JPS5925013A - Valve operation switching device of internal combustion engine - Google Patents

Abstract

PURPOSE:To cause to normally start from an all-cylinder operating condition at the restarting of operation, by switching a direction switching valve to a switching position corresponding to an all-cylinder operating condition in a condition to forcibly release a stopper. CONSTITUTION:In case a direction switching valve is switched to the recess side to bring an engine to a stop, the direction switching valve 41, during a stop, is locked by a stopper 47 in a condition to move rightwardly. At the restarting, a starter switch 64 is turned ON, an electromagnetic actuator 60 is energized, an output rod 61 thereof is sucked leftwardly, the stopper 47 is released, and the direction switching valve 41 moves leftwardly through the elastic force of a spring 65 in a chamber 42b. Namely, the firection switching valve 41 is rapidly switched to the operating side, and this brings an engine to an all-cylinder operating condition, resulting in improving a starting ability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to valve operation of intake valves and exhaust valves of cylinders that are switched between operation and deactivation during cylinder number control in which combustion in some cylinders of a multi-cylinder internal combustion engine is deactivated depending on engine operating conditions. The present invention relates to a valve operation switching device for switching.

When a vehicle such as a car is running under conditions that require high output, such as when accelerating or climbing, it is better to fill all cylinders of the engine with air-fuel mixture to obtain high output, but when the load is low, However, if all cylinders continue to operate, the filling rate of fresh air in each cylinder will decrease, resulting in poor combustion and increased pumping loss. Therefore, by stopping the operation of some cylinders during low loads, the air-fuel mixture is transferred to the remaining cylinders to improve combustion, reduce pumping losses, and improve fuel efficiency. The concept already exists and is well known (see Japanese Patent Laid-Open No. 104116/1983).

In addition, when controlling the number of cylinders in a four-cylinder engine, the combustion interval becomes longer by 360 degrees in terms of crank angle due to the deactivation of two cylinders, and this increases torque fluctuations, but this is due to the fact that the deactivated cylinders The applicant has already confirmed that a significant improvement can be achieved by replenishing air for pressure regulation.

To briefly describe this torque fluctuation suppression method, as shown in FIG. 1, two cylinders that are switched between operating and inactive during cylinder number control are operated with the intake valve 1 open during the intake stroke and compressing the two cylinders. It provides the same opening characteristics of the intake and exhaust valves as in a normal 4-cycle, in which the exhaust valve 2 closes during the stroke and opens from the end of the expansion stroke to the exhaust stroke.
At rest, the exhaust valve 2 is always closed, and the intake valve 1 is slightly opened near the piston bottom dead center (either the suction bottom dead center, the expansion bottom dead center, or both). That is, the valve lift characteristics are set as shown in FIG.

According to this, the in-cylinder pressure of the dormant cylinder at the time when compression starts is always equal to the suction negative pressure of the operating cylinder, and after that, simple compression and expansion are repeated by raising and lowering the piston, and when controlling the number of cylinders, The in-cylinder pressure of each cylinder has a change characteristic as shown in FIG. The pressure change in the idle cylinders (#2, 3) is about half that of the operating cylinders (#1, 4) at its peak value, but
Since the pressure of the two idle cylinders changes synchronously every 360 degrees of crank angle, the change in engine torque appears to be good, but the torque changes generated from these two idle cylinders are combined.
Since the effect is doubled, it becomes possible to cope with the peak pressure level of the operating cylinder. Therefore, engine torque changes, including those of the operating cylinders, are obtained at every 180 degrees of crank angle, close to those due to the peak value of combustion pressure, and the smoothness of rotation is significantly improved.

In order to switch the valve operation of the intake and exhaust valves in this way when switching between operation and stop, it is rational to selectively use a pair of cams with different profiles, Examples of switching devices include those shown in FIGS. 4 to 6, for example.

