JPS6059413B2 - Intake system for multi-cylinder engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake device for a multi-cylinder engine.

For multi-cylinder engines, the number of operating cylinders is increased or decreased depending on the operating conditions. For example, in the case of a 3-cylinder engine, when idling or under light load, only one cylinder is operated and the engine is operated for 40 km.
Some engines operate with two cylinders under medium loads, such as Ih, and with all three cylinders under higher loads, in order to maintain the optimum air supply ratio at all times, thereby improving fuel efficiency. .

In such a multi-cylinder engine, in order to achieve the above technical concept, a control valve is generally provided in a part or all of the intake manifold, and the control valve is controlled by the opening of the throttle valve. We are trying to open the valve accordingly. but,
In all of these, the opening degree of the control valve corresponds to the opening degree of the throttle valve, so especially in the early stage of opening the control valve, the first
As shown in FIG. 1, there is a drawback that a shock occurs while the irregular combustion range α is exceeded, impairing the riding feeling.

An object of the present invention is to provide an intake device for a multi-cylinder engine that does not impair the ride feeling, and is characterized by a normally closed control valve in at least a portion of the intake pipe of the manifold. At the same time, negative pressure actuators are linked to these control valves, and the pressure chambers of these negative pressure actuators are located upstream of the throttle valve or in the idle link position, and are controlled as the throttle valve opens. The control valve is connected to an intake pipe section located downstream thereof, and the control valve is opened by the negative pressure of the intake section. The present invention will be described below with reference to embodiments shown in the drawings. The intake device for a multi-cylinder engine according to the present invention includes each intake pipe 1 of a manifold,
, 12, . . . 1n, at least part of the intake pipe 1m
, 1m+1, 1n with normally closed control valves 2m, 2m+1,...
・In addition to installing 2n, negative pressure actuators are installed in those control valves. Connect Eta 3m, 3m+1,...3n,
Those negative pressure actuator pressure chambers 4m, 4m+1,・
4n is an intake pipe portion located upstream of the throttle valve 5 when it is in the idling position, and located downstream as the throttle valve 5 is opened. 6,
The control valves 2m, 2m+1,... are activated by the negative pressure of the intake part.
・It is designed to open the 2n valve. Examples are:
This technical idea was applied to a three-cylinder engine.
In the embodiment shown in FIG.
1 is linked to the throttle valve 5, and control valves 22 and 23 are linked to a negative pressure actuator 3233, respectively. The throttle valve 5 is connected to an accelerator pedal (not shown) via a throttle lever 81 fixedly connected to its shaft 7 and a wire 9 connected to the upper end of the throttle lever, and furthermore, the throttle lever 81 is connected to a link rod 121. , are connected to the control valve 21 via the shaft 101. The control valves 22 and 23 have their shafts 10
Lever 112, 11 fixedly connected to 2, 103, respectively.
3 is a negative pressure actuator 3. , 33 rod 132,1
33, and the negative pressure actuators 32, 3
3 communicates the pressure chambers 42 and 43 with an intake pipe section 6 located upstream of the throttle valve 5 when it is in the idling position and located downstream as the throttle valve 5 is opened. . In addition, in the embodiment, the negative pressure actuators 32, 33
Negative pressure intake ports 142, 143 are arranged one above the other as shown in FIG. The above embodiment works as follows.

