JPS6318761Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an intake system for a multi-cylinder engine, and more particularly to an intake system for a multi-cylinder engine in which the intake passages of some cylinders are closed by shutter valves during deceleration.

Conventionally, in order to prevent HC emissions due to misfires during deceleration, the intake passages of some cylinders are closed off with shutter valves during deceleration, thereby diverting the intake air from the intake passages to other cylinders, thereby reducing the number of cylinders in use. An intake system for a multi-cylinder engine is known that improves combustibility and ignition performance by increasing filling efficiency. In such an intake device, the shutter valve is generally formed to be driven by a negative pressure actuator operated by intake negative pressure, for example.
During deceleration, negative pressure is applied to the negative pressure actuator for the shutter valve to close the shutter valve,
At other times, atmospheric air is introduced into the negative pressure actuator and the shutter valve is opened.

When moving from deceleration to acceleration, when operating the negative pressure actuator to open the shutter valve, the shutter valve opens relatively gently in the low rotation range to alleviate the shock of acceleration, while in the high rotation range, there is a delay in acceleration response. It is desirable to open the shutter valve quickly to prevent this from occurring.
However, when intake negative pressure is used as a negative pressure source, the intake negative pressure increases as the rotation speed increases. A negative pressure that is greater than the negative pressure that overcomes the spring force of the actuator is acting. Therefore, when opening the shutter valve by introducing atmospheric air into the negative pressure actuator, there is a problem that the higher the rotation speed, the longer it takes to introduce atmospheric pressure, and the opening operation of the shutter valve is delayed, which is a phenomenon contrary to the above-mentioned requirement. Therefore, in order to meet such demands, Japanese Patent Application Laid-Open No. 55-10049 states that when opening the shutter valve in a high rotation range, it not only introduces atmospheric air into the negative pressure actuator, but also actively uses an air pump etc. Although an intake device has been disclosed that supplies pressurized air to quickly open a shutter valve, the problem is that the structure is complicated and the cost is increased.

The present invention was developed in view of the above circumstances, and is used in an intake system for a multi-cylinder engine equipped with a shutter valve driven by a negative pressure actuator that operates with negative intake pressure. It is an object of the present invention to provide an intake device that does not cause a delay in acceleration response when shifting to the engine speed, can reliably prevent the aforementioned acceleration shock particularly in the low rotation range, and can be formed at low cost with a simple configuration. It is something.

In other words, in the present invention, as the engine moves to a high rotational speed range, the intake negative pressure gradually increases (that is, decreases in absolute pressure).
The higher the rotation speed is, the longer it takes to introduce atmospheric pressure, resulting in a delay in the opening of the shutter valve.On the other hand, in the lower rotation range, the intake negative pressure is low, so atmospheric pressure is introduced quickly, making it easier for the shutter valve to open suddenly. This was obtained based on the knowledge that a relief valve is provided to keep the negative pressure acting on the negative pressure chamber of the negative pressure actuator below a predetermined value (that is, above a predetermined absolute pressure), and when the shutter valve is opened. The present invention is characterized in that the passage for introducing atmospheric air into the negative pressure chamber is provided with a delay means for slowing the introduction of atmospheric air.

If the above relief valve is provided, when the negative pressure chamber of the negative pressure actuator is communicated with the intake passage and set to a negative pressure state in order to close the shutter valve, no matter how high the intake negative pressure is, the negative pressure chamber of the negative pressure actuator will maintain a predetermined value ( Of course, this predetermined value is set to a value that can operate the negative pressure actuator), and is not set to an unnecessarily high negative pressure. Therefore, when moving from deceleration to acceleration, atmospheric air can be introduced quickly, the shutter valve can be opened quickly, and acceleration can be performed with good responsiveness.

On the other hand, if the above-mentioned delay means is provided, the introduction of air into the negative pressure chamber will be slow in the low rotation range where the introduction of air into the negative pressure chamber tends to be rapid.
As a result, the shutter valve opens relatively slowly.

