JPH0355645B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a valve operation switching device for switching the valve operation of an intake valve and an exhaust valve of an internal combustion engine.

In general, the intake and exhaust valves of an internal combustion engine are open not only during the intake stroke and exhaust stroke, but also before and after the stroke, and there is a period of so-called valve overlap.

This is because when gas is exchanged within the cylinder, there is a delay in the inflow and outflow of the working gas due to its inertia and throttle resistance.

However, the strength of such intake and exhaust inertia effects differs depending on the driving conditions, so the opening characteristics of the intake and exhaust valves are changed depending on the driving conditions to improve fuel efficiency in all driving ranges. A valve operation switching device has been proposed that aims to increase the output.
131714).

This will be explained based on Figures 1 to 3, but here the ignition order of a 4-cylinder engine is #1-#3.
- #4 - As #2, a case will be described in which only the intake valves among the intake and exhaust valves are switched for all cylinders. Second
In the figure, 1 and 2 are intake valves for the #1 and #2 cylinders, respectively, and 3 and 4 are exhaust valves for the #1 and #2 cylinders, respectively.

The camshaft 5 includes a pair of cams 6a, 6b with different profiles for the intake valve 1 (cam 6a for high speed, cam 6b for low speed) and cams 7a, 7b for the intake valve 2 (cam 7a for high speed). , cam 7b for low speed) are fixed adjacent to each other. As for the exhaust valves 3 and 4, dedicated cams 8 and 9 are fixed to the camshaft 5 since the valve operation is not changed in this example.

When the profiles of the pair of cams 6a, 6b for intake valve 1 and the pair of cams 7a, 7b for intake valve 2 follow the cams 6a, 7a for high speed, they expand before and after the intake stroke, the intake valve opens, and at low speed cams 6b, 7 for
According to b, the intake valve is set to open so as not to expand before and after the intake stroke.

The rocker arms 10, 11 for the intake valves 1, 2 are positioned with a collar 12 interposed between them as a means for interlocking the rocker arms 10, 11 in the axial direction of the rocker shaft, and a pair of actuators 13, 14 move the rocker arms 10, 11 in the axial direction. The movement of the cams 6a and 7a is controlled at high speeds, and the cams 6b and 7b are moved at low speeds.
selectively engages with either one of them.

On the other hand, the same mechanism provided for #1 and #2 cylinders is also provided for #3 and #4 cylinders,
The locker arms for the intake valves of #3 and #4 cylinders are similarly controlled to move in the axial direction by a set of hydraulic actuators 15 and 16, and are selectively engaged with either the cam at high speed or the cam at low speed. do.

These hydraulic actuators 13, 14, 1
5, 16 are hydraulic chambers 13a, 14a, 15a, 16
Pistons 13b, 14b, 15 according to the oil pressure of a.
FIG. 2 shows a hydraulic circuit to a set of actuators 13, 14 and 15, 16.

The oil pump section 17 is a high pressure oil pump 18
The oil pump 18 is an oil pump consisting of an oil pump driving cam 21 attached to a camshaft 20 and a plunger 22 driven by the cam 21, and the check valve 19 is connected to an oil gear gallery (not shown). The oil supplied through the hydraulic pressure control unit 24 is force-fed to the hydraulic control unit 24.

The discharge side of the oil pump 18 is connected to a timing lifter 25, which will be described later, and a check valve 2.
6 to an accumulator 27, and from this accumulator 27 via a check valve 28 to a supply side port P of a 4-port, 2-position directional control valve 29.

The directional control valve 29 receives a signal hydraulic pressure from a pilot valve 30 (described later) into chambers a and b on both sides thereof, and is switched by this signal hydraulic pressure to the supply side port P.
is connected to either output side port A or B. Here, output side port A is connected to hydraulic chambers 13a and 15a, and output side port B
are connected to hydraulic chambers 14a, 16a, and communicate with each hydraulic chamber 13a, 14a, 15a, 16a via a through hole 31 formed in the rocker bracket.

