JP2000345872A - Valve timing control device in engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly switch valve timing from a low-speed to a high-speed, while suppressing energy consumption for driving an oil pump to the minimum, in an engine equipped with a valve actuation characteristic variable mechanism. SOLUTION: In this control device, oil pressure outputted to an oil pressure control valve CV is increased toward for a high speed from for a low speed, by controlling the actuation of an electric oil pump and an motor-operated relief valve, when the operation condition of an engine E is in a preliminary switching region directly before switching a valve timing region from low to high speeds. Consequently, when the operation condition of the engine E is in a high-speed valve timing region via the preliminary switching region, the valve CV can quickly increase hydraulic pressure to be outputted to a valve actuation characteristic variable mechanism VT to high-speed hydraulic pressure, to establish high-speed valve timing by the minimum time lag. Moreover suppressing the actuation quantity of the electric oil pump required to increase hydraulic pressure to the minimum can contribute the save of energy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control device for an engine having a variable valve operating characteristic mechanism for establishing a low valve timing and a high valve timing by switching hydraulic pressure.

[0002]

2. Description of the Related Art In order to improve intake efficiency and exhaust efficiency in a wide operating range, an engine equipped with a variable valve operating characteristic mechanism for establishing a low valve timing and a high valve timing by switching hydraulic pressure is known. The variable valve operating characteristic mechanism receives low-pressure hydraulic pressure and establishes low-speed valve timing, and receives high-speed hydraulic pressure that is higher than the low-speed hydraulic pressure to establish high-speed valve timing. Switching between the hydraulic pressure for use and the hydraulic pressure for high speed is performed by a hydraulic control valve provided downstream of the oil pump.

In an engine equipped with such a variable valve operating characteristic mechanism, when switching from low-speed valve timing to high-speed valve timing is performed by using hydraulic pressure supplied from an oil pump driven by a crankshaft,
Since a time lag occurs from when the hydraulic control valve is activated to when the hydraulic pressure supplied to the valve operating characteristic variable mechanism rises, there is a problem that switching from the low-speed valve timing to the high-speed valve timing is delayed.

In view of this, an electric oil pump driven by a motor is provided in addition to an oil pump driven by a crankshaft, and hydraulic pressure generated by both oil pumps is supplied to a valve operating characteristic variable mechanism to change a low speed valve timing to a high speed valve. A system for quickly switching to the timing is proposed in Japanese Utility Model Laid-Open No. Hei 3-10006.

[0005]

However, in the above-mentioned conventional apparatus, since it is necessary to drive both an oil pump driven by a crankshaft and an electric oil pump driven by a motor, the energy required for the drive is increased. As a result, there is a problem that fuel consumption increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is intended to quickly switch from a low-speed valve timing to a high-speed valve timing while minimizing the energy consumption for driving an oil pump. The purpose is to do.

[0007]

According to the first aspect of the present invention, there is provided an electric oil pump for generating a hydraulic pressure, and an electric relief for adjusting a hydraulic pressure generated by the electric oil pump. A valve, a hydraulic control valve for switching the hydraulic pressure output from the electric relief valve to a low-speed hydraulic pressure and a high-speed hydraulic pressure higher than the low-speed hydraulic pressure, and a low-speed hydraulic pressure output from the hydraulic control valve to establish a low-speed valve timing, In an engine including a variable valve operating characteristic mechanism that establishes high-speed valve timing with high-speed hydraulic pressure output by a hydraulic control valve and control means that controls the operation of an electric oil pump and an electric relief valve, the operating state of the engine is low. When in the preliminary switching area immediately before switching from the valve timing area to the high-speed valve timing area, A valve timing control device for an engine is proposed, wherein the control means controls the operation of an electric oil pump and an electric relief valve to increase a hydraulic pressure output to a hydraulic control valve from a low-speed hydraulic pressure to a high-speed hydraulic pressure. Is done.

According to the above configuration, when the operating state of the engine is in the preliminary switching region immediately before switching from the low-speed valve timing region to the high-speed valve timing region, the operation of the electric oil pump and the electric relief valve is controlled to control the hydraulic pressure. Since the hydraulic pressure output to the valve is increased from the low-speed hydraulic pressure to the high-speed hydraulic pressure, the hydraulic pressure output by the hydraulic control valve is quickly increased when the engine operating state enters the high-speed valve timing area through the preliminary switching area. It is possible to establish high-speed valve timing with a minimum time lag by starting up to high-speed hydraulic pressure. In addition, the amount of operation of the electric oil pump required for increasing the hydraulic pressure can be minimized, which can contribute to energy saving.

According to the invention described in claim 2,
In addition to the configuration according to claim 1, the control means includes a fuel injection amount for low-speed valve timing when a predetermined delay time elapses after the hydraulic control valve switches between low-speed hydraulic pressure and high-speed hydraulic pressure. A valve timing control device for an engine, wherein the delay time is changed according to the rotation speed of an electric oil pump. Suggested.

