JPH04301104A - Hydraulic drive system for engine valves for internal combustion engines - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a hydraulic drive device for engine valves (intake valves, exhaust valves) for internal combustion engines, and in particular detects the position of hydraulically driven engine valves and uses the detection results to drive the valves. The present invention relates to a hydraulic drive device that performs control.

0002

[Prior Art] In order to appropriately control the operation of an internal combustion engine equipped with a hydraulically driven valve drive device, it is necessary to accurately detect the timing at which the engine valve completes closing (the timing at which it seats on the valve seat). be. As related technologies, the following have been proposed in the past.

[0003] ■ Valve drive device that detects the position of the valve using a magnetic displacement sensor (Japanese Patent Application Laid-open No. 1983-
No. 198710).

■ In order to prevent the effective stroke of the engine valve from changing depending on the engine temperature and violently colliding with the stopper and valve seat during the opening/closing operation of the valve, a valve drive device (specially Kaihei 1-2949
No. 06).

[0005] ■ A valve driving device in which the impact force generated when an engine valve opens or closes is detected by a piezoelectric element, and the detection timing is used as the timing for opening and closing the valve (Japanese Patent Application Laid-open No. 128971/1983). .

[0006]

[Problem to be Solved by the Invention] The above device (①) requires a large space for mounting the sensor, is expensive,
There was a problem with low detection accuracy. This point also applies to the case where an eddy current type, capacitance type, or optical displacement sensor is used.

[0007]Furthermore, the above-mentioned device (2) detects the effective stroke of the valve, and cannot accurately detect the timing at which the valve closes.

[0008] Furthermore, in the above device (①), the impact force generated by the actuator for driving the valve is detected.
The detection timing of the impact force does not accurately correspond to the valve closing completion timing.

The present invention has been made in view of the above-mentioned points, and provides a hydraulic drive device that can accurately detect the timing of completion of closing an engine valve using a small and inexpensive sensor. The purpose is to

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a cylinder body fixed to an internal combustion engine main body, a cylinder body that is slidably fitted into a cylinder hole provided in the cylinder body, and a cylinder body that is slidably fitted into a cylinder hole provided in the cylinder body. a valve drive piston whose front end abuts the rear end of the engine valve while forming an operating oil pressure chamber between the valve drive piston and the engine body; A return amount of hydraulic oil is provided between the hydraulic pressure chamber and the hydraulic pressure generating means in response to the rear end of the valve driving piston passing in the valve closing direction through a hydraulic buffer start position set in the middle of the cylinder hole. In a hydraulic drive device for an engine valve for an internal combustion engine, the hydraulic drive device for an engine valve for an internal combustion engine is provided with a hydraulic oil return amount limiting mechanism that limits the flow of hydraulic oil, and a check valve that only allows flow of hydraulic oil from the hydraulic pressure generating means to the hydraulic pressure chamber. pressure detection means for detecting a parameter value representing the hydraulic pressure in the hydraulic chamber or the differential pressure between the hydraulic pressure in the working hydraulic chamber and the hydraulic pressure of the hydraulic pressure generating means; A signal processing means for determining the valve completion timing is provided.

[0011] Furthermore, the signal processing means is configured to process the signal processing means at the time when the peak value of the parameter value exceeds a predetermined value, or when the positive peak value of the one-time differential value of the parameter value exceeds a predetermined value; It is desirable that the valve closing completion timing be set at the time when the negative peak value of the second differential value becomes smaller than a predetermined value.

[0012] Furthermore, it is preferable that the predetermined value be set depending on the engine operating state, or that a learned value be used as the predetermined value.

[0013] Further, it is preferable that the signal processing means compares and determines the parameter value and a predetermined value only within a predetermined crank angle range set depending on the engine operating state. Further, the signal processing means may directly detect a point in time when the parameter value reaches a peak value within a predetermined crank angle range, and set the detected point in time as the timing at which the engine valve completes closing.

[0014]

[Operation] When the oil pressure generating means shifts from the oil pressure generation state to the oil pressure generation stop state, the valve driving piston moves in the valve closing direction. At this time, the hydraulic oil in the hydraulic pressure chamber tries to return to the hydraulic pressure generating means, but since the check valve is closed, the hydraulic oil return amount limiting mechanism increases the hydraulic pressure in the hydraulic pressure chamber.

