JPH03151506A - 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 by detecting the position of a cam so as to drive a high frequency vibrator during the open time of the engine valve driven by the cam and thereby vibrate the engine valve. CONSTITUTION:At the engine operating time, an engine valve 1 is switched being elevated by a cam 12. While a valve opening detecting sensor 28 and a valve closure detecting sensor 29 output detection signals respectively in association with the change-over of the engine valve 1, an electrostrictive vibrator 20 is vibrated. 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 the intake valve of an internal combustion engine, engine oil for lubrication 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 the combustion heat from the combustion chamber. As a result, carbon and carbide deposits are formed. This deposit increases the volume of the intake valve and deteriorates the 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 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/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 the engine valve and a shim on which a cam for driving the lifter slides, and a shim for driving the engine valve is installed. a cam position sensor that detects the valve opening state of the cam; and a vibrator drive circuit that receives a detection signal from the cam position sensor and applies a high frequency voltage to the front distribution distortion vibrator while the engine valve is open. It is characterized by what it did.

(Function) In the intake and exhaust valve device of the present invention, the vibrator drive circuit applies a high frequency voltage to the electrostrictive vibrator while the engine valve is open in response to the detection signal of the cam position sensor. The vibrator expands and contracts to vibrate the engine valve in the axial direction, and this high-frequency vibration shakes off carbon, carbide, etc. that try to adhere to the engine valve, and prevents it from accumulating on the engine valve.At this time, each Since a high frequency voltage is applied to the electrostrictive vibrator using the detection signal of the cam position sensor that directly detects the open state of the cam for driving the engine valve, each engine valve can be reliably vibrated at high frequency in the open state. can.

Since the electrostrictive 15 actuator is located on the top side of the lifter, it is easy to inspect and route the lead wire of the electrostrictive vibrator, and a shim is interposed between the electrostrictive vibrator and the cam to prevent electrostrictive vibration. Prevent child wear and tear. 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〕

An 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 to the vicinity of the shaft 913a 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. The valve spring 11 biases the engine valve 1 upward, causing the valve head portion 2 to move 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.

Reference numeral 20 denotes a disk-shaped electrostrictive vibrator, the lower 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 vibrator 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 has a contact 23 fixed on the outer periphery of the lifter 14 via an insulator, and a contact 22 on the wall of the guide hole 15 opposite to this contact 23. It consists of an elastic metal lead frame 24 attached to the 16 parts provided through an insulator. One lead wire 25 of the front distribution strain vibrator 20 is connected to the contact point 23 through a through hole near the top of the lifter 14 . And the other lead wire 26 of the electrostrictive vibrator 20
A lead wire 27 connected to the lead frame 24 is connected to a vibrator drive circuit 32, not shown in FIG. Further, 28 is a valve open detection sensor, and 29 is a valve closed detection sensor, both of which constitute a cam position sensor that detects the open state of the cam 12, and a proximity switch that detects the position of the tip of the cam 12 and issues a signal. , are connected to the vibrator drive circuit 32. The valve open detection sensor 28 emits a cam detection signal when the cam 12 rotates by 81 minutes of valve lift crucible from the valve opening start position shown by the solid line in FIG. The respective mounting positions are determined so that a cam detection signal is generated when the valve reaches a position a distance of valve lift ff182 before the valve opening end position shown by a chain line 30. Note that the contacts 23 of the lifter 14 and the lead frame 24 are
The position of the lead frame 24 is determined so that contact is started at a position where the valve lift amount is less than 81, and the lead frame 24 is in an open state when the valve lift amount is less than 82.

Further, in FIG. 2, the vibrator drive circuit 32 includes a frequency generation circuit 33 that generates a high frequency signal of, for example, 1 llz or more, a power source 34 that supplies a voltage to be applied to the electrostrictive vibrator 20, and a It consists of a drive circuit 35 that outputs a high frequency voltage to the child 20, and a control circuit 36 that outputs a high frequency signal to the drive circuit 35 at a predetermined timing. This control circuit 36 is connected to the valve opening detection sensor 2 provided on each cam 12 for driving the engine valve 1 for each engine valve 1.
The high frequency signal F from the high frequency generation circuit 33 is output to the drive circuit 35 from when the cam detection signal from the valve closing detection sensor 8 is input until when the cam detection signal from the valve closing detection sensor 29 is input. . Further, as shown in FIG. 3, the drive circuit 35 has a circuit configuration including N-type FETs 37 and 38 and a P-type FET 39 as switching elements, and inverters 40 to 43 for waveform shaping and signal inversion, respectively. When a high frequency signal F is input via the control circuit 36 to the voltage Vc that is constantly applied from the power supply 34, N
Application of voltage to the electrostrictive vibrator 20 due to conduction of type FET 37 and P-type FET 39 and release of voltage application due to conduction of N-type FET 3B are repeated.

