JPH03189309A - Engine brake system by sub-exhaust valve - Google Patents

Abstract

PURPOSE:To enable it to exhaust compressed air in a combustion chamber surely owing to a small-sized electromagnetic driver by driving a sub-exhaust valve in its opening direction by means of an electromagnet at the closing period of a compression stroke at time of engine brake operation. CONSTITUTION:In an electromagnetic force valve driver 2, a core 22 consisting of a magnetic substance is installed in a position a little lower than an upper end in a closing state of a sub-exhaust valve 21, forming a fixed magnetic pole being excited by an exciting coil 23. A magnetic substance plate 25 is held in this fixed magnetic pole part free of slide motion via guide bar 24 consisting of a nonmagnetic substance. Here, at the closing period of a compression stroke at time of engine brake operation, the core 22 attracts the magnetic substance plate 25, making it contact with a spindle end of the sub-exhaust valve 21, and further it drives this valve 21 in the opening direction. With this constitution, compressed air in a combustion chamber is discharged to the outside, so that powerful engine brake force is thus generable.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides engine braking using a sub-exhaust valve that increases engine braking force by opening a sub-exhaust valve installed in parallel with an exhaust valve at the end of the compression stroke. Regarding equipment.

(Prior Art) The intake and exhaust valves of a conventional engine are driven to open and close by a camshaft. Since the camshaft is linked to the crankshaft, it is not possible to change the opening/closing timing of the intake and exhaust valves relative to the crank angle in response to changes in engine speed. Therefore, high efficiency is achieved at a specific speed. Since the opening/closing timing of the intake and exhaust valves is adjusted in this manner, there is a problem in that efficiency decreases when the engine is operated at a rotation speed other than the specified rotation speed.

Therefore, by driving the intake and exhaust valves to open and close using electromagnetic force using electromagnets, the opening and closing timing of the intake and exhaust valves can be changed in accordance with changes in engine speed, allowing the engine to operate with high efficiency at each rotation speed. is proposed.

On the other hand, when engine braking is applied, that is, when the accelerator pedal is released while the vehicle is running, the engine braking force is increased by changing the engine exhaust valve opening/closing timing and opening the exhaust valve at the end of the compression stroke. It has been known.

(Problem to be Solved by the Invention) In the engine in which the intake and exhaust valves are driven to open and close by electromagnets, the driving force required to open and close the exhaust valves is relatively small, but when the engine brake is activated, the inside of the combustion chamber Because the exhaust valve must be driven against the pressure of the compressed air, a large driving force is required. Also,
Even when opening the exhaust valve at the normal opening/closing timing, a large driving force is required because the exhaust valve must be driven open against the pressure inside the combustion chamber. Therefore, there is a problem that the electromagnet for driving the exhaust valve becomes large, or the exhaust valve becomes unable to open due to insufficient driving force.

For example, the internal pressure of the combustion chamber at the end of the compression stroke when the engine brake is applied is 30 kg/crr? , assuming that the side area of the combustion chamber of the exhaust valve is 8 cm', the electromagnetic force required for the exhaust valve to open against the internal pressure is 240 k.
g (2352N).

The present invention has been made in view of the above points, and is a sub-exhaust valve that is capable of reliably exhausting compressed air from the combustion chamber using a small electromagnetic drive device when the engine brake is activated, thereby obtaining a strong engine braking force. The purpose of the present invention is to provide an engine braking device according to the present invention.

(Means for Solving the Problems) According to the present invention, in an electromagnetic force valve drive device that opens and closes at least an exhaust valve of an engine by electromagnetic force, a sub-exhaust valve arranged in parallel with the exhaust valve is driven in the opening direction. a movable magnetic plate, an electromagnet having a fixed magnetic pole facing the movable magnetic plate, which drives the sub-exhaust valve in the open direction by an attractive force to the movable magnetic plate; and an electromagnet that always biases the sub-exhaust valve in the closed direction. It is possible to provide an engine braking device using a sub-exhaust valve, which is characterized by having a spring that operates the electromagnet at the end of the compression stroke.

(Function) In the engine braking device using the sub-exhaust valve of the present invention, at the end of the compression stroke when the engine brake is activated, the magnetic plate facing the shaft end face of the sub-exhaust valve is attracted by an electromagnet, and the magnetic plate is attached to the sub-exhaust valve. Place it in contact with the shaft end face of the exhaust valve,
Furthermore, by driving the auxiliary exhaust valve in the opening direction, the compressed air inside the combustion chamber is discharged to the outside.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a two-stroke engine equipped with an engine braking device according to the present invention.

Reference numeral 11 denotes a main exhaust valve made of ceramic, which is a lightweight, high-strength material, or a heat-resistant lightweight alloy material, and a drive device 1 for opening and closing the main exhaust valve 11 is provided at the shaft end of the main exhaust valve 11. is connected. Adjacent to the main exhaust valve 11, a sub-exhaust valve 21 whose umbrella portion has a smaller diameter than the main exhaust valve 11 is provided. Like the main exhaust valve 11, the sub-exhaust valve 21 is made of ceramic or a heat-resistant lightweight alloy material, and the drive device 2 is connected to the shaft end.