Further, the direction switching valve 29 is formed with a return side port R, and a supply side port P is formed with an output side port A.
or B, the other side communicates with the return side port R. This return side port R is connected to the oil gear rally side and is connected to the oil tank 33 via the relief valve 32.
It is connected to the.

The pilot valve 30 has a hydraulic pressure _A1 between the output side port A of the directional control valve 29 and the hydraulic chambers 13a and 15a,
The hydraulic pressure _B1 between the output side port B and the hydraulic chambers 14a, 16a is received via the throttles 35a, 35b, respectively, and is switched depending on the size of the throttles 35a, 35b, so that the hydraulic pressure B1 on both sides of the directional control valve 29 is connected to the chambers a or b. The hydraulic pressure supply source, that is, the hydraulic pressure of the accumulator 27 is applied to one of the two, and the other is connected to the return side, that is, the oil tank 33. This switching characteristic is such that the pilot valve 30 is switched to return the directional switching valve 29 to its original switching position by the oil pressures A ₁ and B ₁ changed by switching the directional switching valve 29 .

On the other hand, the directional control valve 29 has two grooves 3 in the axial direction.
6a, 36b, and these grooves 36a, 36b
When the stopper 37 is engaged with either of the switching positions, the switching position is locked. The stopper 37 is urged in the engaging direction by a spring 38.

This locked state is caused by the timing lifter 2.
Output rod 25 connected to piston 25a of No. 5
b is designed to be released by rotating the stopper 37 via the arm 39 in the opposite direction to the urging direction, but only when the electromagnetic actuator 41 connected to the arm 39 is in the suction operation. , output rod 25 of timing lifter 25
b is adapted to engage with arm 39.

The timing lifter 25 receives the pressure on the discharge side of the oil pump 18 directly through a piston 25a, and reciprocates the output rod 25b in synchronization with the lift of the plunger 22a of the oil pump 18, that is, the cam lift.

The electromagnetic actuator 41 is controlled by a control circuit 43 that receives a signal from a rotational speed sensor 42 that detects rotational speed to maintain a constant state when moving from a high-speed operating range to a low-speed operating range or from a low-speed operating range to a high-speed operating range. It is supposed to be energized for hours.

Now, in the high-speed operating range, the directional control valve 29 is in the state shown in the figure, hydraulic pressure is introduced into the hydraulic chambers 13a and 15a, and the intake valve rocker arms 10 and 11 for the #1 and #2 cylinders are in the state shown in the figure. As shown in Fig. 1), it is driven by high-speed cams 6a and 7a, and #3,
Assuming that the rocker arm for the intake valve of the #4 cylinder is also driven by the high-speed cam (not shown), the hydraulic pressure acting on the pilot valve 30 is greater at _A1 , so the pilot valve 30 is in the state shown in the diagram. Accordingly, in order to apply hydraulic pressure to the chamber a of the directional control valve 29, the directional control valve 29 attempts to switch to a state opposite to the illustrated state, but this is prevented by the stopper 37.

In this state, when the control circuit 43 detects a change in the operating conditions, that is, a decrease in the rotation speed from a change in the output of the rotation speed sensor 42, the control circuit 43 operates the electromagnetic actuator 41 for a certain period of time to move the arm 39 as shown in FIG. Since it is moved to the left, the output rod 25b of the timing lifter 25 and the arm 39
are in a state where they can be engaged.

On the other hand, the timing lifter 25 reciprocates in synchronization with the cam lift as described above, but the output rod 25b is adjusted by setting the phase of the oil pump drive cam 21.
protrudes, and by rotating the stopper 37 via the arm 39, the stopper 37 is released near the bottom dead center.

When the stopper 37 is released, the pilot valve 3
The directional control valve 29 is switched to the right in FIG. 2 by the signal oil pressure from 0, and the stopper 37 is once again locked in the switched state. This is because the timing lifter 25 will not lift until the accumulator 27 is filled with oil pressure again, and the electromagnetic actuator 41 will be turned off again during that time.

