Throttle valve control apparatus

Throttle valves are individually disposed in a plurality of intake passages of an engine. In normal operation condition of the throttle valves, a first control device controls the throttle valves according to the detection result of an operation condition detecting device to control the amounts of intake air of the individual intake passages, thereby obtaining good engine performance from low-speed to high-speed ranges. When an abnormality detecting device detects an abnormality in a throttle valve, a determination device determines a normal throttle valve, and a second control device controls only the normal throttle valve in preference to the first control device to control the intake air amount, thereby ensuring continued operation even if a malfunction occurs in one of the throttle valves. Also, intake passages of the engine are divided into two systems and are individually connected with surge tanks, a communication passage communicating with the surge tanks and a communication control valve ae provided, throttle valves and intake control valves are disposed in the individual passages, and the throttle valves, the communication control valve and the intake control valves are open/closed controlled by the operation condition detecting device and control device, thereby obtaining good engine performance and ensuring continued operation of the engine even if a malfunction occurs in the throttle valve control system, to maintain the stability of the vehicle.

FIELD OF THE INVENTION 
This invention relates to a throttle valve control apparatus of a so-called 
drive by wire (DBW) type which drives a throttle valve to open and close 
an air intake passage of an engine by a motor. 
BACKGROUND OF THE INVENTION 
Recently, in most of gasoline engines used in passenger cars, the fuel 
supply amount, ignition timing and the like are electronically controlled 
in view of pollution control of exhaust gas and in order to assure the 
engine performance such as output. The carburetor and throttle valve of an 
electronic fuel injection device have heretofore been opened and closed 
according to the intention of the driver through a cable directly 
connected to the acceleration pedal. However, with the advance of 
auto-cruising devices and mechanical automatic transmissions, there has 
been developed a DBW type throttle valve control apparatus which 
electronically controls the throttle valve by an electric actuator such as 
a servo motor. 
In general, in this type of throttle valve control apparatus, various data 
such as the clutch connection condition and intake air temperature, in 
addition to the pressing-down amount of the acceleration pedal, are 
processed by a microprocessor to control the throttle valve to an optimum 
opening according to the current running condition of the vehicle. As a 
result, while an auto-cruising device is in operation, for example, the 
throttle valve opening can be automatically controlled so that the vehicle 
speed is maintained at a preset value regardless of the load conditions 
such as running on an ascending slope, or, in a clutch-off state in a 
mechanical automatic transmission, the throttle valve can be easily closed 
independently of the operation amount of the acceleration pedal. 
However, in a DBW type throttle valve control apparatus, there may a case 
in which the throttle valve opening becomes uncontrollable due to a 
malfunction of its control system including the motor. 
To cope with such a case, there is a method in which the throttle valve is 
provided with a return spring to urge the throttle valve to the closing 
direction, and, when a malfunction occurs, the throttle valve is fully 
closed by the force of the spring. However, with this method, there may be 
a case in which desired output characteristics cannot be obtained when a 
malfunction occurs, resulting in an impaired running stability of the 
vehicle. 
SUMMARY OF THE INVENTION 
With a view to eliminate the prior art problems, it is a primary object of 
the present invention to provide a throttle valve control apparatus for an 
engine which, when a malfunction occurs, continues operation to assure the 
running stability of the vehicle and provides a good engine performance 
during normal operation. 
In accordance with the present which attains the above object, there is 
provided a throttle valve control apparatus comprising an engine mounted 
on a vehicle, an intake passage unit divided into at least two air intake 
systems for forming intake passages to supply air to the engine, throttle 
valves disposed in the individual intake passages, operation condition 
detecting means for detecting the operation condition of the vehicle, 
first control means for controlling the amount of air taken into the 
engine by open/close controlling the throttle valves according to the 
operation condition of the vehicle detected by the operation condition 
detecting means, abnormality detecting means for detecting an abnormality 
in any of the throttle valves to output a detection result, a 
determination means for determining a normal throttle valve from the 
detection result of the abnormality detecting means when an abnormality is 
detected in any of the throttle valves by the abnormality detecting means 
to output a determination result, and second control means for controlling 
the amount of air supplied to individual cylinders of the engine by 
controlling only a normal throttle valve determined by the determination 
means when an abnormality is detected in any of the throttle valves 
according to the operation condition of the vehicle detected by the 
operation condition detecting means in preference to the first control 
means. 
Thus, in normal operation of the vehicle, the first control means 
open/close controls the individual throttle valves of the individual 
intake passages according to the operation conditions detected by the 
operation condition detecting means, thereby functioning as a variable air 
intake system. 
