JPH06257493A - Fail-safe device for throttle control device - Google Patents

Abstract

PURPOSE:To improve reliability and the like for a throttle control device by mechanically monitoring an operating condition of a throttle control device and cutting off a motor power source in case of abnormal condition. CONSTITUTION:A mechanical comparator switch 130 is provided in a throttle control device. The mechanical comparator switch 130 compares a force corresponding to actuating of an accelerator pedal 103 with a force of an intake negative pressure corresponding to actual engine torque, and mechanically detects the case when the actual engine torque is abnormally large. The mechanical comparator switch 130 is connected into the power source side circuit of a motor driving circuit in an electronic controller so as to cut off the motor power source in case of abnormal condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fail-safe device which is mounted on a vehicle engine and electrically controls the opening of a throttle valve to release the throttle control when a failure occurs.

[0002]

2. Description of the Related Art In recent years, automobiles have been equipped with a throttle control device for electrically controlling the operation of a throttle valve, such as a vehicle constant speed traveling control device. By the way, if this throttle control device breaks down during traveling, the engine output will inadvertently increase. Therefore, it is indispensable to provide a fail-safe device that accurately detects the presence or absence of a failure and releases the throttle control when a failure occurs.

Conventionally, as a fail-safe device for a throttle control device, there is a "vehicle speed control device" disclosed in JP-A-57-51932. This prior art discloses the provision of an accelerator limit switch that shuts off the motor power when the accelerator is off.

[0004]

However, in the above-mentioned prior art, since the motor power is cut off by the accelerator limit switch only when the accelerator is off, the engine output is suddenly increased due to a failure. The above situation cannot be avoided unless the accelerator is returned. In addition, if a limit switch is provided on the accelerator pedal or throttle valve, or if the difference between the output signals of the throttle opening and the accelerator opening is compared and an electrical failure is detected and fail-safe is detected, the signal line The failure detection device itself may fail or malfunction due to disconnection, power interruption, etc., and the reliability of failure detection is reduced.

The present invention has been made in view of the above, and mechanically monitors the operating state of the throttle control device and mechanically shuts off the motor power source in the event of an abnormality, thereby improving the reliability of the device. The purpose is to improve sex.

[0006]

In order to achieve the above object, the present invention provides an accelerator via a normally closed first electromagnetic clutch that is normally open to a throttle valve on the engine side and is connected when not energized. A state in which the pedal is connected, connected to the motor through a normally open second electromagnetic clutch that is connected when energized and released when not energized, and in normal time, the second electromagnetic clutch is connected by the control means. In a throttle control device that controls a motor according to an accelerator operation, the operating state is monitored by comparing the force according to the amount of depression of the accelerator pedal with the suction negative pressure force according to the actual engine torque. A slot having a comparator switch and connecting the comparator switch to a power supply side circuit of a motor drive circuit in the control means. There is provided a fail-safe device of the control device.

Further, the comparator switch defines an atmospheric pressure chamber and a negative pressure chamber into which a negative suction pressure is introduced by dividing the inside of the case with a diaphragm, and the accelerator pedal is located on the atmospheric pressure chamber side. An elliptic drum connected to the pedal, a first spring connected to the elliptic drum,
The diaphragm is connected to the diaphragm via a pressing means connected to the first spring so as to exert a spring force according to the accelerator opening degree, and a negative pressure and a second spring are applied to the diaphragm on the negative pressure chamber side. Are connected so as to act on the spring force, and a contact point between the diaphragm and the case side is provided so as to be turned on / off by the displacement of the diaphragm.

Further, the elliptic drum has a characteristic that at each accelerator opening, the elliptic drum always lifts so as to correspond to the maximum engine torque that the engine can generate at this accelerator opening.
The characteristic is always applied to one of the diaphragms, and the spring force and the force on the negative pressure chamber side are opposed to each other, so that the contact is turned off only when the actual engine torque becomes larger than the maximum engine torque. It is a thing.