According to the above configuration, the delay time from when the low-speed hydraulic pressure and the high-speed hydraulic pressure are switched to when the fuel injection amount and the ignition timing are switched depends on the rotation speed of the electric oil pump, that is, the valve operating characteristics. Since it changes according to the magnitude of the hydraulic pressure output to the variable mechanism, the fuel injection amount and ignition timing can be switched for low-speed valve timing or at the moment when high-speed valve timing is actually established. It is possible to minimize the occurrence of torque shock due to the switching of the timing.

The electronic control unit U of the embodiment corresponds to the control means of the present invention, and the low-speed valve timing delay timer t _LVT and the high-speed valve timing delay timer t _HVT of the embodiment correspond to the delay time of the present invention.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 14 show an embodiment of the present invention. FIG. 1 is an overall perspective view of an engine, FIG. 2 is an enlarged view in two directions of FIG. 1, and FIG. 3 is a sectional view taken along line 4-4 of FIG. 2, FIG. 5 is a sectional view taken along line 5-5 of FIG. 3, FIG. 6 is a view for explaining the overall structure of a hydraulic control system of the engine, and FIG. FIG. 8 is a first sectional view of a flowchart of a main routine, FIG. 9 is a first sectional view of a flowchart of a main routine, and FIG. 10 is a flowchart of a control routine of an electric oil pump and an electric relief valve. 11 is a flowchart of a delay timer setting routine for high-speed valve timing, FIG. 12 is a flowchart of a delay timer setting routine for low-speed valve timing, and FIG. 13 is a map for searching for a correction coefficient for calculating a reference oil pressure. To FIG. FIG. 14 is a diagram showing a map for searching a valve timing region.

As shown in FIG. 1, a four-cylinder DOHC type engine E has a crankshaft 3 to which four pistons 1 are connected via connecting rods 2. A driving sprocket 4 provided at the shaft end of the crankshaft 3, an intake camshaft 5, and an exhaust camshaft 6;
The driven sprockets 7 and 8 provided at the shaft ends are connected via a timing chain 9, and the intake camshaft 5 and the exhaust camshaft 6 are driven to rotate at a rate of one rotation for every two rotations of the crankshaft 3. You.

For each of the four cylinders, two intake valves 10, 1 driven by an intake camshaft 5 are provided.
0, and two exhaust valves 11, 11 driven by the exhaust camshaft 6. Intake camshaft 5
A valve operating characteristic variable mechanism for changing the valve lift and opening angle of the valves 10, 10; 11, 11 between the intake camshaft 6 and the exhaust valves 11, 11 and between the exhaust camshaft 6 and the exhaust valves 11, 11. VT, VT
Are respectively provided.

The variable valve operation characteristic mechanism VT on the intake valves 10, 10 and the variable valve operation characteristic mechanism VT on the exhaust valves 11, 11 have substantially the same structure. The structure of the 10-side variable valve operating characteristic mechanism VT will be described with reference to FIGS.

The intake camshaft 5 has a pair of low-speed cams 14, 14 corresponding to each cylinder, and both low-speed cams 14,
And a rocker shaft 16 fixed below and parallel to the intake camshaft 5, the low-speed cam 14 and the high-speed cam 1.
The first rocker arm 17, the second rocker arm 18, and the third rocker arm 19 are swingably supported corresponding to the cam 5 and the low-speed cam 14, respectively.

A pair of low speed cams 14, 14 are intake cams.
The height of the protrusion of the shaft 5 along the radial direction is relatively small.
Position 14₁And the base circle portion 14_TwoIt is composed of High
The speed cam 15 has a protruding amount that is equal to that of the low speed cams 14 and 1.
Higher part 14 of 4₁, 14₁Greater than the protrusion amount of
High section 15 over a wide angle range₁And the base circle 15 _Two
It is composed of

Valve stem 2 of intake valves 10 and 10
At upper ends of 0 and 20, flanges 21 and 21 are provided,
Compressed state between cylinder head 22 and flanges 21 and 21
Intake by valve springs 23, 23 mounted at
The valves 10, 10 are biased in the valve closing direction. One end
First and third swingably supported by the rocker shaft 16
The rocker arms 17 and 19 are provided at the intermediate portions thereof.
Muslippers 17₁, 19 ₁Are a pair of low speed cams 14 and 1
4 and the other end is an intake valve 10,
The tape stem that contacts the upper ends of the valve stems 20
Toe screws 24, 24 are provided to be able to move forward and backward, respectively.

A second rocker arm 18 disposed between the pair of intake valves 10 and 10 and one end of which is swingably supported by a rocker shaft 16 includes a cylinder head 2.
It is biased by the elastic biasing means 25 which is mounted in a compressed state between the 2, cam slipper 18 ₁ formed on the other end abuts against the high-speed cam 15. The resilient urging means 25 includes a cylindrical lifter 26 having a closed end abutting on the second rocker arm 18 and a lifter 26 having a closed bottom.
And a lifter spring 27 biased toward.

