JP2611979B2 - Engine intake system - Google Patents

Description

The present invention relates to an intake device for an engine, and more particularly, to a technique for preventing knocking during cranking.

<< Conventional Technology >> As is well known, in recent engines, especially electronically controlled fuel injection engines, an intake expansion chamber having an appropriate volume called a surge tank is provided between an intake pipe and a throttle body ( For example, JP-A-58-172434.

The role of the surge tank is to prevent the pulsation of the intake air (this increases the accuracy of the air flow meter that measures the intake air amount), and to control the calculation of the injected fuel according to the intake air amount detected by the air flow meter during acceleration. Prevent lean air-fuel ratio due to system delay, prevent intake interference of each cylinder, improve intake efficiency by intake inertia effect as reverse part of pressure wave generated at intake port near intake valve, etc. It is. In addition, it also has a role as an assembling portion that connects the intake pipe of each cylinder and the throttle body.

<< Problems to be Solved by the Invention >> Even if the throttle valve is not widely opened at the time of cranking of the engine start, since the volume of the surge tank is large and there is a lot of air in the intake passage downstream of the throttle valve,
The intake air amount at the time of cranking becomes considerably large, and is substantially the same as when the throttle valve is fully opened.

The state where cranking is performed in a state where the intake air amount is large as described above is the same as the operation state where the load is low and the engine speed is low, and knocking is likely to occur. That is, the conventional one has a problem that knocking easily occurs during engine start.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to prevent occurrence of knocking during engine start.

<< Means for Solving the Problems >> Accordingly, in the present invention, a throttle valve for controlling an intake air amount in response to an accelerator operation, and an intake expansion chamber formed in an intake passage downstream of the throttle valve (the above-described surge tank) ), A divided passage formed at a downstream portion of each of the intake passages that communicates the intake expansion chamber with each of the cylinders, and divided into a plurality of intake passages, and a partial passage among the plurality of divided passages. A throttle means provided to control the amount of intake air introduced into the combustion chamber through the partial passage; and a means for detecting that the engine is cranked. At the time of ranking, the throttle means is configured so that some passages are throttled in order to control the introduction of intake air from the intake expansion chamber into the combustion chamber.

<Operation> According to the present invention relating to the above configuration, at the time of cranking, the throttle means provided at a downstream portion close to the intake port of the intake passage portion communicating the surge tank with each cylinder is provided at the time of cold start. Alternatively, since the throttled state is set regardless of the time of the warm start, the amount of air introduced into the combustion chamber of each cylinder is limited, and a large-capacity intake expansion chamber such as a surge tank is provided in the intake passage downstream of the throttle valve. Even if it does, the intake air amount does not become excessive, and cranking is performed in a state where the pressure temperature in the cylinder is low, and the occurrence of knocking is reduced.

In addition, the intake passage portion that communicates the enlarged intake chamber with each cylinder divides a downstream portion adjacent to the intake port into a plurality of divided passages, and a throttling means is provided in a part of the divided passages. While preventing excessive intake of air at extremely low speeds, the diameter of the intake passage downstream of the enlarged intake chamber can be increased up to just before the split passage, thus increasing the wall resistance. And smooth introduction of intake air during normal operation.

<< Embodiment >> FIG. 1 shows a configuration of an embodiment of the present invention. 1
Is an engine main body, which is composed of a cylinder block 2, a cylinder head 3, a cylinder head cover 4, etc., and has a cylinder 5, a piston 6, a combustion chamber 7, and an intake port 8.
It includes an exhaust port 9, an intake valve 10, an exhaust valve 11, a valve train 12, a spark plug (not shown), and the like.

Reference numeral 19 denotes an intake passage, which is provided with an air cleaner 16, an air flow meter 17, a throttle valve 18, and a surge tank 14 from the upstream side to the downstream side. Downstream from the surge tank 14, an intake pipe 15 for each cylinder is connected.
Are connected to the respective intake ports 8 of the cylinder head 3.

A partition wall 20 is formed in the intake passage near the intake port 8, and is divided into two paths, a primary intake passage 21 for swirl generation having a small passage sectional area and a secondary intake passage 22 having a large passage sectional area. ing. That is, the downstream portion of the intake passage near the intake port 8 is divided into a plurality of divided passages (a primary intake passage 21 and a secondary intake passage 22).

The fuel injection valve 24 is arranged so as to inject fuel toward a portion where the primary intake passage 21 and the secondary intake passage 22 join, that is, toward the intake port 8.

As the above-described aperture means, in this embodiment, 2
A shutter valve 23 is provided in a portion of the next intake passage 22. The shutter valve 23 is moved by the electromagnetic actuator 25 and also by the negative pressure actuator 28, and is fully closed or slightly opened at low rotation and low load according to the intake negative pressure, while at the time of high rotation or high load. The effective sectional area of the secondary intake passage 22 is changed so as to be opened.

As means for detecting that the engine is cranked, a switch signal of a starter switch 40 for operating a starter motor and an engine speed sensor 33 are provided.
Use the output signal of These signals are processed by the control unit (microcomputer) 31 as described later.

