JP3175243B2 - Valve timing control device for internal combustion engine - 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 provided with a variable valve timing mechanism for continuously changing the opening / closing timing of an intake valve or an exhaust valve according to the operating state of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, output control of an internal combustion engine has been generally performed by opening and closing a throttle valve provided in the middle of an intake passage. However,
At a partial load when the throttle valve is not fully opened, a negative pressure is generated in the intake stroke of the engine, causing a pumping loss at the time of intake of the air-fuel mixture, resulting in a large friction and a deterioration in fuel efficiency.

Therefore, Japanese Utility Model Laid-Open No. 57-174712 proposes to abolish the throttle valve and to provide a variable valve timing mechanism (VVT) for changing the opening / closing timing of the intake valve immediately before the cylinder instead. I have. By driving and controlling the VVT by operating the accelerator pedal to change the opening / closing timing of the intake valve, the amount of intake air to the cylinder is adjusted to reduce pumping loss, thereby improving fuel efficiency.

[0004]

However, in the above-mentioned prior art, the drive of the VVT is only controlled by operating the accelerator pedal, and the control is simply performed according to the load, that is, the accelerator opening. Therefore, the engine temperature is not particularly taken into consideration. At low temperatures, particularly in a light load region where the effective compression ratio of the engine is small, the combustion may be deteriorated, and the engine may have problems such as unstable rotation.

The present invention has been made in view of the above circumstances, and has as its object to reduce the pumping loss as much as possible when the engine is at a low temperature, and to reduce the effective compression ratio more than necessary to reduce the light load. It is an object of the present invention to provide a valve timing control device for an internal combustion engine capable of preventing deterioration of combustion in a region.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, as shown in FIG. 1, the combustion engine M1 is driven at a predetermined timing in accordance with the rotation of the internal combustion engine M1, and combustion is performed. an intake valve M5 and an exhaust valve M6 for opening and closing the intake passage M3 and an exhaust passage M4 leading to chamber M2, respectively, the variable valve driven at least one of the opening and closing timing of their intake valve M5 and exhaust valve M6 to the variable Timing mechanism M7 and internal combustion engine M1
Operating state detecting means M8 for detecting the operating state of the internal combustion engine M1 based on the detection result of the operating state detecting means M8.
Opening and closing timing to reduce pumping loss
And set the opening and closing timing to the target opening and closing timing.
In a valve timing control device for an internal combustion engine provided with a drive control means M9 for driving and controlling the variable valve timing mechanism M7 such that the temperature detection means M10 for detecting the temperature of the internal combustion engine M1 and the temperature detection means M10 Set a limit value for the target opening / closing timing so that the lower the detected temperature, the narrower the control range of the opening / closing timing,
If the target opening / closing timing exceeds the limit value,
Set the limit value as the target value and set the limit value as the target opening / closing timing.
If the target opening / closing timing does not exceed
And a low-temperature control range setting means M11 for setting the control range of the variable valve timing mechanism M7 in the drive control means M9. The invention according to claim 2 includes:
Driven at a predetermined timing in synchronization with the rotation of the fuel engine,
Opening and closing the intake passage and exhaust passage leading to the combustion chamber respectively
Intake and exhaust valves,
Variable opening and closing timing of at least one of the exhaust valves
Variable valve timing mechanism driven to
Operating state detecting means for detecting an operating state of the internal combustion engine,
Based on the detection result of the operating state detecting means, the po
Target opening and closing timing to reduce pumping loss
Set the opening / closing timing to the target opening / closing timing
Drive control of the variable valve timing mechanism so that
Timing of Internal Combustion Engine with Driving Control Means
A temperature control device for detecting a temperature of the internal combustion engine.
Temperature detection means and the temperature detected by the temperature detection means are low
So that the control range of the opening / closing timing becomes narrower
Set a limit value for the target opening / closing timing, and
The goal of the limit value in the case where the target opening and closing timing more than
If the target opening / closing timing does not exceed the limit value
In this case, the drive control
Control range of the variable valve timing mechanism
Low-temperature control range setting means. Again
In the invention according to claim 3, according to claim 1 or 2,
In the valve timing control device for an internal combustion engine, the control
Limit value as the upper limit value of the advance value of the opening / closing timing.
And the lower the detected temperature is, the smaller the value of the limit value becomes.
I try to make it cheaper. Further, according to the invention described in claim 4,
In addition, the valve of the internal combustion engine according to any one of claims 1 to 3
In the timing control device, the limit value is
Set as the lower limit of the advance value of the closing timing
In addition, the lower the detected temperature, the larger the value of the limit value.
Like that.

[0007]

SUMMARY OF] According to the configuration of claim 1, wherein, as shown in FIG. 1, during operation of the internal combustion engine M1, the intake valve M5 and exhaust valve M6 is driven at a predetermined timing in accordance with the rotation of the internal combustion engine M1 The intake passage M3 and the exhaust passage M4 are opened and closed, respectively, so that the intake and exhaust in the combustion chamber M2 is performed. The operating state detecting means M8 detects the operating state of the internal combustion engine M1, and the temperature detecting means M10 detects the temperature of the internal combustion engine M1.

