JPH0754563Y2 - Valve drive for internal combustion engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a valve operating system for an internal combustion engine, and more particularly to a valve operating system for an internal combustion engine having a plurality of intake valves and / or a plurality of exhaust valves in one cylinder. Regarding

(Prior Art) In an engine having a pair of intake valves or exhaust valves in each cylinder, a valve operating device in which operation of one of the pair of intake valves or exhaust valves is stopped according to the engine speed (Patent Document 1) Akira
61-19911 gazette) or a part of a plurality of intake valves provided in one cylinder are cam-driven and the rest are hydraulically-operated, and hydraulically-operated intake valves are selectively operated according to engine operating conditions. Alternatively, a valve operating device that has been stopped (actual opening flat
1-61411) has been proposed in the past.

(Problems to be solved by the invention) However, in the above-mentioned conventional valve operating device, since the valves to be stopped are always the same, the service side valve that is not stopped has a relatively large number of actuations as compared to the stop side valve. Therefore, there is a problem that the wear is fast.

Further, as shown in FIG. 4, in an engine having one fuel injection valve in each cylinder and two intake valves, the intake port (4a) corresponding to the valve (5a) on the rest side is connected to the intake port (4a). There is also a problem that a large amount of the injected fuel stays and the stayed fuel is sucked into the cylinder at once when the valve operation is started, so that the air-fuel ratio largely changes.

The present invention has been made in order to solve the above-mentioned problem, and it is possible to appropriately perform the operation stoppage of a part of a plurality of valves having the same function, and thereby to improve the deviation of the wear degree of the plurality of valves and the air-fuel ratio. An object of the present invention is to provide a valve operating system for an internal combustion engine that can prevent fluctuations.

(Means for Solving the Problem) In order to achieve the above object, the present invention is provided with a plurality of valves having the same function for each cylinder, and an operating state detecting means for detecting an operating state of an internal combustion engine, and the detecting means. In the valve operating device of the internal combustion engine, which is provided with a valve drive means capable of suspending the operation of a part of the plurality of valves in the same cylinder according to the engine operating state, the valve drive means detects the A stop valve changing means for determining a stop condition for stopping the operation of the valve in accordance with an engine operation state, and changing the valve for stopping the operation in the same cylinder while the state where the stop condition is satisfied is continued. It was done like this.

Further, it is preferable that the pause valve changing means changes the valve to be paused for each cycle of each cylinder.

(Operation) A stop condition for stopping the operation of some of the valves is determined according to the detected engine operating state, and the valve to be stopped is changed in the same cylinder while the state where the stop condition is satisfied continues. Further, the change is performed for each cycle of each cylinder.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.
FIG. 1 is a diagram showing a main part of an internal combustion engine and its control device according to the present invention.

In FIG. 1, E is a four-cylinder type internal combustion engine in which each cylinder is provided with a pair (two) of intake valves and a pair of exhaust valves. Since the drive mechanism for the pair of intake valves and the exhaust valve has the same structure, only one intake valve and its drive mechanism will be described below.

The cylinder head 1 of the engine E is provided with an intake valve port 3 having one opening at the top of a combustion chamber 2 of the internal combustion engine and the other communicating with an intake port 4. The intake valve 5 is arranged so as to be guided in the cylinder head 1 so as to open and close the intake valve port 3 in the vertical direction in the drawing. A valve spring 7 is contracted between the collar portion 6 of the intake valve 5 and the cylinder head 1. The valve spring 7 biases the intake valve 5 upward (in the valve closing direction) in the drawing. It

On the other hand, above the cylinder head 1, a cam shaft 9 having a cam 8 is rotatably arranged. This cam shaft 9
It is connected to a crankshaft (not shown) via a timing belt (not shown). A plurality of hydraulically driven valve units 10, which will be described in detail later, are provided for each cylinder between the cam 8 integrally formed with the camshaft 9 and the intake valve 5 (one hydraulically driven valve in FIG. 1). Only the unit is shown). Hydraulic pressure is supplied to the hydraulically driven valve unit 10 from an oil tank 11 through an oil pump 12 and an oil passage 13, and an electronic control unit (hereinafter referred to as “ECU”) 14 controls the closing timing of an intake valve 15. Is supplied with a control signal (θ _OFF ).