When the directional control valve 29 is switched, the hydraulic pressure from the accumulator 27 is transferred to the hydraulic chamber 14.
a, 16a, and the hydraulic pressure in the hydraulic chambers 13a, 15a is discharged. Here, referring to FIG. 3, when the lift of the intake valve 1 of the #1 cylinder at high speed ends after the crank angle exceeds 180 degrees, the intake valve of the #1 and #2 cylinders Since a clearance is created between the contact surfaces between the first and second rocker arms 10, 11 and the cams 6a, 7a, the rocker arms 10, 11 move all at once toward the low speed cams 6b, 7b due to the hydraulic pressure supplied to the hydraulic chamber 14a. , whereby these cams 6b, 7b and the rocker arm 1
0 and 11 become opposite to each other.

At this time, the high-speed lift of the intake valve of the #3 cylinder has already started before 180 degrees, and even if the directional control valve 29 switches around 180 degrees, the high-speed lift of the intake valve of the #4 cylinder continues. #3 until the end of
The high-speed cam drives the rocker arm for at least one of the intake valves of the #4 cylinder, and the rocker arm does not move in the axial direction because of the large frictional force caused by the load of the valve spring (not shown). When the lift of the cylinder's intake valve at high speed is completed, a clearance is generated, and the valve similarly moves all at once, thereby completing the switching (see FIG. 3).

Furthermore, when the directional control valve 29 is switched, the hydraulic pressure applied to the pilot valve 30 is reversed, so the pilot valve 30 is switched and the signal hydraulic pressure from the pilot valve 30 returns the directional control valve 29 to its original state. act. However, since the directional switching valve 29 is locked by the stopper 39, it is not actually switched, but is prepared for the next switching.

By switching the signal oil pressure in advance in this way, when the stopper 39 is released during switching, the directional control valve 29 is switched all at once, so responsiveness can be improved.

Therefore, in the high-speed operating range, the intake valve close timing is delayed, increasing the intake efficiency of the intake air amount and increasing the engine output.In the low-speed operating range, the intake valve closing timing is earlier, so the throttle is reduced. This prevents backflow of exhaust gas when the valve opening is small, increasing suction efficiency and maintaining engine output even in low-speed operating ranges.

As mentioned above, here we have explained the case where only the operation of the intake valve is switched, but if a similar mechanism is provided for the exhaust valve so that both the intake and exhaust valves can be switched, the intake efficiency etc. in the low speed driving range can be improved. It can be set even higher.

However, if the intake and exhaust valves of all cylinders can be switched according to operating conditions using such a conventional method, not only will the number of expensive actuators be proportional to the number of intake and exhaust valves, but the configuration will also be complicated. This results in the problem of complication.

The present invention has been proposed in order to solve this problem, and it is possible to select a plurality of intake and exhaust valves in which interference between the cam and the rocker arm cannot occur at the same time when switching the valves, and to switch these multiple intake and exhaust valves at once. The purpose of the present invention is to reduce practical fuel consumption and increase maximum output even though the valve switching operation is performed using a minimum number of actuators.

To this end, the present invention supports a rocker shaft and a camshaft in parallel on the cylinder head, attaches a rocker arm to the rocker shaft so as to be movable in the axial direction, and arranges a plurality of cams with different profiles in the axial direction on the camshaft, so that the engine can be operated. In a valve operation switching device that switches the operating characteristics of the intake and exhaust valves by moving a rocker arm and selectively engaging one of the above cams according to conditions, Of these, half of the intake and exhaust valves in which interference between the cam and the rocker arm cannot occur at the same time are selected and classified into two groups, and each group is provided with a plurality of forks that hold the rocker arm. Equipped with holders that connect each group, two hydraulic actuators that independently move each holder in the axial direction of the rock shaft, and a hydraulic control device that selectively supplies pressure oil from a hydraulic pump to the hydraulic actuators. It is characterized by

Embodiments of the present invention will be described below based on the drawings.