The drive control means M9 controls the drive of the variable valve timing mechanism M7 based on the detection result of the operation state detection means M8 so as to control the opening / closing timing so as to reduce the pumping loss of the internal combustion engine M1. At this time, the low-temperature control range setting means M11 is connected to the temperature detection means M
10. The lower the temperature detected by 10, the more the opening / closing timing is controlled.
Set a limit value for the target opening / closing timing to narrow the range.
If the target opening / closing timing exceeds the limit value
The limit value as the target value and the limit value as the target
If the timing does not exceed the target opening / closing timing
As a target value, setting the control range of the variable valve timing mechanism M7 by the drive control means M9.

For this reason, when the temperature of the internal combustion engine M1 is low, control is performed so that the control range of the opening / closing timing is narrowed, that is, the upper limit value of the opening / closing timing is small and the lower limit value is large. Therefore, at a low temperature, the pumping loss of the internal combustion engine M1 can be reduced as much as possible, and the effective compression ratio of the internal combustion engine M1 can be prevented from being reduced more than necessary.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying a valve timing control device for an internal combustion engine according to the present invention will be described in detail with reference to FIGS.

FIG. 2 is a schematic structural view (only one cylinder is shown) illustrating a gasoline engine 1 as an internal combustion engine mounted on a vehicle according to this embodiment. A piston 3 is provided in a cylinder bore 2a formed in a cylinder block 2 of the engine 1 so as to be vertically movable. The piston 3 is connected to a crankshaft (not shown) via a rod 4. A space surrounded by the piston 3, the cylinder bore 2a, and the cylinder head 5 covering the upper side of the bore 2a is a combustion chamber 6.

An intake passage 7 and an exhaust passage 8 are provided in the combustion chamber 6 so as to communicate with each other. An intake valve 9 for opening and closing is mounted on an intake port 7a opening to the combustion chamber 6 of the intake passage 7. An exhaust valve 8 for opening and closing is provided in an exhaust port 8a opening to the combustion chamber 6 of the exhaust passage 8.
Is assembled.

Outside air is introduced into the intake passage 7 via an air cleaner (not shown). An injector 1 for fuel injection is provided near the intake port 7a in the intake passage 7.
1 is provided so that fuel is taken into the intake passage 7. As is well known, fuel at a predetermined pressure is supplied to the injector 11 from a fuel tank (not shown) by the operation of a fuel pump.
Then, a mixture of fuel and outside air injected from the injector 11 and taken into the intake passage 7 is introduced into the combustion chamber 6 through the intake port 7a when the intake valve 9 is opened. Further, the mixture introduced into the combustion chamber 6 explodes.
By the combustion, the driving force of the engine 1 is obtained via the piston 3, the crankshaft, and the like. Further, the burned gas burned in the combustion chamber 6 is discharged from the exhaust port 8a to the outside through the exhaust passage 8 when the exhaust valve 10 is opened.

In the middle of the intake passage 7, the accelerator pedal 1
2 is provided with a throttle valve 13 which is opened and closed in conjunction with the operation of Step 2. When the throttle valve 13 is opened and closed, the amount of air taken into the intake passage 7 is adjusted.

In the vicinity of the throttle valve 13, a throttle sensor 14 for detecting the throttle opening TA,
"ON" when the throttle valve 13 is in the fully closed position
Fully-closed switches 14a that output the fully-closed signals LL are provided. Further, a surge tank 15 for smoothing the pulsation of the intake air is provided downstream of the throttle valve 13. Furthermore, throttle valve 1
The upstream side of the air flow meter 3 is provided with a well-known air flow meter 16 for detecting an intake air amount Q taken into the intake passage 7 from the outside.
Is provided.

Next, a valve operating mechanism for the intake valve 9 and the exhaust valve 10 will be described. An intake valve 9 and an exhaust valve 10 are stems 9a, 10 extending upward, respectively.
The valve springs 17 and 18 and the valve lifters 19 and 20 are mounted on the upper portions of the stems 9a and 10a, respectively. Cams 21a and 22a are provided on the respective valve lifters 19 and 20 so as to engage with each other. The cams 21a and 22a are formed on the camshaft 21 on the intake side and the camshaft 22 on the exhaust side supported by the cylinder head 5 by the number of all cylinders. The intake valve 9 and the exhaust valve 10 are urged upward by the urging forces of the valve springs 17 and 18 and in a direction to close the intake port 7a and the exhaust port 8a. In this biased state, each stem 9
The upper ends of a and 10a are always in contact with the cams 21a and 22a via the valve lifters 19 and 20.

In this embodiment, in order to make only the opening / closing timing of the intake valve 9 variable, the camshaft 21 on the intake side is provided.
A variable valve timing mechanism (hereinafter simply referred to as “V
A VT 23 is provided with a timing pulley assembly 24 and a step motor 25. The step motor 25 includes a plurality of electromagnetic coils, and sequentially selects an electromagnetic coil to be excited among them, so as to rotate in a predetermined direction at each step. On the other hand, only the timing pulley 26 is provided at the tip of the camshaft 22 on the exhaust side. The timing pulley assembly 24 and the timing pulley 26 are drivingly connected to a crankshaft via a timing belt (not shown).