A lift sensor 18 that detects the lift amount of the intake valve 5 is provided near the flange portion 6 of the intake valve 15, and the detection signal is supplied to the ECU 14.

A cylinder discriminating sensor (hereinafter referred to as "CYL sensor") 19 that outputs a signal pulse (hereinafter referred to as "CYL signal pulse") at a predetermined crank angle position of a specific cylinder is arranged in a holder (not shown) of the camshaft 9. In addition, a TDC signal pulse is output to the crankshaft of the engine at a crank angle position that is a predetermined crank angle before the top dead center (TDC) at the start of the intake stroke of each cylinder (every 180 ° of crank angle in a 4-cylinder engine). The generated TDC sensor 20 and a crank angle sensor (hereinafter referred to as “CRK sensor”) that generates one pulse (hereinafter referred to as “CRK signal pulse”) at a constant crank angle (for example, 20 °) cycle shorter than the cycle of the TDC signal pulse. 21) is attached. These sensors 19 to 21 are electrically connected to the ECU 14, and CYL signal pulse, TDC signal pulse and CRK signal pulse are sent to the ECU 14. The output signal pulses of these three sensors 19, 20, 21 are used for various timing controls such as the closing timing of the intake valve, the fuel injection timing, the ignition timing, and the detection of the engine speed.

Further, the ECU 14 includes an accelerator opening sensor (θ _ACC sensor) 22, which indicates the amount of depression of an accelerator pedal, as a request detecting means that represents the driver's request to the engine, and an atmospheric pressure (P _A ).
Atmospheric pressure sensor (P _A sensor) 23 to detect the, intake air temperature (T _A )
Intake air temperature sensor (T _A sensor) 24 for detecting the oil pressure, and the oil pressure (Poil) and oil temperature (To) of the hydraulic oil of the hydraulically driven valve unit 10.
oil pressure sensor (Poil sensor) 25, oil temperature sensor (Toil sensor) 26, water temperature sensor (T _W sensor) 27 that detects engine cooling water temperature (T _W ), and oxygen concentration in exhaust gas Oxygen concentration sensor (O ₂ sensor) 28 is electrically connected, and output signals from these sensors 22 to 28 are transmitted to the ECU 1
It is supposed to be supplied to 4.

Further, the ECU 14 detects the output voltage (V _B ) of the battery.

The ECU 14 includes a central processing unit, a memory, a control signal output circuit, etc. (not shown), and based on the detection signals from the various sensors 18 to 28 and the battery output voltage (V _B ), a control procedure (to be described later) ( According to FIG. 6), a hydraulically driven valve unit
Determine the control signals (θ _OFF , θ _ON ) to 10 and supply fuel to the engine (open time of fuel injection valve 29)
T _OUT and the ignition timing θ _IG of the spark plug 30 are determined to be optimum values according to the operating state of the engine. The fuel injection valve 29
Is the two intake ports 4a, 4 of the intake pipe as shown in FIG.
It is located slightly upstream of the point where the part communicating with b is connected.

The hydraulically driven valve unit 10 is installed in each cylinder corresponding to an intake valve and / or an exhaust valve, and as shown in FIG. 2, the intake valve 5 is connected to the valve spring 7 according to the profile of the cam 8. Hydraulic drive mechanism that pushes downwards to open and close
51, and a hydraulic pressure release mechanism 52 that nullifies the pressing force of the hydraulic drive mechanism 51 during the valve opening operation and thus closes the intake valve 5 regardless of the cam profile.

The hydraulic drive mechanism 51 is slidably fitted to the cylinder body 53 fixed to the block 1a integrally formed with the cylinder head 1, and the lower end of the cylinder body 53 by abutting the upper end of the intake valve 5. A valve-side piston 54, a lifter 55 that is in sliding contact with the cam 8, a cam-side piston 56 that is slidably fitted to an upper portion of a cylinder body 53 with its upper end abutting the lifter 55, and the cylinder body.
53, a hydraulic oil chamber 57 defined by the valve-side piston 54 and the cam-side piston 56 as main components, and when the hydraulic pressure in the hydraulic oil chamber 57 is a predetermined value or more, the intake valve 5 follows the profile of the cam 8. Open and close. The hydraulic oil chamber 57 communicates with the oil passage 58 of the hydraulic pressure release mechanism 52.

