JP2005083330A - Intake system for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new intake system having a simple link mechanism between a main valve and a sub-valve and enabling flexible and preferable first idle control responding to operating environment or the like. <P>SOLUTION: In the intake system 10, the main valve 31 and the sub-valve 21 are respectively mounted on shafts 32, 22 arranged at intervals in an intake direction, so as to enable opening/closing of an intake flow passage by angular displacement. The main valve 31 is opened/closed linked with throttle operation, and the sub-valve 21 is opened/closed by opening control by a control means. A cam 25 is mounted on the shaft 22 of the sub-valve 21, and a lever 36 is mounted on the shaft 32 of the main valve 31. Due to this construction, when the throttle operation is not received, the main valve 31 is displaced in a closing direction and the lever 36 can contact with a circumferential face of the cam 25. The lever 36 is connected to the shaft 32 of the main valve 31 via a coil spring (buffer member) 37. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an intake device for an engine mounted on a motorcycle or the like, and relates to an intake device in which two valves (a main valve and a sub valve) are provided side by side in the intake direction.

  An intake device of an engine for an automobile or a motorcycle may be provided with a throttle body having two valves, a main valve and a sub valve. The main valve is connected to an accelerator grip, an accelerator pedal, etc., and opens and closes in conjunction with the throttle operation. The sub valve is connected to a drive motor and is controlled by an ECU (electronic control unit). The opening degree is controlled by means. In an intake device having only a main valve, the engine speed change may not be smooth due to an abrupt throttle operation, so a sub valve is provided in series with the main valve and the opening thereof is appropriately controlled. By doing so, the fluctuation of the intake air flow rate is smoothed and the engine speed is smoothly changed, thereby improving the driving feeling of an automobile or the like. However, in a motorcycle, since the engine rotation state is easily transmitted to the rider, such a merit by providing the sub-valve is more conspicuous than in an automobile (four-wheeled vehicle).

  When the intake device has two valves as described above, the idling at the start when the engine is cold, i.e., the first idle, may be performed by controlling the opening of the two valves. For example, in Patent Document 1 shown below, the first idle by the intake control device having the two valves 51 and 61 as shown in FIGS. 7A and 7B is introduced as follows.

1) A main valve (main throttle valve) 61 that opens and closes in response to a driver's operation on a throttle body to which an injector for fuel injection is attached, and a sub-valve (sub-throttle that opens and closes by motor drive according to engine operating conditions) Valve) 51.
2) The throttle body includes a driving side rotating body that rotates integrally with the shaft of the sub-valve 51, a driven side rotating body that operates the main valve 61, and an interlocking mechanism that interlocks both. As shown in FIG. 7, the driving side rotating body includes a cam lever 55, and the driven side rotating body includes a throttle pulley 63 and a stopper portion 66 provided integrally therewith. As the interlocking mechanism, there are a link bar 56, an intermediate cam 57, a stopper cam 58, and the like.
3) When the main valve 61 is closed as shown in FIG. 7 (a), if the sub valve 51 is fully opened, the rotation is transmitted via the interlocking mechanism, and the main valve 61 is shown in FIG. 7 (b). Valve 61 opens slightly. That is, when the cam lever 55 rotates together with the sub valve 51, the intermediate cam 57 is angularly displaced through the link bar 56 to rotate the stopper cam 58, and the adjusting bolt 59 attached to a part of the stopper cam 58 pushes and moves the stopper portion 66. The main valve 61 is slightly opened.
4) When the engine is cold-started (first idle), for example, the electronic control unit fully opens the sub valve 51 for a certain period of time based on the detected value from the water temperature sensor. The main valve 61 is opened by a predetermined minute angle required for the above.
JP 2002-129987 A

  The intake control device having the configuration of FIG. 7 described in Patent Document 1 has room for improvement in the following points.

  B) A mechanism (interlocking mechanism) for transmitting the change in the opening degree of the sub valve 51 to the main valve 61 requires a large number of parts, which complicates the structure and increases the cost. Specifically, the link bar 56, the intermediate cam 57, the stopper cam 58, and the like are required, as well as a shaft for attaching the cams 57 and 58, a pin for connecting the link bar 56, and the like. .

