JPH02286810A - Supply/exhaust valve device of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent deposit of carbons and/or carbides for a long period of time certainly by impressing a high-frequency voltage on an electrostrictive vibrator inconformity to a crank position sensing signal while an engine valve is opened. CONSTITUTION:An electrostrictive vibrator 20 is installed between a lifter 14 mounted at the stem end 3a of an engine valve 1 and a shim 21 with which a lifter driving cam 12 is in slide contact. A high-frequency voltage is impressed on this vibrator 20 through a lead 22 in conformity to a crank position sensing signal when the engine valve 1 is opened. Thereby the vibrator 20 is elongated/ contracted to cause vibration of valve 1 in the axial direction. Thus carbons and/or carbides likely to be attached to the engine valve 1 are shaked off, and their deposition on the engine valve 1 is precluded.

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 weight of the intake valve and deteriorates the valve operating characteristics, gets caught between the valve guide and the sealing performance, coats the valve body and deteriorates heat dissipation, and further increases the fuel consumption. This causes various problems, such as adsorption and release of air-fuel ratios, which worsens responsiveness to changes in the 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 molecular 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, polymeric materials have low heat resistance, with a melting point of around 300°C. On the other hand, the temperature in the middle of the valve exceeds 300°C due to heat accumulation and backfire caused by engine operation, so the polymeric material coating is The gold RFfi material is melted and exposed, 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 of 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 is in sliding contact, and and a vibrator drive circuit that receives a detection signal from the crank position sensor and applies a high frequency voltage to the electrostrictive vibrator while the engine valve is open. Features.

[Effect]

In the intake and exhaust valve device of the present invention, the vibrator drive circuit operates according to the crank position detection signal of the crank position sensor.
A high frequency voltage is applied to the electrostrictive vibrator while the engine valve is open. As a result, the electrostrictive vibrator expands and contracts, vibrating the engine valve in the axial direction, and this vibration shakes off carbon, carbide, etc. that tend to adhere to the engine valve, thereby preventing deposition on the engine valve. Since the electrostrictive vibrator is located on the top side of the lifter, it is easy to route the lead wires of the electrostrictive vibrator, and a shim is interposed between the electrostrictive vibrator and the cam to prevent the electrostrictive vibrator from moving. Prevent wear damage. 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 end 3a of the stem portion 3 by means of a retainer 10 provided on the stem portion 3 and which is fully fitted. The installed valve spring 11 urges the engine valve 1 upward and presses the valve head portion 2 against the seat 7.

12 is a cam fixed to the camshaft 13; 14 is a lifter driven by this cam 12;
The guide hole 15 is slidably inserted into the guide hole 15 formed in the guide hole 15 . 20 is a disc-shaped electrostrictive vibrator, the lower surface of which is a lifter 14.
A cam 12 is attached to the upper surface of this electrostrictive vibrator 20.
A shim 21 made of a hard wear-resistant material that slides into contact is bonded. This electrostrictive vibrator 20 is made of a piezoelectric body made of piezoelectric ceramic such as PbTiO3, and extends in the axial direction when a voltage is applied between electrodes at both upper and lower ends, and the lead 1122 connected to the electrode is a second It is connected to a vibrator drive circuit 32 shown in the figure.

In Fig. 2, numeral 31 is a crank position sensor that detects the rotational position of the crankshaft of the engine 30. A rotor plate type sensor consisting of a head and a signal disk plate attached to the crank boot is used, but a type with a built-in distributor is used. You may use the reputation type one. Furthermore, if a crank position sensor is provided for electronic control of the engine's gasoline injection system or ignition system, it may be used. Further, the vibrator drive circuit 32 includes a high frequency generation circuit 33 that generates a high frequency signal of 1 flz or more, a power source 34 that supplies a voltage to be applied to the electrostrictive vibrator 20, and a high frequency voltage that applies a high frequency voltage to the electrostrictive vibrator 20. It consists of a drive circuit 35 that outputs an output, and a control circuit 36 that outputs a high frequency signal to the drive circuit 35 at a predetermined timing. This control circuit 36 controls, for each engine valve 1, a crank position θ+F3 at which the valve is fully open to a small lift MS+a far open position.
The crank position θ2 at which the valve is closed to the fully open joint lift amount S2 is stored in the memory section of the built-in microcomputer, and compared with the detected value by the crank position sensor 31 to determine the time T2 during which the crank position is between θ1 and θ2. During this period, the high frequency signal F of the high frequency generation circuit 33 is output to the drive circuit 35. Further, as shown in FIG. 3, the drive circuit 35 has N as a switching element.
It has a circuit configuration including type FETs 37 and 38 and a P type FET 39, and inverters 40 to 43 for waveform shaping and signal inversion, respectively. High frequency signal F
When input, N type FET37 and P type FET39
Application of voltage to the electrostrictive vibrator 20 due to conduction of the N-type FE
The release of voltage application due to conduction of T38 is repeated.

In the device configured as described above, the engine valve 1 begins to open by the cam 12 that is rotationally driven in accordance with the operation of the engine 30, and as shown in FIG. Later the lift amount was 82
During the time T2 up to the point in time, a high frequency voltage tuned to the ^frequency signal F outputted by the control circuit 36 is applied to the electrostrictive vibrator 20, and the electrostrictive vibrator 20 receives this voltage Vc. It expands and contracts at a rate of 1'' δ corresponding to . Electrostrictive vibrator 20
Since the upper end surface is restrained by the cam 12 via the shim 21, the lifter 14 is restrained by the expansion and contraction of the electrostrictive vibrator 20.
At the same time, 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. that tend to adhere to the valve head section 2 and stem section 3 of the engine valve 1 (while the valve is closed). (including those that have begun to adhere to the engine) are scraped off, preventing them from accumulating on the engine valves. In addition, since the engine valve 1 is vibrated 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 valve rotation is facilitated by the vibration while the valve is open. Since the seating position changes, there is no local contact.

The present invention is not limited to the above-mentioned embodiments. For example, as shown in FIG. The output of the generating circuit 44 is
The electrostrictive vibrator 20 is controlled by the control circuit 36, which turns on and off according to the crank position, only when the valve lift is equal to or greater than a predetermined value (for example, Sl and 82 in FIG. 4).
It is also possible to have a circuit configuration that is attached to the circuit.

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, since the electrostrictive vibrator is located on the top side of the lifter, the lead wires of the electrostrictive vibrator can be easily routed and the structure is simple, and the shim prevents abrasion and damage to the electrostrictive vibrator, resulting in excellent durability. You can get sex.

[Brief explanation of drawings]

Fig. 1 is a scaled-down plan 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 drive circuit section of Fig. 2. Circuit diagram, 4th
The figure is a diagram of the operating characteristics of engine valves and electrostrictive vibrators.
This figure is a block diagram showing another embodiment of the vibrator drive circuit of FIG. 1. 1...Engine valve, 3...Stem part, 3a...
・Shaft end, 14... Lifter, 15... Guide hole, 20
... Electrostrictive vibrator, 21... Shim, 30... Engine, 31... Crank position 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 the lifter attached to the shaft end of the engine valve and the shim on which the cam for driving the lifter comes into sliding contact, and a crank position sensor detects the rotational position of the engine crankshaft. An intake and exhaust valve device for an internal combustion engine, comprising: a vibrator drive circuit that receives a detection signal from a position sensor and applies a high frequency voltage to the electrostrictive vibrator while the engine valve is open.