Accordingly, when the engine 1 is operated, power is transmitted from the crankshaft to the timing pulley assembly 24 and the timing pulley 26 via the timing belt, whereby each of the camshafts 21 and 22 is driven to rotate, and each of the camshafts 21 and 22 is rotated. 21a and 22a are respectively rotated. Further, the valve lifters 19 and 20 are pressed against the urging forces of the valve springs 17 and 18 according to the profile of each of the cams 21a and 22a to be rotated.
The intake valve 9 and the exhaust valve 10 move downward, and the intake port 7a and the exhaust port 8a are opened. As is well known, the basic opening and closing timings of the intake valve 9 and the exhaust valve 10 include four strokes of the piston 3 performed during two rotations of the crankshaft (an intake stroke, a compression stroke, and a compression stroke).
It is set in advance in relation to the vertical movement accompanying the expansion stroke and the exhaust stroke. Here, when the intake port 7a is opened by the downward movement of the piston 3 during the intake stroke, that is, when the intake valve 9
Is opened, the air-fuel mixture is sucked into the combustion chamber 6. or,
The exhaust port 8a is moved by the upward movement of the piston 3 during the exhaust stroke.
Is opened, that is, when the exhaust valve 10 is opened, the burned gas is discharged from the combustion chamber 6 to the exhaust passage 8.

The VVT 23 on the intake side is driven and controlled to change the basic opening / closing timing of the intake valve 9 according to the operating state at each time.
1. The rotation phase of each cam 21a is appropriately changed. That is, the drive of the VVT 23 on the intake side is controlled so as to change the intake timing of the air-fuel mixture into the combustion chamber 6. Then, by changing the basic opening / closing timing of the intake valve 9, the valve overlap between the intake valve 9 and the exhaust valve 10 is changed.

In order to ignite the air-fuel mixture introduced into the combustion chamber 6, an ignition plug 2 is mounted on a cylinder head 5 at the center of the cylinder.
7 is fixed, and a discharge portion 27 a thereof is arranged in the combustion chamber 6. This spark plug 27 is connected to the distributor 2
It is driven based on the ignition signal distributed at 8. The distributor 28 synchronizes the high voltage output from the igniter 29 with the crank angle of the engine 1 and
7 for distribution. Distributor 2
Reference numeral 8 denotes a rotor 2 which rotates in conjunction with the rotation of the engine 1.
8a, and a rotation speed sensor 30 for detecting the engine speed NE from the rotation of the rotor 28a. Further, the distributor 28 is provided with a cylinder discriminating sensor 31 which detects a crank angle reference position of the engine 1 at a predetermined ratio in accordance with the rotation of the rotor 28a and outputs a reference position signal G.

The above-described throttle sensor 14, fully-closed switch 14a, air flow meter 16, rotation speed sensor 30
The cylinder discriminating sensor 31 constitutes operating state detecting means for detecting the operating state of the engine 1.
A cooling water temperature sensor 32 for detecting the cooling water temperature (cooling water temperature) THW. The water temperature sensor 32 also serves as a temperature detecting means for detecting the temperature of the engine 1.
In the middle of the exhaust passage 8, an oxygen sensor 33 for detecting the oxygen concentration in the exhaust gas is mounted. Further, in this embodiment, a vehicle speed sensor 34 is provided as vehicle speed detecting means for detecting the running speed (vehicle speed) SP of the vehicle. The vehicle speed sensor 34 is attached to a transmission (not shown) and is driven by rotation of a gear. In addition, in this embodiment, a brake sensor 36 that is turned on by detecting the operation of the brake pedal 35 operated for vehicle braking and outputs a brake signal BS is provided.

The brake pedal 35 is provided with a brake booster 37 connected thereto. The brake booster 37 includes a one-way valve 37a, and is communicated from the valve 37a to the intake passage 7 downstream of the throttle valve 13 through a communication pipe 37b. As is well known, the brake booster 37 is a braking force doubling device using the negative pressure of the intake passage 7, and the detailed description of the structure is omitted here.

In addition, in this embodiment, the engine 1
Is provided with a starter 38 for applying a rotational force by cranking at the time of starting. The starter 38 is provided with a starter switch 39 for detecting the on / off operation. As is well known, the starter 38 is turned on / off by operating an ignition switch (not shown). While the ignition switch is being operated, the starter 38 is turned on, and the starter signal ST is output from the starter switch 39. It is output.

As shown in FIG. 2, the throttle sensor 14, the fully closed switch 14a, the air flow meter 16, the rotational speed sensor 30, the cylinder discriminating sensor 31, the water temperature sensor 32, the oxygen sensor 33, the vehicle speed sensor 34, and the starter The switch 39 and the like are electrically connected to the input side of an engine electronic control unit (hereinafter simply referred to as “engine ECU”) 40. The injector 11 and the igniter 29 described above are electrically connected to the output side of the engine ECU 40. And the engine ECU 40
Is based on output signals from the fully closed switch 14a, the air flow meter 16, the sensors 14, 30 to 34, and the starter switch 39, based on the injector 11 and the igniter 29.
Etc. are suitably controlled.

