JPH03151507A - Intake/exhaust valve device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent the adhesion and accumulation of foreign material to an engine valve positively by closing a feeder switch at the engine valve open time so as to drive an electrostrictive vibrator and thereby vibrate the engine valve. CONSTITUTION:At the engine operating time, an engine valve is switched being elevated by a cam 12. In this case, a feeder switch is closed in linkage with the descent of a lifter 14 driven by the cam 12 so as to vibrate an electrostrictive vibrator 20. As the upper end face of the electrostrictive vibrator 20 is constrained to the cam 12 through a shim 21, the engine valve 1 is excited axially with high frequency by the vibration of the electrostrictive vibrator 20. As a result, foreign material on the verge of being adhered to the engine valve 1 is shaken off. Moreover, as the excitation of the engine valve 1 is performed during the valve open time, damage caused by the vibration of a contact part between a seat 7 and a valve head part 2 can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve device used as an intake valve or an exhaust valve in an internal combustion engine.

[Conventional technology]

In an internal combustion engine intake valve, engine oil for lubricating between the valve stem and its guide is sucked into the intake boat during the intake stroke, and as it flows down the stem and valve head, it is carbonized by combustion heat from the combustion chamber. As a result, carbon and carbide deposits are formed. This deposit increases the air intake valve length and deteriorates valve operating characteristics, gets caught between the valve guide and reduces sealing performance, coats the valve body and deteriorates heat dissipation, and further This causes various problems such as adsorption and release of fuel and deterioration of responsiveness to changes in air-fuel ratio.

Therefore, as an improvement plan for this,
In the above publication, an intake valve is proposed whose valve head is coated with a removable polymer material, but if there is a defect such as a pinhole in the coating of this polymer material, it may be a very small pinhole. However, there is a problem in that carbon and carbide start to adhere and deposit from this point, and the deposition progresses even on a healthy film. Additionally, polymer materials have low heat resistance, with a melting point of around 300°C. On the other hand, the temperature of the valve head exceeds 300°C due to heat accumulation and backfire caused by engine operation, so the polymer material coating melts, exposing the metal base material, and the deposition of carbon and carbides begins, and the deposition prevention effect can only be obtained for a very short period of time.

[Problem to be solved by the invention]

This invention solves the above-mentioned conventional problems, and aims to provide an intake and exhaust valve device for an internal combustion engine that can reliably prevent the accumulation of carbon and carbides over a long period of time.

[Means to solve the problem]

However, in the intake and exhaust valve device for an internal combustion engine according to the present invention, an electrostrictive vibrator is installed between a lifter attached to the shaft end of an engine valve and a shim with which a cam for driving the lifter slides, and the electrostrictive vibrator a vibrator drive circuit that generates a high-frequency voltage for driving; a power supply switch that is connected between the electrostrictive vibrator and the vibrator drive circuit and closes when the engine valve is opened in conjunction with the lifter; It is characterized by having the following.

[Effect]

In the intake and exhaust valve device of the present invention, when the engine valve opens, the power supply switch is closed in conjunction with the lifter, and the high frequency voltage generated by the vibrator drive circuit is applied to the electrostrictive vibrator. As a result, the electrostrictive vibrator expands and contracts, vibrating the engine valve in the axial direction, and this high-frequency vibration shakes off carbon, carbide, etc. that tend to adhere to the engine valve, thereby preventing deposition on the engine valve. At this time, the power supply switch linked to the lifter starts and stops applying high frequency voltage to the electrostrictive sensor, so that each engine valve can be reliably vibrated at high frequency in an open state. The electrostrictive transducer is located on the top side of the lifter, so inspection and the lead wires of the electrostrictive transducer can be routed in the chamber.A shim is interposed between the electrostrictive transducer and the cam, and the electrostrictive transducer is Prevents wear and tear on the vibrator. In addition, high-frequency vibrations during the opening of the engine valve cause valve rotation and change the seating position, eliminating local wear and atomizing the fuel in the intake air-fuel mixture.

〔Example〕

A first embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

In FIG. 1, reference numeral 1 designates an engine valve used as an intake valve, which is composed of a valve head portion 2 and a stem portion 3. The stem portion 3 is slidably fitted into a valve guide 5 fixed to a cylinder head 4 of the engine. It is inserted. Further, the valve head portion 2 is adapted to come into contact with and separate from a seat 7 provided at the opening of the intake boat 6.

Reference numeral 8 denotes a retainer, which is attached near the shaft end 3a of the stem portion 3 by a retainer 10 that fits into a groove 9 provided in the stem portion 3, and is interposed between the retainer 8 and the spring bearing surface 4a of the cylinder head 4. Installed valve spring 11. forces the engine valve 1 upward, and pushes the valve head part 2 toward the seat 7.
It is being forced on.

12 is a cam fixed to the camshaft 13, and 14 is a lifter driven by the cam 12, which is slidably inserted into a guide hole 15 formed in the cylinder head 4.

20 is a disk-shaped electrostrictive vibrator, the lower end surface of which is adhered to the lifter 14, and the upper surface of this electrostrictive vibrator 20 is adhered to a shim 21 on which the cam 12 slides. The electrostrictive sensor 20 is made of a piezoelectric material made of piezoelectric ceramic such as PbTiO3, and expands in the axial direction when a voltage is applied between electrodes at both ends thereof. 22 is a power supply switch provided between the lifter 14 and the cylinder head 4, and is connected to a contact 23 fixed to the outer circumference of the lifter 14 via an insulator, and this contact 2.
A lead frame 24 made of elastic metal is attached to a groove 16 formed in the wall surface of the guide hole 15 opposite to the lead frame 3 through an insulator.
It consists of One lead wire 25 of the electrostrictive vibrator 20
is connected to the contact 23 through a through hole near the top of the lifter 14. Then, the other lead wire 26 of the electrostrictive vibrator 20 and the lead wire 27 connected to the lead frame 24
is connected to a vibrator drive circuit 32 shown in FIG.