To explain this, cams 5a and 5b with different profiles (the cam 5a is for use during operation, and the cam 5b is for use when at rest) are fixed adjacent to each other on the camshaft 4.

The rocker arm 6 is attached to the rocker shaft 7 so as to be movable in the axial direction, and is positioned via springs 11 and 12 between the rocker bracket 8 and a switching ring 10 that moves on the rocker shaft 7 by an electromagnetic actuator 9. Its movement in the axial direction is controlled by the movement of the switching ring 10, and it selectively engages with either one of the cams 5a, 5b.

For example, switching from operation to rest is performed using the electromagnetic actuator 9.
This is done by moving the switching ring 10 in the A direction. However, when the cam 5a is in contact with the rocker arm 6 and is driving it, the load of the valve spring 13 is added and the frictional force becomes extremely large, making it difficult to move the rocker arm 6 in the axial direction. In this state, even if the switching ring 10 moves in the A direction, the spring 12 is only compressed. Then, when the cam ridge portion of the cam 5a ends and a clearance is created at the contact surface with the rocker arm 6, the load of the valve spring 13 no longer acts.
The rocker arm 6 moves in the direction A by the acting force of the compressed spring 12, so that the cam 5b and the rocker arm 6 come to face each other.

Therefore, when stopping cylinders #2 and #3 in a four-cylinder engine, the valve operation is switched for the intake valve and exhaust valve of these cylinders, but even if each switching ring 10 is moved simultaneously by a single actuator 9, each rocker arm 6
move separately, and move one after another when a clearance is created between the contact surfaces of each rocker arm 6 and each cam 5a.

On the contrary, when switching from rest to operation, that is, when the switching ring 10 is returned to the direction B by the electromagnetic actuator 9, the action force of the compressed spring 11 causes the cam 5b to come into contact with the rocker arm 6. The rocker arm 6 is moved when a clearance is created between the surfaces.

Incidentally, since the #1 and #4 cylinders (not shown) are always in operation, the valve train may have a normal configuration (only the cam 5a and no switching mechanism).

However, in such conventional valve operation switching devices, the rocker arm was moved by the biasing force of the spring, but due to constraints such as installation space, it was difficult to obtain sufficient biasing force from the spring. Because of this, the moving speed was low, making it difficult to switch during high-speed operation.

In addition, the actuator must be quite large in order to function against the spring force, and depending on the timing of the actuator's operation, the cam may start lifting before the rocker arm has completely moved. There was a problem in that the surface pressure at the contact portion became excessive and caused damage, which was a major obstacle in ensuring reliability and durability.

Therefore, as will be explained later in an embodiment of the present invention, the present inventors formed hydraulic chambers on both sides of the rocker arm, and connected these pressure chambers, the hydraulic supply passage, and the hydraulic return passage with a directional control valve. Furthermore, this directional control valve is equipped with a stopper that restricts its switching operation, and when switching, the directional control valve is biased in the direction of the next switching using a pilot valve, and the stopper holds it in the current switching position. The idea was to release the stopper at an optimal timing synchronized with the rotation of the camshaft as engine operating conditions change, thereby allowing the rocker arm to move quickly and at an appropriate time.

However, with this &-1, when the engine is stopped for some reason (when the engine stalls) while the engine is switched to the idle side (during 2-cylinder operation), the directional control valve is switched to the idle side. Since it is regulated by the stopper, it remains switched to the pause side even when the engine is restarted, and there is a risk that starting performance will deteriorate. Furthermore, this problem occurs not only when the engine stalls, but also when the ignition switch is turned off, and was expected to become a major problem in practical use.

The present invention was made in view of the above-mentioned circumstances, and if the engine stalls while the engine is switched to the rest side or the engine stops due to turning off the ignition switch, the above-mentioned problem occurs when the engine is stopped or started. The stopper is forcibly released and the directional control valve is switched to a switching position corresponding to the all-cylinder operating state, so that when the operation is restarted, it starts from the all-cylinder operating state.

