JP3203967B2 - Engine valve gear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve train for an engine.

[0002]

2. Description of the Related Art There is a valve operating apparatus that makes valve opening characteristics of an intake valve and an exhaust valve of an engine variable. A variable valve timing mechanism that changes the opening and closing timing of a valve by switching the rotation phase of a camshaft and a variable valve that changes the valve lift and the like by switching a cam that opens and closes the valve are provided in such a valve train. There is one provided with both a lift mechanism (see JP-A-64-3208).

[0003]

However, in such a valve train, the variable valve timing mechanism and the variable valve lift mechanism are each operated by hydraulic pressure supplied from an oil pump for an engine lubrication system. It has become.

For this reason, when the operating regions of both mechanisms overlap,
The amount of oil leaking from the hydraulic operating part increases, and the supplied oil pressure decreases, so that the operating performance of both mechanisms may decrease or the amount of oil supplied to each part of the engine may decrease. Therefore, it is necessary to increase the capacity of the oil pump.

Further, if the switching of the rotation phase of the intake camshaft by the variable valve timing mechanism and the switching of the intake valve cam by the variable valve lift mechanism overlap, the torque step at the time of switching becomes large.

In this case, it is better that the early closing area of the intake valve is wider in terms of fuel efficiency and that the area of the low-speed cam (low lift) used on the low rotation side of the engine is narrower in terms of torque. Is switched after switching from the low-speed cam to the high-speed cam (high lift), the change in the opening and closing timing of the intake valve at the time of switching becomes large, and the torque step is further increased during acceleration. Becomes larger.

An object of the present invention is to solve such a problem.

[0008]

[0009]

[0010]

[0011]

According to a first aspect of the present invention, there are provided an intake camshaft and an exhaust camshaft each having a plurality of cams having different profiles, and at least one of the intake camshaft and the exhaust camshaft. Hydraulically operated variable valve timing mechanism that can switch the rotation phase of the camshaft, a hydraulically operated intake side variable valve lift mechanism that can switch the cam that opens and closes the intake valve, and a cam that opens and closes the exhaust valve A hydraulically actuated exhaust-side variable valve lift mechanism capable of switching the pressure and drive control means for controlling the supply of hydraulic pressure to these mechanisms, and a cam for rotating the camshaft and opening and closing the intake and exhaust valves. In the valve operating system of the engine, each of which is switched to a predetermined operating range, the entire operating range of the engine is The operating area and non-operating area of both variable valve lift mechanisms are set so that the supply of operating hydraulic pressure to the intake-side variable valve lift mechanism and the supply of operating hydraulic pressure to the exhaust-side variable valve lift mechanism are not performed simultaneously. I do.

According to a second aspect of the present invention, there is provided an intake camshaft having a plurality of cams having different profiles, a hydraulically operated variable valve timing mechanism capable of switching the rotational phase of the intake camshaft, and opening and closing the intake valve. A hydraulically operated variable valve lift mechanism capable of switching cams to be driven, and drive control means for controlling supply of hydraulic pressure to these mechanisms. In the valve operating device for an engine that switches to a predetermined operating range, supply of operating hydraulic pressure to the variable valve timing mechanism and supply of operating hydraulic pressure to the variable valve lift mechanism are not performed simultaneously in the entire operating range of the engine. The operating range of the variable valve timing mechanism is Set the operation area of the lift mechanism to the high rotation side of the engine, and set the interval between the operation area of the variable valve lift mechanism to be activated and deactivated and the operation area of the variable valve timing mechanism close to this switching area to be activated or deactivated. Set wider as the engine load increases.

A third invention is the second invention, the opening and closing timing of the intake valve during the operation of the variable valve timing mechanism is adapted to advance.

[0014]

[0015]

[0016]

[0017]

According to the first aspect of the invention, when the variable valve lift mechanisms are provided on the intake side and the exhaust side, the supply of the hydraulic pressure to both variable valve lift mechanisms is not performed simultaneously in the entire operation range of the engine. Since the operation region and the non-operation region of both mechanisms are set, the amount of oil leakage is reduced, and a decrease in oil pressure can be prevented.

[0018] In the second invention, barriers Bull valve timing mechanism, without overlapping the operation of the variable valve lift mechanism, it is possible to supply hydraulic pressure when hydraulic pressure there is room in both mechanisms, the operation of the variable valve lift mechanism, The interval between the non-operation switching area and the operation and non-operation switching areas of the variable valve timing mechanism close to this switching area is set wider as the engine load is higher. Therefore, the torque step at the time of switching can be accurately reduced.