Further, in FIG. 2, the vibrator drive circuit 32 is, for example, one
High frequency generation circuit 3 that generates a high frequency signal of KIIz or higher
3, and a power supply 3 that supplies voltage to be applied to the electrostrictive vibrator 20.
4, and a drive circuit 35 that outputs a high frequency voltage to the electrostrictive vibrator 20. As shown in FIG. 3, this drive circuit 35 includes N-type FETs 37 and 38 as switching elements.
It has a circuit configuration including a P-type FET 39 and inverters 40 to 43 for waveform shaping and signal inversion, respectively.
When the high frequency signal F is input from the high frequency generation circuit 33,
Application of voltage to the electrostrictive vibrator 20 due to conduction of the N-type FET 37 and P-type FET 39 and release of voltage application due to conduction of the N-type FET 38 are repeated.

In the device having the above configuration, the engine valve 1 begins to open by the cam 12 which is rotationally driven in accordance with the operation of the engine, and the lift is stopped at 81 after time T1 as shown in FIG.
During the time T2 from when the valve is fully opened until the lift reaches 82, the power supply switch 22 is closed as the lifter 14 is lowered, and the high frequency voltage output from the vibrator drive circuit 32 is turned off. This voltage is applied to the strain vibrator 20, and the electrostrictive vibrator 20 expands and contracts with an amplitude δ corresponding to this voltage VC.

Since the upper end surface of the electrostrictive vibrator 20 is restrained by the cam 12 via the shim 21, the expansion and contraction of the electrostrictive vibrator 20 causes the engine valve 1 to be excited in the axial direction at a high frequency. Due to high-frequency vibration, engine oil, carbon, carbide, etc. that try to adhere to the valve head part 2 and stem part 3 of the engine valve 1 (including those that begin to adhere while the valve is closed) are shaken off and deposited on the engine valve. is prevented. In addition, since the engine valve 1 is vibrated while the valve is open, there is no damage to the contact parts of the seams 1 to 7 and the valve head 2 due to vibration, and the vibration while the valve is open prevents valve rotation. It is easy to perform, and since the seating position changes, there is no local hit.

Next, FIG. 5 shows a second embodiment of the present invention, in which two power supply switches 22 are provided for supplying power to the electrostrictive vibrator 20.
The only difference from the first embodiment is that the two lead wires 25 and 26 (see FIG. 1) of the electrostrictive vibrator 20 are connected to separate contacts 23, but the effect is similar to that of the first embodiment. It is effective. In the figure, the same parts as in FIG. 1 are given the same reference numerals as in FIG. 1, and only one set of power supply switch and lead wire is shown.

The present invention is not limited to the above-described embodiments; for example, the lead frame 24 of the power supply switch 22 may be provided on the lifter 14 side, and the contact 23 may be provided on the cylinder head 4 side.

Furthermore, although the above description has been given to an intake valve device, the present invention can also be applied to an engine exhaust valve device. It is possible to prevent adhesion and accumulation.

〔Effect of the invention〕

As explained above, according to the present invention, the engine valve is vibrated at high frequency by the electrostrictive vibrator while the valve is open.
It reliably prevents the accumulation of carbon and carbide on engine valves over a long period of time, and valve rotation reduces local wear between the valve head and seat, extending the life of the valve. The fuel is atomized by the vibration of the engine valve, which improves fuel efficiency. In addition, the power supply switch linked to the lifter starts and stops applying high frequency voltage to the electrostrictive vibrator.
High-frequency vibration can be performed only when the engine valve is reliably in the open state, and there is no risk of damaging the contact portion between the valve head and the seat due to vibration during the valve closing. Since the electrostrictive vibrator is located on the top side of the lifter, it is easy to inspect and route the lead wires of the electrostrictive vibrator, and the shims prevent wear and tear on the electrostrictive vibrator, resulting in excellent durability. is obtained.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of an engine valve section showing a first embodiment of the present invention, FIG. 2 is a circuit (block) diagram of a drive system for an electrostrictive vibrator, and FIG. 3 is a drive circuit section of FIG. 2. FIG. 4 is an operating characteristic diagram of an engine valve and an electrostrictive vibrator, and FIG. 5 is a vertical sectional view of the upper part of an engine valve showing a second embodiment of the present invention. 1...Engine valve, 3...Stem part, 3a...
・Shaft end, 14... Lifter, 20... Electrostrictive vibrator, 2
1...Shim, 22...Power supply switch, 23...
Contact, 24... Lead frame, 25... Lead wire, 26... Lead wire, 27... Lead wire, 32... Stationary element drive circuit, 3... Frequency generation circuit, 34 ...Power source, 35...Drive port path.

Claims (1)

[Claims] 1. A vibrator drive circuit that installs an electrostrictive vibrator between a lifter attached to the shaft end of an engine valve and a shim on which a cam for driving the lifter slides, and generates a high-frequency voltage for driving the electrostrictive vibrator. and a power supply switch connected between the electrostrictive vibrator and the vibrator drive circuit and closed when the engine valve is opened in conjunction with the lifter. Exhaust valve device.