Hereinafter, the present invention will be explained based on the drawings.

7 to 12 show an embodiment of the present invention, FIGS. 7 and 8 are structural diagrams of a valve operating mechanism, and FIG. 9 is an overall diagram of a valve operation switching system. However, in order to make it easier to understand, the positional relationship in FIG. 9 is not necessarily the same as that in FIGS. 7 and 8. Also, Figure 10 is an enlarged view of the main part of Figure 9,
11 is a side view of FIG. 10, and FIG. 12 is an operating circuit diagram of the electromagnetic actuator in FIG. 11.

In the figure, 1 is the intake valve, 2 is the exhaust valve, and 13 is these valves 1.2.
14 is a cylinder head, and 15 is a rocker cover.

20 is a camshaft, 21 is a cam 21a having a profile for use during operation, and a cam 21b having a profile for use when not in use.
22 is a cam for the exhaust valve 2 consisting of a cam 22a having a profile for operation and a cam 22b having a profile for rest. A rocker arm 24 is for the intake valve 1, and a rocker arm 24 is for the exhaust valve 2.

These rocker arms 23, 24 are rotatably and axially movably attached to a rocker shaft 26 supported by a rocker bracket 25.

27 is a space ring.

Then, one rocker arm 24 and the rocker bracket 2
Hydraulic chambers 29.30 surrounded by collars 28 are formed between the end surfaces of the rocker arm 23 and the rocker bracket 25, and between the end surfaces of the other rocker arm 23 and the rocker bracket 25.
According to the oil pressure of
, 22b is selected. 3
1 is an O-ring. Further, a spring 32 is interposed between one collar 28 and the rocker arm 24,
The rocker arms 23 and 24 are connected to the cams 21a and 2 so that all cylinders operate normally when the oil pressure does not rise when starting the engine.
It is biased towards the 2a side.

Incidentally, the cams 21a and 22a are divided into two in order to reduce the amount of movement of the rocker arms 23 and 24.

Next, the hydraulic circuit to the hydraulic chambers 29 and 30 will be explained.

33 An oil pump drive cam 34 attached to the camshaft 20 and a piston 3 driven by the cam 34
An oil pump consisting of an oil tank 36 and an oil tank 36.
The oil sucked in through the check valve 37 is fed under pressure.

The discharge side of the oil pump 33 is connected to a timing lifter 49, which will be described later, and is also connected to an accumulator 39 via a check valve 38.
9 is connected via a check valve 40 to a supply port (P) of a 4-point, 2-position directional switching valve 41.

The directional control valve 41 receives a signal hydraulic pressure from an electromagnetic pilot valve 59 (described later) into chambers 42a and 42b on both sides thereof, and is switched by this signal hydraulic pressure so that the supply side port P is switched to either the output side port A or B. It is designed to be connected to. Here, the output side boat A is connected to the hydraulic chamber 29, the output side port B is connected to the hydraulic chamber 30, and each hydraulic chamber 29.30 is connected to the through hole 43 formed in the rocker bracket 25 and the rocker shaft 26. It communicates via a groove 44 formed in.

Further, a return side port R is formed in the directional switching valve 41 so that when the supply side port (P) communicates with either one of the output side boats A or B, the other side communicates with the return side boat R. It has become. This return side port R is connected to the oil tank 36 via a relief valve 45.

Furthermore, the directional control valve 41 has two grooves 45a, 46b in the axial direction, as clearly shown in FIGS. 10 and 11, and a stopper 47 is engaged with either of these grooves 46a, 46b. When the switch is in the switching position, it is locked in one of the switching positions. The stopper 47 is urged in the engaging direction by a spring 48.

This locked state is maintained by the arm 52 by the output rod 51 connected to the piston 50 of the timing lifter 49.
The stopper 49 is released by rotating the stopper 49 in the opposite direction to the biasing direction, but the output rod 54 of the electromagnetic actuator 53 connected to the arm 52 is attracted against the spring 55. The output rod 51 of the timing lifter 49 engages with the arm 52 only when the timing lifter 49 is rotated.