In the device having the above configuration, the engine valve 1 begins to be opened by the cam 12 which is rotationally driven in accordance with the operation of the engine, and the lift amount is 81 after time T+ as shown in FIG.
During the time T2 from the time when the valve open detection sensor 28 issues a cam detection signal to the time when the lift amount becomes S2 after the valve is fully opened and the valve close detection sensor 29 issues a cam detection signal, the control circuit 36 outputs the ^frequency signal. In response, an eight-frequency voltage tuned to the signal is applied to the electrostrictive vibrator 20, and the electrostrictive vibrator 20 has an amplitude δ corresponding to this voltage Vc.
It expands and contracts. Since the upper end surface of the electrostrictive vibrator 20 is restrained by the cam 12 via the shim 21, the electrostrictive vibrator 20
Due to the expansion and contraction of the engine valve 1, the engine valve 1 is vibrated in the axial direction at a high frequency, and this high frequency vibration causes engine oil, carbon, carbide, etc. ( (including those that begin to adhere during valve opening) are shaken off and prevented from accumulating on the engine valves. In addition, the vibration of engine valve 1 is
Since this is done while the valve is open, there is no damage caused by vibration to the contact area between the seat 7 and the valve head 2, and the valve rotation is easily performed due to the vibration while the valve is open, and the seating position changes. Local hit disappears.

The present invention is not limited to the above-mentioned embodiment. For example, as shown in FIG.
The output of the high frequency voltage generation circuit 44 that generates a frequency voltage is
The electrostrictive vibrator 20 may be provided with a control circuit 36 that performs ON-OFF in response to cam detection signals from the valve open detection sensor 28 and the valve closed detection sensor 29. Further, in the above embodiment, in order to supply power to the electrostrictive sensor 20, one lead wire of the electrostrictive vibrator 20 is connected to the power supply switch 22, and the other lead wire is connected directly to the vibrator drive circuit 32. However, instead of this, both of the two lead wires may be directly connected to the vibrator drive circuit 32 via the power supply switch 22, or the two
Each lead wire may be connected to the vibrator drive circuit 32 via two sets of power supply switches 22.

Further, the power supply switch 22 may be of a type in which the contacts 23 and the lead frame 24 are always in contact with each other.

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, since the engine valve is imaged 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, since high-frequency voltage is applied to the electrostrictive vibrator using the cam position sensor detection signal that directly detects the open state of the cam for driving each engine valve, it is applied only when each engine valve is definitely in the open state. High-frequency vibration can be generated, and there is no risk of damage to the contact area between the valve head and the seat due to additional exposure during 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 also prevent wear and tear of the electrostrictive vibrator.
Damage is prevented and superior durability is achieved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an engine valve section showing an 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 diagram of the drive circuit section of FIG. Circuit diagram, 4th
The figure is a diagram of the operating characteristics of engine valves and electrostrictive vibrators.
The figure is a block diagram showing another embodiment of the vibrator drive circuit of FIG. 2. 1...Engine valve, 3...Stem part, 3a...
・Shaft end, 14... Lifter, 20... Electrostrictive vibrator, 2
1...Shim, 28...Valve open detection sensor, 29...
Valve closed detection sensor, 32... Vibrator drive circuit, 33...
- High frequency generation circuit, 34... Power supply, 35... Drive circuit, 36... Control circuit, 44... High frequency voltage generation circuit.

Claims (1)

[Claims] 1. An electrostrictive vibrator is installed 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 a cam position sensor detects the open state of the cam for driving the engine valve. and a vibrator drive circuit that receives a detection signal from the cam position sensor and applies a high frequency voltage to the electrostrictive vibrator while the engine valve is open. Device.