In this embodiment, the engine ECU 40
Is a control device that mainly controls fuel injection amount control and ignition timing control of the engine 1. In addition, in this embodiment, as shown in FIG. 2, drive control means for driving and controlling the VVT 23 is provided. A constituent VVT ECU 41 is provided. The VVT ECU 41 controls the rotation direction and the rotation amount of the output shaft of the step motor 25. Therefore, the throttle opening degree TA and the fully closed signal L are input from the engine ECU 40 to the input side of the VVT ECU 41.
L, the engine speed NE, the coolant temperature THW, the vehicle speed SP, the detected values of the starter signal ST, and the like are input as data signals. A brake signal BS from the brake sensor 36 is input to the input side of the VVT ECU 41. Further, the VVT ECU 41 controls the opening / closing timing of the intake valve 9 so as to reduce the pumping loss of the engine 1, and based on an input data signal or the like, the magnitude of the valve overlap according to the current operating state of the engine 1. Is determined, and a valve timing control signal for suitably controlling the step motor 25 is output from the output side. In addition, the VVT ECU 41 constitutes a low-temperature control range setting means. The lower the cooling water temperature THW corresponding to the temperature of the engine 1 is based on the input data signal and the like, the more the control range of the opening / closing timing of the intake valve 9 becomes. That is, the control range of the VVT 23 is set so that the difference between the upper and lower limit values of the opening / closing timing is reduced.

Next, the aforementioned engine ECU 40 and V
The configuration of the VT ECU 41 will be described with reference to the block diagrams of FIGS. FIG. 3 is a block diagram illustrating an electrical configuration of the engine ECU 40. Engine ECU
Reference numeral 40 denotes a central processing unit (CPU) 42, a read-only memory (ROM) 4 in which a predetermined control program and the like are stored in advance.
3. A random access memory (RAM) 44 for temporarily storing the calculation results of the CPU 42, a backup RAM 45 for storing previously stored data, and the like, and these components, an external input circuit 46, an external output circuit 47, and the like are connected by a bus 48. It is configured as a connected theoretical operation circuit.

The external input circuit 46 includes the above-described throttle sensor 14, fully closed switch 14a, air flow meter 16, rotation speed sensor 30, cylinder discrimination sensor 31, water temperature sensor 32, oxygen sensor 33, vehicle speed sensor 34, and starter switch 39. Are connected respectively. On the other hand, the external output circuit 47 includes the injector 11, the igniter 29
And VVT ECU 41 are connected respectively.

Then, the CPU 42 reads, as input values, signals from the fully closed switch 14a, the air flow meter 16, the sensors 14, 30 to 34, the starter switch 39, and the like, which are input via the external input circuit 46. When reading the input value, the external input circuit 46 controls the throttle sensor 14, the air flow meter 16, the water temperature sensor 3
2 and the input values from the oxygen sensor 33 are subjected to analog / digital conversion processing. In the external input circuit 46, input values from the rotation speed sensor 30, the cylinder discrimination sensor 31, the vehicle speed sensor 34 and the like are subjected to waveform shaping processing. Then, the CPU 42 sets the fully closed switch 1
4a, air flow meter 16, each sensor 14, 30-3
4 and the input values read from the starter switch 39 and the like, and the injector 11 and the igniter 29 are suitably controlled.

Further, the CPU 42 of the signals read as input values from the fully closed switch 14a, the air flow meter 16, the sensors 14, 30 to 34, the starter switch 39, and the like via the external input circuit 46, the throttle opening degree T
A, fully closed signal LL, engine speed NE, cooling water temperature TH
W, vehicle speed SP, starter signal ST, etc. to external output circuit 4
7 to the VVT ECU 41 as a data signal.

FIG. 4 is a block diagram illustrating an electrical configuration of the VVT ECU 41. The VVT ECU 41 includes a micro processing unit (MPU) 50 and a VVT 2
R in which a predetermined control program for 3 etc. is stored in advance.
RA for temporarily storing the operation results of the OM 51 and the MPU 50
M52 and the like, and these units and the input / output port 53 and the output port 54 and the like are connected as a theoretical operation circuit by a bus 55. The VVT ECU 41 is a clock generator 5 for generating a periodic clock pulse.
6, and a clock pulse is supplied from the generator 56 to the MPU 50. In addition, VVT
The ECU 41 includes a latch circuit 57 and a gate 58 connected to the output port 54.

The input / output port 53 is connected to the engine ECU 40. The brake sensor 36 is connected to the input / output port 53, and the gate 58 is connected to the step motor 2.
5 is connected.