A parameter value representing this pressure increase is detected by the pressure detection means, and the timing at which the engine valve completes closing is determined in accordance with this detection signal.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the overall configuration of an internal combustion engine including a hydraulic drive device and its control device according to an embodiment of the present invention. In the figure, reference numeral 1 denotes an internal combustion engine, which has a hydraulically driven valve unit 20 for hydraulically driving an intake valve and an exhaust valve (engine valve). An electronic control unit (hereinafter referred to as "ECU") 2 is connected to the engine 1, and a hydraulically driven valve unit 20 is connected to the ECU 2.
control signals θOFF, θON, fuel injection amount control signal T
A control signal θIG for OUT and ignition timing is supplied to the engine 1 . Furthermore, as will be described later, a pressure sensor (50 in FIG. 2, which will be described later) is provided in the hydraulically driven valve unit 20 of the engine 1 to detect the valve closing completion timing.
The detection signal V is input to the ECU 2.

The ECU 2 includes a cylinder discrimination sensor (hereinafter referred to as ``CYL signal pulse'') that outputs a signal pulse (hereinafter referred to as ``CYL signal pulse'') at a predetermined crank angle position of a specific cylinder of the engine 1.
3. A TDC that generates a TDC signal pulse at a crank angle position a predetermined crank angle before the top dead center (TDC) at the start of the intake stroke of each cylinder (every 180 degrees of crank angle in a 4-cylinder engine). sensor 4, and a crank angle sensor (hereinafter referred to as "CRK signal pulse") that generates one pulse (hereinafter referred to as "CRK signal pulse") at a constant crank angle (for example, 20 degrees) period shorter than the period of the TDC signal pulse.
5 is electrically connected to CYL
A signal pulse, a TDC signal pulse and a CRK signal pulse are sent to the ECU2. The output signal pulses of these three sensors 3, 4, and 5 are the intake valve closing timing, fuel injection timing,
It is used for various timing controls such as ignition timing and for detecting engine rotation speed.

Furthermore, the ECU 2 includes an accelerator opening sensor (θACC sensor) that indicates the amount of depression of the accelerator pedal and serves as a demand detection means that indicates the driver's demand for the engine.
6. Atmospheric pressure sensor (PA sensor) 7 that detects atmospheric pressure (PA), intake air temperature sensor (TA sensor) 8 that detects engine intake air temperature (TA), and hydraulic oil for hydraulically driven valve unit 20 of engine 1 Oil pressure (Poil) and oil temperature (To
Hydraulic pressure sensor (Poil sensor) 9 that detects il), respectively.
, an oil temperature sensor (Toil sensor) 10, a water temperature sensor (TW sensor) 11 that detects engine cooling water temperature (TW),
Oxygen concentration sensor (O2) that detects the oxygen concentration in exhaust gas
sensors) 12 are electrically connected, and these sensors 6 to 1
The output signal from 2 is supplied to the ECU 2.

The ECU 2 is composed of a central processing unit, a memory, a control signal output circuit, etc. (not shown), and controls the operation of the hydraulically driven valve unit based on the detection signals from the various sensors mentioned above, as well as controlling the amount of fuel supplied. and controls ignition timing.

FIG. 2 is a sectional view of the hydraulically driven valve unit 20, which is mounted on the cylinder head 21 of each cylinder of the engine 1. cylinder head 21
is opened at the top of the combustion chamber (not shown) of the engine 1,
An intake valve port 23 is provided, the other end of which communicates with an intake port 24 . The intake valve 22 is arranged so as to be guided so as to be freely movable in the vertical direction in the figure within the cylinder head 21 in order to open and close the intake valve port 23. A valve spring 26 is compressed between the flange 25 of the intake valve 22 and the cylinder head 21, and the valve spring 26 biases the intake valve 22 upward in the figure (in the valve closing direction). Ru.

On the other hand, a cam shaft 28 having a cam 27 is rotatably disposed on the left side of the cylinder head 21 in the drawing. This camshaft 28 is connected to a crankshaft (not shown) via a timing belt (not shown). A hydraulically driven valve unit 20 is interposed between the cam 27, which is integrally formed with the camshaft 28, and the intake valve 22. The hydraulically driven valve unit 20 includes a hydraulically driven mechanism 30 that presses the intake valve 22 downward against the valve spring 26 to open and close it according to the profile of the cam 27, and the hydraulically driven mechanism 30.
Hydraulic release mechanism 31 that closes the intake valve 22 regardless of the cam profile by nullifying the pressing force during the valve opening operation.
It consists of