As is apparent from FIG. 5, a connection switching mechanism 31 for switching the connection state between the first, second and third rocker arms 17 to 19 connects the third rocker arm 19 and the second rocker arm 18 to each other. Possible first switching pin 32
A second switching pin 33 for connecting the second rocker arm 18 and the first rocker arm 17, a third switching pin 34 for restricting the movement of the first switching pin 32 and the second switching pin 33, A return spring 35 for urging the pins 32-34 toward the connection release side.

[0022] The third rocker arm 19, the rocker shaft 16 are parallel to a bottom of the guide hole 19 ₂ is formed by the open end side second rocker arm 18, the in this guide hole 19 ₂ the first switching pin 32 is slidably engaged, the hydraulic pressure chamber 36 is formed between the first closed end of the switching pin 32 and the guide hole 19 _2. A communication passage 37 communicating with the hydraulic chamber 36 is formed in the third rocker arm 19, and a hydraulic supply passage 38 is formed in the rocker shaft 16. The communication path 37 and the hydraulic pressure supply path 38 always communicate with each other via the communication path 39 formed on the side wall of the rocker shaft 16 irrespective of the swing state of the third rocker arm 19.

[0023] The second rocker arm 18, the guide hole of the same diameter that corresponds to 19 _second guide hole 18 ₂ are parallel to penetrate the rocker shaft 16, the guide hole 18
₂ , the second switching pin 33 is slidably fitted.

[0024] The first rocker arm 17, the guide hole 18 of the same diameter that corresponds to ₂ bottomed cylindrical guide hole 17
_2, the parallel and open end and the rocker shaft 16 is formed in the side second rocker arm 18, the guide hole 17 ₂ third switching pin 34 is fitted slidably. Moreover is slidably guided by the guide portion 17 ₃ shank 34 ₁ formed integrally formed on the closed end of the guide hole 17 ₂ in the third switching pin 34. Return spring 35 is mounted in a compressed state between the third switching pin 34 fitted to the outer periphery of the shaft portion 34 ₁ in the guide hole 17 _{and second} closed end, and a third switching pin 34, the elastic of the return spring 35 By force, the three switching pins 32-34 are urged toward the connection releasing side, that is, toward the hydraulic chamber 36 side.

When the hydraulic pressure supplied to the hydraulic chamber 36 is released, the three switching pins 32-34 move to the uncoupling side by the elastic force of the return spring 35. In this state, the first switching pin 32 and the second switching pin The contact surface of the pin 33 is the third rocker arm 19
And the contact surface between the second switching pin 33 and the third switching pin 34 is located between the second rocker arm 18 and the first rocker arm 17, and therefore, the first to third rocker arms 17. 19 are in a non-connected state. Three switching pins 32 through 34 is supplied hydraulic pressure to the hydraulic chamber 36 against the elastic force of the return spring 35 moves to the connection side, the first changeover pin 32 is fitted into the guide hole 18, _second the second changeover pin 33 is fitted into the guide hole 17 ₂ 1
To the third rocker arms 17 to 19 are integrally connected.

Next, based on the schematic diagram of FIG.
The overall structure of the hydraulic control system will be described.

The engine E has a lubricated part such as a journal supporting a crankshaft or a valve operating mechanism.
Oil is supplied from the oil pan 41 to these lubricated parts and the valve operating characteristic variable mechanisms VT, VT. In an oil supply passage 42 that supplies oil from the oil pan 41 to the engine E, an oil strainer 43, an oil filter 44, an electric oil pump OP, and an electric relief valve RV are sequentially arranged from the upstream side to the downstream side. .
The electric oil pump OP includes a pump body 45 composed of a trochoid pump and a gear pump,
5 for driving the electric motor 5. Excess oil discharged from the electric relief valve RV is returned to the oil supply passage 42 between the oil filter 44 and the electric oil pump OP via the relief passage 47. The oil supplied to the engine E branches into a lubricated portion around the crankshaft 3 and a lubrication / control system of the valve mechanism. The oil pressure of the oil supplied to the lubrication / control system of the valve mechanism is controlled by a hydraulic control valve CV. Thus, the valve operating characteristic variable mechanisms VT and VT are operated in two steps of high and low. Engine E
Lubrication of the lubricated part of the valve operating mechanism V
The oil that has activated T and VT is returned to the oil pan 41 via the oil return passage 48.

The hydraulic control valve CV is composed of an ON / OFF solenoid valve, and supplies hydraulic pressure to the operation characteristic variable mechanisms VT and VT by opening the valve to establish high-speed valve timing, and closes the valve to operate the operation characteristic variable mechanism VT. , VT to shut off the supply of hydraulic pressure to establish low-speed valve timing.