[0009]

According to the present invention, the motor is controlled by the electronic controller of the throttle control device in response to the depression of the accelerator pedal when the vehicle is traveling by the accelerator operation, and the throttle valve is electrically controlled by this motor. . At this time, in the mechanical comparator switch, the operating state is mechanically monitored by comparing the force corresponding to the depression of the accelerator pedal with the force of the suction negative pressure corresponding to the actual engine torque. If the actual engine torque increases abnormally, the switch immediately shuts off the power supply to the motor drive circuit in the electronic controller to release the motor operation, and the accelerator pedal causes the throttle valve to fail-safe to mechanically operate. It

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is an explanatory diagram showing a schematic configuration of a throttle control device. In the figure, a throttle body 301 of an engine has a throttle valve 3 for adjusting an intake air amount.
02, and the throttle valve 302 is equipped with an electronic controller 320. That is, the accelerator pedal 103 on the driver's side is connected to the valve shaft 302a of the throttle valve 302 via the accelerator wire 304, the throttle cam 305, and the normally closed first electromagnetic clutch 306 which is opened when energized and is connected when de-energized. When the first electromagnetic clutch 306 is engaged, the throttle valve 302 is mechanically opened / closed by depressing the accelerator pedal 103.

On the other hand, the valve shaft 302a of the throttle valve 302
On the other hand, the DC motor 307 is connected to the gear mechanism 308 via a normally open second electromagnetic clutch 309 which is connected when energized and is disengaged when de-energized, and when the second electromagnetic clutch 309 is engaged. The motor 307 is configured to electrically open and close the throttle valve 302.

At normal times, the normally closed first electromagnetic clutch 306 is released by applying a voltage, and the normally open second electromagnetic clutch 30 is opened.
9 is connected, and at the time of failure, the normally closed first electromagnetic clutch 306 is connected and the normally open second electromagnetic clutch 309 is released.

As a control system, an accelerator opening sensor 311 provided on the accelerator pedal 103 to detect an accelerator opening, a throttle opening sensor 312 provided to a throttle valve 302 to detect a throttle opening, a transmission output shaft A vehicle speed sensor 313 that outputs a pulse signal having a frequency proportional to the vehicle speed by an electromagnetic pickup or the like provided in the vehicle. Further, an ASCD set switch 314 for instructing the start of the automatic constant speed traveling control (ASCD), an ASCD cancel switch 315 for instructing the cancellation of the automatic constant speed traveling control (ASCD), and a brake limit switch 316 for detecting a brake non-operation. Have. Furthermore, a mechanical comparator switch 1 for mechanically monitoring the system operating state
30. The various sensor signals and switch signals are input to the electronic controller 320 to execute throttle control.

The electronic controller 320 comprises a one-chip microcomputer 321, a motor drive circuit 322, a self-holding relay circuit 323, and an electromagnetic clutch drive circuit 324. Then, the motor drive circuit 322 causes the motor 307 to
Is connected to the motor drive circuit 322 through the brake limit switch 316 and the self-holding relay circuit 323, and the mechanical comparator switch 130 is connected to the brake limit switch 316 and the self-holding relay circuit 323. Connected in parallel. Also,
The clutch power source is connected to the electromagnetic clutch drive circuit 324, and the electromagnetic clutch drive circuit 324 is connected in series to the first and second electromagnetic clutches 306 and 309.

The one-chip microcomputer 321 is an RO that stores programs for executing various control processes.
M, a CPU that executes various processes in accordance with a program stored in the ROM, a RAM that stores results and data processed by the CPU, a digital port, an A / D port, and various timers. Then, when the system is normal, a signal for instructing energization is output to the electromagnetic clutch drive circuit 324. In addition, the accelerator opening sensor 31
1, the target throttle opening is calculated based on various sensor signals from the throttle opening sensor 312, the vehicle speed sensor 313 and the switch signals from the set switch 314 and the cancel switch 315, so that the actual throttle opening matches the target value. A signal for instructing the forward / reverse rotation direction of the motor and a signal for instructing the motor drive current are output to. Furthermore, in the event of a system failure, it instructs the motor drive current and the clutch drive current to be cut off.