FIG. 2 shows the opening degree of the throttle valve 5 and each negative pressure intake port 14. , 143 shows the relationship with the negative pressure generated. As is clear from the figure, when the set pressures of the compression springs 15., 153 of each actuator 32, 33'' are both set to S, as the throttle valve 5 opens, the actuator 32 first operates at point a; Subsequently, the actuator 33 operates at point b.In other words, in the embodiment shown in FIG. The control valve 21 is opened at an appropriate opening degree (opening degree exceeding the irregular combustion range α).
It is becoming. Therefore, the air-fuel mixture is taken into the engine only through the intake pipe 11. Then press the accelerator pedal (
(not shown), the wire 9
, the throttle valve 5 is opened via the throttle lever 81 and the shaft 7. The throttle valve 5 is rotated counterclockwise from the position shown in FIG. , the negative pressure at the negative pressure intake increases, and this negative pressure resists the urging force of the compression spring 152 and pulls the rod 132 upward, causing the control valve 22 to move clockwise via the lever 112. Rotate to open. Therefore, the air-fuel mixture flows through the intake pipe 11.
, 12, and is sucked into each engine. Further, the throttle valve 5 is opened, and the end portion 5a of the throttle valve is connected to the negative pressure intake port 14.
3, the negative pressure at the negative pressure intake increases, and this negative pressure resists the urging force of the compression spring 153, pulling the rod 133 upwards and clocking the control valve 23 via the lever 113. Rotate in the direction to open. Therefore, the mixture passes through the air-fuel mixtures 11, 12, and 13 and is inhaled into each engine. FIG. 5 shows the opening degree of the Mu control valve according to this embodiment. As is clear from the figure, the control valves 22,
23 is so. At the initial stage of valve opening, the valve opens suddenly and instantaneously exceeds the irregular combustion range α, so that the riding feeling is not impaired. Note that in this embodiment, the control valve 21
Even without this, the characteristics shown in FIG. 5 will hardly change. Also, among the characteristic lines shown in FIG. 5, control valve 2. , 23 to soften the shock caused by output changes, as shown in FIG. Flow control valve 16 between the pressure chambers 42 (and 43) of. (and 163), and in addition, if it is desired to quickly cut off the air-fuel mixture of the control valves 22 and 23 during deceleration, the seventh flow control valve 162 (and 163) can be used instead of the As shown in the figure, a flow rate adjustment valve 172 (and 173) with a check valve may be used. FIG. 8 shows another embodiment of the present invention, in which the control valves 21, 22, and 23 are all normally closed, and the control valve 21 is closed when the engine is idling; 23 is configured such that when the throttle valve 3 is at a constant opening, each opening is instantaneously opened to a constant opening (opening beyond the irregular combustion range α). That is, the control valve 21 disposed in the intake pipe 11 is always urged to be closed by a tension spring 181, and is opened by an interlocking lever 191 that interlocks with the throttle valve 5 via a rod 121. , or is opened by the negative pressure actuator 31, detects the idle operating state of the engine, and in that case operates the negative pressure actuator 31 according to the detection signal,
Control valve 2 is opened to a certain degree (opening that exceeds the irregular combustion range α)
Similarly, the control valve 22 is controlled by the tension spring 18. When the throttle valve 5 is at a constant opening (medium speed engine operation), the negative pressure actuator 32 is actuated, and the control valve 2 is energized so as to be always closed. is opened to a certain degree (an opening degree exceeding the irregular combustion range α), and then the lever 82 and the rod 12 are opened. , is adjusted to open in conjunction with the throttle valve 5 via an interlocking lever 192,
Similarly, the control valve 23 is always energized to close by the tension spring 183, and when the throttle valve 5 is at a constant opening (high-speed engine operating state), the negative pressure actuator 33 is actuated, and the control valve 23 is opened to a certain degree (an opening degree exceeding the irregular combustion range α), and then the rod 123 is adjusted to be opened in conjunction with the throttle valve 5 via an interlocking lever 193. FIG. 9 shows specific means for causing the control valves 21, 22, 23 to perform the above operations.