The hydraulic drive mechanism 30 includes a cylinder head 21
A first cylinder body 33 is fixed to a block 32 that is integrally formed with the cylinder hole 33 of the first cylinder body 33 with its lower end (front end) abutting the upper end (rear end) of the intake valve 25.
A valve-side piston (valve-driving piston) 34 that is slidably fitted into the first cylinder body 33 and the valve-side piston 3
4, a second cylinder body 36 fixed to the block 32, a lifter 35 in sliding contact with the cam 27, and a second cylinder body with its lower end in contact with the lifter 35.
a cam-side piston 37 slidably fitted to the lower part of the cylinder body 36; a hydraulic pressure generation chamber 39 defined by the second cylinder body 36 and the cam-side piston 37; The main component is an oil passage 40 connecting the chamber 38, and when the hydraulic pressure in the hydraulic pressure chamber 38 is above a predetermined value, the intake valve 22 is opened and closed according to the profile of the cam 27.

The first cylinder body 33 has a stepped portion 33b, and a pressure sensor 50 made of a piezoelectric element is interposed between the stepped portion 33b and the block 32. This pressure sensor 50 detects the pressure generated by the distortion of the first cylinder body 33 caused by the operation of the intake valve, and its detection signal is supplied to the ECU 2. In addition, the first
A male thread is carved in the upper part of the cylinder body 33,
The load applied to the pressure sensor 50 by the nut 51 is set to a predetermined value.

The pressure sensor 50 may have one or several chip-shaped piezoelectric elements arranged on a shim shaped like a ring, a semicircle, an ellipse with a hole near the center, or a polygon. . Further, in order to obtain a sensor rotation prevention effect for the purpose of preventing breakage of the lead wire, the shape may include a straight portion, a hole, or a protrusion in part.

FIG. 3 is an enlarged view showing the vicinity of the hydraulic pressure chamber 38 defined by the first cylinder body 33 and the valve-side piston 34, and the illustrated state is when the intake valve 22 is in the completely closed position. (The position where the valve seat 21a is seated in FIG. 2) is shown, that is, the valve side piston 34 has moved to the uppermost position.

The first cylinder body 33 has an oil passage 40a forming a part of the oil passage 40, a fixed orifice 33c communicating the oil passage 40a with the top of the hydraulic pressure chamber 38, and a valve-side piston 34. An annular recess 33 forming an annular oil passage 33d therebetween.
e is provided.

The valve side piston 34 has a valve hole 341a,
The valve body 341 has a spherical valve body 341b that can close the valve hole 341a from the hydraulic pressure chamber side, and a plurality of communication holes 341d.
A check valve 3 consisting of a retainer 341c that holds b.
41 is provided, and this check valve 341 only allows flow of hydraulic oil from the oil passage 40a to the hydraulic pressure chamber 38. Further, the valve-side piston 34 is provided with first and second variable orifices 34a and 34b, as shown in FIG. These orifices 34a, 34b, together with the fixed orifice 33c, are located at a hydraulic buffer start position P (at the upper end of the annular recess 33e) set in the middle of the cylinder hole 33a when the valve-side piston 34 operates in the valve-closing position (raises). ) constitutes a hydraulic oil return amount control mechanism that exhibits a function of limiting the amount of hydraulic oil returned to the oil passage 40a in response to the upper end (rear end) of the valve-side piston 34 passing through.

According to the above-mentioned hydraulic oil return amount limiting mechanism, the first and second variable Since the orifices 34a and 34b are fully open with respect to the annular oil passage 33d, the lift amount of the intake valve 22 decreases relatively rapidly (the valve closes at a relatively high speed). Thereafter, as the valve-side piston 34 rises, the opening area of the first variable orifice 34a and then the second variable orifice 34b with respect to the annular oil passage 33d decreases, and as a result, the leakage amount of hydraulic oil also decreases, so that the intake valve The valve closing operation speed of 22 gradually decreases. Furthermore, after the lower end of the second variable orifice 34b passes through the hydraulic buffer start position P, the hydraulic oil is returned to the oil passage 40a only by the fixed orifice 33c, and the intake valve 22 slowly moves toward the valve seat 21.
Sit on a. Note that the check valve 341 is in a closed state after the upper end of the valve-side piston 34 passes through the hydraulic buffer start position P.