  B) The state of the first idle may vary depending on the environment in which the engine is operated. At the time of cold start, the main valve 61 opens only when the sub valve 51 is fully opened (or almost fully opened), and the opening (angle) of the main valve 61 is limited to a predetermined angle set in advance. Because. In other words, if the set opening of the main valve 61 or the like is set assuming, for example, normal temperature and normal pressure, it may be difficult to start in high altitudes or cold regions. On the contrary, if the opening degree is set according to the high altitude / cold region, the rotation speed of the first idle may be too high at normal temperature and normal pressure. An excessively high first idle speed is not preferable in terms of engine quietness, fuel consumption, environmental effects due to exhaust gas, and the like, and is disadvantageous in terms of the commercial properties of automobiles and motorcycles.

  C) It is not easy to change the specifications according to the operating environment in terms of structure and cost. In order to change the opening ratio and the opening characteristics between the sub valve 51 and the main valve 61, it is necessary to replace the above-mentioned many parts such as the link bar 56 and the intermediate cam 57, and it is difficult to change the specifications flexibly. Because.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a new intake device that has a simple interlocking mechanism between a sub-valve and a main valve, and that enables flexible and preferable fast idle control according to the operating environment.

The intake device for an engine according to claim 1 enables opening and closing of the intake flow passage by angular displacement (rotational displacement) on each shaft where the main valve and the sub valve are arranged at intervals in the intake direction. It is installed and the main valve opens and closes in conjunction with the throttle operation, while the sub valve is an engine intake device that opens and closes with the opening controlled by the control means.
a) A cam is mounted on the shaft of the sub-valve and a lever is mounted on the shaft of the main valve. When the throttle is not operated, the main valve is displaced in the closing direction and the lever can come into contact with the circumferential surface of the cam. What I did,
b) The lever is connected to the shaft of the main valve via a buffer member (an elastic member such as a spring or a shock absorber).

  In such an intake system for an engine, the interlocking mechanism between the sub-valve and the main valve is very simple, and the number of components constituting it is small. This is because the angular displacement from the sub-valve to the main valve is transmitted only by the cam and lever to be mounted as described in a) above. That is, when the cam on the shaft rotates together with the sub valve, the lever swings according to the cam profile, and the main valve is angularly displaced. The cam and the lever are attached to the shaft of the sub valve and the shaft of the main valve, respectively, and it is not necessary to provide a dedicated mounting shaft separately, so that the number of parts can be effectively reduced.

  In the above-described interlocking mechanism using the cam and the lever, the main valve when the throttle is not operated can be continuously opened and closed in a wide range according to the opening degree of the sub valve. Since the lever is continuously angularly displaced according to the cam profile as long as it contacts the circumferential surface of the cam, the main valve is also continuously angularly displaced along with the shaft to which the lever is attached. Therefore, when the first idle is performed in cold weather, if the opening degree of the sub valve is appropriately operated by the above control means, the opening degree of the main valve can be continuously controlled according to a specific purpose. It is. For example, an appropriate target speed is determined each time based on the detected coolant temperature, etc., and the actual engine speed is detected, and the engine speed is changed while changing the opening of the main valve through the sub-valve angle operation. It is also possible to perform preferable feedback control such as optimizing. If such control is performed, it is possible to eliminate the influence of so-called disturbances such as the operating environment of the engine, and it is possible to always realize the first idle at a preferable rotational speed.

  Since the interlocking mechanism between the sub valve and the main valve is simple as described above, it is possible to easily change the specifications relating to the first idle. For example, if the cam profile is changed by changing the cam, the opening ratio and the opening characteristics can be changed between both valves.