The means is to fixedly connect a lever 20 to the shaft 10 of the control valve 2, and to loosely fit an interlocking lever 19 and a quick-actuation lever 21 onto the shaft, and to rotate the interlocking lever 19 and the quick-action lever 21 counterclockwise. Only when rotating, the control valve 2 is brought into abutting engagement with the lever 20 to operate the control valve 2 in the opening direction. The quick-actuation lever 21 has an end connected to the negative pressure actuator 3 via the rod 13. Therefore, the control valve 2 is always biased clockwise (closing direction) by the tension spring 18 via the lever 20 and shaft 10, and when the negative pressure actuator 3 is operated, the quick-actuation lever 21 is biased counterclockwise. The lever contacts the lever 20, and then the lever 20 is rotated counterclockwise to instantaneously open the control valve 2 to a constant opening. Further, the operating force from the accelerator pedal transmitted to the interlocking lever 19 via the rod 12 rotates the lever counterclockwise, brings the lever into contact with the lever 20, and then rotates the lever 20 counterclockwise. The control valve 2 is rotated to interlock with the throttle valve 5. In the embodiment shown in FIG. 8, the pressure chamber 41 of the negative pressure actuator 31 is connected to the downstream side of the control valve 22 in the intake pipe 12 via the switching valve 22.
The switching valve 22 normally opens the pressure chamber 4 to the atmosphere, confirms the idling operating state by an appropriate means, such as detecting the engine rotation speed, and uses the signal to switch between the pressure chamber 41 and the intake air. It communicates with the downstream side of the control valve 22 in the pipe 12.

Also, a negative pressure actuator 3. , 33 pressure chambers 42, 4
Similarly to the embodiments shown in FIGS. 3 and 4, negative pressure intake ports 142 and 143 are provided in the intake pipe portion 6, respectively. The operation of the above embodiment will be explained below, and the configuration will also be explained in detail.

First, when the engine is in an idling operating state, the pressure chamber 4 of the negative pressure actuator 31 is in communication with the downstream side of the control valve 22 in the intake pipe 12 via the switching valve 22. Therefore, negative pressure from the intake pipe 12 acts on the pressure chamber 41 of the negative pressure actuator 31, opening the control valve 21 to a certain opening degree (an opening degree exceeding the irregular combustion range α). In such a state, the negative pressure in the intake pipe 11 is not so large that the negative pressure actuator 32 is not actuated, and similarly, since almost no negative pressure is generated in the intake pipe 12, the negative pressure is not large enough to operate the negative pressure actuator 32. Pressure actuator 33 also does not operate. Therefore, the air-fuel mixture is drawn into the engine only through the intake pipe 11. Subsequently, the throttle valve 5 is opened, and in conjunction with this, the control valve 21 is opened.
When the engine is opened and the engine enters a low-medium speed operating state, the negative pressure inside the intake pipe 11 becomes large, and the negative pressure actuator 32 is actuated by the negative pressure, and the control valve 2 is activated. is opened to a certain degree (opening degree exceeding the irregular combustion range α). When the throttle valve 5 is further opened, not only the control valve 21 but also the control valve 22 are further opened, and the engine enters a high-speed operating state. Therefore, similarly to the above, the negative pressure inside the intake pipe 13 increases,
The negative pressure actuator 83 is actuated by the negative pressure.
The control valve 23 is opened at a certain degree (opening degree exceeding the irregular combustion range α)
develop. After that, depending on the opening degree of the throttle valve 5, the control valve 21,
Both 22nd and 23rd will be opened. The graph in FIG. 10 shows such characteristics. When the accelerator pedal is gradually released from this state, each control valve 21,
22, 23 are the control valves 23, 2 by following the operation opposite to the above.
2 are closed one after another, and finally the opening degree of throttle valve 5 becomes slightly, and the
When the engine is in idling operation, the switching valve 2
2 is activated, the negative pressure in the intake pipe 12 acts to operate the negative pressure actuator 31, and maintains the control valve 21 at a constant opening degree.

As explained above, in this embodiment, a control valve is provided in each intake pipe of the multi-cylinder engine, thereby increasing the number of cylinders used depending on idling, low-medium speed, and high-speed operation, and increasing the number of cylinders used during deceleration. The basic technical idea is to bring all control valves into a fully closed state at times, and a negative pressure actuator is linked to the control valves, and the actuator is communicated with an intake portion related to the opening degree of the throttle valve.