On the other hand, the hydraulic release mechanism 31
and an oil passage 41 connecting the oil supply gallery 42 and the oil passage 4
1, a feed valve 43 and a check valve 44 arranged in the oil passage 41, and an accumulation circuit 41a defined by these valves 43, 44 and the spill valve 45. The main component is an accumulator 46 for maintaining oil pressure at a predetermined value. The oil supply gallery 42 is provided to supply hydraulic pressure to a hydraulically driven valve unit provided for each cylinder, and is connected to an oil pump 47.
It is connected to the. The oil pump 47 supplies hydraulic oil in an auxiliary oil pan 48 provided in the cylinder head 21 to the oil supply gallery 42 as a hydraulic pressure within a predetermined range. Note that the hydraulic oil supplied to the oil supply gallery 42 may be supplied by an oil pump from an oil pan provided at the bottom of the crankcase (not shown).

The spill valve 45, as shown in FIG.
It consists of a control valve section 100 and an electromagnetic drive section 200 that drives the control valve section 100, and the control valve section 100 includes:
The valve housing 101 has an oil passage 41 and an accumulation circuit 41a.
A main valve body 102 that can switch between communication and cutoff is slidably fitted, and a pilot valve 103 that controls opening and closing movement of the main valve body is provided. It is connected to the control valve section 100 to be driven to open and close. That is, the casing 2 of the electromagnetic drive unit 200
A valve housing 101 of a control valve section 100 is connected to 01.

The main valve body 102 is formed into a cylindrical shape with a bottom. The main valve body 102 is slidably fitted into the valve housing 101 while applying the hydraulic pressure of the passage 41 in the valve opening direction to the front surface of the main valve body 102. A chamber 104 is formed. Moreover, a spring 105 is housed in the pilot chamber 104, which biases the main valve body 102 in a direction to cut off the passage 41 and the accumulator circuit 41a. Therefore, the oil pressure in the passage 41 acts on the main valve body 102 in the valve opening direction, and the oil pressure in the pilot chamber 104 and the spring force of the spring 105 act on the main valve body 102 in the valve closing direction. Furthermore, the main valve body 102 has a passage 41 in the pilot chamber 1.
An orifice 106 is provided that communicates with 04.

The pilot valve 103 is interposed between the pilot chamber 104 and the auxiliary oil pan 48, and is biased by a spring 107 in the direction of cutting off the pilot chamber 104 and the oil pan 48. . Further, the electromagnetic drive unit 200 includes a solenoid 202 and a solenoid 20
The movable core 203 is biased by a spring 204 having a smaller spring load than the spring 107 in the direction of coaxially abutting the upper end of the pilot valve 103. When the solenoid 202 is energized, the movable core 203 presses the pilot valve 103 in the downward direction against the spring force of the spring 107 to bring the pilot valve 103 to the closed position, and the solenoid 202 is demagnetized. The pilot valve 103 moves upward while pushing the movable core 203 by the spring force of the spring 107, and opens.

In such a spill valve 45, when the solenoid 202 of the electromagnetic drive section 200 is demagnetized, the pilot valve 103 opens and the hydraulic oil in the pilot chamber 104 is led out to the auxiliary oil pan 48. Therefore, main valve body 1
The oil pressure acting on both sides of the valve 02 is unbalanced, and the opening force due to the oil pressure of the passage 41 acting on the front surface overcomes the oil pressure of the pilot chamber 104 and the valve closing force of the spring 105, causing the spill valve 45 to open. The valve operates.

When the pilot valve 103 is closed by the excitation of the solenoid 202, the hydraulic pressure in the passage 41 acts on the pilot chamber 104 through the orifice 106, and the main valve body 10
2 operates in the valve closing direction, and the spill valve 45 enters the closed state.

The solenoid 202 is connected to the ECU 2, and demagnetization/excitation is controlled by a control signal from the ECU 2.

Returning to FIG. 2, the accumulator 46 maintains the oil pressure in the accumulator circuit 41a at a predetermined pressure.
A cap 463 provided in the middle of the accumulator circuit 41a and having a cylinder hole 461 bored in the block 32 and an air hole 462, a piston 464 slidably fitted in the cylinder hole 461, and the cap 463 and the piston 46
4 and a spring 465 compressed between the spring 465 and the spring 465.

Hydraulic drive mechanism 30 configured as above
The operation of the hydraulic pressure release mechanism 31 will be explained below.

Spill valve 4 is activated by a control signal from ECU 2.
When the solenoid 202 of No. 5 is energized, the spill valve 45 is closed, and the oil pressure in the oil pressure generation chamber 39, oil passage 40, and working oil pressure chamber 38 of the hydraulic drive mechanism 30 is maintained at high pressure (a predetermined value or higher). The intake valve 22 is driven to open and close according to the profile of the cam 27. Therefore, the valve operating characteristics (relationship between crank angle and valve lift amount) in this case are as shown by the solid line in FIG. 12.