When the interlocking mechanism between the sub-valve and the main valve is simple and only a small number of parts are interposed between the two valves, in general, it is easy to cause an impact in force transmission between the two valves. Also in the device of the invention, when both valves are connected only by the cam and lever shown in a) above, for example, when the main valve is rapidly closed by a throttle operation, the lever hits the cam and a strong impact is emitted, so that May cause discomfort to the person.
However, in the intake device according to the claims, since the lever and the shaft (the shaft of the main valve) are coupled via the buffer member as described in b) above, such an impact is effectively mitigated. Further, since the buffer member is used as described above, the main valve is not completely defined by the opening degree of the sub-valve, and can be excessively displaced toward the closing side by an angle corresponding to the deformation of the buffer member. . Therefore, there is a merit that the deceleration performance can be improved by forcibly performing the throttle operation toward the closing side of the main valve.

  The intake device according to claim 2 is characterized in that an initial angle of the lever with respect to the shaft of the main valve (an angle in a static state where the buffer member does not function) can be changed by an adjusting screw. To do.

  In the intake device thus configured, it is possible to appropriately adjust the timing at which the main valve starts to open as the sub-valve opens and closes. This is because if the initial angle of the lever can be changed, each angular position of the sub-valve and the main valve when the lever starts to come into angular displacement by contacting the peripheral surface of the cam on the axis of the sub-valve can be changed. Therefore, in this intake device, the specification change of the first idle by changing the opening ratio and the opening characteristics of both valves can be performed particularly easily.

The intake device according to a third aspect is further characterized in that the cam is attached to the shaft of the sub valve in an easily replaceable manner.
Examples of easy replacement modes include, for example, a structure in which a cam is inserted into a shaft including a key and a spline, and the cam is prevented from being removed (or prevented from falling off) with a screw or the like. A mode in which the attached cam can be fixed easily.

  If the cam can be easily replaced, the opening ratio between the sub valve and the main valve and the opening characteristics can be easily changed by replacing the cam with a different profile. Then, the specification change regarding the first idle can be particularly easily performed, which is advantageous in adapting the first idle pattern to the characteristics, application, environment, etc. of the motorcycle.

The engine intake device according to claim 1 is:
-The interlocking mechanism between the sub-valve and the main valve is very simple and the number of components is small, so it can be easily configured at low cost.
-Since the main valve can be opened and closed continuously in a wide range according to the opening degree of the sub valve when the throttle is not operated, it is possible to perform preferable control for the first idle. It is easy to change the specifications for the first idol.
-Since the lever and the shaft of the main valve are connected via a buffer member, a strong impact does not occur even when the main valve is closed by a sudden throttle operation. There is also an advantage that the speed reduction performance can be improved by the action of such a buffer member.

  In the intake device according to the second aspect, it is possible to appropriately adjust the timing at which the main valve starts to open as the sub-valve opens and closes, and it is possible to easily change the specifications of the first idle.

  In the intake device according to the third aspect, it is easy to change the opening ratio and the opening characteristic between the valves by changing the cam, and the specification change regarding the first idle can be particularly appropriately performed.

  An embodiment of the invention is shown in FIGS. FIG. 1 is an overall side view of the engine 1, and FIG. 2 shows the inside of a throttle body 11 provided in an intake device 10 of the engine 1 (with a cross section opposite to the cross section shown in FIG. 1). FIG. FIG. 3 shows the throttle body 11 and the devices attached to the outside thereof by three views according to the third trigonometric method. FIG. 3 (a) is a right side view, FIG. 3 (b) is a front view, and FIG. 3 (c). Is a left side view. FIG. 4 is a rear view of the throttle body 11 and is a view taken along arrows IV-IV in FIG. FIG. 5 is a diagram showing the opening relationship between the sub valve 21 and the main valve 31, and FIG. 6 is a block diagram showing a control system at the time of first idling in the intake device 10.

  An engine 1 shown in FIG. 1 is a two-cylinder / water-cooled four-cycle engine mounted on a motorcycle (not shown). In the drawing, reference numeral 1a denotes a cylinder head, 1b denotes a crankshaft, and 1c denotes an oil pan. As shown in the drawing, an intake chamber 13 and a throttle body 11 are connected to the cylinder head 1a as an intake device 10 for supplying intake air and fuel (air mixture) to an internal combustion chamber. The throttle body 11 is provided with an injector 12 for injecting fuel into a portion of the intake passage downstream (portion close to the cylinder head 1a), and a sub valve 21 and a main valve 31 are provided in the intake passage. Are arranged in this order from the upstream side.