As a similar embodiment to achieve such a technical idea, for example, each pressure chamber 42, 4 of the negative pressure actuator 3.
3 to the intake pipe 11, 1. The control valves 21 and 22 may be communicated with the downstream side of the control valves 21 and 22.

In this case, the negative pressure actuators 32 and 33 have the direction of negative pressure applied to the diaphragm and the biasing direction of the compression spring opposite to those of the negative pressure actuators 32 and 33 of the above embodiment, so that the negative pressure in the intake pipes 11 and 12 is It is sufficient if the negative pressure actuators 32 and 33 are activated when the pressure becomes small. In addition, the negative pressure actuator 3) 1'' disposed in relation to the control valve 21 of the intake pipe 11 can maintain the control valve 21 at a constant opening degree when the engine is idling.゛ first
As shown in FIG. 1, it is used as a stopper, and its pressure chamber 41'' is communicated with the downstream side of the control valve 22 of the intake pipe 12.
In addition, the set pressure of the compression spring may be determined so that the spring does not operate under negative pressure during idling, but operates under negative pressure during deceleration (the negative pressure increases). Figures 12 and 13
The figure shows a negative pressure switching valve 23 added to the embodiment shown in FIG.
The switching valve 23 is operated by the negative pressure of the intake port, and the downstream side of the control valve 23 in the intake pipe 13 is communicated with the pressure chamber 43 of the negative pressure actuator 33.
The negative pressure downstream of the negative pressure actuator 33 is actuated to open the control valve 23 by applying the negative pressure downstream of the negative pressure actuator 33 to the pressure chamber 43 of the negative pressure actuator 33. Considering that the negative pressure may not become sufficiently large, the negative pressure is used to operate the switching valve 23, and the control valve 2
This is an attempt to obtain the negative pressure for operation of No. 3 from the intake pipe 13 on the downstream side.

The operation of the embodiment shown in FIGS. 12 and 13 will be explained below.

Since this embodiment operates almost the same as the one shown in FIG.
Only operation 3 will be explained. While the end portion 5a of the throttle valve 5 is located below the negative pressure intake port 143, that is, during idling, low speed operation, and medium speed operation, the negative pressure switching valve 23
is not operated, and the pressure chamber 43 of the negative pressure actuator 33 communicates the actuator side boat 25 and the atmosphere side boat 26 of the switching valve 23, and closes the intake pipe 13 side boat 2. Therefore, in this state, the control valve 23 is in a fully closed state (see FIG. 13). When the throttle valve 5 is rotated counterclockwise and the end portion 5a is positioned directly above the negative pressure intake port 143, negative pressure is generated in the negative pressure intake port, and the negative pressure is switched by the negative pressure. Valve 23 is activated. When the switching valve operates, the atmospheric side boat 26 is closed, and the pressure chamber 43 of the negative pressure actuator 33 and the intake pipe 13 are communicated with each other.
The negative pressure in the intake pipe 13 operates the negative pressure actuator 33 . Therefore, the control valve 23 is instantaneously opened to a certain opening degree (see FIG. 13 (2)). Subsequently, when the throttle valve 5 is rotated counterclockwise, the interlocking lever 193 that is interlocked with the throttle valve 5 comes into contact with the lever 203 , and then the control valve 23 is moved by the interlocking lever 193 to rotate the throttle valve 5 . It is opened in accordance with the opening degree (see Fig. 13 ■). Therefore, even if the negative pressure in the negative pressure intake port 143 or the negative pressure in the intake pipe 13 decreases thereafter, the control valve 23 is not affected in any way. Figure 14,
The embodiment shown in FIG. 15 is a further development of the embodiment shown in FIG.
2 is used, and these are operated by the negative pressure of the negative pressure intakes 142 and 143, and when negative pressure is generated only in the negative pressure intake 142, the downstream of the control valve 23 in the intake pipe 13 is controlled. The pressure chamber 42 of the pressure chamber 32 of the negative pressure actuator 32 that operates the valve 22 is connected to the negative pressure intake port 142.
, 143, when negative pressure is generated in both the intake pipe 13
The downstream side of the control valve 23 is communicated with a pressure chamber 43 of a negative pressure actuator 33 that operates the control valve 23.