The self-holding relay circuit 323 is turned on only when the set switch 314 is operated during the automatic constant speed traveling control, and thereafter, the cancel switch 31 is operated.
The ON state is maintained until 5 is operated, the brake is operated, or the ignition switch is turned off. When the self-holding relay circuit 323 is ON and the brake limit switch 316 is also ON without operation, the motor drive circuit 322 and the motor power supply are connected to enter the power supply state. Mechanical comparator switch 130
Turns on when the system operating state is normal, supplies power to the motor drive circuit 322 even when automatic constant-speed traveling control is not performed, turns off when there is an abnormality, and cuts off power supply to the motor drive circuit 322.

When the power is normally supplied, the motor drive circuit 322 turns on only one set of power transistors at the diagonal positions of the bridge circuit based on the microcomputer output signal to drive the motor 307 with the drive current and current. Control the direction. The electromagnetic clutch drive circuit 324 turns on / off the power transistor based on the microcomputer output signal. That is, when the system is operating normally, the second electromagnetic clutch 309 is connected and the first electromagnetic clutch 306 is disengaged by energizing the system to turn the throttle valve 302 on the motor 3
It is electrically operated by 07. In addition, when the system fails, the second electromagnetic clutch 309 is disengaged and the first electromagnetic clutch 306 is turned off.
The throttle pedal 302 to the accelerator pedal 103.
Operate mechanically by operating.

Next, referring to FIG. 1, the structure of the mechanical comparator switch 130 will be described. It has a cylindrical case 131 whose both ends are closed, and the inside of the case 131 is partitioned by a diaphragm 132. One of the diaphragms 132 has an atmospheric pressure chamber 1 having an atmospheric leak hole 133.
34, and the other is a negative pressure chamber 136 that communicates with an intake system of the engine through a pipe 135 and introduces an intake negative pressure.
Then, in the negative pressure chamber 136, contact points 1 are respectively provided to the diaphragm 132 and the mounting member 137 on the case 131 side.
38, 139 are provided, and both contacts 138, 139 are arranged so as to face each other and be turned on / off by the movement of the diaphragm 132. Also, both contacts 138, 139
Are connected to the switch terminal 141 by a connection 140.

In the negative pressure chamber 136, the second spring 142 is biased against the diaphragm 132, so that the suction negative pressure introduced by the conduit 135 and the spring force of the second spring 142 are applied to one side of the diaphragm 132. Works. Therefore,
When the engine torque is small and the suction negative pressure is large, the diaphragm 132 moves to the negative pressure chamber 136 side to close both contacts 138 and 139, and conversely, if the suction negative pressure decreases due to the increase of the engine torque. The diaphragm 132 moves to the atmospheric pressure chamber 134 side and operates in a direction to open both contacts 138, 139.

On the other hand, the accelerator pedal 103 is connected to an elliptic drum 151 via an accelerator wire 150, and the elliptic drum 151 is connected to the wire 1 having a first spring 152.
It is connected to the pressing means 155 inside the atmospheric pressure chamber 134 via 53. The pressing means 155 has a support arm 156 at the center.
Has a lever 157 for direction change supported by a wire 153 connected to one end of the lever 157.
The other end of 7 is connected to the diaphragm 13 via the pressing rod 158.
It is connected to 2. As a result, the accelerator pedal 10
When step 3 is depressed, the first spring 152 is expanded and displaced according to the shape of the elliptic drum 151 to generate a spring force, and this spring force is applied via the wire 153 to the lever 157 and the pressing rod 15
8 and the pressing rod 158 is transferred to the diaphragm 132.
Press.