When a malfunction occurs in the control system of one of the throttle 
valves of the intake passages, the abnormality detecting means detects the 
malfunction, the determination means determines a normal throttle valve, 
the second control means open/close controls the normal throttle valve 
according to the operation condition detected by the operation condition 
detecting means, thereby maintaining a normal operation of the vehicle. 
There is also provided according to the present invention a throttle valve 
control apparatus comprising an engine mounted on a vehicle, a first 
divided passage unit comprising two first divided passages, two surge 
tanks individually and independently connected to the downstream of the 
first divided passages of the first divided passage unit, a communication 
passage providing communication between the surge tanks, a communication 
control valve to open and close the communication passage, a second 
divided passage unit comprising second divided passages individually and 
independently connected to the downstream of the surge tanks, intake air 
control valves disposed in the individual second divided passages, 
confluence passages formed to join the second divided passages of the 
second divided passage unit and communicating with individual cylinders of 
the engine, throttle valves disposed in the individual first divided 
passages of the first divided passage unit, operation condition detecting 
means for detecting the operation condition of the vehicle, and control 
means for open/close controlling the throttle valves, the communication 
control valve, and the intake air control valves according to the 
operation condition of the vehicle detected by the operation condition 
detecting means. 
Thus, in normal operation of the vehicle, the control means open/close 
controls the individual intake air control valves and the communication 
control valve according to the operation condition of the vehicle detected 
by the operation condition detecting means to obtain an inertial air-boost 
effect or a resonant air-boost effect in both the low-speed and high-speed 
ranges. 
When a malfunction occurs in the control system of one of the throttle 
valves of the intake passages, the control means open/close controls the 
individual intake air control valves and the communication control valve 
to open/close control a normal throttle valve, thereby maintaining a 
normal operation condition of the vehicle.

DETAILED DESCRIPTION OF THE INVENTION 
A first embodiment of the throttle valve control apparatus according to the 
present invention will now be described with reference to FIG. 1 to FIG. 
3. 
As shown in FIG. 1, an engine 11 used in this embodiment is a 4-cylinder 
engine, provided with an air intake unit forming intake passages 
comprising two divided air intake systems to supply air to the engine 11. 
Specifically, each cylinder 12 is provided with two intake ports 12a and 
12b individually for low speed and high speed, and has intake valves (not 
shown). Exhaust ports are not shown. 
The individual low-speed intake ports 12a are connected with relatively 
long low-speed passages 13 as a divided passage unit, and these 
communicate with a surge tank 14 as a common confluence passage unit. The 
individual high-speed ports 12b are connected with high-speed passages 15 
as a divided passage unit which are shorter than the low-speed passages 
13, and these communicate with a surge tank 16 as a common confluence 
passage unit. 
An air intake hole is provided with an air cleaner 17, and an air flow 
sensor 19 is disposed in an adjacent common passage 18. The passage 18 is 
divided into passages 20 and 21, which individually communicate with the 
surge tanks 14 and 16. Individual throttle valves 22 and 23 are attached 
to the throttle valves 22 and 23 to control the flow rates of air. 
Thus, the low-speed intake port 12a and the high-speed intake port 12b have 
the common air intake hole, but individually have independent intake 
passages comprising respectively the passage 20, the surge tank 14 and the 
passage 13; and the passage 21. the surge tank 16 and the passage 15, and 
the individual intake passages have throttle valves 22 and 23. 
Then, the throttle valves 22 and 23 will be described, but since these are 
same in structure, description will be made with reference to a single 
drawing. 
As shown in FIG. 2, a throttle valve 22 (23) is rotatably disposed halfway 
in the passage 20 (21), and its opening is varied with its rotational 
angle position. A throttle position sensor 25 for detecting the opening is 
attached to one end of a rotating shaft of the throttle valve 22 (23), and 
the other end is connected to a drive shaft of a servo motor 26 (27) fixed 
to a frame (not shown). 
Furthermore, a return spring 28 as a torsion coil spring is wound around 
the rotating shaft 24 to urge the throttle valve 22 (23) towards the 
full-closed position. Thus, the throttle valve 22 (23) is opened by the 
driving force of the servo motor 26 (27) against the force of the return 
spring 28, and is fully closed when the servo motor 26 (27) does not 
operate. 