In the third invention, the opening and closing timing of the intake valve is advanced to the operation area of the variable valve timing mechanism of the second invention, so that the early closing area of the intake valve is widened and the practical range where the load is not so high is set. Fuel efficiency is improved.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, reference numeral 10 denotes a variable valve timing mechanism (VTC) for switching a rotation phase of a camshaft, and reference numeral 11 denotes a variable valve lift mechanism (VVL) for switching a cam for opening and closing a valve.

The variable valve timing mechanism 10
A boss 13 fixed to a camshaft 12 and a sprocket (or pulley) 1 to which rotation of a crankshaft is transmitted
4 comprises a housing 15 integrally formed, and a helical gear 16 and the like meshing with helical splines formed on the inner and outer circumferences thereof. When the helical gear 16 is displaced in the axial direction, the camshaft 12 via the helical spline Is rotated relative to the sprocket 14 by a predetermined angle.

A hydraulic chamber 17 formed on one side of the helical gear 16 has an oil passage 1 provided in the camshaft 12.
An oil gallery 20 to which oil pressure from an oil pump 19 is guided from 8 via a bearing portion of the camshaft 12 is connected, and a control valve 21 is provided in the oil gallery 20.

When the control valve 21 is opened, the oil pump 1
When a predetermined oil pressure is supplied from the oil pressure chamber 9 to the helical gear 16 as shown in FIG. 2, the helical gear 16 is displaced rightward in the figure against the return spring 22 (operating position) and the control valve 21 is closed. The helical gear 16 is returned to the initial position (non-operating position) by the return spring 22 as shown in FIG.

In the case of the intake-side camshaft, the rotational phase, that is, the opening / closing timing of the intake valve, is advanced at the operating position where a predetermined hydraulic pressure is supplied, and the opening / closing timing of the intake valve is delayed at the non-operating position. Next, a corresponding variable valve timing mechanism is set. In the case of the exhaust side camshaft, the rotational phase, that is, the opening / closing timing of the exhaust valve is retarded at the operating position where a predetermined hydraulic pressure is supplied, and the opening / closing timing of the exhaust valve is advanced at the non-operating position. , The corresponding variable valve timing mechanism is set.

As shown in FIGS. 3 and 4, the variable valve lift mechanism 11 includes a high-speed cam (high lift, large operating angle) 25 on the camshaft 12 for each cylinder and a low-speed cam (low Lift, small operating angle) 26
a and 26b are formed.

The rocker shaft 27 has a low-speed cam 26
rocker arms 28a, 28a,
The rocker arm 28a, 28b is provided with a sub rocker 29 corresponding to the high-speed cam 25.
It can be swingably mounted on the base of the.

A rocker arm 28a, 28b has a prop 31 attached to a shaft 30 inserted between the arms below the sub rocker 29, and when a plunger 32 provided at the base of the rocker arm 28a, 28b is advanced, a return spring (not shown) is provided. The tip of the prop 31 is engaged with the sub rocker 29.

An oil gallery 36 into which the oil pressure from the oil pump 19 is guided through an oil passage 35 formed in the rocker shaft 27 into a hydraulic chamber 33 of the plunger 32.
Is connected, and a control valve 37 is provided in the middle of the oil gallery 36.

When the control valve 37 is closed, the oil pressure from the oil pump 19 to the hydraulic chamber 33 is cut off (or reduced), and the tip of the prop 31 engages with the sub rocker 29 as shown by the solid line in FIG. In this state, the low-speed cams 26a and 26b
Valve 38 via rocker arms 28a, 28b.
a and 38b are driven to open and close.

When the control valve 37 is opened, a predetermined oil pressure is supplied to the oil pressure chamber 33, and the tip of the prop 31 is engaged with the sub rocker 29 as shown by the dotted line in FIG. 4, so that the sub rocker 29 and the rocker arms 28a and 28b are engaged. (Operating position), and in this state, the sub rocker 2 is
9. Valve 38 via rocker arms 28a, 28b
a and 38b are driven to open and close.

The sub-rocker 29 and the rocker arms 28a, 28b are provided so that the high-speed cam 25 is always in rolling contact with the sub-rocker 29.
A lost motion mechanism 39 is provided between the base and the base of 28b.

Reference numeral 40 denotes a variable valve timing mechanism 1
0, a drive control device for the variable valve lift mechanism 11, in which an engine speed signal, an engine load signal, and the like are input to the drive control device 40, and the control valves 21, 37 are controlled by the drive control device 40 based on these signals. Is done.