  The engine 1 employs so-called EFI (Electronic Fuel Injection) control in which the fuel supply amount by the injector 12 is automatically adjusted according to the state of the engine. For this reason, the engine 1 includes an ECU (Electronic Control Unit) that calculates an appropriate fuel supply amount based on detection signals from these sensors and sends an instruction signal to the injector 12 together with several sensors for detecting the driving situation. ) Is connected (reference numeral 2 in FIG. 6). As the above-described sensor, for example, in order to detect the opening degree of the sub valve 21 and the main valve 31 of the throttle body 11, opening degree sensors 24 and 34 are provided as shown in FIG. A crank angle sensor (not shown; reference numeral 3c in FIG. 6) is provided in the vicinity of the shaft end of the crankshaft 1b shown in FIG. 1, and an oil temperature sensor (not shown in FIG. 6) is provided in the oil pan 1c. It is also provided. Similarly, although not shown, the engine 1 includes an atmospheric pressure sensor (reference numeral 3b in FIG. 6) for detecting atmospheric pressure, a water temperature sensor for detecting the cooling water temperature of the engine 1, and the temperature and pressure of intake air. An inspiratory temperature sensor and an intake pressure sensor are also provided.

  As shown in FIG. 2, the sub-valve 21 and the main valve 31 in the throttle body 11 are butterfly valves whose opening degree is changed by rotating circular plates (valve bodies) attached to the shafts 22 and 32, respectively. The main valve 31 is attached along the center line of the shaft 32 disposed at the center of the flow path of the throttle body 11, and the sub valve 21 is also several mm from the center line of the shaft 22 at the center of the flow path ( The main valve 31 is attached at a location that is eccentric by an amount equivalent to the plate thickness). Both valves 21 and 31 are arranged with a large distance in the flow path direction (distance between the shafts). When both valves are fully opened, both valve bodies are positioned by the amount of eccentricity as shown in the figure. They are parallel to each other and are in a positional relationship where a part of both are in contact with each other.

  Since two intake passages are formed in parallel in the throttle body 11 as shown in FIG. 4, there are two sub-valves 21 and two main valves 31 provided for each passage. Each of the sub valves 21 is mounted on a common shaft 22, and a stepping motor 23 as a drive unit 20 is connected to one end of the shaft. As with the sub valve 21, the main valve 31 (FIG. 2) is also mounted on a common shaft 32, and a throttle pulley 33 as a drive unit 30 is provided at one end of the shaft.

  The throttle pulley 33 is connected with two throttle cables 33a and 33b shown in FIG. 3A, which are connected to a throttle grip (not shown) of the motorcycle. When one throttle cable 33a is pulled by a throttle grip operation (throttle operation), the main valve 31 rotates together with the throttle pulley 33 to open the flow passage in the throttle body 11, and when the other throttle cable 33b is pulled, Conversely, the throttle pulley 33 and the main valve 31 rotate in a direction to close the flow path. The throttle pulley 33 is provided on the throttle body 11 via a coil spring 33d as shown in FIG. 3B, and receives a force from the spring 33d when the throttle is not operated to close the main valve 31. Returned to

  The opening of the sub valve 21 is controlled by the stepping motor 23 (see FIGS. 3 and 4) connected as described above and the control means 2 (the ECU, see FIG. 6) for controlling the motor 23. Is controlled. The sub-valve 21 is operated to an appropriate opening suitable for the driving situation detected by the various sensors so that unpleasant acceleration / deceleration or the like does not occur even when the main valve 31 is suddenly opened and closed by the throttle operation. is there.

  In the intake device 10 shown in FIG. 3 and the like, the idling at the time of cold start called first idle is controlled by using the sub-valve 21 and the main valve 31 and their drive units 20 and 30 to control the engine speed. While trying to do. The outline of the control is that the opening degree of the main valve 31 which is returned to the closing direction so as not to receive the throttle operation is controlled together with the opening degree of the sub valve 21 via the stepping motor 23 which is the driving unit 20 of the sub valve 21. That is. The configuration for such control and details of the control are as follows.