On the other hand, the hydraulic pressure release mechanism 52 includes an oil passage 58 that connects the hydraulic oil chamber 57 and the oil supply gallery 61 via a feed valve 62 and a check valve 63, and a spill valve 59 installed in the middle of the oil passage 58.
And a feed valve 62 and a check valve 63 arranged in the oil passage 58.
And an accumulator 60 for maintaining the hydraulic pressure in the accumulator circuit 58a defined by the valves 62 and 63 and the spill valve 59 at a predetermined value. The oil supply gallery 61 is provided to supply hydraulic pressure to the hydraulically driven valve unit provided for each cylinder, and is connected to the oil passage 13 via the pressure adjusting unit 64. The pressure regulation unit 64 is
It is provided to adjust the hydraulic pressure pressurized by the oil pump 12 to a hydraulic pressure within a predetermined range.

As shown in FIG. 3, the spill valve 59 has a first valve body 69.
a pilot valve 69 including a and a first valve seat 69b, a main valve 73 including a second valve body 73a and a second valve seat 73b, and a first valve
And a solenoid 71 for moving the valve body 69a as a main constituent element. The first valve body 69a is integrally formed with the rod 68 and the armature 67, and is slidably fitted in a cylinder hole 66 formed in the housing 65. First valve body 69a
A spring 70 is contracted between the first valve seat 69b and the
Further, the first valve body 69a is provided with a hole 69c and an oil passage 69d for leaking oil in the hydraulic chamber 75 from the outlet port 78 when the valve body moves upward and is in a valve open state. There is. The main valve 73 is provided below the pilot valve 69 to connect / disconnect the first port 76 and the second port 77, and the second valve body
A spring 74 is contracted between the valve body 73a and the first valve seat 69b to press the 73a downward. Further, the valve body of the main valve 73
An orifice hole 73c is provided in 73a.

The solenoid 71 is arranged in the chamber 65b of the housing 65 and is connected to the ECU 14.

Further, the accumulator 60, in order to maintain the hydraulic pressure in the accumulator circuit 58a at a predetermined pressure, is provided in the middle of the accumulator circuit 58a, a cylinder hole 80 formed in the block 1a, and a cap 81 having an air hole 81a, It comprises a piston 82 slidably fitted in the cylinder hole 80, and a spring 83 compressed between the cap 81 and the piston 82.

The operation of the hydraulic drive mechanism 51 and the hydraulic release mechanism 52 configured as described above will be described below.

When the solenoid 71 is energized by the control signal from the ECU 14, the valve body 69a of the pilot valve moves downward together with the armature 67 and the rod 68 against the force of the spring 70, and the pilot valve 69 closes. It will be in a valve state (the valve body
Since the movement amount of 69a is very small, the gap between the upper end of the valve body 69a and the housing 65 in FIG. 3 is very narrow even when the pilot valve is closed). At this time, the hydraulic pressure on the first port 76 side and the hydraulic pressure on the hydraulic chamber 75 side are equal, the second valve body 73a is pressed downward by the force of the spring 74, and the main valve 73 is closed. As a result, the hydraulic oil chamber 57 of the hydraulic drive mechanism 51
The internal hydraulic pressure is maintained at a high pressure (greater than or equal to a predetermined value), and the intake valve 5 is opened / closed according to the profile of the cam 8. Valve operating characteristics in this case (crank angle θ and valve lift Lif
(Relationship with) is, for example, as shown by the broken line in FIG.

On the other hand, when the solenoid 71 is deenergized, the first valve body
69a moves upward by the force of the spring 70, and the pilot valve 69 is opened. As a result, the oil in the hydraulic chamber 75 is discharged via the oil passage 69d and the outlet port 78, the second valve body 73a moves upward, and the main valve 73 is driven to open. As a result, the hydraulic pressure in the hydraulic oil chamber 57 of the hydraulic drive mechanism 51 decreases, and the intake valve 5 starts the valve closing operation regardless of the profile of the cam 8. Therefore, for example, when the solenoid 71 is deenergized at each θ _OFF of the crank in FIG. 5, the valve operating characteristic shown by the solid line is obtained. When the solenoid 71 is deenergized (θ _OFF )
From when the intake valve 5 actually starts to close (θ _ST )
There is a slight delay before.