Fuel injection valves can be located, for example, as in an SPI system, in 
which the valves are disposed in the common passage 18, in a 2-way SPI 
system, in which the valves are disposed at upstream sides of the throttle 
valves 22 and 23, or in a 2-way MPI system, in which the valves are 
disposed individually in the low-speed passage 13 and the high-speed 
passage 15 of each cylinder 12. 
The throttle valve control system will now be described. 
The throttle valve control apparatus of this embodiment comprises operation 
condition detecting means comprising acceleration pedal operation amount 
detecting means and engine operation condition detecting means, first 
control means for controlling intake air amount by open/close controlling 
the throttle vale according to the acceleration pedal operation amount and 
the load condition or the rotation speed of the engine when all of the 
throttle valves are normal, abnormality detecting means comprising 
throttle valve opening detecting means, opening deviation calculation 
means, integrating calculation means, and abnormality determination means, 
determination means for determining a normal throttle valve according to 
the detection result of the abnormality detecting means, and second 
control means for controlling the intake air amount by fully closing the 
abnormal throttle valve and controlling only the normal throttle valve in 
preference to the first control means. 
With this arrangement, in a low-speed operation, the throttle valve 23 of 
the high-speed intake passage side is fully closed, and intake air control 
is made only by open/close controlling of the throttle valve 22 of the 
low-speed intake passage side. As a result, since the intake passage is 
small in cross section and long in length in low-speed operation, a 
pulsation effect of intake air in the low-speed range can be sufficiently 
utilized to improve the output torque. 
In high-speed operation, on the other hand, intake air control is made with 
the throttle valve 23 of the high-speed intake passage side opened in 
addition to the low-speed side. As a result, in high-speed operation, the 
intake passage cross section is increased, the intake resistance is 
reduced, and the passage length is reduced, the pulsation effect of intake 
air can be utilized up to the high-speed rotation range. 
When any of the control systems of the motors 26 and 27 to drive the 
throttle valve 22 and 23 malfunctions, power supply is stopped to the 
motor 26 or 27. By the action of the return spring 28, the malfunctioned 
throttle valve 22 or 23 is fully closed to close the intake system of the 
malfunctioned side. Thereafter the normal side motor 27 or 26 is operated 
to make intake control, thereby continuing operation. Therefore, operation 
of the vehicle can be assured to run by itself at least to a repair shop 
even if a malfunction occurs in one of the control systems. 
Determination of whether or not a malfunction occurs in a throttle valve 
control system is made as follows. 
The operation condition detecting means detects a measured value of 
throttle opening from a target throttle opening and the throttle position 
sensor 25, and the abnormality detecting means calculates and outputs a 
difference between the target throttle opening and the measured value. The 
determination means determines whether or not the calculated value exceeds 
a certain value and, if exceeds, it determines a malfunction in the 
control system of a throttle valve because the throttle valves 22 and 23 
do not follow. And, the second control means controls only the abnormal 
throttle valve in preference to the first control means to control the 
amount of intake air. 
FIG. 3 shows an example of malfunction determination flow chart. 
In FIG. 3, in view of a response delay of valve, target opening 
.theta..sub.t is passed through a primary filter and compared with 
measured opening .theta..sub.m. First, in step S1, target filter value 
.theta..sub.te is calculated from previously calculated .theta..sub.te 
using the equation .theta..sub.te =.alpha..theta..sub.te 
+(1-.alpha.).theta..sub.t, wherein .alpha. is a filter constant which is 
selected within the range 0.ltoreq..alpha.&lt;1. In step S2, difference 
.DELTA..theta. between the target filter value .theta..sub.te and the 
measured opening .theta..sub.m is determined, and, in step S3, whether or 
not the difference .DELTA..theta. is smaller than allowable deviation 
.epsilon..sub.0 is determined. When the difference .DELTA..theta. is 
smaller than the allowable deviation .epsilon..sub.0, integrated deviation 
S is set to a value subtracted by integrated deviation reduction value 
.epsilon..sub.1 in step S4. When, in step S3, the difference 
.DELTA..theta. is greater than the allowable deviation .epsilon..sub.0, 
the integrated deviation value S is set to a value increased by 
.epsilon..sub.0. 
Then, in step S6, whether or not the integrated deviation value S is 
greater than integrated deviation limit .epsilon..sub.2 is determined. If 
greater, it is determined as a malfunction, and a throttle malfunction 
flag is set in step S7. If smaller, the flag is reset in step S8. 
This malfunction determination is made for each throttle valve. 
In the embodiment shown in FIG. 1, the throttle valves 22 and 23 are 
disposed at the upstream side of the individual surge tanks 14 and 16. 
However, alternatively, these may be disposed as port valves at the 
downstream side of the surge tanks. 
FIG. 4 is a schematic view showing part of the air intake system of the 
engine of a second embodiment according to the present invention. In FIG. 
4, the same portions or those having the same functions as those in FIG. 1 
are indicated by the same reference marks. As shown in FIG. 4, in this 
embodiment, the individual low-speed passages 13 and the individual 
high-speed passages 15 are provided with the throttle valves 22 and 23. 
A plurality of throttle valves 22 disposed in the individual low-speed 
passages 13 are linked with a common drive shaft 29 to move simultaneously 
and opened and closed by the servo motor 26 connected to one end of the 
drive shaft 29. Similarly, a plurality of throttle valves 23 disposed in 
the individual high-speed passages are linked with a common drive shaft 30 
and opened and closed by the servo motor 27 connected to one end of the 
drive shaft 30. The drive shafts 29 and 30 are individually provided with 
return springs (not shown) urging the throttle valves 22 and 23 towards 
the closing directions. 
Also with this arrangement, as in the previous embodiment, in normal 
operation the throttle valves 22 and 23 are independently controlled to 
obtain good engine performance from the low-speed range to the high-speed 
range, and, continued operation is possible even if a malfunction occurs 
in one of the control systems of the motors 26 and 27. 
A third embodiment of the throttle valve control apparatus according to the 
present invention will now be described with reference to FIG. 5 and FIG. 
6. Parts and components having the same functions as in the 
above-described embodiments are indicated by the same reference marks and 
detailed description thereof is omitted. 
As shown in FIG. 5, this embodiment is applied to a V-type 6-cylinder 
engine, in which a surge tank 41 forming an intake passage unit is divided 
inside by a partition wall 42 into chamber A and chamber B, and the 
individual chambers communicate with three each of intake pipes 43 and 44. 
The intake pipes 43 and 44 communicate with cylinders (not shown) of the 
engine, a group of three of six cylinders connecting through the intake 
pipes 43 to the chamber A of the surge tank 41, and a group of three of 
six cylinders connecting through the intake pipes 44 to the chamber B of 
the surge tank 41. 
The surge tank 41 is connected with conduits 45 and 46 individually 
communicating with the chamber A and the chamber B, and intake air is 
introduced into the surge tank 41 through the conduits 45 and 46. These 
conduits 45 and 46 are individually provided with throttle valves 47 and 
48, and the amounts of intake flowing through the individual conduits 45 
and 46 are controlled according to the openings of these throttle valves 
47 and 48. 
Thus, the six cylinders are divided into two groups of three cylinders, 
each having an independent air intake system, and have throttle valves 47 
and 48 which are independently controlled. 
These throttle valves 47 and 48 are the same in structure as the 
above-described throttle valves, and detailed description thereof is 
omitted. 
The partition wall 42 of the surge tank 41 is provided with a communication 
hole 49 as a communication portion, where a shutter valve 50 as a 
communication control valve is mounted. The two chambers are made 
communicating with each other and isolated according to the open/close 
operation of the shutter valve 50. 
While the throttle valves 47 and 48, of which openings are required to be 
delicately controlled, are driven by the servo motors 26 and 27, the 
shutter valve 50 is sufficient to achieve fully-open and fully-closed 
states and can thus be driven by a simple drive unit (not shown). For 
example, a diaphragm type vacuum actuator utilizing a negative pressure of 
intake air or the like can be inexpensively used. 
Then, the control systems of the throttle valves will now be described. 
The throttle valve control apparatus of this embodiment comprises operation 
condition detecting means comprising acceleration pedal operation amount 
detecting means and engine operation condition detecting means, first 
control means having throttle valve control means for controlling throttle 
valves according to the acceleration pedal operation amount and intake 
control means for open/close controlling a communication control valve 
(shutter valve 50) according to the engine operation condition, 
abnormality detecting means for detecting an abnormality of the throttle 
valves, determination means for determining a normal throttle valve 
according to the detection result of the abnormality detecting means, and 
second control means for controlling the intake air amount by fully 
closing the abnormal throttle valve according to the detection result of 
the determination means and fully closing the communication valve to 
control only the normal throttle valve in preference to the first control 
means. 
With this arrangement, in low-speed operation, as shown in FIG. 6(a), the 
shutter valve 50 is closed to partition the surge tank 41 and intake air 
to the individual intake pipes 43 and 44 is controlled by the throttle 
valves 47 and 48. In this case, intake air pulsation passes through the 
portion indicated by the arrow L, and the resonant air-boost rotation 
range is shifted to the low-speed side, thereby improving the output 
torque in the low-speed range. 
In high-speed operation, as shown in FIG. 6(b), the shutter valve 50 is 
opened to make communication between the two partitioned chambers of the 
surge tank 41. As a result, intake air pulsation passes through the 
portion indicated by the arrow H, and the resonant air-boost rotation 
range is shifted to the high-speed range, thereby improving the output 
torque in the high-speed range. 
Now, a case when a malfunction occurs in one of the throttle valves 47 and 
48 will be described. 
Suppose that a malfunction occurs in the control system and the throttle 
valve 47 or 48 is fully closed by the return spring 28. If, for example, 
the throttle valve 47 is fully closed and becomes uncontrollable, the 
shutter valve 50 is opened to make intake air control by the normal 
throttle valve 48, as shown in FIG. 6(c). As a result, operation of the 
engine can be continued without discontinuing operation of the two 
cylinder groups. In this case, alternatively, the shutter valve 50 may be 
closed to discontinue operation of the cylinder group which intakes air 
through the intake pipe 43. 
When an uncontrollable condition occurs with the throttle valve 47 or 48 
opened, due to jamming of a foreign substance or the like; for example, 
the throttle valve 47 is fixed in the open state, as shown in FIG. 6(d), 
the shutter valve 50 is closed, and fuel supply is stopped to the cylinder 
group handled by the throttle valve 47, which intakes air through the 
intake pipe 43, to discontinue the operation of that cylinder group. 
Intake air control of the remaining cylinder group is made by the throttle 
valve 48 through the intake pipe 44. This prevents the occurrence of a 
runaway condition and ensures continued operation. 
A malfunction in the throttle control system can be determined as described 
above. Furthermore, that the malfunction occurs with the throttle valve 
opened or closed can be determined from whether or not the idle switch is 
on, or, whether or not the throttle position sensor output exceeds a 
predetermined value. 
A third embodiment of the throttle valve control apparatus according to the 
present will now be described with reference to FIG. 7 and FIG. 8. Parts 
and components having the same functions as in the above-described 
embodiments are indicated by the same reference marks and detailed 
description thereof is omitted. 
As shown in FIG. 7, a surge tank 51 disposed in the air intake system of 
the engine is internally divided by a partition wall 52 into chambers A 
and B. 
This partition wall 52 is provided with a communication passage to make 
communication between the two chambers, and a shutter valve 53 as a 
communication control valve is provided in the communication passage. The 
two chambers communicate with each other or separated from each other by 
open/close operation of the shutter valve 53. 
The surge tank 51 is connected with conduits 54 and 55 as a first divided 
passage unit to communicate respectively with the chamber A and the 
chamber B, and intake air is introduced into the surge tank 51 through the 
conduits 54 and 55. The conduits 54 and 55 are individually mounted with 
throttle valves 56 and 57, and the amounts of air flowing in the 
individual conduits 54 and 55 are controlled according to the opening of 
the throttle valves 56 and 57. 
Furthermore, the surge tank 51 is connected with intake pipes 58 and 59 as 
a second divided passage unit individually communicating with the chamber 
A and the chamber B, connected at the downstream sides with respect to the 
air flowing direction. These intake pipes join at their common ends to 
form confluence passages, which supply air to the combustion chambers of 
the engine (not shown). These intake pipes 58 and 59 differ in length from 
each other, the intake pipe 58 being relatively shorter for use as a 
high-speed passage, and the intake pipe 59 being relatively longer for use 
as a low-speed passage. The individual intake pipes 58 and 59 are provided 
with variable intake valve 60 and 61 as intake control valves, which are 
opened and closed to open and close the individual intake pipes 58 and 59. 
The throttle valves 56 and 57 are the same in structure as the 
above-described throttle valves, and detailed description thereof is 
omitted. 
Then, the throttle valve control system will now be described. 
The throttle valve control apparatus of this embodiment comprises operation 
condition detecting means comprising acceleration pedal operation amount 
detecting means and engine operation condition detecting means, and 
control means comprising throttle valve control means for controlling 
throttle valves according to the acceleration pedal operation amount and 
intake control means for open/close controlling a communication control 
valve (shutter valve 53) and intake control valves (variable intake valves 
60 and 61). 
With this arrangement, in low-speed operation of the vehicle, as shown in 
FIG. 8(a), a variable intake valve 60 of a high-speed intake pipe 58 is 
closed and a variable intake valve 61 of a low-speed intake pipe 59 is 
opened to intake air using only the low-speed intake pipe. As a result, 
because the intake passage is small in the cross sectional area and long 
in length in the low-speed range, the output torque can be increased due 
to an inertial air-boost effect. 
In high-speed operation of the vehicle, as shown in FIG. 8(b), the variable 
intake valves 60 and 61 are both opened to intake air through both the 
intake pipes 58 and 59. As a result, the intake passage cross sectional 
area is increased in the high-speed range, and the inertial air-boost 
range is shifted to the high-speed range, thereby increasing the output 
torque. In this case, alternatively, the variable intake valve 61 of the 
low-speed intake pipe 59 may be closed to use only the high-speed intake 
pipe 58. 
To obtain a resonant air-boost effect of the chambers A and B of the surge 
tank 51, it is advisable to close the shutter valve 53 of the partition 
wall 52 as shown in FIG. 8(a) in the low-speed range, and open the shutter 
valve 53 as shown in FIG. 8(b) in the high-speed range. 
Then, a case where a malfunction occurs in any of the throttle valves 56 
and 57 will now be described. 
Suppose that the control system malfunctions and the throttle valve 56 or 
57 is fully closed by the return spring 58. If, for example, the throttle 
valve 56 is fully closed and becomes uncontrollable, the shutter valve 53 
is opened to achieve intake air control by the normal throttle valve 57, 
as shown in FIG. (c). Also, the variable intake valves 60 and 61 are 
caused to operate as in the normal condition. This allows continued 
operation to be ensured. The shutter valve 53 may be closed, and, in this 
case, the variable intake valve 61 of the normal-side intake pipe 59 is 
opened. 
Suppose that the system becomes uncontrollable with the throttle valve 56 
or 57 opened due to jamming of a foreign substance or the like. If the 
throttle valve 56 become uncontrollable in the open state, as shown in 
FIG. 8(b), the shutter valve 53 and the variable intake valve 60 of the 
malfunctioned-side intake pipe 58 are both closed, and the variable intake 
valve 61 of the normal-side intake pipe 59 is opened to make intake air 
control by the normal throttle valve 57, thereby ensuring continued 
operation. 
The malfunction determination of the throttle valve control system is the 
same as described above, and detailed description thereof is omitted. 
Since, in the above embodiment, the shutter valve 53 is provided which 
controls communication and blocking between the two chambers of the surge 
tank 51, the valve can be adequately opened and closed to increase the 
output torque in the low-speed and high-speed ranges and, as shown in FIG. 
8(c), the long and short intake pipes 58 and 59 can be adequately used 
even if one of the throttle valves becomes malfunctioned in the closed 
state. However, in the present invention, the shutter valve 53 may be 
omitted and the two chambers of the surge tank 51 may be isolated from 
each other. 
Furthermore, since, in the present invention, running stability of the 
vehicle is ensured even if a throttle valve malfunctions in the open 
state, the return springs 28 of the individual motors 26 and 27 are not 
necessarily required. 
As described above with reference to the embodiments, since the throttle 
valve control apparatus of the present invention comprises individual 
throttle valves provided in the plurality of intake passages of the 
engine, and the throttle valves are controlled by the operation condition 
detecting means, the first control means for controlling the intake air 
amount, the determination means for determining a normal throttle valve, 
and the second control means for controlling only the normal throttle 
valve in preference to the first control means, the amounts of intake air 
flowing through the individual intake passages are independently 
controlled in normal operation condition, and, even if a malfunction 
occurs in one of the throttle control systems continued operation is 
ensured using the other intake passage. 
Furthermore, since, in the throttle valve control apparatus of the present 
invention, the surge tanks are individually connected to the first divided 
passages divided into two systems and having the throttle valves, the two 
surge tanks communicate through the communication passage and the 
communication control valve, the surge tanks are provided with the second 
divided passages having intake control valves connecting to the confluence 
passages, and the throttle valves, the communication control valve, and 
the intake control valves are open/close controlled by the operation 
condition detecting means and the control means, a good engine performance 
is obtained from the low-speed range to the high-speed range by open/close 
controlling the communication control valve and the intake control valves, 
and, even if the throttle valve control system malfunctions, continued 
operation can be ensured, thereby maintaining the running stability of the 
vehicle. Furthermore, the present invention can also be achieved at a 
reduced cost by utilizing conventional art variable intake systems.