The MPU 50 receives the throttle opening TA and the fully closed signal LL input through the input / output port 53,
Signals such as the engine speed NE, cooling water temperature THW, vehicle speed SP, starter signal ST, and brake signal BS are read as input values, and the step motor 25 is suitably controlled based on the read input values. That is, the MPU 50 calculates and determines the direction to rotate the step motor 25 and the number of steps according to the control program stored in the ROM 51 based on the read input value, and latches the calculation result as a valve timing control signal via the output port 54. Output to the circuit 57. Latch circuit 57 receives the valve timing control signal and applies a gate 58 to execute it.
Are output in accordance with a predetermined sequence. Then, the gate 58 selects an electromagnetic coil to be excited and drives the step motor 25 according to the opening / closing command.

Next, the configuration of the above-described VVT 23 will be described in detail with reference to FIG. The camshaft 21 on the intake side that drives the intake valve 9 has its cam journal 2
At 1b, it is rotatably supported by the cylinder head 5. Then, at the tip of the camshaft 21,
A timing pulley assembly 24 and a step motor 25 constituting the VVT 23 are provided. The timing pulley assembly 24 includes a pulley main body 62 having a plurality of external teeth 61 on the outer periphery, an inner cap 63 and a cylindrical gear 64 attached to the pulley main body 62.

That is, the pulley body 62 has a boss 62a and a circumferential wall 62b near the center thereof, and a space between the boss 62a and the circumferential wall 62b is a circumferential groove 62c. Helical teeth 62d are formed on the inner periphery of the circumferential wall 62b. The pulley main body 62 is mounted on the camshaft 21 with its boss 62a so as to be relatively rotatable.
On the other hand, the inner cap 63 includes a large cylindrical portion 63a and a small cylindrical portion 63b extending to the opposite side, and helical teeth 63c are formed on the outer periphery of the large cylindrical portion 63a. The inner cap 63 is fitted so that the large cylindrical portion 63a covers the boss 62a, and is attached to the pulley main body 62 so as to be relatively rotatable. Further, the inner cap 63 is fixed to the tip of the camshaft 21 so as to be integrally rotatable by a bolt 65 and a knock pin 66. Further, the cylindrical gear 64 is attached to the outer peripheral wall 6.
4a and an inner peripheral wall 64b.
4c is formed. Helical teeth 64d and 64e are formed on the inner and outer circumferences of the inner peripheral wall 64b, respectively.
A circumferential groove 64f is formed between a and the inner peripheral wall 64b.
The inner peripheral wall 64b of the cylindrical gear 64 and the circumferential groove 6
4f is a circumferential wall 62b and a circumferential groove 62 of the pulley body 62.
It is assembled in an uneven relationship with c.

In this assembled state, the helical teeth 62d, 63c, 64d, and 64e are meshed with each other. Due to the meshing relationship, the cylindrical gear 64 is relatively rotatable with the camshaft 21 by moving in the axial direction. I have. The timing pulley assembly 24 is drivingly connected to the crankshaft via a timing belt (not shown) mounted on the external teeth 61 of the pulley body 62.

Accordingly, when the drive is transmitted from the crankshaft to the timing pulley assembly 24, the pulley main body 62 and the inner cap 63 connected by the cylindrical gear 64 are integrally rotated, and furthermore, the bolt 65 and the knock pin 66 are used. The camshaft 21 connected to the inner cap 63 is driven to rotate integrally.

The above-described step motor 25 is attached to the engine 1 by a bracket (not shown). The step motor 25 is for moving the cylindrical gear 64 in the axial direction. A worm gear 67 having a cylindrical shape and having teeth 67a on the outer periphery is attached to an output shaft thereof. The worm gear 67 is a small cylinder 6 of the inner cap 63.
3b so as to be rotatable relative to each other, and is disposed so as to pass through a hole 64c of the cylindrical gear 64. On the other hand, around the hole 64c of the cylindrical gear 64, a ring gear 68 having teeth 68a on its inner periphery is assembled by a ball bearing 69 so as to be relatively rotatable. The ring gear 68 is meshed on the outer periphery of the worm gear 67, and is movable in the axial direction by the rotation of the worm gear 67 due to the meshing relationship. In order to prevent the rotation of the ring gear 68, a long groove 6 extending in the axial direction is provided on the outer periphery of the ring gear 68 on the step motor 25 side.
8b are formed. At the same time, a detent member 70, which has a tubular shape and extends toward the timing pulley assembly 24, is attached to the casing of the step motor 25. On the inner periphery of the detent member 70, the aforementioned long groove 6 is provided.
A projection 70a engaging with the projection 8b is formed. And
Due to the relationship between the engagement of the projection 70a and the long groove 68b, the ring gear 68 is prevented from rotating, and is allowed to move only in the axial direction.

Accordingly, when the timing pulley assembly 24 and the camshaft 21 are integrally rotating, the step motor 25 is driven to rotate the worm gear 67 by a predetermined amount in a certain direction, so that the ring gear 68 is rotated.
Is moved in the axial direction while being prevented from rotating on the worm gear 67. Accordingly, the cylindrical gear 64 is moved in the same axial direction, a relative rotation occurs between the pulley main body 62 and the camshaft 21, and the camshaft 21 is twisted. As described above, in the VVT 23 of this embodiment, the drive of the step motor 25 is controlled so that the cylindrical gear 6 is driven.
The position of the camshaft 21 in the axial direction is changed, so that the camshaft 21 is twisted. When the camshaft 21 is twisted, the opening / closing timing of the intake valve 9 is changed, and the valve overlap is changed.