As described above, the solenoid 71 is deenergized or energized by the control signal from the ECU 14, and the action of the hydraulic drive mechanism 51 is invalidated when the solenoid 71 is deenergized, so that the closing timing of the intake valve 5 can be arbitrarily set. Can be set,
The operation of the intake valve 5 can be stopped. as a result,
The intake air amount of each cylinder can be controlled by the control signal of the ECU 14.

FIG. 6 shows the ECU 14 opening timing of the spill valve 59 (timing for deactivating the solenoid 71), that is, the timing for instructing the closing of the intake valve 5 (hereinafter referred to as “off timing”) θ _OFF and the spill valve. 9 is a flowchart showing a control procedure of a valve closing instruction timing 59 (timing for energizing the solenoid 71, hereinafter referred to as “on timing”) θ _ON .

In step S1, read the detection signal of each sensor,
An engine operating condition and an atmospheric condition are detected, and an operating condition in which the operation of one intake valve and one exhaust valve should be stopped (for example, the engine water temperature is equal to or higher than a predetermined temperature and the engine speed is equal to or lower than a predetermined speed, Further, it is determined whether or not the accelerator opening θ _ACC is equal to or less than a predetermined value (hereinafter referred to as “rest condition”) (step S2). When this answer is negative (No), that is, when the stop condition is not satisfied, the flag F _STP is set to the value 0 (step S3) and the detected engine speed Ne is detected.
Also, the normal θ _OFF map is searched according to the accelerator opening θ _ACC (step S4), and the process proceeds to step S7. θ _OFF
The map is a map in which the reference value of the off-timing θ _OFF is set according to the accelerator opening θ _ACC and the engine speed Ne, and is stored in the memory in the ECU 14. This map is preset as a function of the engine speed Ne and the accelerator opening θ _ACC as shown in FIG. 7,
A predetermined value Nei of the engine speed is provided in 20 steps in the range of, for example, 500 rpm to 8000 rpm, while a predetermined value θ of the accelerator opening is set.
_ACC j is provided in 19 steps in the range from fully closed to fully open, and the map value θ _OFF i, j is stored corresponding to these Nei, θ _ACC j. Engine speed Ne other than map grid points
And the map value corresponding to the accelerator opening θ _ACC is obtained by interpolation calculation by the 4-point interpolation method.

The map value θ _OFFMAP is set assuming a standard state (that is, a state in which the multiplication term = 1.0 and the addition / subtraction term = 0) in which correction by the later-described multiplication term and addition / subtraction term is not actually executed.

Returning to FIG. 6, the answer in step S2 is affirmative (Yes),
That is, when the rest condition is satisfied, the flag F _STP is set to the value 1 (step S5), and the rest θ _OFF map is searched according to the detected engine speed Ne and the accelerator opening θ _ACC (step S6). ), And proceeds to step S7. The resting θ _OFF map is set for a predetermined engine speed range and accelerator opening range corresponding to the low and medium speed rotation range and the low and medium load range, and when one of the intake valves is deactivated. It is set to a suitable value.

In step S7, the map value θ _OFFMAP retrieved in step S4 or S6 is corrected by the following equation (1) according to atmospheric conditions and the like.