As is apparent from FIG.
The electric relief valve RV is provided with a bottomed cylindrical valve housing 51, and a valve body 52 slidably housed therein is urged by a valve spring 53 in a direction to be seated on a valve seat 54. The valve housing 51 has an electric oil pump O
An inlet port 55 connected to P, an outlet port 56 connected to the engine E, and a relief port 57 connected to the relief passage 47 are formed. The inlet port 55 and the outlet port 56 are always in communication, and the inlet port 55 and the relief port 57 resist the elastic force of the valve spring 53 when the hydraulic pressure transmitted from the electric oil pump OP to the inlet port 55 increases. When the valve body 52 is separated from the valve seat 54, the communication is established. A solenoid 58 is disposed at the bottom of the valve housing 51 facing the back of the valve body 52. When the solenoid 58 is excited, the valve body 52 is sucked against the resilience of the valve spring 53, and the electric relief valve is provided. The hydraulic pressure at which the RV opens is arbitrarily controlled.

The electronic control unit U has an engine speed
Engine speed detecting means S for detecting Ne₁And the engine
Engine load (for example, intake pipe absolute pressure Pb)
Load detection means S_TwoAnd left the electric relief valve RV
Oil pressure (first oil pressure Po ₁) To detect the first hydraulic pressure
Delivery means S_ThreeAnd an oil temperature detecting means for detecting the oil temperature To of the oil
Step S_FourAnd the oil pressure immediately upstream of the oil pressure control valve CV (the second oil
Pressure Po_Two) For detecting the second hydraulic pressure S_FiveAnd electric
Oil pump for detecting the pump rotation speed Np of the oil pump OP
Pump rotation number detecting means S₆Are connected. Electronic control uni
U is the detection means S₁~ S₆Based on the output of
Electric oil pump OP, electric relief valve RV, valve
The hydraulic control valve CV of the valve operating characteristic variable mechanism VT, VT,
The fuel injection amount control device 59 and the ignition timing control device 60
Control the operation.

Next, the operation of the embodiment of the present invention will be described with reference to the flowcharts of FIGS.

[0032] First, at step S1 of the main routine of FIG. 8 and FIG. 9, to retain the first hydraulic Po ₁ oil supplied to the engine E to an appropriate value, the electric oil pump O
It controls the operation of P and the electric relief valve RV. Hereinafter, the contents will be described based on the flowchart of FIG.

First, when the ignition switch is turned on in step S31, the electric oil pump OP is driven at a preset rotational speed in step S32, and then the engine E is started in step S33. As described above, by driving the electric oil pump OP prior to the start of the engine E, it is possible to prevent the occurrence of abnormal wear by supplying oil to the lubricated portion in advance before the start of the engine E.

The subsequent detects the engine speed Ne by the engine speed detecting means S ₁ in step S34, detects the engine load Pb by the engine load detecting means S _2, further first hydraulic detecting means S in step S35
₃ to detect the first oil pressure Po ₁ and oil temperature detecting means S
_{At 4} , the oil temperature To is detected. Then at step S36, FIG. 13 map to search the first correction coefficient K ₁ by applying the engine speed Ne (A), the second correction coefficient by applying the engine load Pb in the map shown in FIG. 13 (B) Search for K _2, searches the third correction factor K ₃ by applying the oil temperature to in the map of FIG. 13 (C).

In the following step S37, the electric relief valve
RV is de-energized and fully closed to release the relief passage 17
It is closed, and in the next step S38, the reference hydraulic pressure P_REFCalculate
You. Reference oil pressure P_REFIs the preset hydraulic pressure P_BASEAbove
First to third correction coefficients K₁, K _Two, K_ThreeMultiply by
It is calculated from:

P _REF = P _BASE × K ₁ × K ₂ × K ₃ FIG.
As is clear from FIG. 1, the first correction coefficient K ₁ increases with an increase in the engine speed Ne, the second correction coefficient K ₂ increases with an increase in the engine load Pb, and the third correction coefficient K ₃
Increases as the oil temperature To increases.
_REF increases as the engine speed Ne, the engine load Pb, and the oil temperature To increase.

In step S39, the first hydraulic pressure check is performed.
Delivery means S_Three1st oil pressure Po detected by ₁Is the reference hydraulic pressure P_REF
If less than, the electric oil pump OP in step S40
Increase the number of revolutions. On the other hand, in step S39,
1 hydraulic pressure Po₁Is the reference hydraulic pressure P_{RE F}If it is above, step
In S41, the rotation speed of the electric oil pump OP is reduced.
Thereafter, when a predetermined time has elapsed in step S42,
In step S43, the first hydraulic pressure Po₁Is the reference hydraulic pressure P_REFLess than
If not, the electric relief valve is set in step S44.
Energize the valve to open the valve and release part of the oil
First hydraulic pressure Po₁With reference hydraulic pressure P_REFReduced to less than
You.

As described above, the operation of the electric oil pump OP and the electric relief valve RV is controlled by the electronic control unit U.
And controls in, by the cooperation of the electric oil pump OP and electric relief valve RV, to control precisely the first hydraulic Po ₁ in accordance with the operating state of the engine E. In addition, not only can the necessary and sufficient amount of oil be supplied to minimize the energy required for driving the oil pump, but also the oil pressure is prevented from being excessively increased at low oil temperature and the filter is prevented from being damaged. be able to.

Returning to the flowcharts of FIGS. 8 and 9,
In step S2, it is determined whether or not the operation state of the engine E is in the preliminary switching range of the valve timing based on the map of FIG. The map of FIG. 14 shows the engine speed Ne.
And the engine load Pb as a parameter, with the switching line shown by a solid line as a boundary, the right side is a high-speed valve timing area, the left side is a low-speed valve timing area, and the hatched part which is a part of the low-speed valve timing area is a preliminary switching. Area.

As shown in FIG. 14, the switching line between the high-speed valve timing area and the low-speed valve timing area is set to a line of the engine speed Ne = 3000 rpm when the engine load Pb is 400 mmHg or more, and the engine load Pb is set to 200 mmHg. In the following region, the engine speed Ne is set to the line of 4000 rpm, and in the region where the engine load Pb is 400 mm to 200 mmHg, the engine speed Ne is set to increase as the engine load Pb decreases. The width of the preliminary switching region is set to 200 rpm for the engine speed Ne and set to 50 mmHg for the engine load Pb.

[0041] when said operating state of the engine E is in the pre-changeover region in step S2, the second immediately upstream of the hydraulic control valve CV by the second hydraulic detecting means S ₅ in step S3
The hydraulic pressure Po ₂ is detected, and the target hydraulic pressure P to be supplied to the valve operating characteristic variable mechanisms VT, VT in step S4.
Search for _OBJ . The target oil pressure P _OBJ is the engine speed Ne
The target oil pressure P _OBJ is set to a value that overcomes the set load of the return spring 35 that holds the variable valve operation characteristic mechanisms VT, VT at low speed valve timing. You.
When searching the map for the target oil pressure P _OBJ , the first oil pressure Po ₁ may be used as a parameter instead of the oil temperature To.

In the following step S5, the second hydraulic pressure Po_TwoGoal
Hydraulic pressure P_OBJCompare with High speed from low valve timing
Entering the preliminary switching area during the process of switching to valve timing
The second hydraulic pressure Po_TwoIs the target hydraulic pressure P_OBJthan
Because it is in a low state, the electric relief valve is
In addition to reducing the opening of the brake RV by a predetermined opening,
In step S7, the rotation speed of the electric oil pump OP is set to a predetermined rotation speed.
The second hydraulic pressure Po_TwoIncrease. The result
As a result, in step S5, the second hydraulic pressure Po_TwoIs the target hydraulic pressure P _OBJLess than
If it is above, the process moves to step S10. Also high speed valve
Switching from low-speed valve timing to low-speed valve timing
If the second hydraulic pressure Po_TwoBut
Already target hydraulic pressure P_OBJAnd the answer of step S5
Steps S6 and S7 are skipped because the result is YES
Then, the process proceeds to step S10.

In step S10, if the vehicle has already entered the high-speed valve timing area through the preliminary switching area in the low-speed valve timing area, the hydraulic control valve C is set in step S11.
V is opened to supply hydraulic pressure to the valve operating characteristic variable mechanisms VT, VT to establish high-speed valve timing. And
After the flag F indicating the open / closed state of the hydraulic control valve CV is set to “1” corresponding to the open state in step S12, step S13 is performed until the high-speed valve timing delay timer t _{HVT expires} in step S13.
In step 1, the fuel injection amount map and the ignition timing map for the low-speed valve timing are selected, and the control of the fuel injection amount and the control of the ignition timing by the fuel injection amount control device 59 and the ignition timing control device 60 are continued based on those maps. I do.
When the high-speed valve timing delay timer t _HVT has timed out in step S13, step S14 is performed.
After setting the low-speed valve timing delay timer t _LVT in step S15, a fuel injection amount map and an ignition timing map for high-speed valve timing are selected in step S15, and the fuel injection amount control device 59 and the ignition timing control device are determined based on those maps. The control of the fuel injection amount and the control of the ignition timing by 60 are started.