The oil passage 7 is provided inside the camshaft 21.
1 and 72 are formed, and lubricating oil is supplied to the inside of the timing pulley assembly 24 through the oil passages 71 and 72.

Next, the operation of the valve timing control device for an internal combustion engine configured as described above will be described with reference to FIGS. 6 and 7 are flowcharts for explaining a “VVT control routine” executed by the VVT ECU 41 to control the drive of the VVT 23, and is executed by a periodic interruption every predetermined time.

When the processing shifts to this routine, first, in step 101, the throttle opening degree T based on the detection of the throttle sensor 14, the fully closed switch 14a, the rotation speed sensor 30, the water temperature sensor 32, the starter switch 39, and the like.
A, fully closed signal LL, engine speed NE, cooling water temperature TH
W and the starter signal ST
Read from. Further, a brake signal BS detected by the brake sensor 36 is read.

Subsequently, in step 102, it is determined whether or not the starter signal ST is "ON", that is, whether or not the engine 1 is being started. Here, when the starter signal ST is “ON”, it is determined that the engine is being started.
In step 103, the advance angle value θCAM for opening / closing timing control of the intake valve 9 is set to “40 ° (CA)”, and then the process proceeds to step 109.

If the starter signal ST is not "ON" in step 102, it is determined that the start of the engine 1 has been completed, and in step 104, it is determined whether or not the fully closed signal LL is "ON". It is determined whether the vehicle is decelerating or idling. Here, the fully closed signal LL
Is "on", it is determined that the vehicle is decelerating or idling, and the routine proceeds to step 105, where step 10 is executed.
5 to execute the processing of step 107.

In step 105, the brake signal B
It is determined whether S is “ON”, that is, whether the brake pedal 35 has been operated to brake the vehicle. When the brake signal BS is “ON”, in step 106, the advance angle value θCAM is set to “20”.
° ”, the process proceeds to step 109.
On the other hand, if the brake signal BS is not “ON” in step 105, the advance angle θCAM is set to “0 °” in step 107, and then step 109 is performed.
Move to.

That is, steps 104 to 107
In the process (1), the advance angle value θCAM for opening / closing timing control of the intake valve 9 is set according to whether or not the brake pedal 35 is operated during deceleration. Thus, only when the vehicle is in a decelerating state and the brake pedal 35 is operated, the closing timing of the intake valve 9 is advanced, so that the negative pressure in the intake passage 7 can be increased. Therefore, the negative pressure in the brake booster 37 communicating with the intake passage 7 increases, and the brake pedal 3
5, a predetermined braking force can be obtained without requiring a large stepping force.

On the other hand, if the full-close signal LL is not "ON" in step 104, it is determined that the vehicle is in a normal running state that is neither deceleration nor idling, and in step 108, the engine speed NE and the engine speed NE previously read in are read. Based on the throttle opening TA, the calculation result of the function f (NE, TA) using these values as parameters is set as the advance angle value θCAM for opening / closing timing control of the intake valve 9, and then the routine proceeds to step 109. This function f (NE,
The calculation of TA) is performed with reference to a map as shown in FIG. Here, the map in FIG. 8 is stored in the ROM 51 in advance. In this map, changes in the throttle opening TA and the engine speed NE, that is, the engine 1
A function f (NE, TA) for controlling the opening / closing timing of the intake valve 9 so as to reduce the pumping loss of the engine 1 according to the load change of the engine 1 is set.

Then, Step 103 and Step 10
6. The process shifts from step 107 or step 108 to step 109 based on the cooling water temperature THW.
That is, the upper limit value θLimitU and the lower limit value θLimitL for controlling the opening / closing timing of the intake valve 9 are calculated according to the temperature of the engine 1. This upper limit θLimitU
The calculation of the lower limit value θLimitL is performed with reference to a map as shown in FIG. Here, the map of FIG.
This is stored in the OM 51 in advance. In this map, the control range of the opening / closing timing of the intake valve 9, that is, the range between the upper limit value θLimitU and the lower limit value θLimitL, is set to be narrower as the cooling water temperature THW is lower.

Subsequently, in step 110, it is determined whether or not the advance angle value θCAM previously calculated is larger than the upper limit value θLimitU. Here, if the advance angle value θCAM is larger than the upper limit value θLimitU, step 1
11, the upper limit value θLimitU is changed to the advance value θC.
After setting as AM, the process proceeds to step 112.
On the other hand, if the advance angle value θCAM is not larger than the upper limit value θLimitU, the process directly proceeds to step 112.

Then, step 110 or step 11
The process proceeds from step 1 to step 112 in which the advance angle value θC
It is determined whether or not AM is smaller than the lower limit value θLimitL. Here, the advance angle value θCAM is equal to the lower limit value θLimitL.
If it is smaller than the threshold value, in step 113, the lower limit value θLimitL is set as the advance angle value θCAM, and then the process proceeds to step 114. If the advance angle value θCAM is not smaller than the lower limit value θLimitL, the process directly proceeds to step 114.