When such a variable valve timing mechanism 10 and a variable valve lift mechanism 11 are provided on the intake side , as shown in FIG. 5, the variable valve timing mechanism 10 is located in a predetermined region on the low rotation speed side of the engine. Thus, the variable valve lift mechanism 11 is operated in a region on the high rotation side of the engine.

That is, the control valve 21 of the variable valve timing mechanism 10 is provided in a predetermined region on the low rotation side of the engine.
The variable valve timing mechanism 10 is actuated by supplying operating hydraulic pressure to the hydraulic chamber 17 by opening the hydraulic chamber 17, and a variable valve lift is provided to a high-speed side region of the engine in which the variable valve timing mechanism 10 is not operated. By opening the control valve 37 of the mechanism 11 and supplying operating hydraulic pressure to the hydraulic chamber 33, the variable valve lift mechanism 11 is operated.

Therefore, the supply of the operating oil pressure to the two mechanisms 10 and 11 does not overlap, thereby reducing the amount of oil leaking from the hydraulic operating unit and the like, and preventing the oil pressure supplied from the oil pump 19 from decreasing. it can.

Further, since the variable valve lift mechanism 11 is provided for each cylinder, the amount of oil leakage is larger than that of the variable valve timing mechanism 10. However, the hydraulic pressure is supplied to the variable valve lift mechanism 11 on the high rotation speed side of the engine. Therefore, when the rotation of the oil pump 19 is high and the hydraulic pressure from the oil pump 19 has a margin, the hydraulic pressure can be supplied to the variable valve lift mechanism 11.

Further, when the respective mechanisms 10 and 11 are switched (at the start of operation), the hydraulic pressure is reduced. However, the switching of these mechanisms or the switching of the other mechanism during operation of one mechanism does not overlap. In addition, a predetermined oil pressure can be maintained at the time of switching.

Therefore, good operation performance of both mechanisms 10 and 11 can be ensured, and a decrease in the amount of oil supplied from the oil pump 19 to each part of the engine can be sufficiently prevented.

[0040]

When at least the variable valve lift mechanism 11 is provided on the intake side and the exhaust side, one of the variable valve lift mechanisms is provided on the low rotation side of the engine.
The other variable valve lift mechanism operates on the high rotation speed side of the engine.

In this case, for example, the variable valve lift mechanism on the exhaust side is changed so that the low-speed cam opens and closes the exhaust valve in an operating state by supplying a predetermined oil pressure, and the high-speed cam opens and closes the exhaust valve in a non-operating state. I do.

In this manner, good operation performance of the two variable valve lift mechanisms 11 having a large amount of oil leakage can be ensured, and a decrease in the amount of oil supplied to each part of the engine can be reduced.

On the other hand, when the variable valve timing mechanism 10 and the variable valve lift mechanism 11 are provided on the intake side, as shown in FIG.
If the variable valve lift mechanism 11 is operated in a predetermined region on the low rotation side of the engine and the variable valve lift mechanism 11 is operated in a high rotation side region of the engine, the switching between the two mechanisms 10 and 11 does not overlap, so that the switching is overlapped. can be reduced torque difference than when the switching area of the two mechanisms 10 and 11
(Operation of both mechanisms 10 and 11, switching zone inoperative) When is approaching, since level difference increases as when the torque is large, the variable valve lift device as in this case 6
The switching area for the operation and non-operation of the structure 11 (VVL switching in FIG. 6)
Line) and variable valve timing close to this switching range
The interval A between the operation and non-operation switching areas of the mechanism 10 is set wider as the engine load increases.

That is, if the switching of the two mechanisms 10 and 11 is overlapped, the torque step at the time of switching between the mechanisms 10 and 11 overlaps to generate a large torque step as shown in FIG. If the switching area is close, the switching of the variable valve timing mechanism 10 proceeds relatively slowly, so that when the torque is large, the torque step cannot be reduced so much.
As described above, the torque steps at the time of switching between the mechanisms 10 and 11 do not overlap, and the torque steps can be sufficiently reduced even when the load is high.

Therefore, good driving performance can be ensured during acceleration. The switching range of the variable valve lift mechanism 11 is set at a point where the torque of the low-speed cam and the torque of the high-speed cam become equal as shown in FIG.

Further, by setting the interval A in this way, the torque step at the time of switching can be reduced, and the rotation speed can be reduced at low and medium speeds.
The operating range of the variable valve timing mechanism 10 in the low to middle load range, that is, the early closing range of the intake valve can be expanded, thereby improving fuel efficiency in a practical range.

