JPH0557934B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a constant speed cruise control device for a vehicle equipped with an automatic transmission (A/T), and is intended to prevent frequent gear changes (O/D hunting), especially on uphill roads. be. [Prior art] Recent A/T vehicles have a 4-speed A/T (1 speed,
2nd, 3rd, 4th speed = O/D) is the mainstream, and approximately 50
At vehicle speeds of Km/h or higher, the vehicle normally runs in O/D (overdrive). However, in the case of automatic drive driving, it is difficult to drive at a constant speed with O/D on a steeply climbing road, resulting in a reduction in vehicle speed. Therefore, an O/D cut signal is output from the auto drive ECU and the O/D
The system uses a method that reduces vehicle speed reduction by increasing the driving force. For example, as shown in Figure 3a, the vehicle speed is set to the target vehicle speed.
When the VM drops by A (for example, 4 km/h), turn on the O/D cut signal. This O/D cut signal is sent to the automatic shift controller to limit its gear selection. In other words, even in the case where the automatic shift controller determines that the vehicle is in the O/D range, there is a function that prohibits the selection and downshifts to 3rd speed.
This function works when the vehicle speed is VM-B (e.g. B=2Km/h)
However, the O/D cut signal is not required if the O/D return timer _returns to
14 seconds) have elapsed. This is to prevent frequent O/D cuts and returns from being repeated when the vehicle speed returns quickly. [Problems to be Solved by the Invention] The automatic gear shift controller on the transmission side has its own gear shift pattern, and determines the gear position based on the relationship between the throttle opening and the vehicle speed. FIG. 4 shows a shift pattern between 3rd speed and 4th speed (O/D), where the broken line represents a downshift and the solid line represents an upshift.
If the control system is independent in this way, the O/D cut vehicle speed (VM-
There are cases where an O/D cut is performed on the transmission side before the voltage drops to A). Figure 3b
VM-J is that. As a result, when the vehicle speed increases, the autodrive ECU returns the throttle valve, so the transmission returns to O/D according to the shift pattern. At this time, since the transmission side does not have a delay function such as an O/D recovery timer, O/D cut and recovery are repeated at a fast cycle (O/D hunting). The present invention detects an O/D cut on the transmission side on the auto drive side, and also uses the O/D recovery timer to detect a short-cycle O/D cut.
The purpose is not only to prevent hunting, but also to prevent long-period O/D hunting at the timer time + α. [Means for Solving the Problems] The present invention provides constant-speed running control for an automatic transmission vehicle equipped with an automatic transmission controller that automatically switches transmission gears based on the relationship between vehicle speed and throttle opening. The device includes a constant speed driving control function that duty-controls the throttle opening according to the traveling vehicle speed and causes the vehicle to travel at a target vehicle speed, and the automatic shift control function when the vehicle speed decreases by a predetermined speed or more with respect to the target vehicle speed. Sends a signal to prohibit the selection of the highest gear to the vehicle, and prohibits the selection when the difference between the target vehicle speed and the traveling vehicle speed becomes less than a predetermined speed and the road surface gradient continues to fall below a predetermined value for a certain period of time. A constant speed running controller is provided which has a transmission restriction function for canceling the signal, and when the automatic shifting controller shifts the transmission down from the highest speed, the shift signal indicative of the downshift is transmitted to the fixed speed. The present invention is characterized in that, by inputting an input to the speed running controller, the transmission limiting function of the constant speed running controller is activated even when the automatic transmission controller is downshifting. [Function] Although the transmission restriction function (O/D cut) of the constant speed driving controller (auto drive ECU) is internal, it can also be activated externally. For example, if the transmission shifts down from the highest gear (O/D) using its own shift pattern using a shift signal from an automatic shift controller or a shift detection signal from a hydraulic switch, the transmission of the constant speed drive controller Activate the mission restriction function. That is, an O/D cut signal is sent out, and an O/D return timer is used at the time of recovery.
In this way, the short-period hunting shown in FIG. 3b is eliminated. However, if the climbing gradient is large, the O/D cut will be made again after returning to O/D as shown in Figure a.
A long-period (10 to 30 sec) O/D hunting of (T _OD +α) remains (α varies depending on the gradient). Therefore, in the present invention, there is a restriction that the O/D recovery is not performed until the slope becomes less than a certain value (for example, 3%). Although a tilt sensor may be used for this purpose, the present invention proposes a method that does not use a tilt sensor. One method is to detect the gradient (or load amount) from the magnitude of the average value DM of duty D, and the other method is to detect the gradient (or load amount) from the magnitude of intake manifold negative pressure. be. The former can be achieved with autodrive ECU software, and the latter can be achieved using an existing vacuum switch. At least one of these two methods is used together with vehicle speed detection. As shown in FIG. 5, the vacuum switch has a hysteresis width (ba) between ON negative pressure a and OFF negative pressure b. The negative pressure is the intake manifold negative pressure, and as the slope increases, the negative pressure decreases. Therefore, one of the O/D recovery conditions is that the OFF negative pressure b is set to a desired value and this switch is turned OFF. [Embodiment] Fig. 1 is a system configuration diagram showing an embodiment of the present invention, in which 1 is an auto drive ECU (controller for constant speed driving), 2 is an electronically controlled automatic transmission controller (for automatic transmission). ECU). The autodrive ECU 1 controls the duty of the actuator 3 to adjust the opening degree of the throttle 4. On the other hand, for automatic transmission
The ECU 2 controls shift solenoids S1 and S2 of a transmission 5 (the main body is not shown) to change the gear stage. In this example, an ON/OFF signal is input to the ECU 1 from the vacuum switch 6. The outline of the constant speed control operation is as follows. The ECU 1 detects the running vehicle speed based on a signal from a vehicle speed sensor equipped with a reed switch that is turned on and off by a magnet that rotates in proportion to the rotation of vehicle drive oil. ECU 1 memorizes the traveling vehicle speed when the set switch is turned on, and after turning it off, actuator 3
Control valve duty. When the control valve is ON, negative pressure is introduced, increasing the force generated by the diaphragm linked to throttle 4. Atmosphere is introduced when OFF, weakening the diaphragm's generating force. During this time, the release valve is closed during control.
It is turned on and cuts off the atmosphere. When a cancel signal (clutch switch (neutral start switch for A/T vehicles), parking switch, or brake switch) is input, both the control valve and release valve are turned OFF, and atmospheric air is introduced from both to quickly control the system. make it stop. If you turn on the resume switch after canceling, driving control at the previously memorized vehicle speed will be restored. A microcomputer is used for ECU1,
Therefore, if the processing is divided into blocks, the result will be as shown in Fig. 2. The output duty D that controls the control valve on and off is the target vehicle speed stored in memory.
It is determined according to the difference between V _M and the running vehicle speed Vn, but in detail, the skip vehicle speed Vs, which is the sum of the vehicle speed change component (differential component), is used instead of the running vehicle speed Vn itself. This is to advance and compensate for dead time due to actuator delay, throttle, drive system hysteresis, and play. Therefore, the skip vehicle speed Vs is determined by the following formula. Vs=Vn+K×(Vn−V _o-1 ) (1) Vn: Current vehicle speed V _o-1 : Previous vehicle speed K: Proportionality constant Further, the output duty D is determined by the following equation. D = G × ΔV + SD ... (2) G: Gain SD: Set duty corresponding to target vehicle speed V _M ΔV: Vehicle speed deviation (= V _M - Vs) Generally, constant speed driving can be performed at a vehicle speed within the O/D range. many. However, since it takes time for the vehicle to return to speed on an uphill road, ECU1 issues an O/D cut signal.
Make ECU2 select 3rd speed. The shift control logic by this ECU 2 is shown in the table below.

