JPS61118517A - Valve operation control device in four-cycle engine - Google Patents

Abstract

PURPOSE:To select the operation and rest of a valve, by disposing a slider abutting against the front end of a valve rod, in a lifter directly driven by a cam, and by controlling the engagement and disengagement of the lifter and the slider in accordance with hydraulic pressure fed into the lifter. CONSTITUTION:A lifter 13 driving an intake valve and driven to be reciprocated by a cam 11a, slidably incorporates therein a pressing member 18 which abuts against the front end of a valve rod 8, and is fed with incompressible fluid. A plunger 21 urged in the direction in which the engagement is released by a spring 24, is disposed in the pressing member 18 so that the pluger 21 is moved perpendicular to the moving direction of the valve. The supply of fluid is controlled in accordance with the load of the engine, and the engagement and disengagement of the lifter 13 and the pressing member 18 are selected in accordance with the position of the plunger 21. With this arrangement, the operation and rest of an intake valve is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a four-stroke engine in which a valve stem is directly driven by a camshaft, and more particularly to an Ill III device for stopping valve operation as necessary.

[Technical background of the invention and its problems]

Conventionally, in a four-stroke engine with a plurality of intake valves per cylinder, one intake valve is stopped operating only during low or medium load operation, as shown in Japanese Patent Application Laid-open No. 55-32929, and this It is known that combustion efficiency is improved by increasing the intake flow velocity during low to medium load operation.

By the way, this prior art engine uses a rocker arm type valve mechanism, so a valve stop mechanism is built into the rocker arm, but in order to reduce inertial weight, the valve stem is attached to the camshaft. In an engine that is directly driven by a valve, it is extremely difficult to incorporate a valve stop mechanism as described above because there is no rocker arm.

[Purpose of the invention]

The present invention was made based on these circumstances, and
In an engine where the valve is directly driven by the camshaft, the operation of the valve can be stopped as necessary, and in this case, the entire device can be compactly housed inside the valve lifter without sacrificing any of the benefits of direct drive. The purpose of the present invention is to provide a valve operation control device for a 4-cycle engine that does not have the same technology.

[Summary of the Invention] That is, in order to achieve the above object, the present invention includes a cylindrical valve lifter in which a pressing member that contacts the tip of the valve stem is fitted so as to be slidable in the axial direction. A cylinder chamber into which an incompressible fluid is introduced is formed, and a plunger is housed in the cylinder chamber to be removably engaged with the peripheral wall of the valve lifter according to the fluid pressure of the incompressible fluid. The valve lifter is biased by a spring in the direction of separating from the peripheral wall of the valve lifter.

[Embodiments of the invention]

A first embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

In FIG. 1, 1 is a cylinder, and 2 is a cylinder head. Three intake boats 4 . . . and two exhaust boats 5 are provided in a combustion chamber 3 formed in the cylinder head 2. These intake boats 4... and exhaust boats 5 are individually opened and closed by three intake valves 6a, 6b, 6c and two exhaust valves 7a, 7b, respectively. Valve stems 8 and 9 are slidably supported by the cylinder head 2. In addition, an intake camshaft 1 is provided in a cam chamber 10 formed between the cylinder head 2 and a head cover (not shown).
1 and an exhaust camshaft 12 are housed therein, and these intake camshafts 11 and exhaust camshafts 12 are connected to intake valves 6a, 6.
b, 6c and exhaust valve 7a.

It is located directly above γb, that is, on the line connecting each pulp axis 0 knee 01. The tip of each valve stem 8.9, the cam surface 11a of the intake camshaft 11, and the exhaust camshaft 12
Valve lifters 13 and 14 are interposed between the cylinder head and the cam surface 12a, and these valve lifters 13 and 14 are slidably fitted into the sliding holes 15 of the cylinder head 2. Therefore, the intake valve 6a.

6b, 6c are intake camshaft 11, exhaust valves 7a, 7
b are each directly driven by the exhaust camshaft 12.

Note that in the figure, reference numeral 16 indicates a valve spring, and reference numeral 36 indicates a spark plug.

By the way, a valve stop mechanism 17 according to the present invention is incorporated in the valve lifter 13 of the first intake valve 6a and the second intake valve 6b that are adjacent to each other among the three intake valves 68 to 6c. . That is, the valve lifter 13 has a cylindrical shape with a closed end face on the intake camshaft 11 side, and a pressing member 18 is fitted into the valve lifter 13 so as to be slidable in the axial direction.

The pressing member 18 liquid-tightly closes the opening of the valve lifter 13 and is urged toward the intake valves 6a and 6b by a return spring 19, so that the end surface on the valve side comes into contact with the tip of the valve stem 8. being touched.