On the other hand, when the solenoid 202 of the spill valve 45 is demagnetized by a control signal from the ECU 2 when the intake valve 22 is opened, the spill valve 45 becomes open, and the oil pressure generation chamber 39 of the hydraulic drive mechanism 30 and the oil passage 40 and operating hydraulic chamber 3
The oil pressure in the intake valve 8 decreases, and the intake valve 22 starts to close regardless of the profile of the cam 27. At this time, the hydraulic oil return amount limiting mechanism slows down the closing speed of the intake valve 22 midway through the valve closing operation, and the intake valve 22 gently seats on the valve seat 21a. The valve operating characteristics in this case are shown by the broken line in FIG.

As described above, by opening and closing the spill valve 45 according to the control signal from the ECU 2 and disabling the action of the hydraulic drive mechanism 30 when the spill valve 45 is opened, the timing at which the intake valve 22 starts closing can be arbitrarily set. Can be set to . As a result, it becomes possible to control the amount of intake air in each cylinder using the control signal from the ECU 2.

In this embodiment, a hydraulically driven valve unit similar to that on the intake valve side is provided on the exhaust valve side (not shown), but the exhaust valve side is normally closed at a fixed timing according to the cam profile. It is also possible to use a variable valve timing mechanism that can set multiple valve opening/closing timings.

Next, changes in the load applied to the pressure sensor 50 will be explained with reference to FIG. 6. FIG. 6 shows the relationship between the lift amount of the intake valve 22 immediately before seating ((a) in the same figure), the output V of the pressure sensor 50 ((b) in the same figure), and the crank angle.

When the spill valve 45 is opened while the intake valve 22 is lifted and the valve-side piston 34 rises, the check valve 341 is closed by the function of the hydraulic oil return amount limiting mechanism, and the hydraulic pressure chamber is The oil pressure in 38 increases. As a result, an upward force is generated in the cylinder body 33, and the pressure sensor 5
The load applied to 0 gradually increases (crank angle CA1)
.

Further, the valve-side piston 34 rises, and before the intake valve 22 is seated on the valve seat 21a, the oil pressure in the working oil pressure chamber 38 rapidly rises to a peak value (crank angle APR).
plummet down. After the crank angle CA2, the oil pressure gradually decreases to the level in the oil passage 40 due to leakage from the fixed orifice 33c (crank angle CA3). Therefore, pressure sensor 5
The load applied to zero also reaches its peak value immediately before the intake valve 22 is seated.

[0046] Here, the intake valve lift amount LFT0 when the pressure sensor output V reaches its peak is the lift amount (for example, about 1 mm) at which air intake is not substantially performed, and is hereinafter referred to as "
In this example, the crank angle APR is used as the intake valve seating timing (valve closing completion timing).
I try to regard it as such. This relationship between the crank angle APR and the fixed lift amount LFT0 has sufficient reproducibility and is constant regardless of the operating state of the engine.

A curve L1 in FIG. 7 shows actual measurement data by the pressure sensor 50, and shows a steep peak characteristic near the crank angle APR.

Note that curves L2 and L3 in FIG. 7 show changes in the first differential value and the second differential value of the output V of the pressure sensor 50, respectively. As is clear from the figure, the timing of the positive peak value in the curve L2 and the timing of the negative peak value in the curve L3 approximately coincide with the crank angle APR, so the detection points of these peak values are detected as the seating timing. You can also.

The above points also apply to the exhaust valve side.

The time when the output of the pressure sensor 50 reaches its peak value (hereinafter referred to as "peak time") APR is determined, for example, as shown in FIG.
As shown in 2(a), the peak value VPR of the sensor output V
It can be detected as the point in time when VTH exceeds a predetermined value VTH. In addition, the peak value VPR is the engine operating state, for example, the engine speed NE, the timing at which the intake valve starts closing (the time when the solenoid 202 of the spill valve 45 is switched from energization to demagnetization, the engine speed NE, and the accelerator opening θACC).
The predetermined value VTH is set based on these engine operating parameters, and is corrected according to detected values such as intake air temperature TA and atmospheric pressure PA). With the program shown in
By learning the predetermined value VTH, it is set to an appropriate value.

