JP2000027618A - Electrodynamic valve driving device in internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve detection accuracy at a present position of a valve and durability of a valve position detection means by providing an immovable member near a moving coil or a valve with the valve position detection means for detecting these relative positions and measuring displacement of the valve. SOLUTION: An electromagnetic actuator is constituted with a permanent magnet 10 and a moving coil 13. Because a magnetic flux is generated in a clearance accommodating a bobbin 11b wound with the moving coil 13, when current is conducted to the moving coil 13, a force for axially moving a valve driving body 11 is applied to the body 11. An electrode 18 is mounted in an air feed hole 8 drilled through a yoke 7, and a small-diameter sensor shaft (iron core) 3d connected with a shaft portion 3a of a valve 3 is positioned in this electrode 18 in the non-contact state. An electrostatic-capacity-type valve- position detection means is constituted with these electrode 18 and the sensor shaft 3d, and relative position between the yoke 7, detects the sensor shaft 3d, and measures vertical displacement of the valve 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodynamic valve driving apparatus for electrically opening and closing intake and exhaust valves in an internal combustion engine.

[0002]

2. Description of the Related Art A valve drive system of an ordinary engine mainly includes a camshaft, a rocker arm (or tappet), a valve spring, and a spring retainer. The valve is transmitted to the valve via the rocker arm to open and close the valve.

Generally, the output performance and fuel efficiency of an engine are
The efficiency is greatly affected by the intake and exhaust efficiency, and the higher the efficiency, the smoother the gas exchange in the cylinder and the higher the performance. However, since the engine for automobiles has a wide rotation range, it is difficult to enhance the engine performance over the entire driving range.When emphasizing high speed performance, low speed performance is sacrificed, and conversely, when emphasizing low speed performance, High speed performance decreases.

To address this problem, at high speeds,
The intake and exhaust valve lifts are increased to increase the intake and exhaust efficiency, and high-speed valve timing with a large overlap area is used. Also, at low speeds where the combustion state tends to be unstable, the lift is small and a strong swirl is used. And the like, and the valve timing is preferably small in the overlap region.

In order to satisfy such demands, recently, a valve operating mechanism for achieving both low speed performance and high speed performance, that is, a variable valve timing / lift mechanism having two valve timings and lifts for low speed and high speed has been assembled. The embedded engine has been put to practical use.

[0006]

However, this variable valve timing / lift mechanism is basically the same as the above-described mechanical valve operating mechanism driven by the camshaft, and therefore, such a variable valve timing / lift mechanism is used. It is not possible to eliminate the performance deterioration factors inherent in the valve mechanism, that is, the performance deterioration factors due to mechanical loss, the ability of the valve to follow the cam, and the like.

Further, since the valve timing and the lift are determined by the phase and profile of the cam, it is impossible to change them over the entire operating range of the engine. Actually, the two valve timings and the lift must be set.

In order to solve such a problem, various electromagnetic valve driving devices have been proposed in which a valve is opened and closed by a magnetic force instead of a mechanical valve driving method using a normal camshaft. For example, JP
0-37726, JP-A-10-142828).

However, most of the conventional electromagnetic valve driving devices simply open and close the valve simply by the attraction of an electromagnet, so that the seating noise of the valve is large,
Also, the response at the time of driving the valve is poor. In addition, since the control range of the valve timing and the lift is small, it is difficult to obtain the optimal valve timing and the lift corresponding to every operating state of the engine, and there is a limit in improving the engine performance over the entire operating range. .

Furthermore, since the movable iron core (or movable piece) is provided on the valve side, the inertial mass at the time of opening and closing the valve is increased, and the response and reliability at the time of control are lacking.

In order to solve the above-mentioned problems of the conventional electromagnetic valve driving device, the applicant of the present application has developed an electrodynamic type in which a valve is driven by an electromagnetic actuator called a voice coil motor. A valve drive has been devised.

In this method, a moving coil wound along the axial direction of the valve is fixed to the shaft of the valve.
A magnet is fixedly provided inside or outside the moving coil so that a magnetic flux is generated in a direction perpendicular to the winding axis of the moving coil, and when a current is supplied to the moving coil, a force for moving the coil in the axial direction. That is, the valve is driven using the force according to Fleming's left-hand rule.

In order to control the electrodynamic valve driving device in accordance with the operating state of the engine, valve position detecting means for detecting the current position of the valve is indispensable. There are still problems to be solved, such as the problem of position detection accuracy and the problem of durability due to heat.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and improves the accuracy of detecting the current position of a valve and improves durability by optimizing the mounting position and detection method of a valve position detecting means. It is an object of the present invention to provide an electrodynamic valve driving device for an internal combustion engine, which can be driven.