Further, a cylinder chamber 20 is formed inside the pressing member 18 along the radial direction of the valve lifter 13, and a plunger 21 is accommodated in the cylinder chamber 20 so as to be slidable in the axial direction. A locking projection 22 is provided at one end of the plunger 21, and this locking projection 22 is connected to the pressing member 1.
The plunger 21 is removably locked in a locking hole 23 formed in the peripheral wall of the valve lifter 13 through the peripheral surface of the valve lifter 13, and the locking protrusion 22 of the plunger 21 is released from the locking hole 23 by a return spring 24. is biased in the return direction. Note that a plunger 21 is provided on the inner surface of the cylinder chamber 20.
A stopper 25 is provided for regulating the return position.

Further, an oil chamber 26 is formed in the valve lifter 13 by fitting the pressing member 18, and this oil chamber 26 communicates with the cylinder chamber 20 through a communication hole 27. It communicates with an oil passage 29 through an introduction hole 28. The oil passage 29 is connected to the oil pump 30 as shown in FIG.
The oil passages 29.2 of the first and second intake valves 6a, 6b communicate with the oil pan 31 through the oil pan 31.
9, there are electromagnetic solenoid valves 32a, 32
b is connected. electromagnetic solenoid valve 32a,
32b is an oil supply port 33 connected to the discharge side of the oil pump 30 and an oil return port 3 connected to the oil pan 31.
4 is selectively switched to open and close, and this opening/closing control is performed by electrical signals from the control unit 35. The control unit 35 controls the two electromagnetic solenoid valves 32 according to the engine operating condition detected from, for example, the engine speed and throttle opening.
In this embodiment, when the engine speed reaches a preset speed, for example, about 5000 ROM as shown in Fig. 6, the electromagnetic solenoid The valve 32b is energized, the oil return hole 34 is closed, and oil pressure is supplied to the oil chamber 26 of the second intake valve stem.

Then, the engine speed increased further to about 70QQr.
When the temperature reaches pm, the other electromagnetic solenoid valve 32a is subsequently energized, and oil pressure is supplied to the oil outlet 26 on the first intake valve 6a side in the same manner as described above. moreover,
When the throttle opening degree is small, the control unit 35 changes the set rotation speed to a high value, and performs valve selection control according to the engine load.

Although not shown in the drawing, the intake valve 6C includes an exhaust valve 7a.
, 7b and l1llilat valve lifters 14 are used, and this intake valve 6C is always opened and closed by the intake camshaft 11.

Next, the operation of the above configuration will be explained.

When the engine speed is low, below 500 rpm, both the electromagnetic solenoid valves 32a and 32b close the oil supply ports 33, 33, and the oil pressure in the oil chamber 26 and cylinder chamber 20 is in a low state. Therefore, the plunger 21 is retracted into the cylinder chamber 20 by the biasing force of the return spring 24, so the locking protrusion 22 is disengaged from the locking hole 23 of the valve lifter 13, and the valve lifter 13 and the pressing member 18 are separated from each other. is in a state where it can vibrate relatively in the axial direction.

Therefore, as shown in FIG. 5, even if the valve lifter 13 is pushed down by the intake camshaft 11 in the direction of opening the intake valves 6a, 6b, the valve lifter 13 and the pressing member 18 only move stepwise relative to each other. , the pressing force is not transmitted to this pressing member 18, and the intake valves 6a, 6
b is not involved. In this way, in the low rotation range, only the third intake valve 6C, which is located offset from the center of the combustion chamber 5, is operated, so that the intake air flow speed increases and the swirl generated within the combustion chamber 3 is strengthened. Combustion efficiency is improved.

On the other hand, when the engine speed reaches 5000 rpm, the electromagnetic solenoid valve 32b is excited in response to an electric signal from the control unit 35, and the oil supply port 33 is opened. For this reason, the engine oil is in the oil passage 2.
The oil is supplied into the cylinder chamber 20 through the oil chamber 9 and the oil chamber 26, and the oil pressure within the cylinder chamber 20 is increased. At this time, since the engine oil is incompressible, it is plunged as shown in Figures 1 and 2. 21 is pushed outward, and the tip of the locking protrusion 22 engages with the locking hole 23 of the valve lifter 13. Due to this engagement, the valve lifter 1
3 and the pressing member 18 are locked immovably, and the pressing force applied to the valve lifter 13 is transmitted to the valve stem 8 via the pressing member 18, and the intake valve 6b is operated.

Therefore, in this operating state, two intake valves, the second intake valve 6b and the third intake valve 6C, are operated.
The intake efficiency is increased accordingly.