Furthermore, in this embodiment, a negative pressure inlet 141 is provided below the negative pressure inlet 142, and the negative pressure generated there is taken out as a signal, and a negative pressure switch 28 is activated by the signal. , and a rotary switch 29 that detects the rotational speed of the engine and issues a signal when the rotational speed becomes higher than the idling operating state, and is actuated by the signal, and is equipped with a rotary switch 29 that is activated by the signal, and is operated by either of the above-mentioned switches 28 and 29. When one of them is activated, the electromagnetic switching valve 30 is activated, thereby opening the negative pressure actuator 31 to the atmosphere and cutting off communication with the intake pipe 13. The negative pressure switching valves 232, 233 used in this embodiment are the first atmospheric side boats 312, 313 and the inlet boats 322, 323.
, first outlet boats 332, 333, second outlet boats 342, 343, and second atmospheric side boat 3
52, 353, and the first outlet boats 332, 333 are connected to the first atmosphere side boat 31 in a normal state. ，
313, and inlet boats 322, 323
and the second outlet boat 34. ，
343 is communicated with the inlet boats 322, 323 and isolated from the second atmospheric side boats 352, 353, and in the operating state, the first outlet boats 332, 33
3 communicates with the inlet boats 342, 343, and the first atmosphere side boat 31. , 313, and further the second outlet boat 34. , 343 to the second atmospheric side boat 3
5. , 353, and communicates with the inlet boat 322,
323. In addition, as the electromagnetic switching valve 30, an inlet boat 36 and an outlet boat 37 are used.
and an atmosphere side boat 38, and in the open state (non-excited state), the outlet boat 37 is connected to the inlet boat 38.
The outlet boat 37 is communicated with the atmosphere side boat 38 and the inlet boat 36 is disconnected when in an activated state (excited state). Such negative pressure switching valves 231, 23
2 and the electromagnetic switching valve 30 are piped and wired as follows. Inlet 1 that generates negative pressure in conjunction with throttle valve 5
41 to the negative pressure switch 28, the intake ports 142 and 143 to the pressure chambers 392 and 393 of the negative pressure switching valves 231 and 232, respectively, and the first outlet boat 37 of the electromagnetic switching valve 30 and the negative pressure switching valve 232233 to Pressure actuator 3
1,3. , 33, and further connect the second outlet boat 342 of the negative pressure switching valve 232 to the electromagnetic switching valve 3.
0, and the inlet boat 32 of the negative pressure switching valve 232. is connected to the second outlet boat 333 of the negative pressure switching valve 233, and the inlet boat 323 of the negative pressure switching valve 233 is connected to the downstream side of the control valve 23 in the intake pipe 13, respectively. The above embodiment works as follows. First, in the idling operating state of the engine, that is, in this state, the throttle valve 5 is almost fully closed, no negative pressure is generated in the negative pressure intake port 141, and the engine is operating at a low speed. Therefore, switch 2
Both valves 8 and 29 are activated, but the electromagnetic switching valve 30 is not energized. Further, since no negative pressure is generated in the negative pressure intake ports 142 and 143, the negative pressure switching valves 232 and 233 are also not operated. Therefore, the negative pressure actuator 31 includes the inlet boat 323 of the negative pressure switching valve 233, the second outlet boat 333, the inlet boat 322 of the negative pressure switching valve 232, the second outlet boat 332, and the inlet boat 36 of the electromagnetic switching valve 30. , the negative pressure of the intake pipe 13 acts through the outlet boat 37 to open and open the control valve 21 as appropriate, while the negative pressure actuators 32 and 33
The first atmospheric side boat 31 of the negative pressure switching valves 232 and 233 is
Atmospheric air is introduced through the first outlet boats 32 and 33, respectively, and the control valves 2 and 23 are kept fully closed.