  First, as shown in FIG. 3A, the cam 25 is attached to the shaft 22 of the sub-valve 21 outside the throttle body 11 so as to rotate integrally with the sub-valve 21, and the lever 36 is attached to the shaft 32 of the main valve 31. To get in touch. That is, the lever 36 is attached so as to rotate together with the main valve 31 around the shaft 32, and is not returned to the right side in FIG. 3A because the throttle valve is not operated so that the main valve 31 is on the closed side. Each position is determined such that the roller 36 a provided at the tip of the lever 36 contacts the peripheral surface of the cam 25. A profile is formed on the circumferential surface of the cam 25 such that the radius gradually increases when the sub-valve 21 is rotationally displaced in the direction of opening from the fully closed state (counterclockwise in FIG. 3A). As a result, when the sub valve 21 changes its opening when the throttle operation is not performed, the cam 25 moves the lever 36 and the main valve 31 continuously changes the opening. If the opening degree of the main valve 31 is changed together with the sub valve 21 in this way, it is possible to realize an appropriate first idle by controlling the opening degree of the sub valve 21 using the stepping motor 23. In addition, since the length of the lever 36 (from the shaft 32 of the main valve 31 to the roller 36a at the front end) is sufficiently longer than the amount of change in the radius of the cam 25, it changes while contacting the cam 25 as described above. The angle range of the lever 36 and the main valve 31 is small (from the fully closed state to a maximum of 2 to 3 °).

  As shown in FIG. 2, the opening and closing of the sub valve 21 by the stepping motor 23 can be performed in a range from a fully closed state to a state slightly exceeding the fully opened state. That is, the sub-valve 21 exceeds the fully closed state (position A in the figure) beyond the 100% opening state (position B in the figure) in which the surface of the plate that is the valve body is parallel to the direction of the intake flow. The angle can be displaced up to an extra rotation of about 5 ° (C position in the figure). If the opening / closing angle range is set in this way, the sub-valve 21 can surely be fully opened, and an error in manufacturing or assembly of the valve main body, the shaft 22, or other parts in the drive unit 20. Even if there is, it will be fully open without hindrance. Since the cam 25 shown in FIG. 3A is also rotationally displaced together with the sub valve 21, the radius of the contact point with the lever 36 to an angle corresponding to the maximum angular displacement of the sub valve 21 (position C in FIG. 2). The cam profile is set to increase.

Regarding the opening and closing of the main valve 31 by the action of the cam 25 and the lever 36 in contact therewith, the following configuration is also employed.
That is, first, the shaft 32 of the main valve 31 and the lever 36 are connected via a buffer mechanism including a coil spring (buffer member) 37 shown in FIG. More specifically, while the rotating frame 35 is integrally attached to the shaft 32 and the throttle pulley 33, a lever 36 is attached so as to be able to rotate relative to the shaft 32 and the like. The projecting piece 36b provided integrally on the side opposite to the tip end portion is put into the frame of the rotating frame 35 together with the coil spring 37 which is mounted by being compressed. By doing so, the lever 36 rotates together with the shaft 32 and the throttle pulley 33 while being restrained by the rotating frame 35 and the coil spring 37. When the main valve 31 is returned to the closed side by an abrupt throttle operation, the lever 36 quickly rotates clockwise in FIG. 3A and hits the cam 25, but the coil spring 37 exhibits a buffering action. The impact at the time is small. Also, with this configuration, when the throttle grip (not shown) is strongly operated to the deceleration side, the main valve 31 is forced closer to the closing side than the opening degree defined by the cam 25 of the sub-valve 21 by the contraction of the coil spring 37. There is also an advantage in terms of deceleration performance that it can be displaced.