[0048]

[0049]

[0050]

[0051]

As described above, according to the first aspect , when the variable valve lift mechanisms are provided on the intake side and the exhaust side, the supply of the hydraulic pressure to both variable valve lift mechanisms is performed in the entire operation range of the engine. Since the operation region and the non-operation region of both mechanisms are set so as not to be performed at the same time, accurate operation of both variable valve lift mechanisms can be secured by the hydraulic pressure supplied from the oil pump .

[0052] According to the second aspect, the supply from the oil pump is performed.
The good operability of the variable valve timing mechanism and the variable valve lift mechanism can be ensured by the supplied hydraulic pressure , and the variable valve lift mechanism can be operated and deactivated in the switching area of the variable valve lift mechanism and the variable valve timing mechanism close to the switching area. Since the interval from the operation switching area is set wider as the load of the engine is higher, the torque step at the time of switching can be accurately reduced, and the operability is greatly improved.

According to the third aspect , the opening / closing timing of the intake valve is advanced to the operation area of the variable valve timing mechanism of the second aspect , so that the early closing area of the intake valve is widened and the fuel consumption in the practical range is sufficiently improved. Can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration sectional view of an embodiment.

FIG. 2 is a configuration sectional view of a variable valve timing mechanism.

FIG. 3 is a configuration perspective view of a variable valve lift mechanism.

FIG. 4 is a sectional view taken along line AA.

FIG. 5 is a setting diagram of an operation area.

FIG. 6 is a setting diagram of an operation area.

FIG. 7 is a characteristic diagram of a torque step when switching of mechanisms is overlapped.

FIG. 8 is a characteristic diagram illustrating an example of a torque step according to the embodiment.

FIG. 9 is a characteristic diagram showing a cam switching area.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Variable valve timing mechanism 11 Variable valve lift mechanism 12 Camshaft 14 Sprocket 16 Helical gear 17 Hydraulic chamber 18 Oil passage 19 Oil pump 20 Oil gallery 21 Control valve 22 Return spring 25 High speed cam 26a, 26b Low speed cam 27 Rocker shaft 28a, 28b Rocker arm 29 Sub rocker 31 Prop 32 Plunger 33 Hydraulic chamber 35 Oil passage 36 Oil gallery 37 Control valve 38a, 38b Valve 39 Lost motion mechanism 40 Drive control device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F01L 13/00 301 F01L 1/34 F02D 13/02

Claims (3)

(57) [Claims] 1. A plurality of cameras each having a different profile.
Intake camshaft and exhaust camshaft
Shaft and intake camshaft or exhaust camshaft
The rotation phase of the camshaft provided on at least one of the
Switchable hydraulically operated variable valve timing machine
Hydraulic pressure that can switch the mechanism and cam that opens and closes the intake valve
Actuated intake-side variable valve lift mechanism and exhaust valve
Hydraulically operated exhaust that can switch cams that drive the lube
Side variable valve lift mechanisms and oil to these mechanisms
Drive control means for controlling the supply of pressure.
Drive phase and opening and closing the intake and exhaust valves
An engine that switches each moving cam to a predetermined operating range
In the valve train of
Supplying hydraulic pressure to the air-side variable valve lift mechanism
Supply of operating oil pressure to the exhaust side variable valve lift mechanism
Are not performed at the same time.
An operating valve device for an engine, wherein an operating region and a non-operating region of a shaft mechanism are set . 2. A plurality of cams having different profiles are formed.
Intake camshaft and rotation of the intake camshaft
Hydraulically actuated variable valve timing switchable phase
Switching mechanism and cam for opening and closing the intake valve
Hydraulically operated variable valve lift mechanism and these
Drive control means for controlling the supply of hydraulic pressure to the
The rotation phase of the intake camshaft and the intake valve
Switches the cams that drive the opening and closing of the
In the engine valve train, the engine
Hydraulic pressure to the variable valve timing mechanism
Supply and supply of hydraulic pressure to the variable valve lift mechanism
Variable valve ties so that
The operating area of the
The operating range of the bull valve lift mechanism is set to the high engine speed
And the variable valve lift mechanism
Active and non-operational switching area and variable near this switching area
Between the operation and non-operation switching areas of the valve timing mechanism
A valve train for an engine, wherein the interval is set wider as the load on the engine is higher . 3. The operation of a variable valve timing mechanism.
Sometimes the opening and closing timing of the intake valve is advanced
An engine valve train according to claim 2 .