JP2517918B2 - Engine control device for vehicles equipped with automatic transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device for a vehicle equipped with an automatic transmission, and particularly to an engine control device when gear shifting is performed when the engine is under heavy load.

[Prior Art] Japanese Patent Application Laid-Open No. 58-17
The technology disclosed in Japanese Patent No. 246 is disclosed. The technique is, for example, a shift pattern as shown in FIG. 6, and
According to a clock-up pattern or the like (not shown), shift control of the automatic transmission is performed based on the vehicle speed and the throttle opening. In the shift pattern of FIG. 6, the horizontal axis represents the vehicle speed (differential drive pinion speed) and the vertical axis represents the throttle opening. The solid line indicates the upshift line (1st gear → 2nd gear, 2nd gear → 3rd gear, 3rd gear). → OD), downshift line with dotted line (OD → 3,3 →
2,2 → 1). In this technique, for example, when the vehicle speed Vb exceeds the allowable limit vehicle speed Va and the traveling state Hb is θb exceeding the throttle opening θa, the automatic transmission is OD.
To be. The allowable limit vehicle speed Va is a boundary vehicle speed at which the engine overruns when the vehicle speed exceeds the Va at the third speed. The vehicle speed Vc is an allowable limit vehicle speed of 2nd speed, and the vehicle speed Vd is an allowable limit vehicle speed of 1st speed.

[Problems to be Solved by the Invention] However, the above-described conventional shift control technique has a problem that frequent shifts (busy shifts) occur. The above problems will be described below with reference to FIG. That is,
While traveling in the traveling state Hb, if the vehicle approaches an uphill or the like where the traveling resistance of the vehicle is large, the vehicle speed decreases. As a result, the traveling state moves in the direction of arrow YA and becomes Hc. Then, when the vehicle speed decreases, it crosses the downshift line of the vehicle speed Ve and downshifts from OD to the third speed. Then, in the state of the third speed, the driving force of the vehicle becomes larger than the OD and becomes larger than the traveling resistance, so that the vehicle speed increases and the traveling state moves from Hc in the arrow YB direction. As a result of this move,
When the vehicle crosses the upshift line of the vehicle speed Va, the automatic transmission is upshifted from the third speed to the OD. That is, in the conventional shift control, a busy shift state in which an upshift is performed immediately after a downshift occurs near the allowable limit vehicle speed.

Next, the state of occurrence of the busy shift will be described with reference to FIG. In FIG. 7, the horizontal axis shows the traveling distance, and the vertical axis shows the altitude, the gradient, the throttle opening, the gear position, and the vehicle speed. That is, at the point Da approaching the uphill at the gear OD, even if the throttle opening is set to 100%, the vehicle speed gradually decreases thereafter due to the steep slope.
Then, when the vehicle speed reaches the point Ob, the vehicle is downshifted from the OD to the third speed. The vehicle speed increases due to the increase in driving force due to the downshift at the point Db, and the vehicle is upshifted from the third speed to OD at the point Dc. In some cases, an upshift operation may occur immediately after such a downshift.

Although not shown in FIG. 7, the downshift and the upshift may be repeated in the same manner.

As described above, the conventional technique has a problem that a full throttle is used and a busy shift occurs on an uphill or the like, which deteriorates drivability.

Therefore, an object of the present invention is to solve the above problems and improve drivability near the limit of the driving force of a vehicle.

[Means for Solving Problems] An engine control device for an automatic transmission-equipped vehicle according to the present invention, which has been made to achieve the above object, determines that a downshift has been performed when an engine load is equal to or more than a predetermined value. Means for determining that the engine speed has reached the permissible limit speed after the downshift, and when the engine speed has reached the permissible limit speed after the downshift, A means for prohibiting the shift, and a means for reducing the engine output so as to maintain the engine speed at the allowable limit speed while prohibiting the upshift are provided.

That is, as illustrated in FIG. 1, when the engine load is equal to or higher than a predetermined value and a downshift is performed (A, B), whether the engine speed has reached the allowable limit speed or not. If it is determined that it has reached (C), and if it is determined that it has reached, the upshift is prohibited and the engine output is reduced (D, E).

The allowable limit rotational speed of the engine is, for example, the maximum allowable rotational speed of the engine in which the output of the engine is effectively used.