〔Effect of the invention〕

As described above, according to the present invention, short-period and long-period O/D hunting on an uphill road in an automatic transmission vehicle (A/T vehicle) can be prevented by the function of the constant speed cruise control device. , there is an advantage that the automatic transmission controller does not need to be modified.

[Brief explanation of the drawing]

Fig. 1 is a system configuration diagram showing an embodiment of the present invention, Fig. 2 is a block diagram of its microcomputer processing, Fig. 3 is a conventional operation waveform diagram, and Fig. 4 is an explanatory diagram of a shift pattern of an automatic transmission. , FIG. 5 is a characteristic diagram of the vacuum switch. In the figure, 1 is a constant speed running controller, 2 is an automatic shift controller, 3 is an actuator, 4 is a throttle,
5 is a transmission, and 6 is a vacuum switch.

Claims (1)

[Scope of Claims] 1. A constant speed cruise control device for an automatic transmission vehicle equipped with an automatic transmission controller that automatically switches the gear position of a transmission based on the relationship between vehicle speed and throttle opening according to the traveling vehicle speed. a constant speed driving control function that duty-controls the throttle opening and causes the vehicle to run at a target vehicle speed; A transmission restriction that sends a prohibition signal and releases the selection prohibition signal when the difference between the target vehicle speed and the traveling vehicle speed becomes a predetermined speed or less and the road surface gradient continues to fall below a predetermined value for a certain period of time. a constant speed running controller having a function, when the automatic shifting controller shifts down the transmission from the highest speed, a shift signal indicating the downshift is input to the constant speed running controller. A constant speed driving control device for an automatic transmission vehicle, characterized in that the transmission limiting function of the constant speed driving controller is activated even when the automatic transmission controller is downshifting. 2. The constant speed running control device for an automatic transmission vehicle according to claim 1, wherein the road surface slope is detected from the average value of the output duty. 3. The constant speed running control device for an automatic transmission vehicle according to claim 1, wherein the road surface slope is detected from the intake manifold negative pressure.