JP3666483B2 - Valve timing control device for internal combustion engine - Google Patents

Description

[0001]
[Industrial application fields]
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 that controls at least one of an opening timing and a closing timing of an intake valve and an exhaust valve.
[0002]
[Prior art]
A valve operation timing control device (hereinafter simply referred to as a “valve control device”) is used to improve intake efficiency and exhaust efficiency in a cylinder by changing the start timing or end timing of intake or exhaust, for example, according to the operating state of the engine. belongs to. For this purpose, the valve control device performs control so as to change the rotation phase of the camshaft with respect to the crankshaft, and accelerates the operation timing of at least one of the intake valve and the exhaust valve driven by the cam rotor on the camshaft (advance angle). Control) Slow down (retard control). A conventional valve control device is disclosed in, for example, Japanese Patent Laid-Open No. 61-268810.
[0003]
In this apparatus, an intermediate gear that meshes with a helical spline is provided between a cam pulley that rotates in synchronization with a crankshaft and the camshaft. The intermediate gear is configured to be slidable in the camshaft direction by hydraulic pressure and spring pressure, and an operating torque is applied to the camshaft at its meshing portion. As a result, the cam shaft is rotated in the rotational direction so that the relative position between the cam pulley and the cam shaft changes.
[0004]
As for the calculation method of the actual advance angle amount of the valve operation timing, as shown in FIG. 2, a crank angle signal and a cam angle signal generally having the same number of pulses as that of the valve operation timing control device are used. The position of the timing rotor and angle sensor is initially set when the device is assembled so that the phase matches (phase difference = 0) when not operating (for example, the most retarded angle), and the valve operation timing control device is activated The phase difference between the crank angle signal (for example, during advance angle control) and the cam angle signal is directly used as the actual advance angle amount.
[0005]
[Patent Document 1]
JP-A-61-268810 (first page, FIG. 1 etc.)
[0006]
[Problems to be solved by the invention]
However, in such a valve control device, the positions of the timing rotor and the angle sensor are initialized when the device is assembled so that the phases of the crank angle signal and the cam angle signal match when the valve operation timing control device is not operating. Special adjustment mechanism is required.
[0007]
Further, if there is a phase difference as a result of adjustment, an error will occur in the phase difference of the crank angle signal when the valve operation timing control device is operated (for example, during advance angle control), that is, the actual advance angle. There is a problem that an error occurs in the calculation of the quantity and the controllability is deteriorated.
[0008]
The present invention aims to improve the controllability, and provides an apparatus that does not cause an error in the calculation of the actual advance amount.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to a first aspect of the present invention, at least one of an opening timing and a closing timing of a valve driven by rotation of the camshaft by changing the rotational phase of the camshaft with respect to the crankshaft. A valve operation timing control device for changing one timing; 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; and a crankshaft angular position (hereinafter referred to as “crank position”). A crank position sensor for detecting a cam shaft angle 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. Means for detecting the rotational phase difference of the camshaft relative to the crankshaft according to the position and grasping the current timing of the valve; and the current timing The valve operation timing is determined based on the control means for achieving the appropriate timing and the crank position detected by the crank angle position sensor and the cam position detected by the cam position sensor when the valve operation timing control device is not operated. Learning means for learning as a rotational phase difference of the cam shaft relative to the shaft,
The crank position sensor outputs a plurality of pulses used for learning in one stroke, and the cam position sensor outputs a pulse corresponding to the pulses used for learning output from the crank position sensor. When the timing moves from the most retarded position to the most advanced position, the pulse output from the cam position sensor is set so as not to jump over the pulse used for learning output from the crank position sensor. The technical means of the characteristic valve operation timing control device is adopted.
[0010]
At this time, as in claim 2, the actual advance angle amount at the time of valve operation of the valve operation timing control device is based on the crank position detected by the crank angle position sensor and the cam position detected by the cam position sensor. You may make it calculate as an angle difference of the rotation phase difference of the cam shaft with respect to the calculated crankshaft, and the learning value at the time of non-operation of a valve operation timing control apparatus.
[0011]
[Action]
According to the embodiment, the valve operation timing (for example, the mechanically determined most retarded angle) when the valve operation timing control device is not operated is learned as the relative phase angle between the crankshaft and the camshaft, and the valve operation timing is determined. When the control device is activated (for example, during advance angle control), the actual advance angle amount is calculated based on the learned value. The cam position sensor outputs a pulse corresponding to the pulse used for learning output from the crank position sensor. When the valve operation timing moves from the most retarded position to the most advanced position, the cam position is The pulses output from the sensor are set so as not to jump over the pulses used for learning output from the crank position sensor.