Also, when the engine speed reaches 700 Or pm,
Since the other electromagnetic solenoid valve 32a is excited by the electric signal from the control unit 35, engine oil is supplied into the oil chamber 20 in the same manner as described above, and the valve lifter 13 and the pressing member 18 are locked so as not to be movable. Therefore, the first intake valve 6a also starts operating, and all three intake valves 6a, 6b, and 6c operate in the high rotation range of 7000rl)m or higher.
Intake efficiency is further improved in the high speed rotation range, and output is obtained.

According to the first embodiment of the present invention, a pressing member 18 that contacts the valve stem 8 and has a cylinder chamber 20 therein is fitted in the valve lifter 13 so as to be openable. Plunge housed inside? 21 is engaged with and disengaged from the valve lifter 13 by the pressure of engine oil, so that the downward force applied to the valve lifter 13 can be transmitted to or blocked from the valve stem 8.

Therefore, even if it is a direct drive type, the intake valves 6a and 6b can be stopped as necessary, similar to the conventional rocker arm type.

Moreover, since the pulp stop mechanism 12 is accommodated in the internal space of the pulp lifter 13, the entire device is lightweight and compact, and the pulp stem 8 is
The force transmission path up to this point is not much different from that of the conventional direct drive type, and therefore has the advantage that the advantages of the direct drive type are not lost in any way.

In addition, in the first embodiment described above, a compression coil spring was used as the return spring 24 of the plunger 21, but as in the seventh embodiment and the second embodiment shown in FIG.
Bins 41 and 44 may be provided at the end of the plunger 21 and the end of the cylinder i2G, respectively, and a tension coil spring serving as the return spring 42 may be stretched between the bins 41 and 41.

Further, as in the third embodiment shown in FIGS. 9 and 10, the pressure introduction chamber 51 into which engine oil is supplied into the pressing member 18 and the cylinder chamber 53 in which the plunger 52 is housed are arranged parallel to each other. A piston body 55 is installed in parallel with the piston body 55 and slidably displaced against a return spring 54 by receiving oil pressure in the pressure introduction chamber 51, and the piston body 55 and the plunger 52 are connected by a pin 56. It's okay.

Furthermore, in carrying out the present invention, the number of intake pulps and exhaust pulps is not specified in the embodiment, and
A pulp stop mechanism may also be incorporated into the pulp lifter on the exhaust pulp side.

〔Effect of the invention〕

According to one embodiment of the present invention described in detail above, it is possible to transmit or cut off the downward force applied to the pulp lifter to the valve stem, and therefore, even if it is a direct drive type, it can be used similarly to the conventional rocker arm type. Pulp can be stopped as necessary. Moreover, since the mechanism for stopping the pulp is housed in the internal space of the pulp lifter, the entire device is lightweight and compact, and the power transmission path from the camshaft to the valve stem is also different from that of the conventional direct drive type. There is no major difference, and therefore there are advantages such as not detracting from the advantages of the direct drive type.

[Brief explanation of drawings]

1 to 6 show a first embodiment of the present invention.
The figure is a cross-sectional view of the entire device, Figure 2 is a cross-sectional view along line 1-II in Figure 1, Figure 3 is a view taken from the direction of line ■ in Figure 1, and Figure 4 is a hydraulic system diagram. , FIG. 5 is an operation explanatory diagram, FIG. 6 is a characteristic diagram showing the order in which the intake valves open, FIGS. 7 and 8 are a second practical example of the present invention, and FIG. 7 is a sectional view, Figure 8 is a sectional view along the line ■-■ in the seventh factor, Figures 9 and 10.
The figure shows a third embodiment of the present invention, FIG. 9 is a sectional view, and FIG.
FIG. 0 is a sectional view taken along the line X--X in FIG. 9. 8... Valve stem, 11... Camshaft (intake camshaft), 13... Pulp lifter, 18... Pressing member, 2
0...Cylinder chamber, 21.52...Plunger,
24.42.54... Spring (return spring). Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] In a four-stroke engine in which a cylindrical valve lifter is interposed between the tip of the valve stem and the camshaft, and the valve stem is directly driven by the camshaft, the tip of the valve stem is located within the valve lifter. A pressing member that comes into contact with the part is slidably fitted in the axial direction, and a cylinder chamber into which an incompressible fluid is introduced is formed inside the pressing member, and the incompressible fluid is introduced into the cylinder chamber. Valve operation control for a four-stroke engine, characterized by housing a plunger that is removably engaged with a peripheral wall of a valve lifter in response to pressure, and biasing the plunger in a direction to separate from the peripheral wall of the valve lifter by a spring. Device.