/
8 or less, and the vehicle speed is at the predetermined vehicle speed V1 (approximately 27K).
m/h), the automatic transmission 40 is in the 3rd gear, and the output characteristic range of the engine 1 is switched from the ON operation to the OFF operation area of the variable valve timing mechanism 20 from the schedule map in FIG. It has become. and,
Even if the vehicle speed further decreases to a predetermined vehicle speed V2 (approximately 15 km/h) and the gear is downshifted, and the variable valve timing mechanism 20 returns to the ON operating range, the switching is not performed and remains in the OFF operating range. maintained. In other words,
When the vehicle decelerates, the variable valve timing mechanism 20 is OF
Switching from F operation to ON operation is prohibited. Therefore, during deceleration when there is no particular demand for output, the variable valve timing mechanism 20 changes from OFF to OFF due to an increase in engine speed due to downshifting.
By preventing unnecessary switching to N operation, it is possible to reduce noise caused by abnormal noises such as torque shock associated with valve timing switching, mechanical noise during switching operation, and changes in intake and exhaust noise. The durability of the variable valve timing mechanism 20 can be improved. Furthermore, since switching of the variable valve timing mechanism 20 from the OFF operation, which is a non-energized state, to the ON operation, which is a energized state, is prohibited, the energized state that consumes power is reduced, and unnecessary power consumption can be reduced. I can do it.

FIG. 7 shows a modification of the operation control of the variable valve timing mechanism 20 in the control unit 50 of the above embodiment. In the same figure, after the start, in step R1, the engine speed N, gear position, throttle opening θ are set.
Load. Then, in step R2, it is determined whether the vehicle is in a deceleration state. This determination is made in Figure 6 of the above example.
Similar to step S2 in , the time when the engine rotational speed N is a predetermined rotational speed (for example, 1000 rpm) or more and the throttle opening degree θ is below a predetermined opening degree (for example, ⅛ opening degree) is considered to be the time of deceleration. This step R2, the rotation speed sensor 30, and the throttle position sensor 31 constitute a deceleration detecting means 51 that detects when the vehicle is decelerating. Here, if NO is not the time of deceleration, the process ends directly. On the other hand, if the answer is YES during deceleration, the process proceeds to the next step R3. Then, in step R3, it is determined whether the gear position is the second gear or the first gear. Here, NO
If the answer is YES, the process ends, and if the answer is YES, the process proceeds to the next step R4. Step R4 is similar to step S4 in FIG. 6 of the above embodiment, and the variable valve timing mechanism 2
0 operation is fixed to the OFF operation, that is, the energized state of the variable valve timing mechanism 20 is fixed to the non-energized state, and switching of the valve timing is prohibited, and the process ends. In steps R2 to R4, the output of the deceleration detection means 51 is received, and when the vehicle is decelerated, the variable valve timing mechanism 2
This constitutes a control means 52 that limits switching of valve timing by zero.

Therefore, in the above modification, when the deceleration of the vehicle is detected and the gear position becomes 2nd gear or 1st gear, the operation of the variable valve timing mechanism 20 is switched to OFF operation, which is a non-energized state. It will be fixed. In this case, when decelerating, the throttle opening is normally 1/8 or less, and when the gear position is 2nd gear or 1st gear, the schedule map in FIG. This is the time when the output characteristic region of the variable valve timing mechanism 20 is switched from the OFF operation region to the ON operation region. However, the variable valve timing mechanism 20 is not switched to ON operation, but remains in the OFF operation range. In other words, when the vehicle is decelerating, the variable valve timing mechanism 20 is prohibited from switching from OFF operation to ON operation. Thereby, the same effects as in the above embodiment can be obtained.

In the above embodiment, the variable valve timing mechanism 20 is driven by an electromagnetic type actuator, but a hydraulically driven type may also be used.

[0022]

As explained above, according to the valve timing control device of the invention as claimed in claim 1, when the vehicle is decelerating, the switching of the valve timing by the variable valve timing mechanism is restricted, so that when the vehicle is decelerating, the transmission Even if the engine speed fluctuates up and down due to downshift operations and frequently passes the switching speed, valve timing switching is restricted, reducing the frequency of unnecessary valve timing switching, and reducing valve timing switching. It is possible to reduce noise caused by abnormal noises such as accompanying torque shock, mechanical noise during switching operation, and changes in intake and exhaust sounds, and it is also possible to improve the durability of the variable valve timing mechanism.

Further, in the invention of claim 2, the variable valve timing mechanism is of an electrically driven type, and when the vehicle is decelerated, the variable valve timing mechanism changes from an OFF operation, which is a non-energized state, to an ON operation, which is a energized state. Since switching to is prohibited, in addition to the same effects as in the case of claim 1, the energization state that consumes power is reduced, and power consumption can also be reduced.

[Brief explanation of the drawing]

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

FIG. 2 is a schematic configuration diagram of an engine equipped with a valve timing control device according to an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of an engine equipped with a valve timing control device according to an embodiment of the present invention.

FIG. 4 is an engine output characteristic diagram.

FIG. 5 is a map diagram showing a shift schedule of an automatic transmission.

FIG. 6 is a flowchart showing operation control of the variable valve timing mechanism in the control unit.

FIG. 7 is a diagram corresponding to FIG. 6 showing a modification.

[Explanation of symbols]

1 Engine 4 Crankshaft 5 Intake camshaft 6 Exhaust camshaft 8 Kam pulley 20 Variable valve timing mechanism 40 Automatic transmission 50 Control unit 51 Deceleration detection means 52 Control means

Claims (2)

[Claims] Claims: 1. A variable valve timing mechanism that changes engine valve timing according to the engine speed; a deceleration detection means that detects when the vehicle is decelerating; 1. A valve timing control device comprising: control means for restricting switching of valve timing by a variable valve timing mechanism. 2. The valve timing control device according to claim 1, wherein the variable valve timing mechanism is of an electrically driven type that is turned ON in a energized state and turned OFF in a de-energized state to switch the valve timing; teeth,
Turning off the above variable valve timing mechanism when the vehicle decelerates
A valve timing control device that prohibits switching from ON to ON operation.