During normal operation, the throttle valve 18 of the intake passage 19
The negative pressure is large, for example, low rotation,
When the load is low, the shutter valve 23 is closed by the negative pressure actuator 28, the intake air is supplied only from the primary intake passage 21, and a swirl is formed in the combustion chamber 7. When the throttle valve 18 is further opened and the negative pressure decreases, the shutter valve 23 opens,
Intake is also supplied from the secondary intake passage 23.

At the time of cranking, the negative pressure generated downstream of the throttle valve 18 is small and the negative pressure actuator 28 does not operate, but a valve closing signal is supplied from the control unit 31 to the electromagnetic actuator 25, whereby the shutter valve 23 operates and the secondary intake Close passage 22. Then, most of the intake air entering the combustion chamber 7 passes through the primary intake passage 21 having a small cross-sectional area, and the amount of intake air is restricted as compared with the state where the shutter valve 23 is fully opened.

The control unit 31 performs various electronic controls of the engine such as the control of the fuel injection valve 24 in addition to the control of the present invention described above. Although not directly related to the present invention, reference numeral 26 denotes an intake passage that bypasses the portion of the throttle valve 18, and 27 denotes a bypass passage.
An opening / closing valve provided in the middle of 26 and a sensor 32 for detecting the opening of the throttle valve 18. The output of the sensor 32, the output of the air flow meter 17, and the like are also input to the control unit 31, and various engine controls are performed according to the input information.

FIG. 2 shows a control procedure of the shutter valve 23 executed by the control unit 31. The operation of this embodiment will be described with reference to this flowchart.

When the starter switch 40 is turned on from off to start the engine, this change is detected and the control unit 31
Starts the process of FIG. First, in step 201, the valve closing signal is turned on to drive the actuator 25, and the shutter valve 23
To close the secondary intake passage 2. In the next step 202, it is determined whether or not the engine speed is, for example, 500 or more (it is determined whether or not the engine has started the self-detonation rotation). If the engine is not running, the routine proceeds to step 203, where it is determined whether or not the starter switch 40 has returned to off. If the starter switch 40 remains on, the process returns to step 202 again.

When the engine starts and the rotation speed becomes 500 or more, the process proceeds from step 202 to step 204, for example, having a timer function for about 10 seconds, and then proceeds to step 206 to turn off the valve closing signal. This returns the shutter valve 23 to the open position. When the starter switch is turned off without starting the engine, the process proceeds from step 203 to step 205, and the valve closing signal is also turned off.

As described above, the shutter valve 23 is closed during cranking at the time of starting the engine, and thereby the intake air amount is limited.

Note that the engine speed comparison constant (step 202) in the above embodiment is not always necessary, and the valve closing signal may be turned on while the starter switch 40 is on. In this case, the valve closing signal may be turned off for a certain period of time after the starter switch 40 changes from on to off.

Further, although the negative pressure actuator 28 is provided separately, the negative pressure actuator 28 may be omitted so that the electromagnetic actuator 25 performs this operation.

<< Effects of the Invention >> As described in detail above, in the engine intake device according to the present invention, during cranking at the time of engine start, the intake air in the intake passage communicating with the intake expansion chamber and each cylinder. The throttle means provided at a downstream portion close to the port is set to a throttle state regardless of a cold start or a warm start, and limits the amount of air introduced into the combustion chamber of each cylinder. Even if there is a large-volume intake expansion chamber such as a surge tank in the middle of the downstream intake passage, the intake volume will not be excessive and cranking will be performed in a state where the pressure temperature in the cylinder is low, and knocking will occur cold. It decreases during both cold start and warm start.

In addition, the intake passage portion that communicates the enlarged intake chamber with each cylinder divides a downstream portion adjacent to the intake port into a plurality of divided passages, and a throttling means is provided in a part of the divided passages. While preventing excessive intake of air at extremely low speeds, the diameter of the intake passage downstream of the enlarged intake chamber can be increased up to just before the split passage, thus increasing the wall resistance. And smooth introduction of intake air during normal operation.

[Brief description of the drawings]

FIG. 1 is a block diagram of an intake system for an engine according to an embodiment of the present invention, and FIG. 2 is a flowchart showing a control operation of the embodiment. 7: Combustion chamber, 8: Intake port 14: Surge tank, 15: Intake pipe 18: Throttle valve, 19: Intake passage 21 ... Primary intake passage, 22: Secondary intake passage 23 ... Shutter valve 25 ... Electromagnetic actuator 31 ... Control unit 40 ... Starter switch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F02M 35/10 F02M 35/10 301P (56) References JP-A-60-35143 (JP, A) JP-A-55-5446 (JP, A) JP-A-54-42525 (JP, A) JP-A-61-98912 (JP, A)

Claims (1)

(57) [Claims] A throttle valve for controlling an amount of intake air in response to an accelerator operation; an intake expansion chamber formed in an intake passage downstream of the throttle valve; A divided passage formed at a downstream portion of the intake passage and dividing the intake passage into a plurality of passages; intake air provided in a part of the plurality of divided passages and introduced into the combustion chamber through the part of the passages Throttle means for controlling the amount of fuel, and means for detecting that the engine is cranked. In response to the output of the detection means, during cranking, the throttle means is moved from the expanded intake chamber into the combustion chamber. An engine control device, characterized in that a part of the passage is restricted in order to control the introduction.