FIG. 4 shows an embodiment in which the present invention is applied to a four-cylinder internal combustion engine, in which 50 is a cylinder head, 51 to 54 are rocker arms on the intake valve side, and 55
58 are rocker arms on the exhaust valve side, and 59 is a rocker shaft serving as a fulcrum for these rocker arms 51 to 58.

One end 51a to 58a of Rotsuka arms 51 to 58
are brought into contact with corresponding intake/exhaust valves (not shown), and the other end is brought into contact with a cam (not shown). In this case, there are two types of cams, for example, high-speed cams and low-speed cams, and these cams are arranged in parallel in the axial direction of the camshaft, and the rocker arms 51 to 5
8 is moved in the axial direction of the rocker shaft 59, thereby selectively switching to the other cam.

Hydraulic actuators 60 and 61 that move the rocker arms 51 to 58 along their pistons 60 and 61
a, 61a are the holders 62, 63 and the fork 6
Locker arm 51 of a predetermined cylinder via 4 to 69
For example, as shown in FIG. 4, the hydraulic actuator 60 drives the four rocker arms 51, 55, 52, and 57 that are closed at a certain timing among the intake and exhaust valves of the #1 to #4 cylinders. is sandwiched between forks 64 to 66, and the shaft is moved within a predetermined time.

Similarly, for the intake/exhaust valves other than the intake/exhaust valves mentioned above, the remaining half rocker arms 58, 54, 53, and 56, which are in the closed state, are held between the forks 67 to 69 at a certain timing.
- 69, another hydraulic actuator 61 connects the rocker arm 5 of a predetermined cylinder.
8, 54, 53, and 56 are moved in the axial direction of the rocker shaft 59.

A hydraulic control device 70 that drives these hydraulic actuators 60 and 61 uses pressure oil from a hydraulic pump 71 as a driving source by a hydraulic circuit shown in FIG. Hydraulic actuator 6 via valve 72
Controls the oil pressure supplied to chambers A to D of 0 and 61.

Specifically, the oil tank 33 is pumped by a hydraulic pump 71 driven by an engine 73 or a motor 74.
The oil sucked from the discharge side of the pump 71 is stored as pressure oil in the accumulator 27, and the excess oil is returned to the oil tank 33 via the pressure control valve 75.

Pressure oil from the accumulator 27 is sent under pressure to the chambers B and D of the hydraulic actuators 60 and 61 shown in FIG. 4 through the directional control valves 72a and 72b, respectively, so that as the pistons 60a and 61a move, the chambers A and D The pressure oil of C is transferred to the directional control valves 72a, 7.
It is relieved to the oil tank 33 via 2b.

When the directional control valves 72a, 72b are switched from the illustrated state based on the signal (operating condition signal) of the control circuit 43 that detects the operating conditions, pressure is reversely applied to the chambers A, C of the hydraulic actuators 60, 61. Since oil is supplied, the pistons 60a and 61b are moved in the opposite direction from the position shown in FIG. Switch the valve opening characteristics.

As shown in FIG. 5, the hydraulic actuators 60 and 61 operate so as to switch valves all at once, aiming at the timing when all predetermined intake and exhaust valves are in the closed state.

The control circuit 43 includes a crank angle signal from the crank angle sensor, a vehicle speed signal, an intake pipe negative pressure signal from downstream of the intake throttle valve, a gear position signal from the gear sensor, a water temperature signal from the water temperature sensor, and an oil temperature signal from the oil temperature sensor. A temperature signal, an electric load signal from the battery, etc. are input, and based on these signals, drive pulse signals are sent to the directional control valves 72a, 72b at predetermined timings.