When the vehicle enters the preliminary switching region in the process of switching from the high-speed valve timing to the low-speed valve timing, the process goes to step S16 because the answer to step S10 is NO, but at this time, the hydraulic control valve CV
Is in the open state to establish the high-speed valve timing, and the flag F is set to "1" indicating the closed state, so that the flow proceeds to step S17. In step S17, the hydraulic control valve CV is closed to shut off the supply of the hydraulic pressure to the valve operating characteristic variable mechanisms VT, VT, and the low-speed valve timing is established. After setting the flag F indicating the open / closed state of the hydraulic control valve CV to “0” corresponding to the closed state in step S18, step S15 is performed until the low-speed valve timing delay timer t _LVT is up in step S19. To select the fuel injection amount map and the ignition timing map for the high-speed valve timing, and based on those maps, control of the fuel injection amount and control of the ignition timing by the fuel injection amount control device 59 and the ignition timing control device 60 are continued. . When the low-speed valve timing delay timer t _LVT has timed out in step S19, the high-speed valve timing delay timer t _HVT is set in step S20, and a fuel injection amount map and an ignition timing map for low-speed valve timing are selected in step S21. The control of the fuel injection amount and the control of the ignition timing by the fuel injection amount control device 59 and the ignition timing control device 60 are started based on these maps.

If it is determined in step S10 that the process is proceeding from the low-speed valve timing region to the high-speed valve timing region but has not yet entered the high-speed valve timing region after exiting the preliminary switching region, the process proceeds to step S1.
Since the flag F indicating the open / closed state of the hydraulic control valve CV is set to “0” corresponding to the closed state in step S6, steps S17 and S18 are skipped and steps S19 to S18 are performed.
21 and the control of the fuel injection amount and the control of the ignition timing are continued based on the fuel injection amount map and the ignition timing map for the low-speed valve timing until the high-speed valve timing region is entered in step S10.

If the operating state of the engine E is continuously in the low-speed valve timing range, the routine proceeds to step S
The control of the fuel injection amount and the control of the ignition timing are continued based on the fuel injection amount map and the ignition timing map for the low-speed valve timing in step S21 through steps S2, S9, S19 and S20, and the operating state of the engine E is continued. If it is in the high-speed valve timing region, step S
The control of the fuel injection amount and the control of the ignition timing are continued on the basis of the fuel injection amount map for high-speed valve timing and the ignition timing map in step S15 after steps S2, S9, S13 and S14.

By the way, the count time of the high-speed valve timing delay timer t _HVT which is set in the step S20 is variably controlled in accordance with the pump speed Np detected by the oil pump rotational speed detecting means S _6. That is,
If the pump rotation speed Np is large in step S51 of the flowchart of FIG. 11, the count time of the high-speed valve timing delay timer t _HVT is set small in step S52. If the pump rotation speed Np is medium in step S53, the process proceeds to step S52. In S54, the count time of the high-speed valve timing delay timer t _HVT is set to a medium level,
If the pump rotation speed Np is small in step S55, the count time of the high-speed valve timing delay timer t _HVT is set to be large in step S56. If the pump rotational speed Np does not correspond to any of the above, it is determined in step S57 that the electric oil pump OP has failed, and the mode shifts to the fail mode.

Similarly, the count time of the low-speed valve timing delay timer t _LVT set in step S14 is variably controlled according to the rotation speed of the electric oil pump OP. That is, if the pump rotation speed Np is large in step S61 of the flowchart of FIG.
At 62, the count time of the low-speed valve timing delay timer t _LVT is set to a large value. At step S63, if the pump rotation speed Np is medium, the count time of the low-speed valve timing delay timer t _LVT is set to medium at step S64. In step S65, the pump rotation speed Np
If is small, the count time of the low-speed valve timing delay timer t _LVT is set to be small in step S66. If the pump rotational speed Np does not correspond to any of the above, it is determined in step S67 that the electric oil pump OP has failed, and the mode shifts to the fail mode.

As described above, when the valve operating characteristic variable mechanisms VT, VT establish the low-speed valve timing, the hydraulic control valve CV is in the closed state, and the valve operating characteristic from the electric oil pump OP to the intake side. Variable mechanism V
Since the hydraulic pressure supplied to the connection switching mechanism 31 of T is shut off, the hydraulic pressure does not act on the hydraulic chamber 36 connected to the hydraulic pressure supply path 38 in the rocker shaft 16, and the first to third switching pins 32 to 34 The spring returns to the connection release position shown in FIG. As a result, the first to third rocker arms 17 to 19 are separated from each other, and the first and third rocker arms 17 and 19 in which the cam slippers 17 ₁ and 19 ₁ abut on the two low-speed cams 14 and 14, respectively. 19 drives the two intake valves 10 and 10 to open and close. At this time, the second rocker arm 18 having the cam slipper 18 ₁ in contact with the high-speed cam 15 idles irrespective of the operation of the intake valves 10.