  The second additional configuration relating to the opening and closing of the main valve 31 by the cam 25 and the lever 36 is the adjustment screw 38 shown in FIG. 3B and the like at the timing when the lever 36 contacts the cam 25 and the main valve 31 starts to open. It can be changed as appropriate. The adjusting screw 38 is attached to the rotating frame 35 that rotates integrally with the shaft 32 of the main valve 31 (attached with a spring for preventing loosening), and its tip is placed in the frame of the rotating frame 35. The lever 36 is brought into contact with the protruding piece 36b. For example, if the angle position (initial angle) of the lever 36 is changed so as to retract the coil spring 37 by pushing the screw 38, the lever 36 (roller 36a) with the main valve 31 closed is slightly separated from the cam 25. The cam 25 starts moving the lever 36 to open the main valve 31 only when the sub-valve 21 is displaced slightly to the opening side. In the case of the intake device 10, as shown in FIG. 5, the main valve 31 that is closed because the throttle is not operated is set to start to open when the opening degree of the sub-valve 21 reaches about 40%.

  A third additional configuration relating to the opening and closing of the main valve 31 is that the cam 25 is mounted on the shaft 22 of the sub-valve 21 so that it can be easily replaced. The cam 25 is attached to the shaft 22 by inserting it with a key (or forming a spline) and fixing it with a nut 26 or the like as shown in FIG. When the nut 26 and the like are removed and the cam 25 is extracted from the shaft 22, a new cam 25 is inserted into the shaft 22 and the nut 26 and the like are mounted again, the replacement of the cam 25 is completed. When the cam 25 having a different profile is used, the mode of the first idle performed through the adjustment of the opening degree of the sub valve 21 is different. Thus, the replacement of the cam 25 is easy because the first idle pattern is characteristic of the motorcycle. It is directly connected to the advantage that it is easy to adapt to the usage, environment, etc.

In the engine 1 of FIG. 1 having the intake device 10 as described above, the control at the start including the first idle is performed as in the following i) to v).
i) When the main switch (not shown) of the engine 1 is turned on, the control means 2 (ECU, see FIG. 6) is activated. The control means 2 resets the angular displacement of the sub-valve 21 as an initialization operation, and stores the atmospheric pressure and the water temperature (or oil temperature) input from each of the aforementioned sensors.

  ii) Based on the above atmospheric pressure and water temperature (or oil temperature), the control means 2 determines the initial opening degree of the main valve 31 for the first idle from a map stored in advance in the ROM (storage section of the control means 2). The stepping motor 23 is driven so that the main valve 31 has such an initial opening, the sub-valve 21 is rotated, and the state is put on standby.

  iii) When a starter switch (not shown) is turned on, the engine 1 is started by a starter motor (not shown). Since the opening degree of the sub valve 21 and the main valve 31 at this time is the appropriate initial opening degree set in the above ii), there is no inconvenience that the engine speed becomes too high at the start.

iv) When the control means 2 determines that the engine 1 has started based on a signal from the crank angle sensor 3c or the like, the first idle with feedback control based on the engine speed is started. The control to be performed will be described as follows according to the block diagram shown in FIG.
1) The control means 2 receives signals from the oil temperature sensor 3a and the atmospheric pressure sensor 3b by the input unit 2a, and determines a target rotation speed (set rotation speed) in the calculation unit 2b based on the signals.
2) The actual engine speed is detected by the crank angle sensor 3c, and the signal is returned to the comparison unit 2c of the control means 2 and compared with the signal of the target speed described above.
3) Based on the difference (control deviation) obtained by the comparison, the adjustment unit 2d of the control means 2 determines an appropriate operation amount and sends it to the operation unit 2e.
4) The operation unit 2e operates the opening degree of the sub valve 21 by rotating the stepping motor 23 shown in FIG. 3 or the like by an appropriate angle corresponding to the operation amount.
5) Since the angle of the cam 25 in FIG. 3 (a) changes according to the opening degree of the sub valve 21, the opening degree of the main valve 31 changes from the relationship with the lever 36, so that the rotational speed (rpm) of the engine 1 is the target. It changes to approach the number of revolutions.
6) The changed engine speed is detected by the crank angle sensor 3c, and it is compared with the target speed determined by the control means 2 in accordance with the oil temperature and the atmospheric pressure that change every moment, and only the appropriate amount corresponds. The control of operating the motor 23 is continued. Thereby, in the engine 1, a fast idle at an appropriate number of revolutions according to the driving environment and the warm-up situation is realized.

  v) When the control means 2 determines that the oil temperature sensor 3a or the water temperature sensor has sufficiently warmed up, or when a considerable time (3 to 5 minutes) has elapsed via a timer (not shown) If this is the case, the first idle is terminated, and a transition is made to normal idling at an idle speed preset by the user with an idle screw (not shown). Note that even when a motorcycle mission is entered for traveling, the first idle is terminated for the purpose of utilizing the effect of engine braking. As long as the oil temperature and water temperature are equal to or higher than a certain temperature, the first idle is not considered unnecessary even when the engine is stopped and restarted after warming up.

