JPH0574965U - Downhill road control structure of automatic speed control device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a downhill road control structure of ASCD in which engine braking is effectively applied to suppress overshoot during traveling on a downhill road. [Structure] In S5 subsequent to S4, it is determined whether or not the idle switch is turned on. If this determination is YES, it means that the throttle opening is at the minimum value and the engine brake is being applied. In this case, whether the deceleration due to the engine brake operation is 1 km / h / sec or more. It is determined whether or not (S5). If this determination is NO, the deceleration due to the action of the engine brake is 1 km / h / sec.
If it is less than the threshold, the engine is still running on a steep downhill road in which the engine brake does not work effectively in overdrive (OD) even when the throttle opening is at the minimum value. Therefore, in such a case, the process proceeds from S5 to S6 and downshifts from the overdrive (OD) to the third speed (D3).

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a downhill road control structure of an automatic speed control device (hereinafter abbreviated as ASCD).

[0002]

[Prior Art]

 As a conventional ASCD, for example, there is one disclosed in Nissan Cima new model car manual GGY32-1 1991 August. This ASCD allows the vehicle to run at the set vehicle speed even if the driver keeps his / her foot off the accelerator pedal by controlling the operation of the vehicle-mounted engine. As shown in Fig. 3, the output port of the ASCD control unit 1 is used. Is connected to the ASCD actuator 9. The ASCD actuator 9 is composed of an air valve 10, a release valve 11, a negative pressure pump 12, and a negative pressure actuator 13 which are operated by a control signal from the ASCD control unit 1. The negative pressure actuator 13 is provided with a diaphragm 19 to which one end of the ASCD axel wire 14 is locked, and a return spring 20 for pressing the diaphragm 19, and the ASCD accel wire 14 serves to connect the engine to the engine. A throttle 15 for increasing / decreasing the fuel supply amount is opened / closed.

Then, it is executed by controlling the air valve 10, the release valve 11, and the negative pressure pump 12 as shown in FIG. 4 based on the set vehicle speed and the current vehicle speed. That is, when the current vehicle speed increases and the set vehicle speed becomes less than the current vehicle speed while traveling on a downhill road, the air valve 10 is opened and the release valve 11 is closed, and the negative pressure pump 12 is stopped.

As a result, the negative pressure in the negative pressure actuator 13 decreases, and the diaphragm 19 is pressed by the return spring 20 and is displaced outward. Therefore, as the diaphragm 19 is displaced outward, the ASCD accelerator wire 14 is pressed, and as a result, the throttle 15 is driven in the closing direction. By driving the throttle 15 in the closing direction, the amount of fuel supplied to the engine is reduced and the current vehicle speed is controlled to be reduced.

When the state where the set vehicle speed = the current vehicle speed is formed, the air valve 10 is driven to be closed at this point, whereby the negative pressure in the negative pressure actuator 13 is maintained at the value at that point. Therefore, the diaphragm 19 and the ASCD accelerator wire 14 are stopped at that time, and the throttle 15 is also stopped at the opening degree at that time, so that the set vehicle speed = current vehicle speed is maintained.

Further, when the current vehicle speed decreases and the set vehicle speed> the current vehicle speed while traveling on an uphill road, the negative pressure pump 12 operates while the air valve 10 and the release valve 11 remain closed. As a result, the negative pressure in the negative pressure actuator 13 increases, and the diaphragm 19 is displaced inwardly against the return spring 20. Therefore, as the diaphragm 19 is displaced inward, the accelerator wire 14 for ASCD is pulled, whereby the throttle 15 is driven in the opening direction. By driving the throttle 15 in the opening direction, the amount of fuel supplied to the engine is increased, and the current vehicle speed is controlled to increase.

When the set vehicle speed = current vehicle speed is finally formed, the negative pressure pump 12 is stopped at this point as described above, and the negative pressure in the negative pressure actuator 13 is set to the value at that point. Maintained. Therefore, the diaphragm 19 and the ASCD accelerator wire 14 are stopped at that time, the throttle 15 is also stopped at the opening degree at that time, and the state of the set vehicle speed = the current vehicle speed is maintained.

[0008]

[Problems to be solved by the device]

 However, in such a conventional ASCD, when traveling on a downhill road, the set vehicle speed becomes less than the current vehicle speed, and the throttle 21 is driven in the closing direction by the control described above to reduce the fuel supply amount to the engine. However, when traveling on a steeply descending slope, the vehicle did not decelerate even when the fuel supply amount was the minimum, and the current vehicle speed sometimes overshooted greatly.