When the hydraulic control valve CV is opened to establish high-speed valve timing, the electric oil pump OP
Is supplied to the connection switching mechanism 31 of the variable valve operation characteristic mechanism VT on the intake side, and the hydraulic pressure is transmitted from the hydraulic pressure supply path 38 in the rocker shaft 16 to the hydraulic chamber 36.
As a result, the first to third switching pins 32 to 34 are connected to the return spring 3
5 to the connecting position against the resilience of the first and third rocker arms 17 by the first and second switching pins 32 and 33.
Since -19 is integrally connected to the cam slippers 1 to the high-speed cam 15 large height and angle range of the higher portion 15 ₁
8 ₁ swing of the second rocker arm 18 is brought into contact with therewith first and third rocker arms 17 connected together,
19, the two intake valves 10 are driven to open and close. At this time, the high-order portion 1 of the low-speed cams 14,
4 _1, 14 ₁ are lost-motion away from the cam slipper 17 _1, 19 ₁ of the first, third rocker arms 17 and 19.

When the variable valve operating characteristic mechanism VT establishes the low-speed valve timing, the intake valves 10, 10 are driven with a low valve lift and a small opening angle.
When establishing high-speed valve timing, intake valves 10 and 1
0 is driven with a high valve lift and a large opening angle. The valve lift and opening angle of the exhaust valves 11, 11 are also controlled by the corresponding exhaust-side valve operating characteristic variable mechanism VT in the same manner as the above-described intake valves 10, 10.

As described above, when the valve operating characteristic variable mechanisms VT are switched from the low-speed valve timing to the high-speed valve timing, the opening of the electric relief valve RV in the preliminary switching region immediately before shifting to the high-speed valve timing region. since increasing the rotational speed of the electric oil pump OP in advance increases the second oil pressure Po ₂ immediately upstream of the hydraulic control valve CV by a slight proportion was opened hydraulic control valve CV entered the high-speed valve timing region Sometimes, the variable valve operating characteristic mechanisms VT, VT are immediately activated, and high-speed valve timing can be quickly established. Moreover, since the rotation speed of the electric oil pump OP is increased only in the preliminary switching region, the amount of energy required for that can be minimized.

When the hydraulic control valve CV is opened to establish the high-speed valve timing, the fuel injection amount map and the ignition timing map for the high-speed valve timing are waited until the high-speed valve timing delay timer t _{HVT expires.} Control of the fuel injection amount and the control of the ignition timing based on the hydraulic pressure control valve are started, so that a slight time lag from the opening of the hydraulic control valve CV to the establishment of the high-speed valve timing is absorbed, and the high-speed valve timing is actually established. The control of the fuel injection amount and the ignition timing for the high-speed valve timing can be started at the moment.

The time lag becomes shorter as the pump rotation speed Np becomes larger, that is, as the second oil pressure Po ₂ becomes higher.
This is because, when the second hydraulic Po ₂ is high, the valve hydraulic pressure control valve CV is from the opening characteristics variable mechanism V
This is because the time required for the hydraulic pressure supplied to T and VT to increase is reduced. Therefore, as shown in FIG. 11, by setting the count time of the high-speed valve timing delay timer t _HVT to be shorter as the pump rotation speed Np is larger, the start timing of the control of the fuel injection amount and the ignition timing for the high-speed valve timing is reduced. It is possible to set more accurately and minimize the occurrence of torque shock due to the switching of the valve timing.

On the other hand, when the hydraulic control valve CV is closed to establish the low-speed valve timing, the fuel injection amount map and the ignition timing for the low-speed valve timing are waited until the low-speed valve timing delay timer t _{LVT expires.} Since the control of the fuel injection amount and the control of the ignition timing based on the map are started, a slight time lag from the closing of the hydraulic control valve CV to the establishment of the low-speed valve timing is absorbed, and the low-speed valve timing is actually established. The control of the fuel injection amount and the ignition timing for the low-speed valve timing can be started at the instant of the start.

The time lag becomes longer as the pump rotation speed Np is larger, that is, as the second oil pressure Po ₂ is higher.
This is because, when the second hydraulic Po ₂ is high, the valve hydraulic pressure control valve CV from when closed characteristic changing mechanism V
This is because the time required for the hydraulic pressure remaining in T and VT to decrease becomes longer. Therefore, as shown in FIG. 12, by setting the count time of the low-speed valve timing delay timer t _LVT to be longer as the pump rotation speed Np is larger, the start timing of the control of the fuel injection amount and the ignition timing for the low-speed valve timing is increased. It is possible to set more accurately and minimize the occurrence of torque shock due to the switching of the valve timing.

Although the embodiments of the present invention have been described above, various design changes can be made in the present invention without departing from the gist thereof.

For example, the mechanism VT, V
T is not limited to that of the embodiment, and any structure having various structures can be adopted as long as it is a mechanism that changes valve operating characteristics including valve stoppage at least by hydraulic pressure.