Note that the initial opening degree of the main valve 31 set in the above ii) and the target rotational speed set in the above iv) are not realized when the sub-valve 21 is fully opened, but at least at normal temperature and normal pressure (15 ° C. In the operating environment of 1 atm), the relationship between the drive units 20 and 30 is defined for the sub valve 21 and the main valve 31 so as to be realized when the opening degree of the sub valve 21 is about 80% maximum. That is, the respective opening degrees of the sub valve 21 and the main valve 31 change only in the range (Y _{1 to} Y ₃ ) in the normal fast idle according to the relationship of the thick line Y ₁ Y ₂ Y ₃ shown in FIG. It will be. As described above, if the sub valve 21 can be in a suitable state at a stage where the sub valve 21 is less than fully open, the accuracy of processing or assembly of the valves 21 and 31 and their drive units 20 and 30 is not high. In addition, the first idle control can be appropriately performed. The line from X ₁ to X ₂ shown in FIG. 5 indicates when the sub-valve 21 is angularly displaced from the fully closed state (position A in FIG. 2) to an angle exceeding the 100% opening (position C in FIG. 2). If the lever 36 is kept in contact with the cam 25 (having a certain standard profile), it is a line indicating the opening degree brought to the main valve 31 (the opening degree of the main valve 31 is 0 or less) An angular displacement in the direction opposite to the opening side).

1 is a side view showing an entire engine 1 as an embodiment of the invention. A part of the intake device 10 is shown in cross section. 2 is a longitudinal sectional view showing the inside of a throttle body 11 provided in an intake device 10 in the engine 1 of FIG. 1 (shown in a cross section opposite to the cross section shown in FIG. 1). The throttle body 11 and the devices attached to the outside thereof are shown in FIGS. 3A, 3B and 3C according to the third trigonometric method. 3A is a right side view, FIG. 3B is a front view, and FIG. 3C is a left side view. FIG. 4 is a rear view of the throttle body 11 and is a view taken along arrows IV-IV in FIG. FIG. 3 is a diagram showing a relationship between opening degrees of a sub valve 21 and a main valve 31 of the intake device 10. 2 is a block diagram showing a control system at the time of first idle in the intake device 10. FIG. FIG. 7 is a side view showing a conventional intake device, and FIGS. 7A and 7B show the structure and operation of the sub valve 51, the main valve 61, and the interlocking mechanism between them.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Control means 3a * 3b * 3c Sensor 10 Intake device 11 Throttle body 20 Sub valve drive part 21 Sub valve 22 Shaft 23 Stepping motor 25 Cam 30 Main valve drive part 31 Main valve 32 Shaft 33 Throttle pulley 36 Lever 37 Coil spring (buffer member) )
38 Adjustment screw

Claims (3)

A main valve and a sub-valve are mounted on each axis arranged at intervals in the intake direction so that the intake passage can be opened and closed by angular displacement, and the main valve opens and closes in conjunction with the throttle operation. The sub-valve is an engine intake device that opens and closes when the opening is controlled by the control means,
A cam is mounted on the shaft of the sub-valve and a lever is mounted on the shaft of the main valve. When the throttle valve is not operated, the main valve is displaced in the closing direction and the lever can contact the circumferential surface of the cam. about,
And an intake device for an engine, wherein the lever is connected to the shaft of the main valve via a buffer member.   2. The engine intake device according to claim 1, wherein an initial angle of the lever with respect to a shaft of the main valve is changeable by an adjusting screw. The intake system for an engine according to claim 1 or 2, wherein the cam is attached to the shaft of the sub valve in an easily replaceable manner.

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