In step S1 of FIG. 8, a predicted peak value VPCn is first calculated according to the engine operating state. In addition,
n indicates that it is a calculated value this time. This VP
The calculation of Cn is performed, for example, by searching a VPC map set according to the engine speed NE and the intake valve closing start timing θOFF. Next, the absolute value ΔVP of the difference between the current value VPCn and the previous value VPCn-1 of the predicted peak value.
CC (=|VPCn-VPCn-1|) is calculated (step S2), and it is determined whether this ΔVPCC value is smaller than a predetermined guard value VPJ (step S3). If the answer is affirmative (YES), that is, ΔVPCC<VPJ holds, and the engine is in a steady operating state, the difference between the previous value VPRn-1 of the measured peak value VPR and the previous value VPCn-1 of the predicted peak value ΔVPRCn-1 (=VPRn-
1-VPCn-1) (see Figure 12(a)).
Step S4). The reason why the previous value of the actually measured peak value VPR is used here is because the current peak value has not yet been actually measured. Next, m of the deviation ΔVPRC is calculated using the following equation (1).
The learning correction term K2 is calculated as a moving average of 5 (for example, m=5) (step S5).

[0052]

According to equation (1), the learning correction term K2 is calculated as the average value of the ΔVPRC values from m times before to the previous time.

In step S7, the predicted peak value VPCn calculated in step S1 is corrected by adding a learning correction term K2, and the corrected predicted peak value VPC is further corrected by a conversion coefficient K3 (for example, set to about 0.67). The predetermined value VTH is calculated by multiplying by The conversion coefficient K3 is a coefficient for converting the predicted peak value VPC into a predetermined value VTH for determining the peak time.

If the answer to step S3 is negative (NO), that is, ΔVPCC≧VPJ holds, and the engine is in a transient state, the learning correction term K2 and the deviation ΔVPRC from m times before to the previous time are both set to 0. Said step S
Proceed to step 7.

According to the program in FIG. 8, the predetermined value VTH
is set according to the engine operating condition and is corrected by learning, so the peak value VPR varies depending on the engine operating condition.
Even if the APR changes, the peak timing APR can be detected accurately.

[0056] In the above-described embodiment, the conversion coefficient K3 was set constant, but it may be set depending on the engine operating state.

FIG. 9 is a diagram showing another embodiment of the program for calculating the predetermined value VTH, in which step S6 of the program in FIG. 8 is changed to S6a, and step S8 is added after step S7. There is.

In step S6a, a K2 map search is performed, and the deviation ΔVPRC from m times before to the previous time is set to the K2 value thus searched. The K2 map uses the K2 value calculated in step S5 based on engine operating parameters at the time of calculation (for example, engine speed NE and intake valve closing start timing θO).
FF), and is updated with the latest calculated value in step S8.

According to this embodiment, since the learning correction term K2 is calculated for each region set according to the value of the engine operating parameter, more appropriate learning correction is possible.

Next, a method of predicting the current peak time based on the previously measured peak time APR, instead of detecting the peak time APR by comparing the sensor output V and the predetermined value VTH, will be described.

[0061] This method assumes that the peak period APR is actually measured, which means, for example, that sensor output values within a predetermined range before and after the peak period are stored in a memory, and the period when the output value reaches its peak is searched. This can be done by

FIG. 10 is a flowchart of a program for calculating the predicted peak time APC.
Now, the predicted peak time A is based on the engine operating condition.
Calculate PCn. This calculation is performed, for example, by searching an APC map set according to the engine speed NE and the intake system valve closing start timing θOFF. Next, the absolute value ΔAPCC of the difference between the current value APCn and the previous value APCn-1 at the predicted peak time (=|APCn-APCn-1
|) is calculated (step S12), and it is determined whether this ΔAPCC value is smaller than a predetermined guard value APJ (step S13). If the answer is affirmative (YES), that is, ΔAPC
When C<APJ holds true and the engine is in a steady operating state, the previous value APRn- of the actually measured peak timing APR
1 and the previous value APCn-1 of the predicted peak time APC ΔAPCn-1 (=APRn-1-APCn-1) (
(see FIG. 12(b)) is calculated (step S14). The reason why the previous value of the actually measured peak time APR is used here is because the current peak time has not yet been actually measured. Next, m deviations ΔAPRC (for example, m=
A learning correction term K1 is calculated as a moving average of 5) (step S15).

[0063]

According to equation (2), the learning correction term K1 is calculated as the average value of the ΔAPRC values from m times before to the previous time.

In step S17, the predicted peak time APCn calculated in step S11 is corrected by adding the learning correction term K1.