[0059]

As described above, according to the first aspect of the present invention, when the operating state of the engine is in the preliminary switching area immediately before switching from the low-speed valve timing area to the high-speed valve timing area, the electric oil pump is used. And the hydraulic pressure output to the hydraulic control valve by controlling the operation of the electric relief valve is increased from the low-speed oil pressure to the high-speed oil pressure. In addition, the hydraulic pressure output from the hydraulic control valve can be quickly increased to the high-speed hydraulic pressure, and the high-speed valve timing can be established with a minimum time lag. In addition, the amount of operation of the electric oil pump required for increasing the hydraulic pressure can be minimized, which can contribute to energy saving.

According to the second aspect of the present invention,
The delay time from when the low-speed hydraulic pressure and the high-speed hydraulic pressure are switched to when the fuel injection amount and the ignition timing are switched depends on the rotation speed of the electric oil pump, that is, the magnitude of the hydraulic pressure output to the valve operating characteristic variable mechanism. Therefore, it is possible to switch the fuel injection amount and the ignition timing for the low-speed valve timing or at the moment when the high-speed valve timing is actually established. Can be minimized.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of an engine.

FIG. 2 is an enlarged view taken in two directions in FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 in FIG. 2;

FIG. 5 is a sectional view taken along line 5-5 in FIG. 3;

FIG. 6 is a diagram illustrating the overall structure of a hydraulic control system of an engine.

FIG. 7 is a sectional view of an electric relief valve.

FIG. 8 is a first branch diagram of a flowchart of a main routine.

FIG. 9 is a second partial diagram of the flowchart of the main routine.

FIG. 10 is a flowchart of a control routine for an electric oil pump and an electric relief valve.

FIG. 11 is a flowchart of a delay timer setting routine for high-speed valve timing.

FIG. 12 is a flowchart of a low-speed valve timing delay timer setting routine.

FIG. 13 is a diagram showing a map for searching for a correction coefficient for calculating a reference hydraulic pressure.

FIG. 14 is a diagram showing a map for searching a valve timing area.

[Explanation of symbols]

CV Hydraulic control valve Np Number of rotations of electric oil pump OP Electric oil pump RV Electric relief valve U Electronic control unit (control means) VT Valve operating characteristic variable mechanism t _LVT low speed valve timing delay timer (delay time) t _HVT high speed valve timing delay Timer (delay time)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 43/00 301 F02D 43/00 301B 3G301 301Z 301H F02P 5/15 F02P 5/15 B F term (Reference) 3G013 AA00 AA06 BB01 BB19 BD35 EA02 EA06 EA08 3G022 AA00 CA00 EA07 GA05 GA07 GA09 3G084 BA13 BA17 BA23 CA00 CA01 DA02 DA11 EC08 FA11 FA18 FA33 3G092 AA01 AA11 BA09 BB01 DA01 DA02 DA04 DF04 EA07 EA04 GA14 HA05Z HA11Z HB01X HC09X HE01Z HE08Z 3G093 BA02 BA15 BA19 CA00 CA01 DA01 DA03 DA05 EA05 EA13 EA15 EC01 EC04 FB04 3G301 HA01 HA19 JA04 JA14 KA01 KA11 LA07 LC01 LC08 MA11 NE23 PA07Z PA17Z PB03Z PE01Z

Claims (2)

[Claims] An electric oil pump (O) for generating hydraulic pressure
P), an electric relief valve (RV) for adjusting the oil pressure generated by the electric oil pump (OP), and an oil pressure output from the electric relief valve (RV) for the low-speed oil pressure and for the high-speed oil pressure higher than the low-speed oil pressure. A low-speed valve timing is established by a hydraulic control valve (CV) that switches to hydraulic pressure, and a low-speed hydraulic pressure output by the hydraulic control valve (CV), and a high-speed valve timing is established by a high-speed hydraulic pressure output by the hydraulic control valve (CV). In the engine (E) including a valve operating characteristic variable mechanism (VT) and control means (U) for controlling the operation of the electric oil pump (OP) and the electric relief valve (RV), the operation of the engine (E) When the state is in the preliminary switching area immediately before switching from the low-speed valve timing area to the high-speed valve timing area, the control means (U) The engine is characterized in that the operation of a dynamic oil pump (OP) and an electric relief valve (RV) is controlled to increase a hydraulic pressure output to a hydraulic control valve (CV) from a low-speed hydraulic pressure to a high-speed hydraulic pressure. Valve timing control device. 2. The control means (U) according to claim 1, wherein a predetermined delay time (t _HVT , t _{LV T} ) has elapsed after the hydraulic control valve (CV) switches between the low-speed hydraulic pressure and the high-speed hydraulic pressure. In addition, the fuel injection amount and the ignition timing for the low-speed valve timing and the fuel injection amount and the ignition timing for the high-speed valve timing are switched, and the delay time (t _HVT , t _LVT ) is set by the electric oil pump (OP). The valve timing control device for an engine according to claim 1, wherein the valve timing control device is changed according to a rotation speed (Np).