In this case, if the driver manually operates the OD release, the automatic transmission is downshifted from the overdrive to the third speed, whereby the engine brake can be effectively operated. However, even though the operation of the accelerator pedal is made unnecessary by the constant speed running control and the operation load on the driver is reduced, it is complicated for the driver to perform the OD release operation on the downhill road. , The convenience of ASCD is lost.

Further, the ASCD has a function of releasing the constant-speed traveling control by giving priority to deceleration when the driver decelerates due to positive operation such as when the brake is operated. It is indispensable for ensuring safety. Therefore, if deceleration is performed by operating the brakes while traveling on a downhill road, after the traveling on the downhill road, the operation necessary for starting the constant speed traveling control such as setting the set vehicle speed must be performed again. Therefore, the operation after the end of traveling on the downhill road becomes complicated.

The present invention has been made in view of such a conventional problem, and an ASCD in which an engine brake is effectively applied to suppress an overshoot while traveling on a downhill road without requiring a driver's operation. It is intended to provide a downhill road control structure.

[0012]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention controls the throttle opening of the engine and the shift operation of the automatic transmission to execute the constant speed traveling control to maintain the current vehicle speed of the vehicle at the set vehicle speed. In the automatic speed control device, an overshoot state detecting means for detecting an overshoot state in which the current vehicle speed is higher than a set vehicle speed by a predetermined value or more, a throttle opening degree detecting means for detecting the throttle opening degree, and the vehicle Based on the detection results of the deceleration detection means and the detection means of each of the detection means, when the throttle opening in the overshoot state is the minimum value and the deceleration rate is less than the predetermined value, the automatic shift Shift down control means for forcibly downshifting the machine are provided.

[0013]

[Action]

 In the above structure, the throttle opening detection means detects the throttle opening, and the deceleration detection means detects the deceleration of the vehicle. When an overshoot condition occurs in which the current vehicle speed increases by a predetermined value or more during traveling on a downhill road, the overshoot condition detecting means detects this. When the occurrence of this overshoot condition is detected, if the throttle opening is the minimum value and the deceleration is less than the predetermined value, even if the throttle opening is set to the minimum value, the current shift position does not It can be said that it is difficult to sufficiently decelerate by engine braking. Therefore, in such a case, the downshift control means forcibly downshifts the automatic transmission, and the engine brake works effectively with the downshift of the automatic transmission.

[0014]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. That is, FIG. 2 is an overall block diagram showing an embodiment of the present invention, and the ASCD control unit 1 forms the overshoot detecting means and the deceleration detecting means in this embodiment, and is a program ROM. , A work RAM, and a micro computer having a CPU are incorporated. Each signal is input to the ASCD control unit 1 from a vehicle speed sensor 2, an idle switch 3, a cancel switch 4, a set switch 5, an accelerator switch 6, a resume switch 7, and an ASCD main switch 8. The vehicle speed sensor 2 detects the current vehicle speed of the vehicle and inputs it to the AS CD control unit 1, and the idle switch 3 is a throttle opening detection means, and when the opening of the throttle 15 described later is the minimum value. That is, it is a switch that is turned on when the throttle opening is at which the engine is in the idle rotation state and is turned off at other throttle openings.

The cancel switch 4 is a switch operated when canceling the constant speed traveling control by the ASCD control unit 1, and the set switch 5 is used when starting the constant speed traveling control at a desired vehicle speed. It is a switch operated by. The accelerator switch 6 is used for instructing execution of constant-speed traveling control with the vehicle speed at the time when the pressing operation is released as the set vehicle speed, as well as for instructing the speed increase by the pressing operation without operating the accelerator pedal. It is a switch operated by. The resume switch 7 is a switch that is operated when the constant speed traveling control is restarted at the original set vehicle speed after the constant speed traveling control is released by the brake operation, and the AS CD main switch 8 is the ASCD control unit. It is a switch that is operated when the power is turned on.

On the other hand, an ASCD actuator 9 is connected to the output port of the ASCD control unit 1. As shown in FIG. 3, the ASCD actuator 9 is composed of an air valve 10, a release valve 11, a negative pressure pump 12 and a negative pressure actuator 13 which are operated by a control signal from the ASCD control unit 1. The negative pressure actuator 13 is provided with a diaphragm 19 to which one end of the ASCD accelerator wire 14 is locked, and a return spring 20 for pressing the diaphragm 19, and the ASCD accelerator wire 14 shown in FIG. The throttle 15 is driven to open and close.

Furthermore, an A / T control unit 16 is connected to the output port of the ASCD control unit 1. The A / T control unit 16 is provided with an OD release solenoid (not shown) that is excited to forcefully downshift the automatic transmission 17 from overdrive (OD) to third speed (D3). The A / T control unit 16 and the ASCD control unit 1 realize the downshift control means in this embodiment. The cruise lamp 18 is an indicator lamp that is kept lit while the ASCD control unit 1 is executing the constant speed traveling control.