The timing lifter 49 controls the discharge of the oil pump 33 (I1
1 pressure is directly received by the piston 50, and the output rod 51 is reciprocated in synchronization with the lift of the piston 35 of the oil pump 33, that is, the cam lift.

The electromagnetic actuator 53 is controlled by a control circuit 58 that receives a signal from an accelerator sensor 57 that detects the amount of depression of the accelerator pedal 56 when the load condition changes from a high load condition to a low load condition or from a low load condition to a high load condition. Sometimes, electricity is applied for a certain period of time (for example, about 0.1 seconds).

The pilot electromagnetic valve 59 is connected to the chambers 42a on both sides of the directional switching valve 41 in a state where the directional switching valve 41 is switched to an arbitrary switching position and locked by the stopper 47.

42b is applied with a hydraulic pressure supply source, that is, the hydraulic pressure of the accumulator 39, and the other is connected to the oil tank 36 on the return side, so that the directional switching valve 41 is biased to switch to the opposite switching position. has become,
The electromagnetic actuator 53 is activated by a signal from the control circuit 58.
is activated and the stopper 47 is released in a timely manner by the timing lifter 49, and the directional switching valve 41 is switched by the bias. After the directional control valve 41 is switched (a predetermined time after the signal to the electromagnetic actuator 53), the pilot valve 59 is switched by another signal from the control circuit 58 to prepare for the next switching. ing.

On the other hand, referring to FIG. 11, an output rod 61 of an electromagnetic actuator 60 is connected to the stopper 47, and when the electromagnetic actuator 60 is energized, the stopper 47 is forcibly rotated in the release direction by its suction operation. That's how it is. Referring to FIG. 12, this electromagnetic actuator 60 is connected to the ignition switch 6 from the battery 62.
3 and a starter switch 64.

Further, a spring 65 is housed in the chamber 42b on one side of the directional control valve 41, so that the directional control valve 41 is biased toward the switching position corresponding to the operating state of all cylinders when there is no hydraulic pressure. .

Next, the action will be explained.

Now, all cylinders are in operation, the directional control valve 41 is switched as shown in the figure, hydraulic pressure is introduced to the hydraulic chamber 29 side, and the rocker arms 23 and 24 are moved to the operating cam 2 as shown in the figure.
1a and 22a, the pilot valve 59 is switched to a state opposite to that shown in the figure, and accordingly, in order to apply hydraulic pressure to the chamber 42a of the directional switching valve 41, the directional switching The valve 41 attempts to switch to a state opposite to that shown, but this is prevented by a stopper 47.

In this state, when the control circuit 58 detects a change in operating conditions, that is, a decrease in load from a change in the output of the accelerator sensor 57, the control circuit 58 operates the electromagnetic actuator 53 for a certain period of time to move the arm 52 to the left in FIG. Therefore, the output rod 51 of the timing lifter 49 and the arm 52 are able to engage with each other.

On the other hand, the timing lifter 49 reciprocates in synchronization with the cam lift as described above, but depending on the phase setting of the oil pump drive cam 34, the intake air of the #2 cylinder is switched between operation and rest, as shown in FIG. At the timing when the normal lift of the valve 1 ends (or the timing when the normal lift of the intake valve 1 of the #3 cylinder ends), the output rod 51 protrudes and rotates the stopper 47 via the arm 52. Release the stopper 47.

When the stopper 47 is released, the directional control valve 41 is switched to the right in FIG. 9 by the signal hydraulic pressure from the pilot valve 59, and in the switched state, the stopper 47 is applied again and locked. This is because the timing lifter 49 will not lift until the accumulator 39 is filled with oil pressure again, and the electromagnetic actuator 53 will be turned off again during that time.