[0012]
This eliminates the need for a special adjustment mechanism for setting the relative phase difference between the crank angle signal and the cam angle signal to zero at the time of assembling the device, and detects the exact valve operation timing (actual advance angle amount). It became possible.
[0013]
Embodiment
The configuration of the first example of the embodiment according to the present invention will be described with reference to FIG. This device performs control of valve operation timing using a hydraulic device, and is roughly divided into an electronic control device 10 (hereinafter referred to as “ECU”), a valve timing variable unit 30, a hydraulic drive unit 50, a camshaft angle. Various sensors such as a position sensor 80 (hereinafter referred to as “cam position sensor”) and a crankshaft angle position sensor 81 (hereinafter referred to as “crank position sensor”) are provided.
[0014]
The ECU 10 includes an input / output circuit 11 for performing sensor signal input and control signal output, a CPU 12 for executing calculation based on the input signal and determining an optimum valve timing control value, a program for the calculation, and constants thereof. Are provided, and a RAM 14 is provided for temporarily storing calculation 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 that will be described in detail later.
[0015]
FIG. 3 shows a twin cam type engine. The intake valve 20 and the exhaust valve 21 are driven by cam rotors 24 and 25 on separate camshafts 22 and 23, respectively. The ECU 10 receives a signal from a cam position sensor 80 disposed in the vicinity of the camshaft 22 and grasps the rotational position of the camshaft 22. Further, the ECU 10 receives a signal from a crank position sensor 81 disposed below the cylinder, and grasps the rotational position of the crankshaft (not shown) and the engine speed. As each sensor, an electromagnetic pickup type, a magnetoresistive element type, an optical element type, or the like is used.
[0016]
The ECU 10 receives a sensor signal such as a throttle opening or an accelerator pedal opening in the exhaust pipe and an engine temperature in addition to the sensor signal as an engine operation signal, and grasps the load state of the engine. The ECU 10 also controls the fuel system and the ignition system at the same time, but this is not detailed here.
[0017]
A control signal from the ECU 10 is output to a hydraulic drive unit to 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 camshaft 22 or 23 to change the operation timing of each valve 20 or 21. In FIG. 3, the variable portion 30 is shown only in the intake valve 20 for simplification of explanation.
[0018]
FIG. 4 shows the configuration of the variable unit 30. A cam shaft member 32 fixed by a 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 between the cam shaft member 32 and the cam pulley 33 in the axial direction of the cam shaft, and a piston 35 that slides the intermediate shaft member 34 are included. An outer spline 32 a formed in a “helical tooth” is formed on the outer peripheral surface of the cam shaft member 32, and is helically engaged with the inner spline 34 a of the intermediate shaft member 34.
[0019]
The intermediate shaft member 34 is helically meshed with an internal spline 33b of a cam pulley formed on the outer peripheral surface 34b of the "helical tooth". A small-diameter cylindrical bearing 34 c is formed at the end of the intermediate shaft member 34, and is in a shaft-attached 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 while maintaining oil tightness in the axial direction of the camshaft via the piston ring 38.
[0020]
The leg portion 37a of the housing is fixed to the fixing portion 39 on the cylinder head with a bolt. A bearing portion 40 is provided inside the housing and supports the intermediate shaft member 34. A first hydraulic chamber 41 is formed between the housing side wall 37 b and the piston 35, and a third hydraulic chamber 42 is formed between the intermediate shaft member 34 and the cam shaft member 32. The hydraulic oil is supplied to the hydraulic chambers 41 and 42 from a hydraulic drive unit described later.
[0021]
In such a configuration, the camshaft member 32, the intermediate member 34, and the camshaft 22 are normally integrated with the cam pulley 33 and rotate in synchronization with the crankshaft. The rotation speed is ½ of the rotation speed of the crankshaft. During these rotations, when hydraulic oil is supplied to the hydraulic chamber 41 and the intermediate shaft member 34 is slid in the axial direction of the camshaft, an operating torque is generated at the helical meshing portion 34a. As a result, an operating torque is applied to the camshaft 22 via the meshing portion 34a, and the camshaft 22 is rotated in its rotational direction.
[0022]
For example, if the intermediate member 34 is slid toward the right side in the figure while the camshaft 22 is rotating clockwise, if the camshaft 22 rotates in the rotation direction, the camshaft 22 and the cam pulley 33 are The relative position, that is, the rotational phase changes. As a result, the phase of the camshaft 22 advances with respect to the crankshaft, and the valve operation timing is advanced. On the other hand, when retarding, hydraulic oil is supplied to the hydraulic chamber 42 and the intermediate member 34 is slid toward the left side.