θ _OFF = θ _OFFMAP × K _TA × K _PA × K ₁ + θ _ADJ1 n (1) where K _TA is the correction multiplication term according to the intake air temperature (T _A ), and K _PA is the atmospheric pressure (P _A ). A correction multiplication term according to the above, K ₁ is another correction multiplication term according to the oil temperature (Toil) oil pressure (Poil), and θ _ADJ1 n (for example, n = 1 to 4 in the case of a four-cylinder engine) is the lift sensor 18 Is a feedback addition / subtraction term calculated for each cylinder based on the detection signal of. K _{TA of the} above correction multiplication term
Is for compensating for the change in the air density due to the change in intake air temperature T _A. The intake air temperature T detected from the T _A -K _TA table shown in FIG.
Is determined based on _A, K _PA is determined based on the atmospheric pressure P _A from P _A -K _PA table shown in FIG. 9 in which compensates for the change in the air density with changes in atmospheric pressure P _A . The reason for providing such correction multiplication terms K _PA , K _TA , and K ₁ is as follows.
That is, firstly, the control of the closing timing of the intake valve 5 is originally
Set the intake air amount to the optimum value according to the engine operating state,
Therefore, set the air-fuel ratio (A / F) to the desired value (eg theoretical mixing ratio).
Therefore, the atmospheric pressure correction and the intake air temperature correction are necessary to compensate the influences of the atmospheric pressure (P _A ) and the intake air temperature (T _A ) on the intake air amount. Secondly, since the hydraulically driven valve unit 10 is hydraulically controlled, it is necessary to compensate for the influence of the oil temperature (Toil) and the hydraulic pressure (Poil) on the operation of the hydraulically driven valve unit itself. .

Further, the feedback addition / subtraction term θ _ADJ1 n is a correction term for absorbing an assembly error of the valve operating mechanism for each cylinder and an error due to manufacturing variations, and the intake valve 5 of each cylinder detected by the lift sensor 18 Of the actual valve closing operation start timing and the valve closing start timing command signal (off timing θ
₍ Signal indicating _OFF ).

Next, at step S8, the closing timing of the spill valve 59, that is, the ON timing θ _{ON of the} solenoid 71 is determined by the following equation (2).

θ _ON = θ _ONTBL + θ _V (2) where θ _ONTBL is, for example, the tenth value according to the engine speed Ne.
Reference value read from the Ne-θ _ON table shown in the figure, θ
_V is a battery correcting variable in accordance with the battery voltage V _B.
The Ne-θ _ON table is set so that the reference value θ _ONTBL becomes smaller as the engine speed Ne increases, so the time per cycle becomes shorter. The start crank angle of the operation becomes faster, and the time from the closing of the spill valve to the start of the next intake stroke (the start of opening the intake valve 5) is constant regardless of the engine speed Ne (the hydraulic oil of the hydraulic drive mechanism 51). The time required for the hydraulic pressure in the chamber 57 to reach the hydraulic pressure required for opening the intake valve 5) can be set. In addition, the battery correction variable θ _V is the time obtained by the V _B −T _V table shown in FIG. 11 in order to compensate for the decrease in the responsiveness of the closing operation of the spill valve 59 that changes with the battery output voltage V _B. It is obtained by time-angle conversion of T _{V according} to the engine speed. In the V _B −T _V table, the time value T _V is set to increase as the battery voltage V _B increases. By setting the value of T _V in this way, even when the battery voltage V _B drops and the responsiveness of the opening / closing operation of the spill valve 59 decreases, the hydraulic oil chamber of the hydraulic drive mechanism 51 is relatively early. A predetermined hydraulic pressure is supplied to the inside of the valve 57, and the valve opening operation of the intake valve 5 in the next stroke can be reliably performed.

In step S9, a control signal for the solenoid 71 is output based on the calculated off-timing θ _OFF and on-timing θ _ON and the value of the flag F _STP .

When the flag F _STP = 0, that is, when the rest condition is not satisfied, the same signal (FIG. 12B) as the control signal (FIG. 12A) that turns ON / _{OFF at} the calculated θ _ON and θ _OFF timings. ，
(C)) is supplied to the spill valves 59a, 59b (not shown) corresponding to the two intake valves 5a, 5b in FIG.
The operating characteristics of a and 5b are shown in FIGS. 12 (d) and 12 (e) (the vertical axis in the figure represents the valve lift amount).

On the other hand, when the flag F _STP = 1, that is, when the rest condition is satisfied,
A control signal as shown in FIG. 13 is output. That is, thirteenth
Figures (a) to (e) correspond to Figures 12 (a) to (e), respectively, and ON / OFF signals are alternately output to the two spill valves 59a and 59b. As a result, the operating characteristics of the two intake valves 5a and 5b are as shown in (d) and (e) of the same figure, and one valve is deactivated and the deactivated valve is changed every cycle. It Here, one cycle means a cycle in which each of the four strokes of intake, compression, explosion, and exhaust of the cylinder is performed once.

