JPS5993953A - Exhaust-gas recirculation type internal-combustion engine equipped with variable valve-timing apparatus - Google Patents

Abstract

PURPOSE:To suppress discharge of NOx by controlling the EGR amount in synchronization with the switching of valve timing and increasing the EGR amount in case of partial loading, in an internal-combustion engine equipped with an EGR apparatus and a variable valve-timing mechanism. CONSTITUTION:A passage 98 for bypassing an EGR valve 38 is formed, and an opening and closing valve 100 is installed. Said opening and closing valve 100 is connected to an actuator 102, which is driven in synchronization with the valve timing switching signal supplied from a control system 82. The signal sent into the EGR actuator 102 is made low, in synchronization with the switching to the valve-timing advance side, and the opening and closing valve 100 is opened. Therefore, exhaust gas is permitted to flow through the bypass passage 98, and the EGR amount can be increased relatively.

Description

[Detailed Description of the Invention] Does the present invention overlap? -Related to an exhaust gas purification technology for an internal combustion engine with exhaust gas recirculation that switches the pulp timing while keeping the timing constant.

Camshaft? Some devices are designed to change the pulp timing by changing the phase relative to the crankshaft. In this case, the timing of the intake valve is controlled to be advanced during one partial load compared to the full load.

Then, the intake valve closes closer to bottom dead center, so
Piston compression efficiency? can be maintained high.

Is this kind of valve timing switching device lHr intake valve and exhaust valve connected to the camshaft? When adopted in a shared engine, for example, a 5OHC type, if the intake valve timing is advanced during partial load, the exhaust valve timing will also be advanced in the same way.
The so-called internal FiGR effect becomes weaker, and N in the exhaust gas decreases.
The problem is that the amount of Oxi-emissions increases.

Solving the drawbacks of such conventional technology, while keeping the overlap constant as in the case of applying it to a 5OHC engine,
Pulp timing? It is an object of the present invention to provide a structure capable of reducing harmful emissions during partial load in a switching device.

To achieve this purpose, the present invention uses the E3GFL device and the variable valve timing mechanism as described above. In the installed internal combustion engine, the EG is synchronized with the switching of the pulp timing.
The amount of R is controlled to increase the amount of 113GR at partial load.

To explain with reference to the drawings below, in FIG. 1, 10 is a cylinder, 12 is a binuton, 14 is a connecting rod, 16 is a crankshaft, 18 is a cylinder head, 20 is an intake valve, 22 is an exhaust valve, 24° 26 is a rocker arm, 28
is a camshaft, 30 is an intake manifold, 32 is a throttle valve, and 34 is an exhaust manifold. These are well-known constituent elements in an internal combustion engine (6e) and are not directly related to the features of the present invention, so a detailed explanation of the connection relationship will be omitted.

The EGR system basically consists of an EGR passage 36 connecting an exhaust manifold 34 and an intake manifold 30, and an EGR passage 36 connecting an exhaust manifold 34 and an intake manifold 30.
The EGRI valve, which is connected to the valve 38, functions as a flow rate control valve that controls the flow rate of exhaust gas introduced into the intake manifold 30 from the EGR throttle 40. EGRI valve 38
is connected to a diaphragm mechanism 42, and negative pressure from an EGR port 46 slightly above the fully closed position of the throttle valve 32 as shown by the solid line acts on this diaphragm via a negative pressure pipe 44. The well-known pressure variable valve 48 is a constant pressure chamber 4 downstream of the throttle 40.
In response to the pressure of 9, E so that the pressure in that chamber remains constant.
Bleed air to the GR pipe 44. 2nd port 5
2 performs load control of the EGR rate as is well known.

The mechanism for switching pulp timing is shown in its entirety at 50. As shown in FIG. 2, this mechanism is provided between the camshaft 28 and a timing pulley 52 (which is connected to a timing pulley on the crankshaft 16 by a timing belt (not shown)) which stops the camshaft 28. That is, camshaft 2
An inner sleeve 54 is installed at the shaft end of the bolt 56 . An outer sleeve 58 extends integrally from the timing pulley 520 knob so as to be coaxial with the inner sleeve 54. Between the inner sleeve 54 and the outer sleeve 58, slits 60 and 62 are formed, one of which is straight and the other is inclined. In the slit the radial axis 6]C of the support 64 carries a bearing 66.68
is provided. The rotation starter 70 is attached to a timing belt cover 72, and the output shaft 74 is threaded into a nut 76VC that is freely guided in the longitudinal direction of the motor housing. A support 64 is provided on the nut 76 by means of a bearing 78 . The rotation of the motor 70 is translated into a linear movement of the nut 76, so that the bearings 66, 68 move to the left or right in the figure, depending on the direction of rotation of the motor. Bearing 66.6
8 are located in the intersecting slits 60, 62, relative rotation occurs between the inner sleeve 60 and the outer sleeve 62 due to the left and right movement of the bearings.