Next, the basic control contents executed by the ASCD control unit 1 in the present embodiment having the above configuration will be described first. That is, by turning on the ASCD main switch 8, the ASCD control unit 1 is activated, and when the desired vehicle speed is reached by the operation of the alcel pedal, the set switch 5 is pressed and released, and then the set switch 5 is released. The vehicle speed when the vehicle is released is stored as the set vehicle speed, and constant speed running control for maintaining the current vehicle speed constantly detected by the vehicle speed sensor 2 at the set vehicle speed is started.

This constant speed traveling control is executed by controlling the air valve 10, the release valve 11 and the negative pressure pump 12 as shown in FIG. 4 based on the set vehicle speed and the current vehicle speed. The operations of the air valve 10, the release valve 11 and the negative pressure pump are the same as those of the conventional one, and thus the description thereof will be omitted.

Then, the ASCD control unit 1 operates according to the flowchart shown in FIG. 1 together with the above-described conventional constant speed traveling control, and first determines whether or not the constant speed traveling control is executed. (S1). If this determination is YES and the vehicle is running at constant speed traveling control, the SET (set switch 5), RES (resume switch 7), and ACC (accelerate switch 5) switches are turned on. It is determined whether there is any (S2).

Of these switches, the set switch 5 is a switch that is operated when the constant speed traveling control is started at the desired vehicle speed as described above, and is the accelerator switch 6. Is a switch for instructing the speed increase by pressing operation and setting the vehicle speed at the time when the pressing operation is released as the set vehicle speed. For the resume switch 7, the constant speed traveling control is released and then the original speed is restored. It is a switch that is operated when the constant speed running control is started at the set vehicle speed. Therefore, if each of these switches 5, 6 and 7 is in the ON state, the constant speed traveling control is temporarily suspended. Therefore, in this case, the standby state is maintained until the switches 5, 6 and 7 are turned off and the constant speed traveling control is executed without proceeding to the subsequent steps.

Next, whether the overshoot is 5 km / h or more, that is, the difference between the current vehicle speed detected by the vehicle speed sensor 2 and the preset vehicle speed is 5 km / h or more. It is determined whether or not (S3). If this determination is YES and the overshoot is 5 km / h, the current vehicle speed increases during traveling on the downhill road described with reference to FIG. 4, and the set vehicle speed <current vehicle speed.

In such a case, as described above, the air valve 10 is driven to open and the release valve 11 is closed, and the negative pressure pump 12 is stopped, whereby the negative pressure in the negative pressure actuator 13 is reduced. The pressure is reduced, and the diaphragm 19 is being pressed by the return spring 20 and is being displaced outward. Further, as the diaphragm 19 is displaced outward, the ASCD accelerator wire 14 is pressed, and the throttle 15 is driven in the closing direction.

Therefore, in S4 subsequent to S3, it is determined whether or not the idle switch 3 is turned on to detect the state of the throttle 15, and the case where the idle switch 3 is turned on is described above. As described above, when the opening of the throttle 15 is at the minimum value, that is, the engine is in the idling state and the engine brake is being applied. That is, when the idle switch 3 is OFF, it is possible to assume a case where the accelerator pedal is operated, for example, when overtaking, so that the speed is intentionally increased. In this case, since the vehicle is out of the control target of the present embodiment for the purpose of deceleration control during traveling on a downhill road, the standby state is maintained without proceeding to the next step.

Therefore, if the determination in S5 is YES, the opening of the throttle 15 is at the minimum value, and the engine brake is being applied, then the reduction due to the action of the engine brake is performed. It is determined whether the speed is 1 km / h / sec or more (S5). That is, as described above, the ASCD control unit 1 has a built-in microcomputer, and the current vehicle speed is sequentially input from the vehicle speed sensor 2. Therefore, the current vehicle speed is used to execute the calculation according to the program. The deceleration can be calculated from the above, and it is determined whether or not the deceleration calculated by this calculation is 1 km / h / sec.

If this determination is YES, and the deceleration due to the action of the engine brake is 1 km / h / s ec or more, even if the overdrive (OD), the engine brake can be effectively acted on the gentle slope. Can be assumed to be traveling downhill. Therefore, in this case, since it is not necessary to shift down, the determination from S3 is repeated without proceeding to S6.

