JP2597904Y2 - Exhaust valve drive for internal combustion engine - Google Patents

Description

[Detailed description of the invention]

[0001]

INVENTION The present invention relates to a device for purifying exhaust gas of an internal combustion engine for reducing the generation amount of NO _X contained in the exhaust gas.

[0002]

Generally BACKGROUND OF devised to solve the above, in the internal combustion engine, as a means to reduce the generation amount of the NO _X in the cylinder to reflux a part of exhaust gas to the intake pipe and combustion A so-called exhaust gas recirculation device (EGR) that lowers the maximum temperature is used. EGR devices of this engine are roughly classified into a mechanical control system and a microcomputer control system. The former is a system that senses and controls an amount proportional to the amount of intake air, such as the exhaust pressure or the venturi negative pressure of a carburetor.It has a negative pressure control system and an exhaust pressure control system.The latter is an electronic control using a microcomputer. It is a method by.

The microcomputer-controlled EGR device described above has a configuration in which the operating state of the engine is detected from various sensors, and an actuator is operated by an electric signal output from a control unit to freely control the EGR valve opening. . FIG. 4 shows an example. In the figure, 1 is an engine, 2 is an intake manifold, 3 is an exhaust manifold, 4 is an EGR valve, 5 is an electronic control unit (EC
U), 6 are EVRV (Electronic Vacuum Regulating V)
alve) and 7 are vacuum pumps. Engine speed signal E and accelerator opening signal A input from the sensor to ECU 5
The EVRV 6 is opened by the signal output to the EVRV 6 under the control of the ECU 5 in response to
The valve 4 communicates, the EGR valve 4 is opened, and a part of the exhaust gas discharged from the exhaust manifold 3 is sucked into the intake manifold 2 via the EGR valve 4 to perform EGR.

FIG. 5 shows a main type of a conventional valve train of an internal combustion engine. These can be classified according to the types of element parts that move the valve 11 between the cam 8 and the valve 11, and those using the valve rocker arm 9 (a, b, d) and those using the valve lifter 10 ( c)
And two types.

[0005] In the above-mentioned conventional EGR devices, a part of the exhaust gas is mixed into the intake air through the intake pipe, so that the amount of intake air is reduced by that amount and the output of the engine is reduced. is there. In addition, as a device for this, all EGR valves are required, but there is a limitation in mounting on the engine, and a large device cannot be attached.
That is the limit of EGR capacity.

In order to solve the above problems, various proposals have conventionally been made. One example is described in
JP-A-2-56211, JP-A-53-97114, and the like, all of which use an exhaust valve at a time other than the exhaust stroke as a means for introducing EGR gas directly from an exhaust valve into a cylinder without passing through an intake pipe. A second cam (auxiliary cam) for an exhaust valve for opening is provided. Therefore, these devices have E
No GR valve is required.

However, Japanese Patent Application Laid-Open No. 52-562 discloses the above.
No. 11 and JP-A-53-97114 are a type of system for mechanically controlling the introduction of EGR gas, and the lift amount and opening timing of an exhaust valve for introducing EGR gas are disclosed. Is uniquely determined by the shape of the second cam for EGR, and it is difficult to appropriately perform delicate control according to various operating states of the engine.

In order to solve the above-mentioned various problems, in the present invention, when the exhaust gas recirculation device is provided in the engine, the deterioration of the charging efficiency of fresh air accompanying the intake of EGR gas is minimized. Prevents the engine output from dropping and supplies the appropriate amount of EGR gas into the cylinder in a timely manner in response to various operating conditions of the engine. Furthermore, the device is simple and takes up a large space for mounting on the engine. It is an object of the present invention to provide an EGR device without any.