[0023]
Next, the hydraulic drive unit 50 that slides the intermediate shaft member 34 in this way will be described. The hydraulic drive unit includes an oil pan 51, a hydraulic pump 52, and a spool valve 53 in the engine. Although the details of the hydraulic pump 52 are omitted, the hydraulic pump 52 is of a normal type in which the pumping 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 and 42 via the spool valve 53.
[0024]
The spool valve 53 opens and closes the oil feed pipes 54 and 55 according to a control signal from the ECU 10 to adjust the amount of hydraulic oil introduced into the hydraulic chambers 41 and 42. This control signal is output as a duty signal from the spool valve control circuit 15 in the ECU and supplied to a solenoid coil 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 the current value, and at the same time, opens and closes the oil feed pipes 54 and 55 while being restrained by a return spring 58 (hereinafter simply referred to as “spring”).
[0025]
FIG. 5 shows an operation state example of the spool valve 53. FIG. 5A shows a state when a control signal having a duty ratio of 0% is given. At this time, the shaft 57 is restrained to the left end by the spring 58, and hydraulic oil is supplied only to the hydraulic pipe 55. 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 increases, and the intermediate shaft member slides in the left direction in the figure.
[0026]
FIG. 5B shows the state of 50%. In this case, the pressing force of the coil and the pressing force of the spring balance at the position where both the hydraulic pipes 54 and 55 are closed, and no hydraulic oil is supplied to both hydraulic chambers 41 and 42, and the sliding mechanism in FIG. Maintains the current state.
[0027]
FIG. 5C shows the state of 100%. In this case, 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 oil in the hydraulic chamber 42 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 is slid in the right direction in the figure.
[0028]
Thus, ECU10 changes a duty ratio finely, supplies a control signal to the coil 56, and controls the oil quantity supplied to each hydraulic chamber. Note that the values of the duty ratio = 0, 50, and 100% may vary depending on the characteristics of the coil 56, the spring 58, and the like.
[0029]
Next, control of the opening timing of the intake valve (that is, equivalent to control of the closing timing of the intake valve) with such a configuration will be described. Such control is executed by, for example, PID feedback control. In this embodiment, the intake valve is described, but the same applies to the exhaust valve.
[0030]
FIG. 6 shows a flowchart of this routine, and this routine is interrupted every predetermined time or at the cam angle signal input timing in the CPU of the ECU. Hereinafter, a system (for example, a four-cylinder engine) in which four cam angle signals exist in one engine stroke (720 ° C.) will be described.
[0031]
First, at step 100, an engine operating state signal is inputted from various sensors such as a crank position sensor and a cam position sensor. Next, in 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. Since the calculation method of the phase angle θi (i = 1 to 4) (actual advance angle amount) is the main part of the present invention, it will be described in detail later.
[0032]
Next, in step 120, the current operating state of the engine is grasped from each signal value input in step 100, and an angle θT (hereinafter referred to as “target angle”) corresponding to the appropriate valve opening timing of the intake valve is determined. For example, as shown in FIG. 7, the target angle is determined using a two-dimensional map of the engine speed and the intake air amount corresponding to the engine load.
[0033]
After determining the target angle θT, in step 130, the angle θ calculated in step 110 is compared with the target angle θT. At this time, if θT = θi, step 160 is executed, and a control value for closing both hydraulic pipes of the spool valve is determined. If θT ≠ θi, the angular difference (θT−θi) is calculated in step 140, and a feedback control value for the angular difference is determined in step 150. Thereafter, the control value is output as a signal toward the coil of the spool valve. (Step 170).
[0034]
If the engine operating state changes midway and the target angle θT changes in step 120, the control element related to the previous target angle θT is cleared in 120, and the newly determined target angle θT is set. On the other hand, a control value is determined. Thus, appropriate valve opening timing control is achieved at a stable response speed over the entire engine operating state.
[0035]
Next, a 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 is a timing chart in a system having four pulses in one stroke (720 ° C.) for both the crank angle signal and the cam angle signal. In addition, an example of a system that mechanically sets the most retarded angle when idling when the valve operation timing control device is not operated is taken as an example.
[0036]
In this embodiment, when the valve operation timing control device is not operated, the most retarded position is learned for each pulse as a phase difference between the crank angle signal and the cam angle signal. In FIG. 1, it is set as θ01, θ02, θ03, and θ04, respectively. The actual advance amount θi at the time of operation of the valve operation timing control device (for example, advance angle control) is calculated as follows. The crank angle signal and cam angle signal phase angle θ1 i (i = 1 to 4) when the valve operation timing control device is operated are obtained and set as θ11, θ12, θ13, and θ14, respectively. The actual advance amount θi (i = 1 to 4) is calculated for each pulse as a difference between the phase angle and the learning value as follows.