On the other hand, if the determination in S5 is NO and the deceleration due to the action of the engine brake is less than 1 km / h / sec, the overdrive (OD) is achieved even if the opening of the throttle 15 is set to the minimum value. Is running on a steep downhill road where engine braking does not work effectively. Therefore, in such a case, the process proceeds from S5 to S6 to downshift from the overdrive (OD) to the third speed (D3). That is, the ASCD control unit 1 outputs a signal to the A / T control unit 16, and the A / T control unit 16 excites the OD release solenoid to forcibly overdrive the automatic transmission 17 ( Forcibly downshift from OD) to the third speed (D3).

By downshifting to the third speed (D3), the engine brake works effectively and the current vehicle speed gradually decreases. Therefore, in the next S7, it is determined whether or not the current vehicle speed converges to the set vehicle speed, and it is determined whether or not the idle switch 3 is turned off when the current vehicle speed converges to the set vehicle speed (S8). If this determination is NO, the vehicle is still traveling on a downhill road in which the opening of the throttle 15 is set to the minimum value and the engine brake is applied, and the process waits in S8 without proceeding to the next S9.

Then, if the determination in S8 is NO and the idle switch 3 is turned off, the traveling on the downhill road is terminated, and the state in which the speedup is started by the constant speed traveling control in the flatland traveling is performed. Can be assumed. Therefore, in this case, the ASCD control unit 1 stops the signal output to the A / T control unit 16 15 seconds after the determination in S8 becomes YES, and the A / T control unit 16 outputs the OD signal. By degaussing the release solenoid, the automatic transmission 17 is shifted up from the third speed (D3) to the overdrive (OD) (S10).

After executing the processing of S9, the routine returns to S1, and thereafter, the ASCD control unit 1 will continue to operate as long as the constant speed traveling control is not released unless the cancel switch 4 is turned on or the brake is operated. It operates according to the flow chart shown in FIG. 1 together with the basic control shown in FIG. Therefore, when the overshoot is 5 km / h or more and the idle switch 3 is on and the deceleration is less than 1 km / h / sec, the automatic transmission 17 moves from the overdrive (OD) to the third position. It is possible to forcibly shift down quickly and prevent an increase in overshoot when driving on a steeply descending slope without the need for occupant shifting or braking.

The real values of 1 km / h / sec, 15 sec, etc. used in the flowchart of FIG. 1 are examples, and appropriate values may be used in relation to the engine displacement and the like. Further, in this embodiment, only the control mode for shifting down from the overdrive (OD) to the third speed (D3) is shown, but in the case of a three-speed automatic transmission, the third speed ( It is only necessary to shift down from D3) to the second speed (D2).

[0032]

[Effect of the device]

 As described above, in the present invention, the automatic transmission is operated when the throttle opening is the minimum value and the deceleration is less than the predetermined value in the overshoot state in which the current vehicle speed is higher than the set vehicle speed by the predetermined value or more. I was forced to downshift. Therefore, when braking by engine braking is insufficient while traveling on a downhill road, automatic downshifting effectively causes engine braking to be applied without overriding the driver's shift operation or braking operation and overshoot. Can be suppressed. Therefore, even when traveling on a downhill road, the driver is not required to operate the vehicle, and constant-speed traveling control can be executed while suppressing overshoot, and the convenience of ASCD can be improved.

Further, since it is possible to perform braking by engine braking accompanied by a brake operation when traveling on a downhill road, there is no release of the constant speed traveling control due to the brake operation, and after the traveling on the downhill road, the set vehicle speed is set. It is possible to eliminate the complexity of performing the operation required to start the constant speed traveling control.

[Brief description of drawings]

FIG. 1 is an operational flowchart of an ASCD control unit according to an embodiment of the present invention.

FIG. 2 is an overall block diagram of the embodiment.

FIG. 3 is a schematic view of the ASCD actuator of the same embodiment.

FIG. 4 is a circuit diagram of a main part of the ASCD.

[Explanation of symbols]

 1 ASCD control unit 2 Vehicle speed sensor 3 Idle switch 9 ASCD actuator 16 A / T control unit 17 Automatic transmission

Claims (1)

[Scope of utility model registration request] 1. An automatic speed control device for controlling a throttle opening of an engine and a shift operation of an automatic transmission to execute a constant speed traveling control for maintaining a current vehicle speed of a vehicle at a set vehicle speed. Is an overshoot state detecting means for detecting an overshoot state increased by a predetermined value or more from a set vehicle speed, a throttle opening degree detecting means for detecting the throttle opening degree, and a deceleration detecting means for detecting a deceleration of the vehicle, Shift-down control means for forcibly down-shifting the automatic transmission when the throttle opening in the overshoot state is the minimum value and the deceleration is less than a predetermined value based on the detection results of the detection means; The downhill road control structure of the automatic speed control device is characterized by being provided with.