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

FIG. 1 shows an intake system for a multi-cylinder engine according to one embodiment of the present invention. A first intake passage 3 and a second intake passage 4 are connected to the first cylinder 1 and the second cylinder 2 of the engine E, respectively, and a first carburetor 5 and a second carburetor are connected to each intake passage 3 and 4, respectively. 6
is provided. Each carburetor 5, 6 is provided with a throttle valve 7, 8 which is operated, for example, by an accelerator pedal. of the second intake passage 4;
A shutter valve 9 is provided downstream of the throttle valve 8 and is capable of opening and closing the intake passage 4 by rotating around a valve shaft 9a. This shutter valve 9
The valve shaft 9a is fixed to one end of a lever 10, and the other end of the lever 10 is connected to the negative pressure actuator 1.
Rod 11 fixed to diaphragm 11a of 1
It is pivotally supported at the tip of b. A spring 11e is compressed in a negative pressure chamber 11d defined by the case 11c of the negative pressure actuator 11 and the diaphragm 11a, and the rod 11b is biased to the left in the figure by the spring 11e. ing. When the negative pressure chamber 11d is set to atmospheric pressure, the rod 11b is pushed to the left in the figure by the spring 11e, and the shutter valve 9 is set to the fully open state via the lever 10. A communication hole 13 is provided in the partition wall 12 between the intake passages 3 and 4.

One end of a negative pressure passage 14 is opened in the intake passage 3 at a position downstream of the throttle valve 7, and the other end of this negative pressure passage 14 is connected to a negative pressure passage 16 via a three-way valve 15. The other end of this negative pressure passage 16 is a negative pressure chamber 11d of the negative pressure actuator 11.
and an air chamber 17 on the way.
is provided. Another connection port 15a of the three-way valve 15 is open to the atmosphere. Further, an orifice 18 that restricts the negative pressure passage 16 is provided between the three-way valve 15 and the air chamber 17.

A relief valve 19 consisting of a spring 19a and a valve body 19b is provided in the negative pressure passage 16 between the air chamber 17 and the negative pressure actuator 11. Valve body 19b of this relief valve 19
When the negative pressure passage 16 is set to an atmospheric pressure state or a low negative pressure state, the spring 19
a to the upper port 19c in the figure to close the port 19c. However, when the negative pressure passage 16 is set to a negative pressure higher than a predetermined value, the spring 19
The port 19c is pushed in by atmospheric pressure against the biasing force of the port 19c.

The three-way valve 15 receives a switching signal S 2 output from a control circuit 21 to which a deceleration signal S ₁ from a deceleration sensor 20 is input, which detects the deceleration state of the engine by detecting, for example, the throttle valve opening and engine speed _. Depending on the condition, the negative pressure passage 16 is set to be in communication with the negative pressure passage 14 or the negative pressure passage 16 is in communication with the atmosphere opening connection port 15a.

The operation of the apparatus of this embodiment having the above configuration will be explained below. When the deceleration signal S ₁ is input to the control circuit 21, the three-way valve 15 is set to communicate the negative pressure passage 16 and the negative pressure passage 14 by the switching signal S ₂ . As a result, the intake negative pressure in the intake passage 3 acts on the negative pressure chamber 11d of the negative pressure actuator 11, pulling the diaphragm 11a to the right in the figure, and rotating the shutter valve 9 via the rod 11b and lever 10. , the intake passage 4 is completely closed. Then, the intake air passing through the second carburetor 6 is detoured to the first intake passage 3 through the communication hole 13 and is supplied to the first cylinder 1. Therefore, the charging efficiency of the first cylinder 1 is increased, and the combustibility and ignition performance are improved. As a result, misfire in the first cylinder 1 is prevented, and the generation of HC is suppressed. When engine E shifts from deceleration to acceleration, deceleration signal _S1 is canceled and three-way valve 1
5 is set in a state in which the negative pressure passage 16 and the atmosphere opening connection port 15a are communicated with each other by the switching signal _S4 . Thereby, the negative pressure chamber 11 of the negative pressure actuator 11
Atmospheric air is introduced into the cylinder d, the shutter valve 9 is opened, and the engine E is returned to its normal state in which both the first cylinder 1 and the second cylinder 2 are used. The air chamber 17 and the orifice 18 reduce the speed of air introduction, especially in the low rotation range where the intake negative pressure is low and the air is easily introduced rapidly, so that the shutter valve 9 is opened suddenly and a large acceleration shock is generated. prevent it from happening.