In this state, the air-fuel mixture is taken into the engine only through the intake pipe 11 (see FIG. 15). When the throttle valve 5 is opened and its end 5a is located upstream of the negative pressure intake port 141, the negative pressure switch 28 is activated and the electromagnetic switching valve 30 is activated, and then the end 5a of the throttle valve 5 is opened to the negative pressure. By passing through the pressure intake port 142, the negative pressure is transferred to the negative pressure switching valve 23. Activate. Therefore, the negative pressure in the intake pipe 13 that was acting on the negative pressure actuator 31 is switched to the negative pressure actuator 32, and the control valve 2 is switched to the negative pressure actuator 32. is opened to a certain degree. In addition,
Since the negative pressure actuator 3 is opened to the atmosphere, the control valve 21 is temporarily rotated in the closing direction, but is subsequently opened together with the throttle valve 5 in conjunction with the throttle valve 5. (See Figure 15■). Further, the throttle valve 5 is opened and its end portion 5a passes through the negative pressure intake port 143, thereby operating the negative pressure switching valve 233 using the negative pressure. Therefore, the negative pressure in the intake pipe 13 that was acting on the negative pressure actuator 32 is switched to the negative pressure actuator 33, and the control valve 23 is opened to a certain degree. Note that the control valve 22 is connected to a negative pressure actuator 32.
Since it is opened to the atmosphere, it is temporarily rotated in the closing direction, but it is subsequently linked with the throttle valve 5 and reopened together with the throttle valve. (See Figure 15 ■). From this situation,
When the accelerator pedal is gradually released, each control valve 21,2 opens.

, 23 closes the control valves 23 and 22 one after another by following the operation opposite to the above, and finally, when the opening degree of the throttle valve 5 becomes small and the engine is in idling operation, the solenoid switching valve closes. 3
0 is demagnetized, and the state shown in FIG. (See the characteristic diagram in FIG. 16 1). Further, when the vehicle is decelerated from the high-speed or medium-speed operation state, that is, when the accelerator pedal is immediately released, the control valves 23 and 22 are sequentially closed in the same manner as described above.

However, unlike the above, the control valve 21 is fully closed without being maintained at a constant opening degree. (Refer to the characteristic diagram in Figure 16 (■)) This means that even if the negative pressure switching valve 28 is deactivated, the engine operating speed is high in the deceleration state, and the rotation switch 29 remains activated. Therefore, negative pressure does not act on the negative pressure actuator 31. In the embodiments shown in FIGS. 14 and 15 described above, the control valve 21
,2.

, 23 are sequentially opened or closed, the control valve is fully opened at their joint. This is an attempt to prevent car shock by making the control valve continuous.The basic technical idea is that the control valve 2. When the control valve 23 is opened, the opening degree of the control valve 21 is temporarily reduced at the same time as the control valve is opened, and similarly, when the control valve 23 is opened, the opening degree of the control valve 21 is temporarily reduced.
The opening degree of the control valve 22 is temporarily reduced. Therefore, in order to achieve such a technical idea, various aspects other than the specific configuration shown in the above embodiment may be adopted. For example, instead of the negative pressure switch 28, a cam may be disposed on the shaft of the throttle valve 5 and a switch operated by the cam may be used, or the electromagnetic switching valve 30 may be replaced with the rotary switch 29 alone. It can also be activated. As described above, the intake system for a multi-cylinder engine according to the present invention has an excellent riding feeling because the control valve is opened instantaneously beyond the asymmetric combustion range at the initial stage of opening of the control valve.