The shape of the elliptic drum 151 has a non-linear characteristic as shown in FIG. The characteristic curve in this case is set to a lift amount that always generates a spring force corresponding to the maximum engine torque at each accelerator opening. Therefore, when the spring force corresponding to the maximum engine torque acts on the diaphragm 132 at a certain throttle opening, and the actual engine torque is normal or less than the maximum torque, the force on the negative pressure chamber 136 side is It becomes smaller than the spring force of the atmospheric pressure chamber 134, and both contacts 138 and 139 are turned on. However, when the actual engine torque becomes abnormally higher than the maximum torque, the suction negative pressure is reduced, and the force on the negative pressure chamber 136 side overcomes the spring force to move the diaphragm 132 to the atmospheric pressure chamber 134 side. Contact points 138, 13
9 is turned off, and thus it becomes possible to mechanically monitor the operating state.

The above operation will be specifically described below by using mathematical expressions. First, assuming that the lift amount of the elliptic drum 151 according to the characteristic curve shown in FIG. 2 at the accelerator opening A is F (A) and the proportional constant is b, the maximum engine torque T _max is given by the following equation (1). Become.

T _max = b · F (A) ··· (1) Further, the suction negative pressure is B, the negative pressure in the idle state is B ₀ , the constant is a, and the engine torque T and the suction negative pressure are When approximated, the following equation (2) is obtained.

B = a · T−B ₀ (2) Next, let the spring constant of the first spring 152 be K ₁ and the spring constant of the second spring 142 be K _2, and let the accelerator pedal 103 Diaphragm 1 at accelerator opening A due to depression of
If 32 is displaced X to the left side, the left side pressing force of the diaphragm 132 in this case is K ₁ (F (A) −
X). When the suction negative pressure according to the engine torque is B, the pressure receiving area of the diaphragm 132 is S, and the displacement amount of the diaphragm 132 is X, the right pressing force of the diaphragm 132 is K ₂ · X + BS. Therefore, the following equation (3) is established by the balance relationship between these left and right forces.

K ₂ · X + BS−K ₁ (F (A) −X) = 0 (3) Here, the above equations (1) and (2) are substituted into the above equation (3). However, if a · S = K ₁ / b = c, then the following equation (4) is obtained.

T−T _max = (B ₀ · S− (K ₁ + K ₁ ) X) / c ───── (4) Then, in a normal state, the maximum engine based on the accelerator opening at that time is the engine torque. When the torque is reached,
By substituting T = T _max into the equation (4), the neutral position X ₀ of the diaphragm 132 becomes the equation (5).

X ₀ = B ₀ · S / (K ₁ + K ₂ )-(5) Therefore, by setting both contacts 138 and 139 at the positions of the above formula (5), all the diaphragms can be used in case of abnormality. Thirteen
2 moves to the right to turn off the contacts 138 and 139.
In this way, it becomes possible to monitor the operating state in all regions of the accelerator opening.

Next, the operation of this embodiment will be described. When the vehicle travels by depressing the accelerator pedal 103, the mechanical comparator switch 130 has a spring force equivalent to the maximum engine torque with respect to the accelerator opening.
The actual engine torque and the force due to the spring force act in opposition to each other, and the operating state is mechanically monitored by the relationship between both forces. Therefore, in the normal case, the contacts 138, 1
39 is turned on, which causes the motor drive circuit 322 of the electronic controller 320 to switch to the mechanical comparator switch 130.
Powered by. Further, during this normal time, the second electromagnetic clutch 30 is driven by the electromagnetic clutch drive circuit 324.
9 is connected by energization, the drive current and current direction of the motor 307 are controlled, and thereby the throttle valve 302 is electrically controlled by the motor 307.

On the other hand, if the actual engine torque increases for some reason, the suction negative pressure decreases, the diaphragm 132 of the mechanical comparator switch 130 moves from the neutral position to the right, and the contacts 138 and 139 are OF.
F Therefore, at the time of this abnormality, the motor drive circuit 322 is cut off from the power supply, and the current signal to the motor 307 is also cut off. On the other hand, in this case, the electromagnetic clutch drive circuit 324 causes a non-energized state, and
The electromagnetic clutch 306 is connected, whereby the throttle valve 302 is connected to the accelerator pedal 103 and is fail-safe so as to be mechanically operated.

[0030]

As described above, according to the present invention,
In the throttle control device, since the operating state is mechanically monitored by the mechanical comparator switch, the influence of disconnection of the signal line is completely eliminated, and the reliability of operating state monitoring is significantly improved. Since the mechanical comparator switch is configured to compare the force according to the depression of the accelerator pedal with the force of the suction negative pressure according to the actual engine torque, it is possible to accurately detect the abnormal state of the actual engine torque. . Since the mechanical comparator switch is connected to the power supply side circuit of the motor drive circuit in the electronic controller and immediately shuts off the motor power supply in the event of an abnormality,
Accidents can be reliably avoided.

Further, since the mechanical comparator switch has a structure in which the contacts are turned on and off by the displacement of the diaphragm, the structure is simple and the operation becomes accurate. The elliptic drum applies a spring force corresponding to the maximum engine torque to one of the diaphragms for each accelerator opening, and a force such as suction negative pressure acts on the other side of the diaphragm. Since it is configured to detect the above, it is possible to accurately detect the case where the accelerator opening is larger than the maximum engine torque.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an embodiment of a fail safe device of a throttle control device according to the present invention.

FIG. 2 is a graph showing characteristics of the elliptic drum shown in FIG.

FIG. 3 is an explanatory diagram showing a schematic configuration of a throttle control device including a mechanical comparator switch according to the present invention.

[Explanation of symbols]

 103 accelerator pedal 130 mechanical comparator switch 302 throttle valve 306 first electromagnetic clutch 307 motor 309 second electromagnetic clutch 320 electronic controller 322 motor drive circuit

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location F02D 41/14 320 C 8011-3G

Claims (3)

[Claims] 1. A normally-closed first valve that is normally opened and connected to a throttle valve on the engine side when not energized.
Is connected to the motor via a normally open second electromagnetic clutch that is connected when energized and is opened when de-energized, and is connected to the motor by the control means during normal operation. In a throttle control device that controls a motor according to accelerator operation with the electromagnetic clutch connected, the force corresponding to the depression amount of the accelerator pedal is compared with the force of suction negative pressure according to the actual engine torque. A fail-safe device for a throttle control device, comprising: a comparator switch for monitoring an operating state of the throttle control device, wherein the comparator switch is connected to a power supply side circuit of a motor drive circuit in the control means. 2. The comparator switch defines an atmospheric pressure chamber and a negative pressure chamber into which a negative suction pressure is introduced by dividing the inside of the case with a diaphragm, and the accelerator pedal on the atmospheric pressure chamber side is the accelerator pedal. A spring force corresponding to the accelerator opening is applied to the diaphragm via an elliptic drum connected to the pedal, a first spring connected to the elliptic drum, and a pressing means connected to the first spring. Is connected to the diaphragm so that negative pressure and a spring force of a second spring act on the diaphragm on the negative pressure chamber side, and a contact between the diaphragm and the case side is turned on / off by the displacement of the diaphragm. The fail safe device of the throttle control device according to claim 1, wherein the fail safe device is provided so as to be turned off. 3. The elliptic drum has a characteristic of always lifting at each accelerator opening so as to correspond to the maximum engine torque that the engine can generate at this accelerator opening, and the characteristic is always applied to one of the diaphragms. 3. The contact is turned off only when the actual engine torque becomes larger than the maximum engine torque by causing the spring force and the force on the negative pressure chamber side to oppose each other by causing them to act. Fail-safe device for the throttle control device.