The main exhaust valve 11 and the sub-exhaust valve 21 are provided in an exhaust pipe line 31 of the cylinder head 3. The cylinder head 3 is connected to the engine block 4 via a gasket 32.

A cylinder sleeve 4 is provided on the inner peripheral surface of the engine block 4.
1, and an intake port 43 is provided around the cylinder sleeve 41 at a position facing the head of the piston 42 near the bottom dead center. The intake port 43 is opened at an angle so that the intake air is rotated clockwise.

Exhaust gas discharged from the exhaust pipe line 31 is guided to a turbine of a turbocharger 44.

An electric motor (not shown) is connected to the rotating shaft of the turbocharger 44, and has a structure that allows boost pressure to be increased by external power supply. The compressor is rotated by exhaust gas or external electric power to apply supercharging pressure to the intake air, and the intake air is supplied to the intake port 43 through the intake pipe 45.

The driving device 1 and the driving device 2 are controlled by signals from an input/output interface of a control unit 5. In addition to the drive device 1 and the drive device 2, a rotation sensor 51 that detects the rotational speed and crank angle of the engine and an accelerator sensor 52 that detects the amount of depression of the accelerator pedal are connected to the human output interface. , the signals from each sensor are manually input. In addition to the input/output interface, the control unit 5 includes a ROM that stores programs and various related tables;
The control unit 5 is composed of a CPU that executes calculations according to a program, a RAM that temporarily stores calculation results and data, and a control memory that controls signal flow inside the control unit 5.

Next, the driving devices 1 and 2 will be explained.

FIG. 2 is a plan view of the drive devices 1 and 2, and FIG. 3 is a sectional view taken along line III-H1 in FIG.

First, the drive device 2 will be explained.

22 is a core made of a magnetic material, and an exciting coil 23 is located at a position slightly lower than the upper end of the sub-exhaust valve 21 in the closed state.
It has a fixed magnetic pole that is excited by. A magnetic plate 25 is slidably held in the fixed magnetic pole portion via a guide bar 24 made of a non-magnetic material. Further, the guide bar 24 is always urged upward by a spring 26, and the sub-exhaust valve 24 is held at the upper limit position of the magnetic plate 25.
It faces the stopper 28 provided at the upper end of the holder with a small gap therebetween. A spring 27 is disposed between the stopper 28 and the core 22, and biases the sub-exhaust valve 21 upward via the stopper 28.

Next, the drive device 1 will be explained.

A movable element is connected to the shaft end of the main exhaust valve 11.

The mover includes a cylindrical magnetic passage 15 and a magnetic passage 15.
It is composed of a plurality of secondary coils 16 disposed around the outer periphery of the coil. The secondary coil 16 is formed by pouring molten aluminum into a groove cut on the outer periphery of the magnetic path 15.

The magnetic path 15 is made of a magnetic material in order to increase the magnetic flux density acting on the secondary coil 16, and is formed by radially arranging amorphous thin plates of magnetic metal into a cylindrical shape, for example. However, since the magnetic path 15 serves as a path for magnetic flux from fixed juxtaposed magnetic poles to be described later, it must be arranged so that the path for the magnetic flux is ensured.

Further, in order to prevent the main exhaust valve 11 from lowering when the engine is stopped, the movable element is biased in the closing direction by a spring 18.

A pair of drive parts 17 are disposed on the side surface of the movable element with the movable element sandwiched therebetween. The drive unit 17 is composed of fixed parallel magnetic poles arranged opposite to the secondary coil 16, and excitation coils wound around each of the fixed parallel magnetic poles. Then, alternating power is supplied from the controller 5, and a traveling magnetic field is applied to the secondary coil 16 of the movable element.

A magnetic plate 14 is disposed on the upper part of the movable element, which faces the main exhaust valve 11 with a small gap therebetween when the main exhaust valve 11 is in the seated state, similar to the drive unit 2, and the drive unit 1 is disposed on the side of the movable element.
7, a lower electromagnet having a pair of fixed magnetic poles sandwiching the main exhaust valve 11 is provided. The fixed magnetic pole of the lower electromagnet is set below the upper end surface of the mover by a predetermined amount when the main exhaust valve 11 is closed, and is composed of a lower coil 13 that excites the fixed magnetic pole.

The magnetic plate 14 is reciprocably connected to both fixed magnetic poles of the lower electromagnet via a guide bar made of a non-magnetic material, as in the case of the drive device 2, and is attracted to the lower electromagnet so that the upper end surface of the mover The movable element is brought into contact with the movable element and drives the movable element downward. Note that the magnetic plate 14 is always biased upward by a spring.

Next, the operation of the present application will be explained.

FIG. 4 is a diagram showing the relationship between the crank angle and the open/closed states of the main and sub-exhaust valves and the intake port.

This figure corresponds to a so-called cam profile curve, and the vertical axis shows the amount of valve movement, that is, the valve lift amount, with respect to the crank angle shown on the horizontal axis. Note that BDC indicates bottom dead center and TDC indicates top dead center.

In addition, this figure (a) shows the time of normal operation, and this figure (b) shows the time of engine brake operation.

During normal operation as shown in FIG. 5(a), when the crank angle detected by the rotation sensor 51 reaches the exhaust start timing calculated by the control unit 5, the control unit 5 first supplies power to the excitation coil 23. , the magnetic plate 25 is attracted and the sub-exhaust valve 21 is opened. Even though the opening area of the auxiliary exhaust valve 21 is small, the exhaust gas is rapidly exhausted because the pressure inside the combustion chamber 4 is high.

After opening the sub-exhaust valve 210, when the crank angle has elapsed by a predetermined angle, the lower coil 13 is energized to attract the magnetic plate 14 to initially drive the main exhaust valve 11, and then the drive section 1
7 is supplied with alternating power in the opening direction to continue driving the main exhaust valve 11 in the opening direction by the current induced in the secondary coil 16 and the advancing magnetic field from the fixed magnetic pole of the drive section 17.

When the main exhaust valve 21 starts to be driven in the opening direction, the power supply to the excitation coil 23 is stopped and the spring 27 is stopped.
The auxiliary exhaust valve 21 is closed by the piascus.

The main exhaust valve 1 can be moved in the closing direction and the main exhaust valve 11 can be closed by reversing the alternating direction of the electric power supplied to each excitation coil of the drive section 17.

Next, when it is detected from the signal from the accelerator sensor 52 that the accelerator pedal has been released during the normal operation, the control unit 5 performs the operation shown in FIG. 3(b) in order to apply the engine brake.

That is, the operation of the main exhaust valve 11 is stopped, and the crank angle detected by the rotation sensor 51 is set to TDC.
When the previous predetermined angle is reached, the sub-exhaust valve 21 is opened in the same manner as during normal operation. Then, the compressed air inside the combustion chamber immediately flows out to the exhaust pipe line 31, and the internal pressure decreases. Next, when the crank angle reaches a predetermined angle after TDC, the power supply to the excitation coil 23 is stopped and the sub-exhaust valve 21 is closed.

In addition, when the engine brake is activated, the auxiliary exhaust valve 2
If the side area of the combustion chamber of the auxiliary exhaust valve is 2 cm', the driving force required to open No. 1 is as follows, since the internal pressure of the combustion chamber is <30 kg/c rri' as above.
kg (588 N), which is 1/4 of the driving force required to drive the main exhaust valve 11.

By the way, an intake valve similar to the main exhaust valve 11 is provided in the cylinder head 3 of the engine, and an intake port 43 is provided.
By adding a device for electromagnetically closing the engine, the engine may be made into a variable cycle engine that can be operated in either two cycles or four cycles as required.

Further, although a configuration in which both the main exhaust valve 11 and the sub-exhaust valve 21 are both one has been described, at least one may be configured with a plurality of valves, and furthermore, the exhaust start timing may be changed in accordance with the engine load. is obvious.

Although the embodiments have been described in detail above, various different embodiments can be easily constructed without departing from the spirit of the present invention. It is not limited to.

(Effects of the Invention) As explained above, according to the present invention, at the end of the compression stroke during engine braking, the magnetic plate facing the shaft end face of the sub-exhaust valve is attracted by an electromagnet, and the magnetic plate By bringing the sub-exhaust valve into contact with the shaft end face of the sub-exhaust valve and further driving the sub-exhaust valve in the opening direction, the compressed air inside the combustion chamber is discharged to the outside, thereby generating a strong engine braking force. An engine braking device using a sub-exhaust valve can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a two-stroke engine equipped with an engine brake Ml according to the present invention, FIG. 2 is a plan view of drive devices 1 and 2, and FIG.
The I sectional view and FIG. 4 are diagrams showing the relationship between the crank angle and the opening/closing states of the main and sub exhaust valves and the intake port. 1.2... Drive device, 3... Cylinder head, 4.
...Engine block, 5...Control unit, 11...Main exhaust valve, 21...Subexhaust valve,
51... Rotation sensor, 52... Accelerator sensor.

Claims (2)

[Claims] (1) In an electromagnetic force valve driving device that opens and closes at least an exhaust valve of an engine by electromagnetic force, a movable magnetic plate that drives a sub-exhaust valve in an opening direction, which is arranged in parallel with the exhaust valve, and a movable magnetic plate that faces the movable magnetic plate. An electromagnet that has a fixed magnetic pole and drives the sub-exhaust valve in the opening direction by an attractive force to the movable magnetic plate, a spring that normally biases the sub-exhaust valve in the closing direction, and an electromagnet that operates the electromagnet at the end of the compression stroke. 1. An engine braking device using an auxiliary exhaust valve, characterized in that it has a control means for controlling the auxiliary exhaust valve. (2) Claim (1) characterized in that the lateral area of the combustion chamber of the auxiliary exhaust valve is smaller than the lateral area of the combustion chamber of the exhaust valve.
) Engine braking device using the auxiliary exhaust valve as described.