By changing the valve to be stopped for each cycle as described above, it is possible to prevent the wear of one valve from being relatively accelerated, that is, the uneven wear degree can be prevented, and the mixture state of the air-fuel mixture can be favorably maintained. can do. Further, since the fuel that remains in the intake port of the valve when it is at rest is only the fuel corresponding to the injection amount of one injection, there is almost no fluctuation in the air-fuel ratio.

In the present embodiment, the exhaust valve side also performs the same control as the intake valve side.

In the above-described embodiment, the engine provided with two intake valves and two exhaust valves in each cylinder has been described, but the present invention is not limited to this, and an engine provided with three or more intake valves and exhaust valves in each cylinder. Also in, it is possible to change the valve to be stopped in the same manner. For example, when only one of the three intake valves (A, B, C) is to be stopped, the valve to be stopped for each cycle is changed to A → B → C → A, and two are stopped. Sometimes A and B → B and C → C
And A → A and B.

Further, in the present embodiment, the valve to be stopped is changed every cycle, but the present invention is not limited to this, and it may be changed in a cycle of two cycles or more.

(Effect of the Invention) As described in detail above, the present invention has the following effects.

According to the valve operating system of claim 1, the pause condition for suspending the operation of a part of the valves is determined according to the detected engine operating state, and the valve to be paused is maintained while the state where the pause condition is satisfied is continued. Since it is changed within the same cylinder, it is possible to prevent uneven wear degrees of a plurality of valves. Further, on the intake valve side, it is possible to prevent the air-fuel ratio from varying due to a large amount of fuel staying in the intake port corresponding to the valve to be deactivated, and to maintain a good mixture state of the air-fuel mixture.

According to the valve gear of the second aspect, the effect of the valve gear of the first aspect can be more remarkably exhibited.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of an internal combustion engine and a control system therefor according to the present invention, FIG. 2 is a diagram showing a valve operating mechanism of the engine of FIG. 1, and FIG. 3 is a partly enlarged view of FIG. Figure 4
FIG. 5 is a diagram showing the positional relationship between the fuel injection valve and the intake valve, FIG. 5 is a diagram showing the operating characteristics of the intake valve, FIG. 6 is a flow chart showing the procedure of operating control of the intake valve, and FIG. 7 is an intake valve. Showing a map (θ _OFF map) for deciding the closing timing of the valve, FIG. 8 shows a table for deciding the intake temperature correction coefficient (K _TA ), and FIG. 9 shows an atmospheric pressure correction coefficient. FIG. 10 shows a table for determining (K _PA ), FIG. 10 shows a table for determining the on timing (θ _ON ) of the solenoid of the spill valve (59) in FIG. 2, and FIG. 11 shows FIG. 12 is a diagram showing a table for determining a correction variable (T _V ) according to the battery voltage (V _B ), and FIGS. 12 and 13 are diagrams showing the relationship between the control signal of the spill valve and the operating characteristic of the intake valve. Is. 5 ... Intake valve, 8 ... Cam, 10 ... Hydraulic drive valve unit, 14 ... Electronic control unit (ECU), 18 ...
Lift sensor, 22 ... Accelerator opening sensor, 51 ... Hydraulic drive mechanism, 52 ... Hydraulic release mechanism, 59 ... Spill valve, 71 ...
…solenoid.

Claims (2)

[Scope of utility model registration request] 1. A plurality of valves having the same function are provided for each cylinder, an operating state detecting means for detecting an operating state of an internal combustion engine, and a plurality of the plurality of valves in the same cylinder according to the detected engine operating state. In a valve operating system for an internal combustion engine, comprising: a valve drive means capable of suspending the operation of a part of the valve, the valve drive means suspends the operation of the valve according to the detected engine operating state. A valve operating system for an internal combustion engine, comprising: a stop valve changing means for determining a condition and changing a valve for stopping the operation in the same cylinder while a state where the stop condition is satisfied continues. 2. The valve operating system for an internal combustion engine according to claim 1, wherein the stop valve changing means changes a valve to be stopped for each cycle of each cylinder.