[0065] If the answer to step S13 is negative (NO),
That is, when ΔAPCC≧APJ holds and the engine is in a transient state, the learning correction term K1 and the deviation ΔAPRC from m times before to the previous time are both set to 0, and the process proceeds to step S17.

According to the program shown in FIG. 10, the predicted peak time APC is set according to the engine operating state and is corrected by learning, so that the predicted peak time APC can be accurately calculated depending on the engine operating state.

FIG. 11 is a diagram showing another embodiment of the program for calculating the predicted peak time APC, in which step S16 of the program in FIG. 10 is changed to S16a, and step S18 is added after step S17. It is said that

In step S16a, a K1 map search is performed, and the deviation ΔAPRC from m times before to the previous time is set to the K1 value thus searched. The K1 map is a map in which the K1 value calculated in step S15 is stored in a memory according to engine operating parameters at the time of calculation (for example, engine speed NE and intake valve closing start timing θOFF). Updated with the latest calculated value.

According to this embodiment, since the learning correction term K1 is calculated for each region set according to the value of the engine operating parameter, more appropriate learning correction becomes possible.

By using the predicted peak timing APC calculated as described above for air-fuel ratio control or intake air amount control (intake valve closing timing control), prompt and appropriate control becomes possible. In addition, as mentioned above, in order to obtain the actually measured peak time APR, it is necessary to set a predetermined range that includes the peak time, and this range is set as shown in Fig. 12(b).
As shown in the figure, by setting the predicted peak time APC±A1 (A1 is a predetermined value), an appropriate range can be set, and the actual measured peak time APR can be reliably and quickly searched.

In each of the embodiments described above, the learning correction coefficients K1 and K2 are calculated only when the engine is in a steady operating state, but they may be calculated all the time.

[0072] Furthermore, the peak timing detection method described above is as follows:
It can also be applied to the first differential value or the second differential value (L2, L3 in FIG. 7) of the pressure sensor output value.

Next, an embodiment in which a second pressure sensor 52 is provided together with a pressure sensor (hereinafter referred to as "first pressure sensor") 50 will be described with reference to FIGS. 13 and 14. The output V1 of the first pressure sensor 50 is shown in FIG.
), the period before the timing when the spill valve 50 is opened (the timing when the intake valve starts to close) θOFF exhibits a characteristic having a plurality of peaks. Therefore, in the embodiment described above,
In order to determine the peak timing APR, the valve closing start timing θ
It was necessary to detect the time when the sensor output V1 reaches its peak within the period after OFF. Therefore, in this embodiment, FIG.
As shown in FIG. 3, a second pressure sensor 52 is provided on the stepped portion 36a of the second cylinder body 36, and the load applied to the second pressure sensor 52 is set to a predetermined value by a nut 53.

The output V2 of the second pressure sensor 52 is as shown in FIG.
4(c), before the valve closing start time θOFF, the output is approximately the same as the output V1 of the first pressure sensor 50, while after θOFF, the value corresponds to the initial load setting. Therefore, the difference DV (
= V1-V2) reaches its peak only when the intake valve is seated, as shown in Fig. 14(d), so the output difference DV
By detecting the timing of the peak, the seating timing of the intake valve can be detected.

According to this embodiment, it is possible to accurately detect the peak time without particularly limiting the detection period of the peak time.

Further, according to each of the embodiments described above, it is possible to accurately detect the seating timing of the intake valve, but as shown by broken lines L4 and L5 in FIG.
Even at DC140° (crank angle based on the crank angle at top dead center), the lift curve will vary depending on the engine operating conditions (e.g. engine speed NE, hydraulic oil temperature Toi).
l, etc.). That is, the curve L4 shows the characteristics when the engine speed NE is higher and/or the hydraulic oil temperature Toil is lower (the viscosity of the hydraulic oil is higher) than the curve L5.

Therefore, in order to determine the amount of intake air from the seating timing of the intake valve, it is necessary to calculate the actual lift curve (intake time area). Therefore, by searching a map set according to the engine speed NE, hydraulic oil temperature Toil, etc. and the intake valve seating timing, or by calculation including correction according to the engine speed NE, hydraulic oil temperature Toil, etc. , to determine the actual amount of intake air.