[0009]

In order to achieve the above object, according to the present invention, there is provided a moving device having a valve rocker arm.
In the valve mechanism, the rocker shaft of the exhaust valve is
The rocker shaft is provided separately and independently for each
Are supported by rocker supports provided for each exhaust valve.
This rocker support has a cylinder head and a screw structure.
On the cylinder head via a pivot screwed by
And the pivot is controlled by an electronic control unit.
Said screw structure driven by a controlled actuator
Is converted into its vertical movement by the
Push the rocker support to move the rocker shaft
The height of the cylinder head is changed,
Different from the opening timing of the exhaust valve by the exhaust valve driving cam
An exhaust valve driving device for an internal combustion engine, characterized in that the exhaust valve is opened at a certain time and a part of exhaust gas in an exhaust pipe is caused to flow directly into a cylinder.

[0010]

[Function] During operation of the engine, a signal detected by each sensor of the engine speed, the accelerator opening, and the cam angle is E.
When the ECU enters the CU, the ECU detects a region that particularly requires EGR, activates the actuator at a time when proper EGR can be performed, pushes the rocker support of the rocker arm of the exhaust valve by pivot, and moves the exhaust gas during the exhaust stroke of the engine. At a time other than the valve opening time, a part of the exhaust gas is discharged from the exhaust pipe directly into the engine cylinder through the exhaust valve.
It is supplied as GR gas.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a partial cross-sectional front view of an exhaust valve driving device according to an embodiment of the present invention, FIG. 2 is a plan view of the device, and FIG. In the figure, 21 is an exhaust valve, 22 is a cylinder head, 23 is a cylinder head cover, 24 is a rocker arm, 25 is a push rod, 26 valve lifter, 27 is a cam, 28 is a rocker support, 29 is a pivot, 30 is a rocker shaft, 31 is an actuator, 32 is a spring, and 33 is an ECU.

As shown in the figure, in the present apparatus, a rocker shaft 30 of an exhaust valve is provided separately and independently for each exhaust valve, and a single common rocker shaft is used as in a normal engine. It does not pass through the rocker arm of each valve. Rocker shaft 3 for each exhaust valve
0 is supported by the rocker support 28 provided for each exhaust valve.
The rocker support 28 is connected to the cylinder head 22.
The pivot 29 screwed by the screw structures 221 and 292
And is fixed on the cylinder head 22 via a. The lower surface 282 of the rocker support 28 is in contact with the upper surface 291 of the pivot 29, and the protrusion 283 extending downward from the center of the lower surface 282 is fitted into a hole 293 formed in the center of the upper surface 291 of the pivot 29. I agree. A male screw 292 is threaded at a lower portion of the pivot 29 and is screwed with a female screw 221 threaded in the cylinder head 22. A spring 32 is disposed between the upper surface 281 of the rocker support 28 and the cylinder head cover 23, and the rocker support 28 is constantly pressed downward by the spring 32. The rocker arm 24 is the rocker shaft 3
0 so as to be freely rotatable. Thereby, the cam 27,
By operating via the valve lifter 26, the push rod 25, and the rocker arm 24, the normal exhaust valve 21 is opened and closed.

The actuator 31 includes arms 294, 2
The pivot 29 is rotated through 95. The actuator 31 operates based on a command from the ECU 33 according to the operating state of the engine to rotate the pivot 29, whereby the screw portion between the pivot 29 and the cylinder head 22 slides, and the pivot 29 moves up and down. And the height of the rocker support 28, that is, the height of the rocker shaft 30 above the cylinder head 22 changes. Thus, it is possible to open the exhaust valve 21 by pushing down the rocker shaft 30 when the exhaust valve 21 is normally closed.

The actuator 31 does not operate when the exhaust valve 21 is open during the exhaust stroke of the engine. During the operation of the engine, the signals detected by each sensor of the engine speed, accelerator opening, and cam angle (each,
E, A, C) enter the ECU 33, and the ECU 33
A light load region or the like requiring a GR is detected, and the actuator 31 is operated at a time when an appropriate EGR can be performed, so that the exhaust valve 2 is operated.
Open 1. The opening timing of the exhaust valve is almost the latter half of the intake stroke, and includes a period during which the cylinder internal pressure is low even after the intake valve is closed. This timing is selected by the control of the ECU 33, and is directly controlled by the exhaust pipe. Part of the exhaust gas is supplied as EGR gas into the cylinder of the engine through the exhaust valve 21.

[0015]

[Effects of the Invention] The present invention has the following effects. (1) it is possible to reduce the generation amount of NO _X contained in the exhaust gas. (2) The exhaust gas recirculation device (EGR) does not require an exhaust gas introduction means such as an EGR valve and various pipes for guiding exhaust gas to the intake pipe, and the device is simple and takes up space. Absent. (3) In the conventional EGR system, high-temperature exhaust gas flows into the cylinder together with the fresh air-fuel mixture, so that the charging efficiency of the air-fuel mixture is deteriorated, and there are many problems such as a decrease in engine output and an increase in fuel consumption rate. However, according to the present invention, almost the latter half of the intake stroke of the engine and the initial stage of the subsequent compression stroke,
In a period when the cylinder internal pressure is relatively low, the exhaust gas flows into the cylinder directly from the exhaust valve, so that there is little adverse effect on the fresh air charging efficiency. (4) By using an electronic control unit (ECU) to control the opening and closing of the exhaust valve for introducing EGR gas, delicate control can be performed according to the operating state of the engine, especially in a light load area where EGR is required. The optimal EGR rate can be obtained by appropriately operating the lift amount and the lift period of the exhaust valve.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, and FIG. 1 is a partially sectional front view of the exhaust valve driving device.

FIG. 2 is a plan view of the device shown in FIG.

FIG. 3 is an exploded perspective view of a main part of the device shown in FIG.

FIG. 4 shows an example of a conventional microcomputer-controlled EGR device.

FIG. 5 shows a main type of a conventional valve train of an internal combustion engine.
5 (a), 5 (b) and 5 (d) show the case using a rocker arm, and FIG. 5 (c) shows the case using a valve lifter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Intake manifold 3 ... Air manifold 4 ... EGR valve 5, 33 ... Electronic control unit (ECU) 6 ... EVRV 7 ... Vacuum pump 8, 27 ... Cam 9, 24 ... Rocker arm 10 ... Valve lifter 11 ... Valve DESCRIPTION OF SYMBOLS 21 ... Exhaust valve 22 ... Cylinder head 23 ... Cylinder head cover 25 ... Push rod 26 ... Valve lifter 28 ... Rocker support 29 ... Pivot 30 ... Rocker shaft 31 ... Actuator 32 ... Spring 221 ... Cylinder head male screw 281 ... Rocker support upper surface 282 ... Rocker Support lower surface 283: Rocker support protrusion 291 ... Pivot upper surface 292 ... Pivot male screw 293 ... Pivot hole 294,295 ... Pivot arm E: Engine speed signal A: Accelerator opening signal C: Cam angle signal

Continuation of the front page (51) Int.Cl. ⁶ identification code FI F02M 25/07 510 F02M 25/07 510B 580 580C (58) Field surveyed (Int.Cl. ⁶ , DB name) F01L 13/00 301 F01L 1 / 12 F01L 1/18 F01L 1/46 F01L 1/34

Claims (1)

(57) [Scope of request for utility model registration] In a valve operating mechanism having a valve rocker arm (24), a rocker shaft (30) of an exhaust valve is provided.
Separately and independently provided for each exhaust valve,
The shaft (30) is a rocker provided for each exhaust valve.
The rocker support (2) is supported by the port (28).
8) is a cylinder head (22) and a screw structure (221, 2).
92) through a pivot (29)
The pivot (2) is fixed on the
9) is an actuator controlled by the electronic control unit (33).
The screw structure (2) driven by the tutor (31)
21 and 292) so that the rotation is
Converted and push and move the rocker support (28)
The rocker shaft (30) with the cylinder head (2
2) the height of the exhaust valve (2
The exhaust valve (21) is opened at a timing different from the opening timing of the exhaust valve (21) by the driving cam (27) of 1), and a part of the exhaust gas in the exhaust pipe is directly injected into the cylinder. An exhaust valve driving device for an internal combustion engine, characterized in that the exhaust valve driving device is configured to be allowed to flow.