[0037]
θ1 = θ01−θ11
θ2 = θ02−θ12
θ3 = θ03−θ13
θ4 = θ04−θ14
Note that the electrical delay time (time constant) related to waveform shaping is reflected in the actual advance amount θi as a correction value.
[0038]
FIG. 9 shows a detailed flowchart of step 110 in FIG. First, in step 210, it is determined what number the pulse of the cam angle signal input this time is, and i is specified. This determination process may be, for example, by sequentially rotating i from 1 to 4 from the start of control, or by adopting a method of determining a specific pulse as the i-th from the relationship with the reference position of the engine rotation. The slap 220 calculates the phase difference θ between the crank angle signal input this time and the cam angle signal.
[0039]
Next, at step 230, it is determined whether or not the current engine operating condition is idling. When idling, at step 240, θ0i is learned as an initial value (cam and crank phase difference when VVT is not operated). When the pulse is the first pulse, (when i = 1) is learned as θ01 = θ. When 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 the VVT operation. When the pulse is the first pulse, θ11 = θ is set.
[0040]
In step 260, the difference between the learning value θ0i updated this time or in the previous step 240 and the current phase difference θ1i is calculated as the actual advance amount θi.
[0041]
As mentioned above, although the preferable Example which concerns on this invention was shown, the structure and structure can be variously changed and changed without deviating from the scope of claims.
[0042]
For example, FIG. 8 shows a timing chart of a system in which the number of pulses of the crank angle signal and the cam angle signal is different as the second embodiment. In this embodiment, the crank angle signal is 24 pulses in one stroke (720 ° C.). Teeth serving as a reference for calculating the amount of advance of the cam angle signal are provided in the 24-pulse crank angle signal. The position of the reference tooth is determined, for example, as the Nth tooth from the TDC of the first cylinder. In addition, even at the most advanced angle of the valve operation timing, 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.
[0043]
【The invention's effect】
As described above, by using the learning value when the valve operation timing control device is not operated for calculating the valve operation timing, the relative phase angle between the crank angle signal and the cam angle signal is set to zero when the device is assembled. An expensive adjustment mechanism is not required, and accurate valve operation timing (actual advance angle amount) can be detected.
[Brief description of the drawings]
FIG. 1 is a first timing chart showing a valve operation timing calculation method according to the present invention.
FIG. 2 is a timing chart showing a valve operation timing calculation method according to the prior art.
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 diagram showing one operation 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 embodiment.
FIG. 8 is a second timing chart showing a valve operation timing calculation method according to the present invention.
FIG. 9 is an operation flowchart of the embodiment.
[Explanation of symbols]
10 ... Electronic control unit,
30 ... Valve timing variable part,
50 ... hydraulic drive,
80: Cam position sensor,
81: Crank position sensor.

Claims (2)

A valve operation timing control device that changes the rotation phase of the cam shaft relative to the crankshaft and changes at least one of the opening timing and the closing timing of the valve driven by the rotation of the cam shaft;
Means for detecting the operating state of the internal combustion engine;
Means for determining an appropriate 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”);
A cam position sensor that detects a cam shaft angular position (hereinafter referred to as a “cam position”), a crank position detected by the crank angle position sensor, and a cam position detected by the cam position sensor. Means for detecting a rotational phase difference of the camshaft and grasping a current timing of the valve;
Control means for making the current timing the aptitude 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 valve operation timing control device is not operated, the valve operation timing is set to the cam shaft relative to the crank shaft. Learning means for learning as the rotational phase difference of
The crank position sensor outputs a plurality of pulses used for learning in one stroke,
The cam position sensor outputs a pulse corresponding to the pulse used for the learning output from the crank position sensor, and when the valve operation timing moves from the most retarded position to the most advanced position. The valve operation timing control device is set so that a pulse output from the cam position sensor does not jump over a pulse output from the crank position sensor and used for the learning. The actual advance amount during valve operation of the valve operation timing control device is calculated with respect to the crankshaft calculated based on the crank position detected by the crank angle position sensor and the cam position detected by the cam position sensor. 2. The valve operation timing control device according to claim 1, further comprising an actual advance angle amount calculating unit that calculates an angle difference between a rotation phase difference of the cam shaft and a learning value when the camshaft is not operated.

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