[0078]

As described in detail above, according to the present invention, the parameter value representing the hydraulic pressure in the hydraulic pressure chamber is detected by the pressure detection means, and the timing of completion of closing the engine valve is determined based on the parameter value. Therefore, it is possible to accurately detect the timing at which the engine valve closes. Further, since the pressure detection means can be small and inexpensive, the device can be made smaller and the cost can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an internal combustion engine including a hydraulic drive device and a control device thereof according to an embodiment of the present invention.

FIG. 2 is a sectional view of a hydraulically driven valve unit.

FIG. 3 is an enlarged view of a part of FIG. 2;

FIG. 4 is a perspective view of a valve-side piston.

FIG. 5 is a cross-sectional view of the spill valve.

FIG. 6 is a diagram showing the relationship between the lift amount of the intake valve and the pressure sensor output.

FIG. 7 is a diagram showing actual measurement data by a pressure sensor.

FIG. 8 is a flowchart of a program for calculating a predetermined value (VTH) for peak period detection.

FIG. 9 is a flowchart of a program for calculating a predetermined value (VTH) for peak period detection.

FIG. 10 is a flowchart of a program for calculating predicted peak timing (APC).

FIG. 11 is a flowchart of a program for calculating predicted peak timing (APC).

FIG. 12 is a diagram for explaining a peak time detection method.

FIG. 13 is a diagram showing the mounting position of a second pressure sensor.

FIG. 14 is a diagram for explaining a peak timing detection method using first and second pressure sensors.

FIG. 15 is a diagram showing a valve lift curve of an intake valve.

[Explanation of symbols]

1 Internal combustion engine (internal combustion engine) 2 Electronic control unit (ECU) 27 Cam 33 First cylinder body 34 Valve side piston (valve drive piston) 35 Lifter 36 Second cylinder body 37 Cam side piston 38 Working hydraulic chamber 39 Hydraulic pressure generation Chamber 40 Oil passage 50 Pressure sensor (first pressure sensor) 52 Second
pressure sensor

Claims

[Claims] Claim 1: A cylinder body fixed to an internal combustion engine main body, and a cylinder body that is slidably fitted into a cylinder hole provided in the cylinder body, and that has a front end while forming an operating hydraulic chamber between the cylinder body and the cylinder body. a valve drive piston that abuts the rear end of the engine valve;
A hydraulic pressure generating means for generating hydraulic pressure corresponding to the opening timing of the engine valve is provided, and a hydraulic buffer start position is provided between the working hydraulic pressure chamber and the hydraulic pressure generating means, and is set in the middle of the cylinder hole. A hydraulic oil return amount limiting mechanism that limits the amount of hydraulic oil returned as the rear end of the valve driving piston passes in the valve closing direction; In a hydraulic drive device for an engine valve for an internal combustion engine in which a check valve for an internal combustion engine is provided, a parameter value representing the hydraulic pressure in the working hydraulic pressure chamber or the differential pressure between the hydraulic pressure in the working hydraulic pressure chamber and the hydraulic pressure of the hydraulic pressure generating means. A hydraulic drive device for an engine valve for an internal combustion engine, comprising: pressure detection means for detecting pressure; and signal processing means for calculating and processing a detection signal of the pressure detection means to determine when the engine valve completes closing. . 2. The hydraulic drive device for an engine valve for an internal combustion engine according to claim 1, wherein the signal processing means determines a point in time when the peak value of the parameter value exceeds a predetermined value as a valve closing completion timing. . 3. The signal processing means calculates a one-time differential value of the parameter value, and sets the point in time when a positive peak value of the differential value exceeds a predetermined value as the valve closing completion timing. The hydraulic drive device for an engine valve for an internal combustion engine according to claim 1. 4. The signal processing means calculates a twice-differential value of the parameter value, and sets the time when the negative peak value of the differential value becomes smaller than a detectable predetermined value as the valve closing completion time. The hydraulic drive device for an engine valve for an internal combustion engine according to claim 1. 5. The hydraulic drive device for an engine valve for an internal combustion engine according to claim 2, wherein the signal processing means sets the predetermined value according to an engine operating state. 6. The hydraulic drive device for an engine valve for an internal combustion engine according to claim 2, wherein the signal processing means uses a learned value as the predetermined value. 7. The signal processing means compares and determines the parameter value with a predetermined value only within a predetermined crank angle range that is set according to the engine operating state. Hydraulic drive system for engine valves for internal combustion engines. 8. The signal processing means directly detects a point in time when the parameter value reaches a peak value within a predetermined crank angle range, and sets the detected point in time as the timing at which the engine valve completes closing. 2. A hydraulic drive device for an engine valve for an internal combustion engine according to item 1.