That is, steps 109 to 113
In the process (1), a process for guarding the advance angle value θCAM is performed. Then, step 112 or step 1
In step 114 after shifting from step S13, in order to drive-control the step motor 25, the target step number Vst corresponding to the advance angle value .theta.
Set.

Thereafter, in step 115, the stepping motor 25 is calculated based on the set target step number Vst.
Is set as the control step number STEP.

Next, at step 116, it is determined whether or not the control step number STEP is "0". Here, when the control step number STEP is “0”,
The subsequent processing is once ended without driving the step motor 25.

On the other hand, if the number of control steps STEP is not "0" in step 116, step 11
In 7, it is determined whether or not the control step number STEP is larger than “0”, that is, whether or not the control step number STEP is a positive number. Here, the number of control steps STEP
Is a positive number, after resetting the control flag DIR to “0” in step 118,
Move to 21.

If it is determined in step 117 that the control step number STEP is a negative number, step 119
, The control flag DIR is set to "1". Next, in step 120, the number of control steps STE
After the absolute value of P is set as the new control step number STEP, the process proceeds to step 121.

Then, step 118 or step 12
In step 121 after shifting from 0, it is determined whether or not the control flag DIR is "1". Here, if the control flag DIR is “1”, step 122
, The step motor 25 of the intake side VVT 23 is set to 1
After the step has been reversed, the process proceeds to step 124. If the control flag DIR is "0", the process proceeds to step 124 after the step motor 25 is rotated forward by one step in step 123.

After shifting from step 122 or step 123, in step 124, the number of control steps ST
A result obtained by subtracting “1” from EP is set as a new control step number STEP. In step 125, it is determined whether or not the new control step number STEP is “0”. Then, the new control step number ST
If the EP is not “0”, the process jumps to step 121 and repeats the processing of steps 121 to 125. That is, the drive control of the intake side VVT 23 is performed.

On the other hand, if the new control step number STEP is "0" in step 125, the subsequent processing is temporarily terminated. As described above, the drive of the VVT 23 is controlled by the control of the step motor 25,
The opening / closing timing of the intake valve 9 is controlled.

As described above, according to the valve timing control apparatus of this embodiment, the VVT 23 is driven and controlled according to the operating state of the engine 1, that is, the load state, so that the pumping loss of the engine 1 is reduced. The opening / closing timing of the valve 9 is controlled. Therefore, since the pumping loss can be reduced, the amount of air taken into the combustion chamber 6 can also be increased in the operation region equal to or higher than the medium load region, and the output of the engine 1 and the fuel efficiency can be improved.

Further, in this embodiment, the advance angle θCAM is set so that the control range of the opening / closing timing of the intake valve 9 becomes narrower as the temperature is lower in accordance with the temperature state of the engine 1.
, And the control range of the VVT 23 is regulated. That is, when the temperature of the engine 1 is low, the control range of the opening / closing timing of the intake valve 9 is narrowed, that is, the upper limit value θLimitU of the opening / closing timing is small and the lower limit value θ
Control is performed so that LimitL is increased.

Therefore, at low temperatures, the effect of reducing the pumping loss of the engine 1 is reduced to some extent. However, the reduction effect of the effective compression ratio of the engine 1 is suppressed from being reduced more than necessary while obtaining the reduction effect as much as possible. That is,
When the temperature of the engine 1 is low, the valve timing control for reducing the pumping loss is not prohibited, but the reduction of the effective compression ratio is minimized while utilizing the valve timing control for reducing the pumping loss as much as possible.

As a result, even at a low temperature, the pumping loss of the engine 1 is reduced as much as possible, so that the deterioration of fuel efficiency can be suppressed to the minimum. Also, at low temperatures,
In particular, even in a light load region where the effective compression ratio of the engine 1 is small, since the decrease in the effective compression ratio is minimized, deterioration of combustion can be suppressed, and problems such as unstable rotation of the engine 1 can be obtained. Can be prevented from occurring.
Further, at low temperatures, in idling, light load range and high load range, misfire and the like can be prevented, and smooth operation of the engine 1 and improvement of exhaust gas characteristics can be achieved.

It should be noted that the present invention is not limited to the above-described embodiment, and may be implemented as follows, with a part of the configuration being appropriately changed without departing from the spirit of the invention. (1) In the above-described embodiment, the VVT 23 that changes only the opening / closing timing of the intake valve 9 is provided.
It is also possible to provide a VVT that makes only the opening / closing timing of 0 variable or a VVT that makes the opening / closing timing of both the intake valve 9 and the exhaust valve 10 variable.

(2) In the above embodiment, the step motor 2
Although the intake-side VVT 23 having the drive source 5 is employed, a hydraulically driven VVT may be employed. (3) In the above embodiment, the present invention is embodied in the gasoline engine 1. However, the present invention can be embodied in a diesel engine.

[0064]

As described in detail above, according to the present invention ,
Suppressed to become smaller effective compression ratio is more than necessary, while reducing as much as possible the pumping loss of the internal combustion engine when a low temperature, in particular it is possible to prevent deterioration of combustion in the low load region, the rotation of the internal combustion engine with An excellent effect of preventing occurrence of inconveniences such as instability is exhibited.

[Brief description of the drawings]

FIG. 1 is a conceptual configuration diagram illustrating a basic conceptual configuration of the present invention.

FIG. 2 is a schematic configuration diagram illustrating a gasoline engine according to an embodiment of the invention.

FIG. 3 is a block diagram illustrating an electrical configuration of an engine ECU according to one embodiment.

FIG. 4 is a block diagram illustrating an electrical configuration of a VVT ECU according to one embodiment.

FIG. 5 is a cross-sectional view illustrating a configuration of a VVT according to one embodiment.

FIG. 6 is a flowchart illustrating a “VVT control routine” executed by a VVT ECU in one embodiment.

FIG. 7 is a flowchart illustrating a continuation of a “VVT control routine” executed by the VVT ECU in one embodiment;

FIG. 8 is a map in which a relationship between an advance value with respect to an engine speed and a throttle opening in one embodiment is determined in advance.

FIG. 9 is a map in which a relationship between an upper limit value and a lower limit value of an advance angle value with respect to a cooling water temperature is determined in advance in one embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as an internal combustion engine, 6 ... Combustion chamber, 7 ... Intake passage, 8 ... Exhaust passage, 9 ... Intake valve, 10 ... Exhaust valve, 23 ... VVT, 14 ... Throttle sensor, 14a ...
Fully-closed switch, 30 rotation speed sensor (14, 14a, 3)
0 denotes an operating state detecting means), 32: a water temperature sensor forming a temperature detecting means, 41 ... a drive control means, and a VVT ECU forming a low temperature control range setting means.

Continuation of front page (56) References JP-A-2-271013 (JP, A) JP-A-4-194331 (JP, A) JP-A-60-150407 (JP, A) JP-A-60-21512 (JP) , U) Japanese Utility Model Application 57-174712 (JP, U) Japanese Utility Model Application Hei 3-95049 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 13/02 F01L 1/34

Claims (4)

(57) [Claims] 1. An intake valve and an exhaust valve which are driven at a predetermined timing in accordance with the rotation of an internal combustion engine to open and close an intake passage and an exhaust passage leading to a combustion chamber, respectively, and at least one of the intake valve and the exhaust valve. a variable valve timing mechanism driven in order to a variable timing, operating condition detecting means for detecting operating conditions of the internal combustion engine, based on the detection result of said operating condition detecting means, the pumping loss of the internal combustion engine Target opening and closing timing
And set the opening / closing timing to the target opening / closing timing.
In the valve timing control apparatus for an internal combustion engine having a drive control means for driving and controlling the variable valve timing mechanism so as to be grayed, a temperature detecting means for detecting a temperature of said internal combustion engine, the temperature detected by said temperature detecting means Is lower, the target opening / closing timer is controlled so that the control range of the opening / closing timing becomes narrower .
Set a limit value for imaging and set the limit value to the target
If the closing timing is exceeded, set the limit value as the target value.
If the target opening / closing timing does not exceed the limit value,
In this case, the target opening / closing timing
A low-temperature control range setting unit for setting a control range of the variable valve timing mechanism by dynamic control means . A predetermined timing synchronized with the rotation of the internal combustion engine;
Intake and exhaust passages that are driven by a piston and communicate with the combustion chamber
Opening and closing an intake valve and an exhaust valve, respectively, and opening and closing at least one of the intake valve and the exhaust valve
Variable valve that is driven to make the timing variable
Imming mechanism and operating state detecting means for detecting an operating state of the internal combustion engine
The internal combustion engine based on the detection result of the operating state detection means.
Opening and closing timing to reduce pumping loss
The opening / closing timing is the target opening / closing timing.
Drive control of the variable valve timing mechanism so that
Valve-timed for an internal combustion engine and a drive control means to
In grayed controller, a temperature detecting means for detecting a temperature of said internal combustion engine, as the temperature detected by the lower the temperature detection means, the opening and closing
The target opening / closing terminal is set so that the timing control range is narrowed.
Set a limit value for imaging and set the limit value to the target
If the closing timing is exceeded, set the limit value as the target value.
If the target opening / closing timing does not exceed the limit value,
In this case, the target opening / closing timing
Control of the variable valve timing mechanism by dynamic control means
Low-temperature control range setting means for setting the range
A valve timing control device for an internal combustion engine, comprising: 3. The method according to claim 1, wherein the limit value is determined by the advance of the opening / closing timing.
While setting as the upper limit of the angle value, the detected temperature
2. The system according to claim 1, wherein the lower the lower, the lower the limit value.
3. A valve timing control device for an internal combustion engine according to claim 2. 4. The method according to claim 1, wherein the limit value is determined by the advance of the opening / closing timing.
While setting as the lower limit of the angle value, the detected temperature
2. The system according to claim 1, wherein the lower the value, the larger the limit value.
The valve timing control of an internal combustion engine according to any one of claims 1 to 3,
apparatus.