Due to this relative rotation, the cam ridge 28' on the camshaft 28
The angular position of the crank, ie, the valve timing, when the valve engages the rocker arm 24 or 26 is controlled.

FIG. 4 is a block diagram of a control system 82t that switches the valve timing.
Signals from a group of sensors such as the rotation speed sensor 84, the load sensor 86, and the temperature sensor 88 are applied to the control circuit 9Ovc.

The control circuit 90 connects the motor 70 via a motor drive circuit 92.
Outputs a drive signal to. At the same time, the nGR acte described below
The motor 102 is driven in synchronization with switching of valve timing.

According to the invention, the passage 98 bypasses the %EGR valve 38i.
is provided, and an on-off valve 100 is located therein. Open/close valve 10
0 is coupled to an actuator 102, which is driven in synchronization with a valve timing switching signal from a control system 82.

To explain the present invention in detail below, the control circuit 90 controls the rotation speed sensor 84 . Load sensor 86. The engine operating conditions are determined based on the signal from the temperature sensor +j88, and it is determined whether the valve timing should be delayed or advanced. If it is determined that it is on the lagging side, the motor drive circuit drives the motor 70, for example, to rotate forward. The pulp timing diagram at this time is as shown in FIG. 5(a), and the intake valve 20 opens at an angle α1 before the top dead center and closes at an angle α2 before the bottom dead center.

- The sword exhaust valve 22 opens at an angle β1 before the bottom dead center and closes at an angle β2 before the top dead center. When the valve timing is on the advanced side, the EGa actuator 102 is operated and the on-off valve 100/Ii is in the fully closed position, so that the exhaust gas does not pass through the bypass passage 98 and the normal value determined by the EGFL-free EGa valve 38 is maintained. . At this time, the end of closing of the exhaust valve 22 is well before the top dead center as shown in β2, so even if the intake stroke starts after the top dead center, the exhaust pulp is still open and the gas that has been exhausted is inhaled. 6 Internal EGR effect occurs, and in combination with EGa from the EGR system, N
Ox emissions can be effectively suppressed.

When the engine is at partial load, the control circuit 90 determines that the pulp timing should be advanced, and at this time the motor drive circuit 92 reverses the motor 70. As a result, the valve timing diagram Fim5 (b) shows that the intake valve 20 starts opening at an angle α1' and closes at α2', and the exhaust valve 22 starts opening at an angle β1' and closes at β2'. By advancing the pulp timing, the compression start timing is closer to the dead center such as α21, the effective compression ratio is increased, and the fuel efficiency at partial load is improved. When the pulp timing is advanced in this manner, since the overlap is constant, the end of opening of the exhaust valve approaches the top dead center as indicated by β2'. Therefore, even after the top dead center and when the intake stroke begins, the internal EGR effect, which is based on the function of sucking in the exhaust gas that has been discharged once, with the exhaust valve still open, becomes weaker. In order to prevent this, in the present invention, the EGR actuator 1 is activated in synchronization with the switching of the pulp timing to the advance side.
The signal to 02 becomes Low, and the on-off valve 100 becomes open. As a result, exhaust gas can flow through the bypass passage 98, which relatively increases the amount of EGR.

By increasing the amount of EGFL from the outside, even if the internal EGR is reduced based on the switching of the pulp timing, the emissions of NOx and FM can be sufficiently controlled.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of the present invention Fig. 2 is a longitudinal cross-sectional view of the pulp timing switching mechanism Fig. 3 is a view as viewed from the ■ direction arrow in Fig. 2 Fig. 4 is a block diagram of the control system Fig. 5 is a pulp timing diagram Diagram 20... Intake valve 22... Exhaust valve 26... EGR passage 38... EGa valve 50... Pulp timing control device 98 ...
... Bypass passage 100 ... On-off valve Patent applicant Toyota Motor Corporation Patent application representative Patent attorney Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Kyo Nakayama Patent attorney Akiyuki Yamaguchi 3rd Figure 4 Figure 5 (Q) (b)

Claims (1)

[Claims] In an internal combustion engine with exhaust gas recirculation that changes valve timing while keeping the overlap constant, a passage is provided that bypasses the exhaust gas recirculation control valve, and the bypass passage is opened and closed in synchronization with the switching of pulp timing. An internal combustion engine equipped with an on-off valve.