When the direction switching valve 41 is switched, the hydraulic pressure from the accumulator 39 is supplied to the hydraulic chamber 30, and the hydraulic pressure in the hydraulic chamber 29 is discharged. Here, referring to FIG. 13, in the #2 cylinder, the normal lift of the intake valve 1 is completed, and both the intake valve 1 and the exhaust valve 2 are moved to the rocker arm 24 and the cam 2.
Since there is a clearance between the contact surfaces with 1a and 22a, the hydraulic pressure supplied to the hydraulic chamber 30 causes the rocker arm to move.
moves all at once toward the rest cams 21b and 22b, and as a result, these cams 21b.

22b and the rocker arm 24 come to face each other. Further, in the #3 cylinder, the normal lift of the exhaust valve 2 has started, and until the subsequent lift of the intake valve 1 is finished, the cam 21a,
22a drives the rocker arm 23.24, and since the frictional force due to the load of the valve spring 13 is large, the rocker arm 23.24 does not move in the axial direction.
By creating a clearance when the normal lift of the intake valve 1 ends, the valve similarly moves all at once, thereby completing the switching.

In this way, it is desirable to set the timing lifter 49 to operate at the point in time when the intake valve 1 of one of the cylinders that is switched between operation and rest ends its normal lift. This allows for the longest amount of time before the lift starts.

Further, when the directional switching valve 41 is switched, the pilot valve 59 is switched by the control circuit 5, and the signal oil pressure from the pilot valve 59 acts to return the directional switching valve 41 to its original state. However, since the directional switching valve 41 is locked by the stopper 47, it does not actually switch, but instead prepares for the next switching.

By switching the signal oil pressure in advance in this way, when the stopper 47 is released during switching, the directional control valve 4
Since 0 is switched all at once, responsiveness can be improved. In other words, even if the electromagnetic pilot valve 59 has a fast response speed, it is only 10 milliseconds, which is usually a bottleneck when switching during high-speed operation, but if the switching is done in advance as described above, even if the response speed is small, Good and easy to design.

Here, if the engine is stopped while the engine is switched to the rest side, the directional control valve 41 remains moved to the right in FIG. 9 and is locked by the stopper 47 during the stop, but when the engine is restarted When the starter switch 64 is turned on, the electromagnetic actuator 60 is energized, the output rod 61 is attracted to the left in FIG. 11, and the stopper 47 is rotated in the release direction. As a result, the stopper 47
is released, and the chambers 42a, 42 on both sides of the directional control valve 41
Although hydraulic pressure is not yet supplied to the chamber 42b, the spring 65 in the chamber 42b causes the directional control valve 41 to move to the left in FIG. That is, the directional control valve 41 is quickly switched to the operating side, thereby bringing all cylinders into an operating state, thereby improving startability.

FIG. 14 shows another embodiment of a circuit for operating the electromagnetic actuator 60 at the time of restart.

In this embodiment, a preset time (for example, 10 milliseconds to 2 seconds) is set from the moment the starter isotiro 4 is turned on.
The electromagnetic actuator 60 is energized via a timer 66 that closes only when the starter switch 64 is turned on.This has the advantage that the operating time of the electromagnetic actuator 60 can be set constant regardless of the length of the conduction time of the starter switch 64. have.

FIG. 15 shows yet another embodiment.

In this embodiment, the electromagnetic actuator 60 is activated via a timer 67 that closes for a predetermined time period (e.g., 5 seconds to several minutes) after the ignition switch 63 is turned off. After the engine is stopped, the electromagnetic actuator 60 operates to release the stopper 47, thereby switching the directional control valve 41 in preparation for restarting. Of course, after the timer 67 is activated, it is completely stopped and unnecessary power consumption is prevented. Note that when the electromagnetic actuator 60 operates after the engine is stopped, the oil pressure in the hydraulic circuit is at atmospheric pressure, so the operating time of the timer 67 does not need to be strictly determined.