[0015]

According to the present invention, the above-mentioned problem is solved as follows. (1) a moving coil provided on the shaft of the valve;
A magnet provided fixedly so that magnetic flux is generated in a direction perpendicular to the winding axis of the moving coil, and by energizing the moving coil to move it in the axial direction, to operate the suction and exhaust valves. In the electrokinetic valve driving apparatus for an internal combustion engine that is opened and closed, a moving coil or a stationary member near the valve is detected by detecting a relative position between the moving coil or the valve and the stationary member, so that a displacement amount of the valve is detected. Valve position detecting means for detecting is provided.

(2) In the above item (1), the air flow passage for cooling the moving coil is concentric with the center of the yoke to which the magnet is mounted so that the shaft end of the valve can be loosely fitted. A non-contact type displacement sensor for detecting the amount of displacement of the shaft of the valve is provided in the flow passage.

(3) In the above item (2), the displacement sensor is any one of a capacitance type, an eddy current type, an optical type and an ultrasonic type.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an electrodynamic valve driving device (A) of the present invention and a control device (B) thereof. First, the configuration of the valve driving device (A) will be described in detail. A valve guide (2) press-fitted into the cylinder head (1) has an intake or exhaust valve (hereinafter referred to as a valve) (3) made of heat-resistant steel.
(3a) is held slidable up and down, and the umbrella at the lower end
(3b) comes into contact with the valve seat (4) press-fitted into the open end of the intake or exhaust port (1a) so that the port (1a) can be sealed.

A valve is provided on the upper surface of the cylinder head (1).
A lower end of a cylindrical bracket (5) coaxial with (3) is fixed by a bolt (6), and a yoke (7) made of a magnetic material, for example, an iron thread is fitted into the upper end of the bracket. It is fixed by a plurality of bolts (6) screwed toward its outer peripheral surface.

The yoke (7) has an air supply hole (8) vertically penetrating at the center thereof, and an annular working space (9) having a lower end opened at a radial center portion. It is formed concentrically with 3).

A cylindrical permanent magnet (10) having an outer N-pole in the radial direction and an S-pole (or vice versa) in the radial direction is provided on the outer inner peripheral surface in the working space (9). It is fixed so that a required gap is formed between the peripheral surface and the inner peripheral surface inside the working space (9).

Bracket for engine valve (3)
(5) A small diameter portion (3c) at the upper end of the shaft portion (3a) located in the bottom plate (11a) of the valve driver (11) having a bottomed cylindrical shape.
The nut (1) is screwed into the male thread at the upper end of the small diameter part (3c).
It is fixed by 2).

FIG. 2 shows an outer peripheral surface of a thin cylindrical bobbin portion (11b) (not shown in FIG. 1) of the valve driving body (11).
As shown in the enlarged view, the moving coil (13) is wound in an even number layer (two layers in the embodiment) by being wound in the axial direction with the winding start as the lower end. In addition, the winding of the even layer is performed because both ends of the coil (13) are bobbins (11b).
In order to facilitate connection to terminals described later. The bobbin part (11b) and the moving coil (13) have a slight gap that does not interfere with the gap between the permanent magnet (10) and the yoke (7) formed in the working space (9). Provided and housed.

As shown in FIG. 2, the moving coil (13) is covered with glass or carbon fiber (14) and then impregnated with a thermosetting resin such as epoxy resin, which has excellent heat resistance and mechanical strength. And is integrally fixed to the bobbin (11b).

The material of the valve driver (11) is preferably made of a light metal such as an aluminum alloy or a hard synthetic resin in order to reduce the inertial mass when the valve (3) is opened and closed.

The permanent magnet (10) and the moving coil (13)
Thus, an electromagnetic actuator called a voice coil motor is configured. That is, the moving coil (13)
In the gap in which the bobbin (11b) is wound, a magnetic flux is generated in a radial direction orthogonal to the winding axis of the moving coil (13).
In the moving coil (13), a force is generated according to Fleming's left-hand rule, and this force acts on the valve driver (11) as a force for moving the valve driver (11) in the axial direction.

Therefore, by controlling the value and direction of the current flowing through the moving coil (13), the valve (3) can be arbitrarily moved in the vertical direction.