Here, the intake negative pressure in the intake passage 3 increases (decreases in terms of absolute pressure) as the engine speed increases.
Therefore, in order to close the shutter valve 9, the negative pressure chamber 1 is
1d is in communication with the intake passage 3, the negative pressure in the negative pressure chamber 11d increases as the engine speed increases at that time. However, as described above, the relief valve 19 provided in the negative pressure passage 16 is relieved when the negative pressure in the negative pressure passage 16 reaches a predetermined value, so that the negative pressure in the negative pressure passage 16 and the negative pressure chamber 11d is As an example, as shown in FIG. 2, the predetermined value is never exceeded. The predetermined relief pressure of the relief valve 19 is set to a value that is the operating pressure of the negative pressure actuator 11 plus some margin.

If the relief valve 19 is not provided, the negative pressure in the negative pressure passage 16 and the negative pressure chamber 11d is
As shown by the broken line in the figure, it increases indefinitely as the engine speed increases. Therefore, the higher the engine speed is in the region, the higher the negative pressure in the negative pressure passage 16 and the negative pressure chamber 11d becomes, and the introduction of atmospheric air into the negative pressure passage and the negative pressure chamber 11d during the next acceleration becomes slower. Therefore, contrary to the ideal state, the shutter valve 9 opens more slowly in the high rotation range, and the acceleration response in the high rotation range becomes extremely poor. In contrast, in the intake system of this embodiment, as described above, the negative pressure passage 16 and the negative pressure chamber 11d
Since the negative pressure does not exceed a predetermined value no matter how high the engine speed is, the opening of the shutter valve 9 does not become slow in the high speed range, and the acceleration response in the high speed range is maintained good. .

It goes without saying that a relief valve having a structure different from that of the relief valve 19 described above may be used as a relief valve that performs such an action.

As explained in detail above, the intake system for a multi-cylinder engine of the present invention has an extremely simple configuration, and prevents the shutter valve from opening slowly in the high-speed range, and particularly from opening the shutter valve suddenly in the low-speed range. This significantly improves the acceleration response in the high rotation range, while also reliably preventing acceleration shock particularly in the low rotation range.

[Brief explanation of the drawing]

FIG. 1 is a system diagram schematically showing one embodiment of the present invention, and FIG. 2 is a graph showing the relationship between the negative pressure in the negative pressure chamber of the negative pressure actuator and the engine speed in the embodiment of FIG. 1. 1, 2... Cylinder, 3, 4... Intake passage, 9...
Shutter valve, 11...Negative pressure actuator,
14, 16... Negative pressure passage, 15... Three-way valve, 17
...Air chamber, 18...Orifice, 19...
...Relief valve, 20...Deceleration sensor, 21...
...control circuit.

Claims (1)

[Scope of utility model registration request] In an intake system for a multi-cylinder engine, in which the intake passage of some cylinders is closed by a shutter valve driven by a negative pressure actuator operated by intake negative pressure during deceleration to increase the filling efficiency of other cylinders, A relief valve is provided to keep the negative pressure acting on the negative pressure chamber of the negative pressure actuator below a predetermined value, and a delay for slowing the introduction of atmospheric air into the passage that introduces atmospheric air into the negative pressure chamber when the shutter valve is opened. An intake device for a multi-cylinder engine, characterized in that a means is provided.