[Brief explanation of the drawing]

Figure 1 is a graph showing the characteristics of a conventional multi-cylinder engine equipped with a control valve, and Figure 2 is a graph showing the negative pressure characteristics at the negative pressure intake hole drilled in the intake pipe in the opening range of the throttle valve. FIG. 3 is a conceptual plan view showing the intake device for a multi-cylinder engine according to the present invention, FIG. 4 is a partial vertical sectional view thereof, and FIG. 5 is a control valve according to the embodiment of FIG. 3. A graph showing the characteristics of the opening degree. Figure 6 is a partial longitudinal sectional view showing the embodiment in Figure 3 with a flow control valve added. Figure 7 is a check valve in the embodiment in Figure 3. 8 is a conceptual plan view showing another embodiment; FIG. 9 1 is a partial longitudinal sectional view thereof; FIG. is a cross-sectional view thereof, FIG. 10 is a graph showing the opening characteristic of the control valve according to the embodiment of FIG. 8, and FIG. 11 is a graph showing another usage mode of the negative pressure actuator in the embodiment of FIG. 8. 12 is a conceptual plan view showing still another embodiment, FIG. 13 1, ■, ■ is a longitudinal sectional view showing its operating mode, and FIG. Conceptual diagram showing examples, Part 1
5 Figure 1, ■, ■ is a conceptual diagram showing its operation mode, No. 16
The figure is a graph showing the opening characteristic of the control valve according to the embodiment of FIG. 14. 119129131 Intake pipe ~ 21922923... Control valve, 31, 32, 33... Negative pressure actuator, 41
942943-0 Pressure chamber, 5゜゜throttle valve, ゜゜intake pipe section, 7...shaft, 81...throttle lever, 82
, 83... Ruber, 101, 102, 103 axis, 111
, 11.

Claims (1)

[Scope of Claims] 1. In a multi-cylinder engine that supplies air-fuel mixture to each cylinder from one throttle valve via an intake manifold, a normally closed control valve is disposed in at least a portion of the intake pipe of the manifold. At the same time, negative pressure actuators are linked to these control valves, and the pressure chambers of these negative pressure actuators are located upstream when the throttle valve is in the idling position and downstream as the throttle valve opens. 1. An intake system for a multi-cylinder engine, characterized in that the control valve is communicated with an intake pipe section located therein, and the control valve is opened by negative pressure in the intake section. 2. In a multi-cylinder engine that supplies air-fuel mixture from one throttle valve to each cylinder via an intake manifold, a normally closed control valve is provided in at least a part of the intake pipe of the manifold, and the control valve is Negative pressure actuators are linked to the valves, and the pressure chambers of these negative pressure actuators are connected to a portion of the intake pipe that is located upstream of the throttle valve when the throttle valve is in the idling position and located downstream of the throttle valve when the throttle valve is opened. The control valve is opened to a certain degree by the negative pressure of the intake portion, and after the control valve is opened, the control valve is opened in conjunction with a throttle valve. This is an intake device for a multi-cylinder engine. 3. In a multi-cylinder engine that supplies air-fuel mixture from one throttle valve to each cylinder via an intake manifold, a normally closed control valve is disposed in at least a portion of the intake pipe of the manifold, and the control valve is Negative pressure actuators are linked to the valves, and the pressure chambers of these negative pressure actuators are connected downstream of the control valve of the intake pipe via a negative pressure switching valve, and the pressure chamber of the negative pressure switching valve is connected to the throttle valve at the idling position. When the throttle valve is opened, the valve is located upstream of the throttle valve, and as the throttle valve opens, the valve is connected to the intake pipe located downstream of the throttle valve, and the negative pressure of the intake pipe operates the negative pressure switching valve. The pressure chamber of the pressure actuator is communicated with the downstream side of the control valve of the intake pipe, so that the control valve is opened to a certain degree, and after the control valve is opened, the control valve is throttled. An intake device for a multi-cylinder engine characterized by opening in conjunction with.