Between a washer (15) placed on the upper surface of the cylinder head (1) and a hard spring receiver (16) abutting on the lower surface of the bottom plate (11a) of the valve driver (11). The compression coil spring (17) is contracted, and the valve (3) is constantly urged upward. The upper end of the compression coil spring (17) is
By the annular piece (11c) downwardly connected to the outer peripheral edge of the lower end of 1a),
Lateral displacement is prevented.

When the moving coil (13) is not energized, the compression coil spring (17) has its own weight of the valve (3), the valve driver (11) and the moving coil (13) wound therearound. This prevents the valve (3) from lowering due to the mass of the valve and keeps the valve at the closed position. Therefore, the spring constant may be considerably smaller than that of a valve spring used in a normal engine valve train.

An air supply hole formed in the center of the yoke (7)
An electrode (18) for detecting a valve position is fixedly attached to the lower end of (8), and the electrode (18) is connected upwardly to the upper end of the shaft (3a) of the valve (3). The provided small-diameter sensor shaft (iron core) (3d) is located in a non-contact state. These electrodes
(18) and the sensor shaft (3d) constitute a capacitance-type valve position detecting means. By detecting the relative position between the yoke (7) and the sensor shaft (3d), the valve (3) is detected. ) Can be detected in the vertical direction.

As shown in FIG. 2, the moving coil (13)
Each of the terminal portions (13a) (13a) is inserted through the guide piece (19) downwardly provided on the outer peripheral surface of the base of the valve driver (11), respectively.
It is connected to a pair of terminal pins (20) (one of which is not shown) press-fitted and fixed thereto.

The terminal pin (20) and the terminal pin (22) of the input terminal (21) attached to the bracket (5)
Flexible and elastic metal lead plate, for example, phosphor bronze
The metal lead plate (23) is connected to the guide piece (19) and the input terminal (21) when the valve driver (11) is displaced up and down.
The rolling deformation is performed while being in close contact with the guide piece (21a) formed in the above.

The air supply hole (8) of the yoke (7) has a connector (24) screwed to the upper end thereof and an air pipe (2) connected thereto.
Compressed air for cooling is supplied through 5), and the air supply holes (8)
The compressed air that has flowed into the inside of the valve driving body (11) has a gap between the inner peripheral surface of the bobbin portion (11b) and the yoke (7), and the outer peripheral surface of the moving coil (13) and the inside of the permanent magnet (10). It flows into the bracket (5) through a gap between the peripheral surface and the outside, and is discharged to the outside through a plurality of ventilation holes (26) formed in the peripheral wall. During the air circulation process at this time, the electrodes (18), the moving coils (13), and the like are cooled to prevent them from overheating. The compressed air can be supplied from an air pump or an air tank powered by an engine.

Next, referring to the block diagram shown in FIG.
The control device (B) of the electrodynamic valve drive device (A) and the control procedure by the control device will be described. A crank angle sensor (27) including a crank angle reference position sensor and a cylinder discrimination sensor, an engine rotation speed sensor (28), a throttle opening sensor (29), a vehicle speed sensor (3
0), various sensor groups such as acceleration / deceleration sensor (31), and other various sensors (not shown) detect the operating state of the engine, and the obtained electric signal is transmitted to CPU (32) of the microcomputer. It is input to the operating state determination section (33).

As shown in FIG. 3, the CPU (32) maps the optimal valve timing / lift pattern corresponding to the operating state of the engine to up to n and sets them in advance, and stores them in, for example, a ROM or the like. A valve timing / lift pattern memory (34), and a valve timing / lift pattern selecting unit (34) for selecting an optimal valve timing and a lift determined based on the operating state determining unit (33) from the memory (34). 35).

The electric signal selected and called from the valve timing / lift pattern memory (34) is a valve.
It is input to the comparator (36) as the optimal position signal of (3).
At the same time, the comparator (36) converts the valve position signal output from the valve position detecting means provided in the valve driving device (A), that is, the electrode (18), into an electric signal by the valve position detector (37). Is entered.

In the comparator (36), the valve timing
The valve position signal called from the lift pattern memory (34) is compared with the current valve position signal from the electrode (18), and the valve (3) is driven so that there is no difference between the two position signals. You. That is, the current value and the direction of the current flowing through the moving coil (13) are feedback-controlled via the amplifier (38) connected to the input terminal (21) so that the two position signals match, and the moving coil (13 ) And the valve driver (11), which is an integral part thereof, are moved up and down.
(34) It is driven with the optimal timing and lift as selected from (34).