Note that the holders 62 and 63 shown in FIG.
are shown on the intake and exhaust sides of the rocker shaft 59 for convenience of explanation, but in reality, these holders 62 and 63 are arranged approximately above the rocker shaft 59, and a hydraulic actuator that drives the holders 62 and 63 is shown. 60 and 61 are also Rotsuka shaft 5
It is installed approximately above 9. Therefore fork 6
The shapes 4-69 are also actually shorter in length than shown. Further, the holders 62 and 63 are made of spring steel, and due to their elastic bending, the rocker arm 5
1 to 58 and the hydraulic actuators 60 and 61.

Next, to explain the operation, the oil pressurized by the hydraulic pump 71 is stored in the accumulator 27, and the directional control valve 72 controls the pressure from the accumulator 27 based on a signal (operating condition signal) from the control circuit 43. Destination of oil (chambers A, B, C,
D) control.

Now, as shown in FIG.
8 is on the left side in the diagram, but if we move the rocker arms 51, 55, 52, and 57 to the right from this state to change the opening characteristics of the intake and exhaust valves of the first group, Figure 5 As can be seen from the graph showing the valve lift, the piston 60a of the hydraulic actuator 60 is activated at the timing when the intake and exhaust valves of the #1 cylinder, the intake valve of the #2 cylinder, and the exhaust valve of the #3 cylinder are closed at the same time. Move to the right.

That is, when the intake valve of the #1 cylinder closes during a transition from high-speed operation to low-speed operation, for example, the directional control valve 72 is activated in accordance with a command from the control circuit 43.
a switches from the illustrated state, that is, from the B line to the A line, thereby causing the piston 60a of the hydraulic actuator 60 to move to the right and contact the high speed cam (not shown) with the low speed cam via the holder 62 and forks 64 to 66. Like Rotsuka Arm 5
1, 55, 52, and 57 to the right.

After that, when the crank angle rotates 360 degrees and the intake valve of the #4 cylinder closes, the other directional control valve 72b changes to
The line is switched to the C line, the piston 61a of the other hydraulic actuator 61 is moved to the right to the low pressure side, and similarly the rocker arms 58, 54, 53, 56 are axially moved to the right from the high speed cam to the low speed cam.

According to this order, the directional control valves 72a, 7
2b is switched at regular intervals, all of the rocker arms 51 to 58 move to the right to switch the operating characteristics of the intake and exhaust valves of all cylinders to the low speed valve opening characteristics.

Conversely, when shifting from low-speed operation to high-speed operation, the directional control valve 72b is switched from the C line to the D line based on the signal from the control circuit 43, and then the other directional control valve 72a is switched from the A line to the B line. By switching to , one end of all the rocker arms 51 to 58 rides on the original high-speed cam, and all the valve opening characteristics of the intake and exhaust valves are restored to the high-speed cam.

In this way, in this embodiment, the intake and exhaust valves of all cylinders are classified into two groups, that is, the intake and exhaust valves of the #1 cylinder, the intake valves of the #2 cylinder, the exhaust valves of the #3 cylinder, and the remaining #4 cylinder intake and exhaust valves,
The #3 cylinder intake valve and the #2 exhaust valve are classified into groups, and the valve operation is switched using the hydraulic actuators 60 and 61 for each group. can ride on the cam smoothly without causing interference with the cam.

In order to group the intake and exhaust valves of all cylinders, as is clear from the lift characteristics of the intake and exhaust valves shown in Figure 5, the intake and exhaust valves of cylinder #2, the exhaust valve of cylinder #1, and the exhaust valve of cylinder #4 are grouped. They may be classified into a group of intake valves, a group of intake/exhaust valves for cylinder #3, an intake valve for cylinder #1, and an exhaust valve for cylinder #4.

FIGS. 7 and 8 show other embodiments, in which the present invention is applied to an in-line six-cylinder engine. Since the configuration and functions are substantially the same as those of the four-cylinder engine described above, the same components are given the same reference numerals, and only the characteristic portions of this embodiment will be described.

In FIG. 8, the opening/closing timing of the intake and exhaust valves of each cylinder and the timing at which the valves can be switched are shown, and as clearly shown in this figure, the rocker arms that simultaneously switch the valve operation are divided into groups as follows.

The first group is the intake and exhaust valves of the #1 cylinder, the intake valve of the #2 cylinder, the exhaust valve of the #3 cylinder, the intake valve of the #4 cylinder, and the exhaust valve of the #5 cylinder, and the second group is the #6 cylinder. Cylinder intake/exhaust valve, #5 Cylinder intake valve, #4
These are the exhaust valve of the cylinder, the intake valve of the #3 cylinder, and the exhaust valve of the #2 cylinder.

In this example, the firing order is #1-#5-#3-
#6-#2-#4, and the first group of rocker arms 80, 86, 81, 88, 83,
The shaft movement start timing of 90 is after the exhaust valve of #3 cylinder is closed, and
The shaft movement start timing of Nos. 1, 85, 84, 89, 82, and 87 is after the exhaust valve of #4 cylinder is closed.

These first and second groups of Rotsuka arms 8
0 to 91 can be switched in the axial direction of the rocker shaft 59 by hydraulic actuators 60 and 61, respectively, as in the embodiment shown in FIG. 4. In this case, the operation of the hydraulic actuators 60 and 61 is as shown in FIG. It may be controlled by a similar hydraulic control device 70.

In the above embodiment, two types of cams, one for high speed and one for low speed, are used as switching cams.
The present invention is not limited to this, and there are two types, one for high load and one for low load, which are switched depending on the engine load state.
Of course, other cams may also be used.

As explained above, according to the present invention, the valve opening characteristics of the intake and exhaust valves of all cylinders of an in-line multi-cylinder internal combustion engine can be switched using the minimum necessary two hydraulic actuators, so that the valve operation switching can be controlled. While reducing the number of components such as hydraulic actuators, it is possible to select the optimal intake and exhaust valve operating characteristics depending on the operating conditions, thereby reducing the engine's actual fuel consumption and increasing maximum output. This has the effect of being able to reliably contribute to

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view showing a part of the configuration of a conventional example, FIG. 2 is a system diagram showing the switching operation of the intake valve, and FIG. 3 is an explanatory diagram showing the opening characteristics of the intake valve. FIG. 4 is a schematic configuration diagram showing the main parts of the embodiment of the present invention, FIG. 5 is a graph showing the valve lift characteristics of the intake and exhaust valves, and FIG. 6 is a system diagram showing the switching operation of the intake and exhaust valves. , FIG. 7, and FIG. 8 are schematic configuration diagrams and graphs corresponding to FIG. 4 and FIG. 5 in other embodiments, respectively. 50... Cylinder head, 51-58... Locker arm, 59... Locker shaft, 60, 61
...Hydraulic actuator, 62, 63...Holder, 64-69...Fork, 70...Hydraulic control device, 71...Hydraulic pump, 72...Directional switching valve.

Claims (1)

[Claims] 1. A rocker shaft and a camshaft are supported in parallel on the cylinder head, a rocker arm is attached to the rocker shaft so that it can move in the axial direction, a plurality of cams with different profiles are installed in parallel on the camshaft in the axial direction, and the rocker arm is moved in accordance with the operating state of the engine. In a valve operation switching device for an internal combustion engine, which switches the operating characteristics of the intake and exhaust valves by moving the cam and selectively engaging one of the cams, the cam and the rocker arm of the intake and exhaust valves of all cylinders are moved. Select half of the intake and exhaust valves that cannot interfere with each other at the same time and classify them into two groups, provide a plurality of forks that hold the rocker arm in each group, and connect these forks to each of the two groups. A hydraulic control device is provided, which includes a holder that moves, and two hydraulic actuators that independently move each holder in the axial direction of the rock shaft, and selectively supplies pressure oil from a hydraulic pump to the hydraulic actuators according to operating conditions. A valve operation switching device for an internal combustion engine, characterized in that: