JPS5951127A - Suction device for engine - Google Patents

Abstract

PURPOSE:To secure good supercharging performance at the whole rotation range, by having the timed superchaging controlled by engine load and speed and the continuous supercharging selected according to the engine load and speed. CONSTITUTION:At a supercharging range, a solenoid valve 17 is set in a state of being normally opened. Therefore, supercharged air is continuously fed to a combustion chamber 1 and thereby continuous supercharging takes place. The amount of supercharged air supplied at this time is varied by a sub-throttle valve 18 according to engine load. At the supercharging range of low or medium engine speed, it comes into a timed supercharging state causing the solenoid valve 17 to be intermittently opened or closed at the specified timing according to the engine load and speed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine intake system, particularly a supercharger,
The present invention relates to an engine intake device including a timing valve that controls supercharging timing.

By pressurizing intake air or air-fuel mixture with a supercharger and supplying it to the engine's combustion chamber, charging efficiency is increased.
BACKGROUND ART It has been widely practiced to improve engine output performance. In addition, in order to further improve the charging efficiency of the supercharger, for example, as shown in Japanese Patent Application Laid-Open No. 56-85522, a supercharging passage downstream of the supercharger is installed in synchronization with the rotation angle of the engine output shaft. There is also known an intake device that is provided with a timing valve that opens and closes intermittently, and that controls supercharging timing using the timing valve.

As mentioned above, in an intake system that has separate natural intake passages and supercharging passages, due to the difference in intake inertia between the two roads, as shown in Figure 1, continuous supercharging increases the maximum torque in the engine high-speed range. In the low to medium speed range, maximum torque can be obtained by so-called timed supercharging, which supplies supercharging air intermittently. This is because the solenoid valve closes once to accumulate pressurized air in the intake passage, and when the solenoid valve opens during the intake stroke, this accumulated large amount of pressurized air is instantly supercharged, increasing the amount of supercharging. This is because the torque during timed supercharging decreases in the high-speed range because the intake inertia is large in the high-speed range, so if timed supercharging is performed in such a state, the effect of the intake inertia decreases and the amount of supercharging decreases. This is thought to be due to the fact that

On the other hand, the timing valve naturally repeats opening and closing at high speed as the engine speed increases, and if the timing valve is an electromagnetic type, the timing valve may not be able to follow the engine rotation at high speeds. Therefore, from this point of view as well, it can be said that continuous supercharging with the timing valve always open is preferable in the high speed range.

The present invention has been made in view of the above circumstances, and has a simple structure that allows the supercharging method to be switched according to the engine speed, such as continuous supercharging in the high speed range and timed supercharging in the low and medium speed range. The purpose of this invention is to provide an intake system for an engine.

An engine intake system according to the present invention uses an electromagnetic on-off valve as a timing valve in an engine intake system having a natural intake passage as described above and a supercharging passage in which a supercharger and a timing valve are interposed. In addition, a rotation speed detector detects the engine rotation speed, and in the supercharging region, when the engine rotation speed detected by the detector is lower than a set value, the on-off valve is intermittently opened and closed, and when the engine rotation speed is higher than the set value. In some cases, the valve is characterized by being provided with a control circuit that keeps the on-off valve normally open.

With the above configuration, the supercharging method can be reliably switched according to the engine speed, and its structure is also extremely simple.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an engine intake system according to one embodiment of the present invention. A natural intake port 2, a supercharging port 3, and an exhaust port 4 are opened in the combustion chamber 1 of the engine, and each port 1-2.3.4 has a natural intake passage 5, a supercharging passage 6, and an exhaust passage. 7 are connected. And for the naturally aspirated boat 2, supercharging port 3, and exhaust port 4, respectively.
An intake valve 8, a supercharging valve 9, and an exhaust valve ]0 are provided.

The upstream end of the natural intake passage 5 is connected to an air intake valve 11, and the natural intake passage 5 includes, in order from the upstream side, an air flow meter 12 for detecting the intake air flow rate, a main throttle valve 13, and a fuel injection valve. A valve J4 is provided. Further, the upstream end of the supercharging passage 6 is connected to the air flow meter 1.
2 and the main throttle valve 13.
The supercharging passage 6 is connected to a known electromagnetic clutch (
an air pump type supercharger 15 that is driven by the engine via an air pump (not shown);
A solenoid valve 17 for opening and closing is provided. The main throttle valve 13 of the naturally aspirated passage 5 is connected to the supercharging passage 6.
An auxiliary throttle valve 18 is provided which operates in conjunction with the auxiliary throttle valve 18.

The control circuit 16 includes, for example, an electromagnetic type, a photoelectric type, etc., consisting of a combination of a gear attached to the engine output shaft and a pink-up coil, and a crank angle sensor 1, such as a photoelectric type.
A throttle valve opening signal S2 consisting of a crank angle signal S+ outputted by the main throttle valve 9 and a voltage signal outputted by the throttle valve opening sensor 20 that detects the opening degree of the main throttle valve 130.
, and an intake flow rate signal S3 output from the air flow meter 12 is input thereto.

The control circuit 16 is composed of, for example, a microcomputer, and outputs an injection valve drive signal S4 corresponding to the intake flow rate signal S3, and controls the fuel injection valve 14 so that fuel injection is performed at a predetermined injection amount commensurate with the intake flow rate. to drive.

The aforementioned supercharger 15 is driven in the supercharging region by the supercharger drive signal So from the control circuit IC, and therefore, when the supercharging valve 9 and the solenoid valve 17 are opened, supercharging air is supplied to the combustion chamber 1. Supercharging is performed. This solenoid valve 1
7 is also driven by the solenoid valve drive signal S5 output from the control circuit 16 described above. Hereinafter, the driving of this solenoid valve 17 will be explained in detail with reference to FIG. 3.

FIG. 3 is a block diagram showing the configuration of a single solenoid valve drive circuit 16a in the control circuit 16 (the portions of the control circuit 16 related to the control of the fuel injection system described above are omitted).

The crank angle signal S1 outputted by the crank angle sensor 19 is input to the rotation speed detection circuit 21.
1, the engine speed is detected. The engine rotation speed signal S6 outputted by the rotation speed detection circuit 21 is inputted to the supercharging pulse generation circuit 22 together with the throttle valve opening signal 3 outputted by the throttle valve opening sensor 20.

This supercharging pulse generating circuit 22 generates a cycle corresponding to the engine speed (for example, in the case of a 4-cycle engine, the crankshaft 2 It generates a pulse signal S7 with a pulse width that increases as the engine load and engine speed increase as the engine load and engine speed increase.

The throttle valve opening signal S2 outputted by the throttle valve opening sensor 20 is also input to the supercharging region determination circuit 23,
The supercharging region determination circuit 23 also uses the throttle valve opening signal S2 to determine whether or not the engine is being operated in the supercharging region.
When operating in the supercharging region, a supercharging signal S8 is generated and input to the supercharging pulse generation circuit 22. This supercharging signal S8 is input to the supercharging pulse generation circuit 22. The pulse signal S7 is output only when the engine is being operated in the supercharging region. This pulse signal S7
is input to the supercharging timing setting circuit 24.

Note that the supercharging area discrimination circuit 23 is a reference voltage generation circuit 23.
The comparison circuit 23b compares the reference voltage signal S9 (carrying the throttle valve opening at the boundary between the supercharging region and the non-supercharging region) outputted from the controller a with the throttle valve opening signal S2, and determines the throttle valve opening. The supercharging region is determined by detecting the magnitude of the signal S2 with respect to the reference voltage signal S9.

The supercharging timing setting circuit 24 receives a crank angle signal S1.
is also input, and the pulse signal S7 is synchronized with the crank angle based on the crank angle signal S1 such that, for example, it rises just before the intake valve 8 closes. The synchronized pulse signal S7' is sent to the drive circuit 26 via the switching circuit 25. In addition, the supercharging signal S8 and the switching signal S+o from the supercharging method determination circuit 27 are input to the switching circuit 25.

The supercharging method determination circuit 27 receives an engine rotational speed signal S6 consisting of a voltage signal and a reference voltage signal S++ (which carries a predetermined engine rotational speed that is the boundary between the medium speed range and the high speed range) and the reference voltage signal S++ generated by the reference voltage generation circuit 27a. ) comparison circuit 2
7b, when the engine rotation speed is equal to or higher than the predetermined rotation speed, that is, when the engine is operated in a high speed range, the switching signal S+.

It is something that emits. The switching circuit 25 receives this switching signal S
When +o is input, the supercharging signal S8, which is a constant signal, is sent to the drive circuit 26, and at other times, the pulse signal 87' is sent.
is sent to the drive circuit 26. Of course, when the engine is operated in a low-load non-supercharging region, the supercharging signal S8 is not output as described above, and therefore the pulse signal S7/ is not output, so even if the switching signal S10 is
5, no signal is output from the switching circuit 25. Reference numeral 28 denotes an electromagnetic clutch drive circuit which operates an electromagnetic clutch upon receiving the supercharging signal S8 from the supercharging range discriminating circuit 23, thereby driving the supercharger 15 by the engine.

When the engine is operated in a high-speed supercharging region and the supercharging signal S8 is input to the drive circuit 26, the drive circuit 26 outputs a valve opening signal consisting of a constant signal as the solenoid valve drive signal S5, and the solenoid valve 17 is activated. Set to always open. Therefore, supercharging air is continuously supplied to the combustion chamber 1 through the solenoid valve 17.
is supplied to provide continuous supercharging.

Note that the amount of supercharging air supplied at this time is determined by the auxiliary throttle valve 18.
can be changed according to the engine load.

Further, when the engine is operated in a low to medium speed supercharging range and the pulse signal 87' is input to the drive circuit 26, the drive circuit 2
6 is a pulse signal with a pulse width corresponding to this pulse signal S 7' (1) Pulse 11] is a solenoid valve drive signal S5
and outputs the solenoid valve 17 as the pulse signal S7.
The opening time corresponds to the pulse width of ', and the valve is opened and closed intermittently at a predetermined timing. As mentioned above, since it corresponds to this number of pulses, the opening time of the solenoid valve 17 corresponds to the engine load and rotation speed, and the amount of supercharging air supplied is controlled by these engine loads and rotation speeds. will be done.

The supercharging valve 9, along with the intake valve 8 and the exhaust valve 1o, is driven by a valve mechanism such as a camshaft, but of course its closing timing is set to be later than the closing timing of the intake valve 8. Also, the solenoid valve 17 is set to remain open at least while the solenoid valve 17 is open.

FIG. 4 shows the non-supercharging area set as explained above,
The ranges of timed supercharging region and continuous supercharging region are shown.

In the above embodiment, the supercharging region and non-supercharging region are set depending on the size of the engine load, but if the supercharging region is set according to the engine load and rotation speed, the non-supercharging region and the quim supercharging region are set. It is also possible to set the feeding area and continuous supercharging area as shown in FIG.

Further, in the above embodiment, when the solenoid valve 17 is kept open at a constant opening in the high-speed supercharging region, the amount of supercharging air supplied is controlled by the auxiliary throttle valve 18, but the solenoid valve 17 is Alternatively, the amount of supercharging air supplied may be controlled by controlling the amount of supercharging air and changing the degree of opening according to the engine load or engine speed.

Furthermore, the above-mentioned supercharger may be always driven by the engine even in the non-supercharging region, but in this case, when the supercharging is not performed, the secondary air for exhaust gas purification is supplied from the supercharging passage on the upstream side of the solenoid valve. It is necessary to introduce pressurized air into the exhaust gas and release the air pressurized by the supercharger from the solenoid valve-upstream supercharging passage.

As explained in detail above, the engine intake system of the present invention has an extremely simple configuration in which the timing valve is an electromagnetic on-off valve, and can switch between timed supercharging and continuous supersaturation depending on the engine speed. Therefore, according to the present device, it is possible to obtain good supercharging performance in the entire rotation range, and it is also possible to prevent the timing valve from following the delay in the high speed range.

[Brief explanation of drawings]

Fig. 1 is a graph explaining the difference in torque characteristics due to the difference in supercharging system, Fig. 2 is a schematic diagram showing one embodiment of the present invention, and Fig. 3 is a graph explaining the difference in torque characteristics due to the difference in supercharging system.
A block diagram showing a part of the control circuit in the embodiment shown in the figure; Fig. 4 is a graph showing the supercharging method settings in the embodiment shown in Fig. 2; and Fig. 5 is a graph showing another example of the supercharging method settings. be. 5...Natural intake passage 6...Supercharging passage 15...
・Supercharger 16... Control circuit 16a... Solenoid valve drive circuit] 7... Solenoid valve 19... Crank angle sensor

Claims (1)

[Claims] A natural intake passage, a supercharging passage provided with a supercharger, an electromagnetic on-off valve that is provided in the supercharging passage downstream of the supercharger and opens and closes intermittently in synchronization with the rotation angle of the engine output shaft, and an engine. a rotational speed detector that detects the rotational speed of the engine, and in the supercharging region, when the engine rotational speed detected by the detector is below a set value, the on-off valve is intermittently opened and closed, and when it is above the set value, the on-off valve is opened and closed; An engine intake device characterized by being provided with a control circuit that keeps a valve normally open.