In order to obtain an accurate lift from the fully closed position of the valve (3), the upper limit position of the valve position detector (37) is set in the closed state of the valve (3). Includes a fully closed position correcting means for detecting and always correcting (resetting) to indicate the closed position, so that there is no error in the current position due to thermal expansion of the valve (3) or wear of the valve face. It is.

In a multi-cylinder engine, the control device (B) is provided individually for each intake and exhaust valve (3) of each cylinder, and independently drives each intake and exhaust valve (3). It is supposed to.

As described above, in the electrodynamic valve driving device (A) of the present invention, the moving coil (13) fixed to the shaft end of the valve (3) is moved in the axial direction, and the valve (3) is moved. It is not necessary to provide a heavy iron core or the like on the side of the valve (3), which is a movable part, unlike the conventional valve driving device using the attractive force of an electromagnet. Therefore, the inertial mass at the time of opening and closing the valve is reduced, so that the seating noise of the valve can be reduced, and the responsiveness and reliability are improved.

Further, the valve timing and lift can be arbitrarily adjusted only by controlling the value and direction of the current flowing through the moving coil (13), so that the control area is significantly larger than that of the conventional electromagnet type. To expand.

Further, the electrodynamic valve driving device of the present invention
(A) is provided with a compression coil spring (17) for urging the valve (3) to the normally closed side, so that the start key switch is turned off and the engine is stopped. When the power supply to the moving coil (13) is interrupted, it is possible to prevent the valve (3) from interfering with the piston.

An air supply hole (8) is formed in the center of the yoke (7),
The compressed air introduced into the air supply hole (8) passes through the gap between the permanent magnet (10) and the moving coil (13), and is discharged to the outside through the air hole (26) of the bracket (5). Therefore, the moving coil (13) is directly cooled by the air, and the temperature rise can be suppressed.

An electrode (18) for detecting the position of the valve (3)
Is effectively cooled because it is provided in the air supply hole (8), and even if the valve (3) is on the exhaust side, it may be affected by radiant heat from the sensor shaft (3d) at the shaft end. Absent.

Since the moving coil (13) is wound in an even-numbered layer and both terminals are located at the same end, connection to the terminal pin (20) and the input terminal (21) is facilitated. In addition, the moving coil (13) is covered with glass or carbon fiber (14), and is further impregnated with epoxy resin and cured, so that it has not only heat resistance but also high tensile and bending strength and vibration. Can withstand.

Terminal pin on the moving coil (13) side
(20) and the terminal pin (22) on the input terminal (21) side are connected by a flexible and elastic metal lead plate (23), and rolling is performed when the valve driver (11) moves up and down. Since it can be deformed, there is no possibility that the metal lead plate (23) is broken and power supply to the moving coil (13) is cut off.

When the valve drive unit (A) is controlled by the control unit (B) of the above-described embodiment, the valve (3) is controlled with an optimal valve timing and lift set in advance assuming all operating conditions of the engine. Can be opened and closed,
The control range is greatly expanded, and the output performance, fuel consumption performance, exhaust gas performance, and the like are improved over the entire operation range of the engine.

If the lift pattern when the valve (3) is closed is set so as to be gentle as shown in FIG. 3, the seating noise due to the cushioning effect when the valve (3) is seated is obtained. Can be reduced.

Further, by the intake side valve (3) itself,
The intake amount of the air-fuel mixture can be controlled, and the throttle valve can be eliminated. At the time of deceleration, if the lift of the exhaust side valve (3) is controlled to be minimized, the braking effect can be enhanced by the action of the exhaust brake.

In the above electrodynamic valve driving device (A),
The permanent magnet (10) may be provided inside the moving coil (13). In some cases, after the key switch of the engine is turned off, a standby power supply that can move the moving coil (13) in the closing direction of the valve (3) may be provided.

When the present invention is applied to an engine arrangement such as a horizontally opposed engine, the compression coil spring (17) may be omitted.

In the above embodiment, as the valve position detecting means, a capacitance type displacement sensor which is not affected by magnetism and has an electrode (18) and a sensor shaft (3d) is used. A displacement sensor such as a mold can also be used.

In the embodiment, the displacement of the shaft end of the valve (3) is detected. For example, as shown in FIG. Piece (39)
The cylinder head (1)
The displacement of the valve (3) may be detected indirectly by detecting with a magnetic or capacitance type proximity sensor (40) or the like provided in the above.

Instead of the above-mentioned detecting means, as shown schematically in FIG. 5, a valve (3) is provided by using an optical displacement sensor comprising a light emitting section (41) such as a laser and a light receiving section (42). The displacement of the valve (3) may be directly detected by detecting the displacement of the valve (3) or, though not shown, transmitting an ultrasonic wave toward the shaft end. The permanent magnet (10) constituting the electromagnetic actuator may be an electromagnet.

The air flow path for cooling the moving coil (13) and the like is provided, for example, in the form of a yoke (7) immediately above the moving coil (13) instead of forming an air supply hole (8) at the center of the yoke (7). ) May be provided with a plurality of air supply holes, or a supply / exhaust hole may be provided in the bracket (5) to discharge hot air in the bracket (5).

[0056]

(A) According to the first aspect of the present invention, the valve position detecting means is provided on a moving coil or an immovable member near the valve, so that the current position of the valve can be determined more accurately than the close distance. Can be detected.

(B) According to the second aspect of the invention, since the displacement of the valve can be directly detected, there is almost no possibility that an error occurs, and the displacement sensor is directly cooled by the air passing through the flow passage. Therefore, it does not reduce the detection accuracy or the durability due to overheating. In addition, since it is a non-contact displacement sensor, its durability and reliability are improved.

(C) When the displacement sensor according to the third aspect of the present invention is used, it is relatively small, inexpensive, and has good responsiveness, so that it can cope with a fast movement of the valve, and a measurement error can be obtained. There is no danger of occurrence.

[Brief description of the drawings]

FIG. 1 is a front view of a central longitudinal section showing an embodiment of the present invention, and a block diagram showing a control device thereof.

FIG. 2 is an enlarged vertical sectional view of a main part showing details of a valve driver and a moving coil wound therearound.

FIG. 3 is an explanatory diagram showing an example of a control pattern of valve timing and lift.

FIG. 4 is an enlarged vertical sectional view of a main part showing a modification of the means for detecting displacement of a valve.

FIG. 5 is a schematic view showing another modification of the means for optically detecting the displacement of the valve.

[Explanation of symbols]

 (1) Cylinder head (1a) Port (2) Valve guide (3) Valve (3a) Shaft (3b) Head (3c) Small diameter part (3d) Sensor shaft (4) Valve seat (5) Bracket (6) Bolt (7) Yoke (8) Air supply hole (9) Working space (10) Permanent magnet (11) Valve driver (11a) Bottom plate (11b) Bobbin (11c) Ring piece (12) Nut (13) Moving coil ( 13a) Terminal part (14) Glass or carbon fiber (15) Washer (16) Spring receiver (17) Compression coil spring (18) Electrode (19) Guide piece (20) (22) Terminal pin (21) Input terminal (23 ) Metal lead plate (24) Connector (25) Air pipe (26) Vent hole (27) Crank angle sensor (28) Rotational speed sensor (29) Throttle opening sensor (30) Vehicle speed sensor (31) Acceleration / deceleration sensor ( 32) CPU (33) Operating state discriminator (34) Valve timing / lift pattern memory (35) Valve timing / lift pattern selector (36) Comparator (37) Valve position detector (38) Amplifier (39) Detector (40) Magnetic sensor (41) Light emitting unit (42) Light receiving unit (A) Electrostatic valve drive (B) Control unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G092 AA11 DA01 DA02 DA07 DG02 DG09 FA01 FA06 FA13 FA14 FA15 FA24 FA38 HA06Z HA13X HA13Z HE01Z HE03Z HF21Z HF23Z

Claims (3)

[Claims] 1. A moving coil provided on a shaft portion of a valve, and a magnet fixedly provided so that a magnetic flux is generated in a direction orthogonal to a winding axis of the moving coil, and energizing the moving coil. By moving this in the axial direction, in the electrodynamic valve driving device in the internal combustion engine to open and close the intake and exhaust valves, the moving coil or a stationary member near the valve,
An electrodynamic valve driving device for an internal combustion engine, comprising a valve position detecting means for detecting a displacement amount of a valve by detecting a relative position between a moving coil or a valve and an immovable member. 2. An air flow passage for cooling the moving coil is formed in the center of the yoke to which the magnet is mounted so as to be concentric with the shaft end of the valve so that the shaft end can be loosely fitted therein. 2. The electrodynamic valve driving apparatus for an internal combustion engine according to claim 1, further comprising a non-contact type displacement sensor for detecting a displacement amount of a valve shaft. 3. A displacement sensor, comprising: a capacitance type, an eddy current type;
3. An electrodynamic valve driving device for an internal combustion engine according to claim 2, wherein the driving device is an optical type or an ultrasonic type.