As explained above, according to the present invention, when resuming operation, the engine always starts with all cylinders in operation, thereby improving startability.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the valve actuation applied to the intake and exhaust valves of the cylinders that are switched between operation and deactivation in order to effectively control the number of cylinders, and Figure 2 is the characteristic of the valve lift shown above. 3 is a characteristic diagram of the change in cylinder pressure of each cylinder during cylinder number control obtained when the same characteristics as above are given, FIG. 4 is a plan view showing a conventional example of a valve operation switching device, and FIG. The figure is an enlarged view of the main part of FIG. 4, FIG. 6 is a VT-VT sectional view of FIG. 5, and FIG. 7 is an embodiment of the valve operation switching device according to the present invention.
21) Plan view, Figure 8 is a side view of the same as above, Figure 9 is an overall view of the same system as above, Figure 10 is an enlarged view of the main part of Figure 9, Figure 11 is a side view of Figure 10, Figure 12 is a side view of Figure 10. 11 is an operating circuit diagram of the electromagnetic actuator shown in FIG. 11, FIG. 13 is an explanatory diagram of the rocker arm movement timing shown in the above, and FIGS. 14 and 15 are operating circuit diagrams showing other embodiments. 1...Intake valve 2...Exhaust valve 20...Cam shirt) 21a, 22a--Cam for operation 2
1b, 22b...cam for rest, 24...rocker arm 25...rocker bracket envy...
・Rocker shaft 29.30...Hydraulic chamber 33...
・Oil pump 34...Oil pump drive cam
39...Accumulator 41...Directional switching valve
47... Stopper 49... Timing lifter
52... Arm 53... Electromagnetic actuator 58... Control circuit 59... Pilot valve 6
0°°°Electric@7 '7+ x x bottom, 63°=41'
Qy'J'''Switch 64...Starter switch 65...Spring 66.67...Timer patent applicant Nissan Motor Co., Ltd. agent Patent attorney Fujio Sasashima No. 1 (carving bandit) (elimination)

Claims (2)

[Claims] (1) In a multi-cylinder internal combustion engine, the rocker arm for driving the intake and exhaust valves of some cylinders whose combustion is paused depending on the engine operating conditions is moved in the axial direction of the rocker shaft according to the conditions, and the camshaft is In a valve operation switching device for an internal combustion engine, the valve operation switching device for an internal combustion engine is configured to switch the valve operation of an intake/exhaust valve of a cylinder by selectively engaging one of a pair of cams with different profiles arranged in parallel in the axial direction. 1. A valve operation switching device for an internal combustion engine, comprising means for moving a rocker arm to an all-cylinder operating position when the engine is stopped or started. (2) In a multi-cylinder internal combustion engine, the rocker arm for driving the intake and exhaust valves of some cylinders whose combustion is paused depending on the engine operating conditions is moved in the axial direction of the rocker shaft according to the conditions, and the camshaft is In a valve operation switching device for an internal combustion engine, the valve operation switching device for an internal combustion engine is configured to switch the valve operation of an intake/exhaust valve of a cylinder by selectively engaging one of a pair of cams with different profiles arranged in parallel in the axial direction. , hydraulic chambers are formed on both sides of the rocker arm, these hydraulic chambers are connected to a hydraulic pressure supply passage and a hydraulic pressure return passage via a directional control valve, and a stopper is provided for regulating the switching operation of the directional control valve. A stopper release device that releases the stopper at a timing synchronized with the rotation of the camshaft due to changes in conditions, and a function that biases the directional control valve in the next switching direction after the directional control valve has been switched in preparation for the next switching. A pilot valve is provided to constitute a means for moving the rocker arm, and a means is provided for forcibly releasing the stopper when the engine is stopped or started and switching the directional control valve to a switching position corresponding to the operating state of all cylinders. A valve operation switching device for an internal combustion engine, characterized by: