JPS59122714A - Valve operation selector device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To remove an air bubble as well as to prevent oil from degradation, by interconnecting a hydraulic passage to a return passage when an oil pump remains unlifted, in case of a device which selects valve operation characteristics by means of hydraulic pressure. CONSTITUTION:Each of rocker arms 6 and 7 is shifted in the axial direction of a rocker shaft 9 by hydraulic pressure to be selectively added to each of hydraulic chambers 12 and 13 and comes into contact with each of cams 4a, 5a or 4b, 5b selectively according to engine conditions. The feed of oil to these hydraulic chambers 12 and 13 takes place by means of an oil pump 17 via both a hydraulic passage 42 and a control part 21. When a plunger 19 of the pump 17 still remains unlifted, an on-off valve gear 44A has the hydraulic passage 42 interconnected through to a return passage 45, replacing oil inside the hydraulic passage 42 with a fresh one by degrees, thus not only deaerating performance in time of starting is improved but also oil degradation is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a valve operation switching device for switching the valve operation of intake valves and exhaust valves of some cylinders of a multi-cylinder internal combustion engine.

Switching the valve operation of intake valves and exhaust valves is used, for example, to control the number of cylinders, and a rocker arm provided on a rocker shaft slides in the axial direction of the rocker shaft to switch one of a pair of cams formed on the camshaft. This is done by selectively engaging with the
No. etc.).

An electromagnetic actuator, a hydraulic actuator, etc. are used to move the rocker arm in the axial direction, and the case where a hydraulic actuator is used will be explained with reference to FIGS. 1 to 3 for a four-cylinder engine.

FIG. 1 is an overall view of the valve actuation switching system, FIG. 2 is an enlarged view of the main part of FIG. 1, and FIG. 3 is a side view of FIG. 2.

In the figure, 1 is an intake valve, 2 is an exhaust valve, 3 is a camshaft, 4 is a cam for the intake valve 1, which consists of a cam 4a with a profile for operation and a cam 4b with a profile for rest, and 5
A cam for the exhaust valve 2 is composed of a cam 5a having a profile for operation and a cam 5b having a profile for rest. 6 is a rocker arm for the intake valve 1, and 7 is a rocker arm for the exhaust valve 2.

For example, the profile of the cams 4b and 5b for when the engine is at rest is set so that the exhaust valve 2 is kept fully closed while the intake valve 1 is opened for a short period of time near the bottom dead center. I try to adjust the pressure of fresh air and replenish it.

These rocker arms 6.7Fi, rocker brackets 8
The rocker shaft 9 is rotatably and axially movably attached to the rocker shaft 9 supported by the rocker shaft 9 .

10 is a spacer ring.

Hydraulic chambers 12.13 surrounded by collars 11 are formed between the end faces of one rocker arm 7 and rocker bracket 8 and between the end faces of the other rocker arm 6 and rocker bracket 8, respectively. The rocker arm 6.7 moves in the axial direction in response to the hydraulic pressure of the cam, and either the operating cam 4a, 5a or the rest cam 4b, 5b is selected. 14 is an O-ring. Additionally, a spring 15 is interposed between one collar 11 and the rocker arm 7, and the rocker arm 6.7 is moved toward the cams 4a and 5a so that normal all-cylinder operation occurs when the oil pressure does not increase when the engine is started. It's a boost. Incidentally, the cams 4a and 5a are divided into two in order to reduce the amount of movement of the rocker arm 6.7.

Next, the hydraulic circuit to the hydraulic chambers 12 and 13 will be explained.

The oil pump section 16 includes an oil pump 17 and a check valve 2.
The oil pump 17 is an oil pump consisting of an oil pump drive cam 18 attached to the camshaft 3 and a plunger 19 driven by the cam 18.
The oil sucked in through the hydraulic pressure control section 21 is sent under pressure through the hydraulic passage 42 .

The discharge side of the oil pump 17 is connected to a timing lifter 34 (described later), and is also connected to an accumulator 23 via a check valve 22, and further from the accumulator 23 via a check valve 24 in the 4-point to 2-position direction. It is connected to the supply side port P of the switching valve 25.

The directional switching valve 25 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 connect the supply side boat P to either the output side boat A or B. It is supposed to be done. here,
Each hydraulic chamber 12.1 has an output side A connected to the hydraulic chamber 12 and an output side B connected to the hydraulic chamber 13.
3 through a through hole 26 formed in the rocker bracket 8 and an FC groove 27 formed in the rocker shaft 9.

In addition, the direction switching valve 25 has a return side port) R-/J ball J cedar configuration, and the supply side boat P is connected to the output side port A or B.
When communicating with one of the two, the other communicates with the return boat. This return side port R is connected to the oil gear gallery side and is also connected to an oil tank 29 via a relief valve 28.

The pilot valve 30 is in the state shown in the figure under high load conditions by a signal from the control circuit 41, and is switched to the state opposite to the state shown in the figure under low load conditions, so that hydraulic pressure is applied to either chamber a or b on either side of the directional control valve 250. The supply source, that is, the hydraulic pressure of the Aki comb generator 23 is applied, and the other side is connected to the return side, that is, the oil tank 29.゛.

On the other hand, the directional control valve 25 has two grooves 31a in the axial direction, as clearly shown in FIGS. 2 and 3.

31b, and when the stopper 32 is engaged with either of these grooves 31a, 31b, it is locked at either of the switching positions. Stopper 32
is urged in the engagement direction by a spring 33.

7. This locked state is established by the output rod 36 connected to the piston 35 of the timing lifter 34.
It is designed to be released by rotating the stopper 32 in the opposite direction to the biasing direction through the 7ft, but only when the electromagnetic actuator 38 connected to the arm 37 is in suction operation, the □timing lifter 34 output lots 36 are adapted to engage the arm 37.

The timing lifter 34 receives the pressure on the discharge side of the oil pump 17 directly through the piston 35 and is urged rightward by a return spring 35A.
The output rod 36 is reciprocated in synchronization with the lift of the plunger 19 of No. 7, that is, the cam lift.

The electromagnetic actuator 38 is controlled by a control circuit 41 that receives a signal from an accelerator sensor 40 that detects the amount of depression of the accelerator pedal 39 when the condition changes from a high load condition to a low load condition or from a low load condition to a high load condition. Sometimes the power is turned on for a certain period of time.

Now, all cylinders are in operation, the directional control valve 25 is switched as shown in the figure, hydraulic pressure is introduced into the hydraulic chamber 12, and the rocker arm 6.7 is activated as shown in the figure.
, 5a, the pilot valve 30 is in the state shown.

When the control circuit 41 detects a change in operating conditions from this state, that is, a decrease in load from a change in the output of the accelerator sensor 40, the pilot valve 30 is switched to the opposite state from the one shown, and the direction is changed accordingly. In order to apply hydraulic pressure to the valve 250 chamber a, the directional control valve 25 is intended to be switched to a state opposite to that shown, but this is prevented by the stopper 32. 't*, the control circuit 41 operates the electromagnetic actuator 38 for a certain period of time to move the arm 37 to the left in FIG.
The output rod 36 and the arm 37 become engageable.

On the other hand, the timing lifter 34 reciprocates in synchronization with the cam lift as described above, but due to the phase setting of the oil pump drive cam 18, the output rod 36 protrudes and the arm 37
By rotating the stopper 32' (ll-
The stopper 32 is released near the bottom dead center.

When the stopper 32 is released, the directional control valve 25 is switched to the right in FIG. 1 by the signal hydraulic pressure from the pilot valve 30, and in the switched state, the stopper 32 is locked once again. This is because the timing lifter 34 will not lift until the accumulator 23 is filled with oil pressure again, and the electromagnetic actuator 38 will be turned off again during that time.

When the direction switching valve 25 is switched, the hydraulic pressure from the accumulator 23 is supplied to the hydraulic chamber 13, and the hydraulic pressure in the hydraulic chamber 12 is discharged. Here, referring to FIG. 4, when the normal lift of the intake valve 10 of the two-cylinder cylinder ends after passing the bottom dead center, the rocker arm 6.7 of both the intake valve 1 and the exhaust valve 2 comes into contact with the cams 4a and 5a. Since a clearance is created between the surfaces, the rocker arms 6 and 7 move all at once toward the rest cams 4b and 5b by the hydraulic pressure supplied to the hydraulic chamber 13, and as a result, these cams 4b and 5b and the rocker arms 6.7 become relative.

In addition, in the case of the 3-cylinder engine, the normal lift of the exhaust valve 2 has already started before the bottom dead center, and the directional control valve 25 has already started lifting near the bottom dead center.
Even if the cam 4a is switched, the cam 4a remains unchanged for at least one of the intake valve 1 and the exhaust valve 2 until the subsequent lift of the intake valve 1 is completed.
, 5a drive the rocker arm 6.7, and the rocker arm 6.7 does not move in the axial direction due to the large frictional force caused by the load of the pulp spring (not shown), but the normal lift of the intake valve 1 When this is completed, a clearance is generated, and the switch similarly moves all at once, thereby completing the switching (see Fig. 4).

When the load increases and the pilot valve 30 switches from the state opposite to the state shown in the figure to the state shown in the figure, the signal hydraulic pressure from the pilot valve 30 acts to return the directional control valve 25 to its original state again. do. However, since the directional switching valve 25 is locked by the stopper (32), it does not actually switch, but instead prepares for the next switching.

By switching the pilot valve 30 in advance in this manner, responsiveness can be improved at the time of switching (Q in which the directional switching valve 25 is switched all at once when 32 is released).

By the way, since this device does not include an air vent device in the hydraulic passage 42 that connects the oil pump section 16 and the hydraulic control section 21, the low-pressure pump pumps hydraulic oil into the oil tank as when starting the engine. In this case, if the air in the passage 42 enters the hydraulic control section 21 after starting, it will not be easily released (partly because the hydraulic passage from the oil pump 17 to the timing lifter 35 is filled with air). If the mixed air does not escape), there is a risk that the hydraulic control section 21 will not operate.

After the accumulator 23 is filled with hydraulic oil, if the switching operation of the hydraulic control unit 21 is not performed, the hydraulic oil supplied to the hydraulic passage 42 will simply flow within the passage 42 in accordance with the lift of the oil pump drive cam 18. When reciprocating motion is performed and high-speed operation is prolonged, this simple reciprocating motion causes friction between the hydraulic fluid and the passage wall, and this frictional heat causes the hydraulic fluid itself to heat up and accelerate its deterioration. was.

The present invention includes a pair of cams formed on a camshaft and a rocker arm provided on a rocker shaft, and the rocker arm is swung by the cam to open and close an intake valve and an exhaust valve, respectively, and pumps pressure oil from an oil pump. In a valve operation switching device for an internal combustion engine, which is controlled by a hydraulic control device according to operating conditions, and the controlled hydraulic pressure causes the rocker arm to slide in the axial direction of the rocker shaft to selectively engage one of the pair of cams. By providing the hydraulic passage connecting the oil pump and the hydraulic control section with an on-off valve device that communicates with the hydraulic passage and the return passage when the plunger of the oil pump is not lifted, air purge performance at startup can be improved. It is an object of the present invention to provide a valve operation switching device that prevents deterioration of the hydraulic oil by gradually draining the hydraulic oil in the hydraulic passage leading to the timing lifter.

The present invention will be explained below based on illustrated embodiments.

FIG. 5 is an overall view of the valve operation switching system according to the first embodiment of the present invention.

The shorter the passage branching from the passage 42 and reaching the timing lifter 34, the better.

Cylinder 4 of the engine 44a (or integrated with the engine)
4b, a rotor 44 that rotates in synchronization with the camshaft 3.
C fits into the cylinder 44b and the hydraulic passage 4.
2) C and return passage 4 to oil tank 29
A boat D is provided which communicates with the rotor 4 via the rotor 4.
A groove 44d formed on a part of the outer periphery of 4C communicates with the ports C and D=i at a predetermined crank angle, so that the hydraulic oil in the hydraulic passage 42 returns to the oil tank 29 and gradually escapes through the passage 45. It has become. This predetermined period of the crank angle is a period in which the oil pump drive cam 18 is not lifted (the fourth
Freely determined within the period when there is no oil pump lift.

Since the other components are the same as those in FIG. 1, the same components are given the same reference numerals and the description thereof will be omitted.

The effect of the above configuration will be explained.

Relatively low pressure attached to the engine (0.5 kg/CJ ~ 4 k
Hydraulic oil is supplied via an oil gear gallery by a pump (not shown) of approximately gA:J, and is supplied to a high-pressure oil pump 17 via a check valve 20.

The oil pump 17 reciprocates its plunger 19 according to the lift of the oil pump driving cam 18, and the oil discharged by this reciprocating movement is directly guided to the timing lifter 34 without passing through a check valve on the way, so that the piston 35 of the timing lifter 34 performs a simple reciprocating motion in synchronization with the lift of the oil pump drive cam 18.

Therefore, the oil pressure in the hydraulic passage 42 that communicates the oil pump 17 and the timing lifter 34 fluctuates within a predetermined range, and the lowest value is at the plunger 1 of the oil pump 17.
If the hydraulic pressure (approximately 0.5 kg/d-□4 kg/c++i) is sent by a low-pressure pump (not shown) when 9 is not lifted, the maximum is the timing lifter 34's screw ton 3.
This oil pressure is determined from the tension of the return spring 35A and the cross-sectional area of the piston 35 when the piston 5 is lifted.

The rotor 44C of the on-off valve device 44A rotates one-to-one in synchronization with the camshaft 3, and the hydraulic passage 42 and the return passage 45 rotate during the period when the oil pump drive cam 18 is not lifted.
Due to the residual pressure in the hydraulic passage 42 (supply pressure by the low-pressure pump), the hydraulic oil inside the oil pump 17, the hydraulic passage 42, and the timing lifter 34 is gradually discharged toward the return passage 45. At the same time, during this discharge process, the air that has entered the oil pump 17, the timing lifter 34, and the passage 42 is also discharged.

This does not impede the lifting of the ring lifter 34.

Therefore, in particular the interior of the oil pump 17 and the hydraulic passage 42
At the time of starting when a large amount of air is contained in the engine, the opening/closing valve device 44A bleeds out the air before the air enters the hydraulic control section 21, so that the air bleed performance at the time of starting is significantly improved.

In addition, in the conventional device, when high-load operation continues, the hydraulic control unit 21 in which the accumulator 23 is filled with pressure oil does not perform a switching operation, and the oil discharged from the oil pump 17 does not flow into the accumulator 23. Therefore, all of the discharge amount is absorbed by the lift of the timing lifter 34, and when the plunger 19 of the oil pump 17 returns from the lifted state, the oil pump 17 is absorbed by the timing lifter 34.
The hydraulic oil remaining in the passage 42 from the oil pump 17 to the timing lifter 34 simply reciprocates and is not replaced, and the temperature of the hydraulic oil itself gradually decreases due to the frictional heat caused by this reciprocating movement. However, in the present invention, even during engine operation, the hydraulic oil in the hydraulic passage 42 is released in synchronization with 30 revolutions of the camshaft, and the hydraulic oil is gradually activated before the temperature rises. Since the oil is being replaced, the rise in hydraulic oil due to frictional heat is prevented.

FIG. 6 is an overall view of a valve operation switching system according to a second embodiment of the present invention.

In the figure, 44e is a cam fixed to a shaft 44f that rotates one-to-one in synchronization with the camshaft 3;
The plunger 44g is moved to the cylinder 44 by the cam lift of e.
The cylinder 44b reciprocates from side to side in the figure as shown in the figure.
port C communicating with the hydraulic passage 42 and the oil tank 29
The plunger 4 is provided in the housing 44a of the port D full opening/closing valve device 44B communicating with the return passage 45.
A groove 4.4d formed on the outer periphery of the cylinder 4g connects the boats C and D at a predetermined period of the crank angle, and allows the hydraulic oil in the hydraulic passage 42 to return to the oil tank 29 and escape through the passage 45. . This predetermined period of the crank angle is controlled by the granger 19 by the oil pump drive cam 18, as shown in FIG.
Freely determined within the non-lifting period.

This case also has the same functions and effects as the first embodiment.

As described above, the present invention provides an on-off valve device in the hydraulic passage connecting the oil pump part and the hydraulic control part, which opens only when the plunger of the oil pump is not lifted to communicate the hydraulic passage and the return passage. Since the hydraulic oil in the passage is replaced gradually, air purge performance at startup is improved and deterioration of the hydraulic oil can be prevented.

[Brief explanation of the drawings] Figure 1 is an overall system diagram of a conventional valve actuation switching device;
3 is a side view of FIG. 2, FIG. 4 is an explanatory diagram of the rocker arm movement timing, and FIG. 5 is a diagram of the valve operation switching device according to the first embodiment of the present invention. Overall System Diagram: FIG. 6 is an overall system diagram of a valve actuation switching device according to a second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Intake valve, 2... Exhaust valve, 3... Camshaft, 4a, 5a... Cam for operation, 4b, 5b...
・Cam for rest, 6.7... Rocker arm, 9...
Rocker shaft, 17...Oil pump, 19...
Plunger, 21...hydraulic control unit, 42...hydraulic. Aisle, 44A. 44B...Opening/closing valve device, 45...Return passage. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] A pair of cams with different profiles are formed on the camshaft, and a rocker arm is provided on the rocker shaft, and the rocker arm is swung by the cam to open and close the intake valve and exhaust valve, respectively, and also opens and closes the check valve from the oil pump. A hydraulic control section controls the pressure oil sent through the oil pressure control section according to the operating conditions, and the rocker arm is slid in the axial direction of the rocker shaft via an actuator that responds to the controlled oil pressure, so that the rocker arm is connected to one of the pair of cams. In a valve operation switching device for an internal combustion engine that selectively engages, a hydraulic passage connecting the oil pump and a hydraulic control section is provided upstream of the check valve to open the hydraulic passage when the plunger of the oil pump is not lifted. A valve operation switching device for an internal combustion engine, comprising an on-off valve device communicating with a return passage.