JP2003201869A - Valve timing controller for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To learn the phase difference between a crankshaft and a camshaft when VVT is not actuated. <P>SOLUTION: This valve timing control device is provided between the crankshaft and the camshaft of an internal combustion engine, and the phase difference between a pulse of a rotary sensor installed to the crankshaft and a pulse of a rotary sensor installed to the camshaft is detected as signals showing an advance angle volume of the valve timing, so as to control the valve timing control device. At the time of idling when the valve timing control device is not actuated, for example, it is mechanically fixed to a most lag position, the phase difference θ is detected for every pulse, and is regarded as a learning value θ0i showing a reference position. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operation timing control device for an internal combustion engine, and more particularly to a valve operation timing control device for controlling at least one of the opening timing and the closing timing of an intake valve and an exhaust valve.

[0002]

2. Description of the Related Art A valve operation timing control device (hereinafter simply referred to as "valve control device") changes intake start or exhaust start timing or end timing according to an engine operating state, for example, to improve intake efficiency and exhaust in a cylinder. It is for improving efficiency. Therefore, the valve control device controls to change the rotation phase of the cam shaft with respect to the crank shaft, thereby advancing the operation timing of at least one of the intake valve and the exhaust valve driven by the cam rotor on the cam shaft (advancing angle). Control) Slow down (retard control). A conventional valve control device is disclosed in, for example, JP-A-61-2688.
It is shown in No. 10.

This device is provided with a cam pulley that rotates in synchronization with the crankshaft and an intermediate gear that meshes with the camshaft and a helical spline between the cam pulley and the camshaft. This intermediate gear is configured to be slidable in the cam shaft direction by hydraulic pressure and spring pressure, and its meshing portion applies an operating torque to the cam shaft. As a result, the cam shaft is rotated in its rotation direction, and the relative position between the cam pulley and the cam shaft is changed.

As for the method of calculating the actual advance amount of the valve operation timing, as shown in FIG. 2, the crank angle signal and the cam angle signal generally having the same number of pulses are used as the valve operation timing. When the control device is not operating (for example, the most retarded angle), the positions of the timing rotor and the angle sensor are initialized when the device is assembled so that the phases match (phase difference = 0), and the valve operation timing control device The phase difference between the crank angle signal and the cam angle signal during the operation (for example, during the advance angle control) is directly used as the actual advance amount.

[0005]

[Patent Document 1] JP-A-61-268810 (first
Page, Fig. 1 etc.)

[0006]

However, in such a valve control device, in order to match the phases of the crank angle signal and the cam angle signal when the valve operation timing control device is not operating, the timing rotor, And a special adjustment mechanism for initializing the position of the angle sensor is required.

Further, if there is a phase difference as a result of the adjustment, an error occurs in the phase difference of the crank angle signal during the operation of the valve operation timing control device (for example, during the advance control), that is, There is an error in the calculation of the actual advance amount,
There is a problem that controllability deteriorates.

The present invention is intended to improve the controllability, and provides an apparatus that does not cause an error in the calculation of the actual advance amount.

[0009]

In order to achieve the above object, according to a first aspect of the present invention, the opening timing of a valve driven by the rotation of the cam shaft is changed by changing the rotational phase of the cam shaft with respect to the crank shaft. And a valve operation timing control device that changes the timing of at least one of the closing timing,
A means for detecting the operating state of the internal combustion engine, a means for determining the proper timing of the valve based on the operating state, a crank position sensor for detecting a crankshaft angular position (hereinafter referred to as "crank position"), and a camshaft. The rotational position of the cam shaft with respect to the crank shaft is determined by the cam position sensor that detects the angular position (hereinafter referred to as "cam position"), the crank position detected by the crank angle position sensor, and the cam position detected by the cam position sensor. A means for detecting the phase difference and grasping the present timing of the valve, a control means for making the present timing the proper timing, and a crank detected by the crank angle position sensor when the valve operation timing control device is not operating. Based on the position and the cam position detected by the cam position sensor, the valve operation timing is set to the camshaft relative to the crankshaft. The crank position sensor outputs a plurality of pulses used for learning in one stroke, and the cam position sensor outputs the pulse used for learning output from the crank position sensor. The learning means outputs the corresponding pulse, and learns the valve operation timing for each pulse of the cam position sensor as the rotational phase difference of the cam shaft with respect to the crank shaft when the valve operation timing control device is inactive. The technical means of valve operation timing control device characterized by

At this time, as described in claim 2, the actual advance amount at the time of valve operation of the valve operation timing control device is determined by the crank position detected by the crank angle position sensor and the cam position detected by the cam position sensor. It may be calculated as an angular difference between the rotational phase difference of the cam shaft with respect to the crank shaft calculated based on the above and the learning value when the valve operation timing control device is not operating.

[0011]

According to the above-described embodiment, the valve operation timing (for example, the most mechanically determined retard angle) when the valve operation timing control device is not operated is learned as the relative phase angle between the crankshaft and the camshaft, During operation of the valve operation timing control device (for example, during advance control), the actual advance amount is calculated based on the learned value. Further, the learning means learns the valve operation timing for each pulse of the cam position sensor as the rotational phase difference of the cam shaft with respect to the crank shaft when the valve operation timing control device is inactive.

Thus, when the device is assembled, an accurate valve operation timing (actual advance amount) can be obtained without requiring a special adjusting mechanism for making the relative phase difference between the crank angle signal and the cam angle signal zero. It has become possible to detect.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the first embodiment of the present invention will be described with reference to FIG. This device controls the valve operation timing using a hydraulic device, and is roughly classified into an electronic control device 10 (hereinafter referred to as “ECU”), a valve timing variable part 30, a hydraulic drive part 50, a camshaft angle. It is configured to include various sensors such as a position sensor 80 (hereinafter referred to as “cam position sensor”) and a crankshaft angular position sensor 81 (hereinafter referred to as “crank position sensor”).

The ECU 10 includes an input / output circuit 11 for inputting a sensor signal and a control signal, a CPU 12 for executing an operation based on the input signal to determine an optimum valve timing control value, and a program for the operation. And a ROM 13 for storing the constants thereof and a RAM 14 for temporarily storing the operation data. The input / output circuit 11 is provided with a spool valve control circuit 15 that supplies a drive signal to a hydraulic drive unit, which will be described in detail later.

FIG. 3 shows a twin-cam type engine in which the intake valve 20 and the exhaust valve 21 are driven by cam rotors 24 and 25 on separate cam shafts 22 and 23, respectively. The ECU 10 receives a signal from a cam position sensor 80 arranged near the cam shaft 22 and grasps the rotational position of the cam shaft 22. Further, the ECU 10 receives a signal from a crank position sensor 81 arranged below the cylinder, and grasps the rotational position of a crankshaft (not shown) and the engine speed. As each of the above-mentioned sensors, an electromagnetic pickup type, a magnetoresistive element type, or an optical element type is used.

The ECU 10 inputs a sensor signal such as a throttle opening degree or an accelerator pedal opening degree in the exhaust pipe, an engine temperature, etc. in addition to the above-mentioned sensor signal as an engine operation signal to grasp a load state of the engine. The ECU 1
0 also controls the fuel system and the ignition system at the same time, but details thereof will not be given here.

A control signal from the ECU 10 is output to a hydraulic drive unit, which will be described later, and determines the amount of hydraulic oil supplied to the valve timing variable unit 30 (hereinafter simply referred to as "variable unit"). The variable portion 30 is combined with each cam shaft 22 or 23 to change the operation timing of each valve 20 or 21. Note that, in FIG. 3, the variable portion 30 is shown only in the intake valve 20 for simplification of description.

FIG. 4 shows the structure of the variable section 30. The variable portion 30 includes a cam shaft member 32 fixed to the cam shaft 22 and a bolt 31, and a cam pulley 33 fitted between the cam shaft 22 and the cam shaft member 32 so as to be slidable in the axial direction of the cam shaft. An intermediate shaft member 34 that slides in the axial direction of the cam shaft between the cam shaft member 32 and the cam pulley 33, and a piston 35 that slides the intermediate shaft member 34 are included. An outer tooth spline 32a formed in a "helical tooth" is formed on the outer peripheral surface of the cam shaft member 32, and helically meshes with an inner tooth spline 34a of the intermediate shaft member 34.

The intermediate shaft member 34 has an outer peripheral surface 34b,
Similarly, it helically meshes with the internal tooth spline 33b of the cam pulley formed on the "helical tooth". A small-diameter cylindrical bearing portion 34c is formed at the end of the intermediate shaft member 34, and is in a shaft-mounted state with the ball bearing 36. This bearing 36
Is fixed to the piston 35. The piston 35 is in a non-rotating state within the inner wall of the housing 37, and is configured to be slidable via a piston ring 38 in the axial direction of the cam shaft while maintaining oil tightness.

The leg portion 37a of the housing is fixed to the fixing portion 39 on the cylinder head with a bolt. Further, a bearing portion 40 is provided inside the housing, and the intermediate shaft member 34
I support you. Housing side wall 37b and piston 35
A first hydraulic chamber 41 is formed between and, and a third hydraulic chamber 42 is formed between the intermediate shaft member 34 and the cam shaft member 32. In these hydraulic chambers 41, 42,
Hydraulic oil is supplied from a hydraulic drive unit described later.

In such a structure, the cam shaft member 3 is usually used.
2, the intermediate member 34 and the cam shaft 22 are integrated with the cam pulley 33 and rotate in synchronization with the crank shaft. The rotation speed is 1/2 of the rotation speed of the crankshaft
Is. During these rotations, when operating oil is supplied to the hydraulic chamber 41 to slide the intermediate shaft member 34 in the axial direction of the camshaft, operating torque is generated in the helical meshing portion 34a.
As a result, an operating torque is applied to the camshaft 22 via the meshing portion 34a, causing the camshaft 22 to rotate in its rotation direction.

For example, when the intermediate member 34 is slid toward the right side in the figure while the camshaft 22 is rotating clockwise, and the camshaft 22 rotates in the rotating direction, the camshaft 22 and the cam pulley 22 are rotated. The relative position between 33, that is, the rotational phase changes. This allows the camshaft 2
In No. 2, the phase advances with respect to the crankshaft and the valve operation timing is advanced. On the contrary, when retarding, the hydraulic chamber 4
The hydraulic oil is supplied to 2, and the intermediate member 34 is slid toward the left side.

Next, the hydraulic drive unit 50 for sliding the intermediate shaft member 34 in this manner will be described. The hydraulic drive unit includes an oil pan 51, a hydraulic pump 52, and a spool valve 53 inside the engine. Although not described in detail, the hydraulic pump 52 is of a normal type in which the pressure feeding drive is performed by crankshaft power. The hydraulic oil in the oil pan 51 is pumped by the hydraulic pump 52 and supplied to the angular hydraulic chambers 41, 42 via the spool valve 53.

The spool valve 53 opens and closes the oil feed pipes 54 and 55 in response to a control signal from the ECU 10, and the hydraulic pressure chambers 4
The amount of hydraulic oil introduced into Nos. 1 and 42 is adjusted. This control signal is current-outputted as a duty signal from the spool valve control circuit 15 in the ECU, and is supplied to the solenoid valve 56 (hereinafter simply referred to as "coil") of the spool valve. The shaft 57 in the spool valve moves in the axial direction according to its current value, and at the same time returns spring 58 against it.
Each oil feed pipe 54, 55 is opened and closed while being restrained by (hereinafter simply referred to as "spring").

FIG. 5 shows an example of the operating state of the spool valve 53. FIG. 5A shows a state where a control signal having a duty ratio of 0% is applied. At this time, the shaft 57
Is restrained to the left end by the spring 58, and the hydraulic pipe 55
Is supplied with hydraulic oil. As a result, the hydraulic oil is supplied to the hydraulic chamber 42, and the hydraulic oil in one hydraulic chamber 41 is returned to the oil pan 51 through the hydraulic pipe 54. as a result,
The volume of the hydraulic chamber 42 in FIG. 4 is increased, and the intermediate shaft member slides in the left direction in the drawing.

FIG. 5B shows the same 50% state. In this case, the pressing force of the coil and the pressing force of the spring are balanced at the position where both hydraulic pipes 54 and 55 are closed, and hydraulic oil is not supplied to both hydraulic chambers 41 and 42.
The sliding mechanism at maintains the current state.

FIG. 5 (c) shows the same 100% state. In this case, the hydraulic oil is supplied only to the hydraulic pipe 54.
As a result, the hydraulic oil is supplied to the hydraulic chamber 41, and the hydraulic chamber 42
The hydraulic oil therein is returned to the oil pan 51 through the oil feed path 59 in the shaft 57. As a result, the hydraulic chamber 41 in FIG. 3 expands, and the intermediate shaft member 34 slides in the right direction in the figure.

In this way, the ECU 10 finely changes the duty ratio and supplies a control signal to the coil 56 to control the amount of oil supplied to each hydraulic chamber. The values of the duty ratio = 0, 50, and 100% may change depending on the characteristics of the coil 56, the spring 58, and the like.

Next, the control of the opening timing of the intake valve (that is, the control of the closing timing of the intake valve) with such a configuration will be described. Such control is executed by PID feedback control, for example. Although the intake valve will be described in the present embodiment, the same applies to the exhaust valve.

FIG. 6 shows a flow chart thereof, and this routine is interrupted in the CPU of the ECU at predetermined time intervals or at the cam angle signal input timing. still,
Hereinafter, a system (for example, a 4-cylinder engine) in which the cam angle signal has 4 pulses in one stroke of the engine (720 ° C.A) will be described as an example.

First, at step 100, an engine operating state signal is input from various sensors such as a crank position sensor and a cam position sensor. Next, at step 110, the relative phase difference of the camshaft with respect to the crankshaft from these signals is calculated, and the phase angle θi (i = 1 to 4) corresponding to the current valve opening timing is calculated. This phase angle θi
The method of calculating (i = 1 to 4) (actual advance amount) is the main part of the present invention, and will be described in detail later.

Next, at step 120, the current operating state of the engine is grasped from the signal values inputted at 100,
An angle θT (hereinafter referred to as “target angle”) corresponding to the proper valve opening timing of the intake valve is determined. This target angle is determined, for example, as shown in FIG. 7, by using a two-dimensional map of the engine speed and the intake air amount corresponding to the engine load.

After determining the target angle θT, step 130
Then, the angle θ calculated at 110 is compared with the target angle θT. At this time, if θT = θi, step 16
0 is executed and a control value for closing both hydraulic pipes of the spool valve is determined. If θT ≠ θi, the angle difference (θT−θi) is calculated in step 140, and
At 50, the feedback control value for the angular difference is determined. After that, the control value is output as a signal to the coil of the spool valve. (Step 170).

Incidentally, the operating condition of the engine changes during the course of
If the target angle θT changes in step 120,
At 120, the control element related to the previous target angle θT 1 is cleared, and the control value is determined for the newly determined target angle θT 2. As a result, proper control of the valve opening timing is achieved with a stable response speed over the entire engine operating state.

Next, the method of calculating the actual advance angle θi in step 110 of FIG. 6 will be described in detail with reference to FIG. Fig. 1 shows 1 stroke for both crank angle signal and cam angle signal (720 ° C)
3 is a timing chart in a system having four pulses in. In addition, a system in which the valve is retarded mechanically at the time of idling when the valve operation timing control device is not in operation is taken as an example.

In this embodiment, when the valve operation timing control device is not operated, the most retarded position is learned for each pulse as the phase difference between the crank angle signal and the cam angle signal.
In FIG. 1, θ01, θ02, θ03, and θ0, respectively.
Set to 4. The actual advance angle amount θi when the valve operation timing control device is operating (for example, during advance angle control) is calculated as follows. The phase angles θ1 i (i = 1 to 4) of the crank angle signal and the cam angle signal during the operation of the valve operation timing control device are obtained and are set as θ11, θ12, θ13, and θ14, respectively. The actual advance angle amount θi (i = 1 to 4) is calculated for each pulse as a difference between the phase angle and the learning value as described below.

[Theta] 1 = [theta] 01- [theta] 11 [theta] 2 = [theta] 02- [theta] 12 [theta] 3 = [theta] 03- [theta] 13 [theta] 4 = [theta] 04- [theta] 14 The electrical delay time (time constant) associated with waveform shaping is reflected as a correction value in the actual advance amount [theta] i. It

FIG. 9 shows a detailed flowchart of step 110 of FIG. First, in step 210, it is determined which pulse the cam angle signal input this time is, and i is specified. This determination process may be, for example, simply cycling i from 1 to 4 from the start of control, or may employ a method of determining a specific pulse as i-th from the relationship with the reference position of engine rotation. Slap 22
At 0, the phase difference θ between the crank angle signal and the cam angle signal input this time is calculated.

Next, at step 230, it is judged if the current engine operating condition is idling. If idling, at step 240, θ0i is set as the initial value (cam and crank phase difference when VVT is not operating). learn. Θ0 if the pulse is the first pulse (if i = 1)
Learned as 1 = θ. If not idling, in step 250, the current phase difference θ is set to θ1i as the phase difference between the crank angle signal and the cam angle signal during VVT operation. If the pulse is the first pulse, then θ11 = θ is set.

Then, in step 260, the difference between the learning value θ0i updated this time or the previous step 240 and the current phase difference θ1i is calculated as the actual advance amount θi.

The preferred embodiment of the present invention has been described above, but the structure and configuration can be variously modified and modified without departing from the scope of the claims.

As a second embodiment, for example, FIG. 8 shows a timing chart of a system in which the crank angle signal and the cam angle signal have different numbers of pulses. In this example,
The crank angle signal is 24 pulses in one stroke (720 ° C). A tooth serving as a reference for calculating the advance amount of the cam angle signal is provided in the 24-pulse crank angle signal. The position of the reference tooth is determined, for example, from the TDC of the first cylinder to the Nth tooth. Further, it is necessary to select a position where each pulse of the cam angle signal does not jump over the reference tooth of the corresponding crank angle signal even at the most advanced valve operation timing.

[0043]

As described above, by using the learning value when the valve operation timing control device is not in operation for calculating the valve operation timing, the relative phase angle between the crank angle signal and the cam angle signal can be determined when the device is assembled. It has become possible to detect an accurate valve operation timing (actual advance amount) without requiring an expensive adjusting mechanism for setting it to zero.

[Brief description of drawings]

FIG. 1 is a first timing chart showing a method for calculating valve operation timing according to the present invention.

FIG. 2 is a timing chart showing a method of calculating valve operation timing according to a conventional technique.

FIG. 3 is a configuration diagram of an embodiment according to the present invention.

FIG. 4 is a valve timing variable portion in the present embodiment.

FIG. 5 is an explanatory view showing one operating state of the spool valve in the present embodiment.

FIG. 6 is an operation flowchart of the embodiment.

FIG. 7 is an explanatory diagram showing an example of a two-dimensional map used in the examples.

FIG. 8 is a second timing chart showing a method for calculating valve operation timing according to the present invention.

FIG. 9 is an operation flowchart of the embodiment.

[Explanation of symbols] 10 ... Electronic control device, 30 ... Valve timing variable part, 50 ... hydraulic drive, 80 ... Cam position sensor, 81 ... Crank position sensor.

Continued front page    F term (reference) 3G018 AB07 AB17 BA34 CA06 CA19                       DA60 DA66 EA12 EA22 FA07                       GA02                 3G084 BA23 CA03 DA04 EA11 EB20                       FA00 FA10 FA20 FA33 FA38                 3G092 AA11 DA09 EC05 FA12 GA04                       HE00Z HE03Z

Claims (2)

[Claims] 1. A valve operation timing control device for changing a rotational phase of a cam shaft relative to a crank shaft to change at least one of an opening timing and a closing timing of a valve driven by the rotation of the cam shaft. A means for detecting an operating state of the internal combustion engine; a means for determining an appropriate timing of the valve based on the operating state; a crankshaft angular position (hereinafter, referred to as "crank position")
A crank position sensor for detecting a cam position sensor, a cam position sensor for detecting a camshaft angular position (hereinafter referred to as "cam position"), a crank position detected by the crank angle position sensor, and a cam detected by the cam position sensor. A means for detecting a rotational phase difference of the camshaft with respect to the crankshaft based on the position and grasping the present timing of the valve; a control means for setting the present timing to the proper timing; Based on the crank position detected by the crank angle position sensor and the cam position detected by the cam position sensor when the timing control device is not operating, the valve operation timing is set to the rotational position of the cam shaft with respect to the crank shaft. And a learning means for learning as a phase difference, wherein the crank position sensor has a plurality of front and rear crank positions. A pulse used for learning is output, the cam position sensor outputs a pulse corresponding to the pulse used for the learning output from the crank position sensor, and the learning unit includes the valve operation timing. A valve operation timing control device, wherein the valve operation timing is learned for each pulse of the cam position sensor as a rotational phase difference of the cam shaft with respect to the crank shaft when the control device is inactive. 2. An actual advance amount of the valve operation timing control device during valve operation is calculated based on a crank position detected by the crank angle position sensor and a cam position detected by the cam position sensor. The valve operation timing according to claim 1, further comprising: an actual advance amount calculating means for calculating an angle difference between a rotational phase difference of the cam shaft with respect to the crank shaft and a learning value when the engine is not operating. Control device.