As a method of reducing the output of the engine, for example, reduction of fuel injection amount, reduction of fuel pressure, fuel injector control, air-fuel ratio control, intake air amount control (second throttle valve, linkless throttle valve), etc. are used.

The automatic transmission is, for example, a stepped or continuously variable automatic transmission.

[Operation] According to the present invention, the output of the engine is reduced and the upshift is performed after the busy shift is desired to be prohibited, that is, after the high load downshift and when the vehicle speed reaches the allowable limit speed. Is prevented. Therefore, even if the vehicle speed increases due to the downshift when the engine load exceeds a predetermined value, for example, when the vehicle approaches an uphill or the like at full throttle, the upshift is not performed. As a result, the upshift immediately after the downshift or the busy shift in which the downshift and the upshift are alternately repeated is prevented.

Further, as the engine output decreases, upshifting is prohibited. As a result, even if the engine output is reduced and the vehicle still crosses the upshift line, the upshift is prohibited and the busy shift is prevented.

[Effects of the Invention] As described above, in the present invention, after the high load downshift, the output of the engine is reduced at the limit time when the engine reaches the allowable limit rotation speed, so that the busy shift is prevented. . Therefore, when traveling uphill with full throttle, busy shift does not occur,
The drivability of the vehicle is improved.

Also, as the engine output decreases, upshifting is prohibited, so even if the engine output is decreased, even if the engine still crosses the upshift line, the upshifting is prohibited to prevent a busy shift. It is more certain.

[Embodiment] An embodiment of the present invention will be described with reference to FIGS. In FIG. 2 and FIG. 3, 10 is an engine, and the engine 10 can control the output by controlling the opening / closing of the throttle valve 13 provided in the intake pipe 12 by the throttle actuator 11. 20 is an automatic transmission, and the automatic transmission 20 has four solenoid valves (NO.1.NO.2) 21a and 21b that enable four-speed shifting. The throttle actuator 11 and the solenoid valves 21a and 21b are driven by a signal from the control circuit 30.
Inputs signals from sensors arranged in various parts of the vehicle including the engine 10 and the automatic transmission 20.

These sensors are a throttle position sensor 14 for detecting the opening of a throttle valve 13 arranged in an intake pipe 12 of the engine 10, an engine speed sensor 15 for detecting the speed of the engine 10, and a depression amount of an accelerator pedal 16. An accelerator pedal depression amount sensor 17 for detecting the vehicle speed, and a vehicle speed sensor 23 for detecting the number of revolutions of an output shaft 22 of the automatic transmission, which is proportional to the vehicle speed.

The throttle position sensor 14 generates a signal proportional to the opening degree of the throttle valve 13, and the accelerator depression amount sensor 17 generates a signal proportional to the depression amount of the accelerator pedal 16. Further, the engine speed sensor 15 outputs a pulse signal whose frequency is proportional to the speed of the engine 10 to the vehicle speed sensor.
23 generates a pulse signal whose frequency is proportional to the vehicle speed.

The control circuit 30 is configured using a microcomputer, and the microcomputer has a CPU31, ROM3
2, the RAM 33, the input port 34, and the output port 35 are connected to each other by the common bus 36. And input port
The above-described sensors are input to the 34 through the A / D converter 37, the pulse input sections 38a and 38b, and directly. To the output port 35, a throttle actuator drive unit 39 and solenoid valve drive units 40a and 40b are connected.

In the automatic transmission 20 described above, the throttle valve 13 that is opened and closed according to the vehicle speed and the accelerator pedal depression amount is used.
The gear shift is performed based on the opening degree of. The above throttle opening and vehicle speed are compared with the shift pattern shown in FIG. 4 and used as control data. The shift pattern of FIG. 4 shows the vehicle speed on the horizontal axis, the throttle opening on the vertical axis, and the upshift point and the downshift point.

Next, the outline of the present embodiment will be described using the shift pattern of FIG. First, when the throttle opening is 85% or more,
In the traveling state H1 where the vehicle speed is V1, when the vehicle approaches an uphill road or the like and the vehicle speed decreases to H2 of the vehicle speed V2 in the direction of the arrow Y1, a downshift from OD to the third speed is performed. Then, in the downshifted state, the vehicle speed increases in the direction of the arrow Y2, and the time at which the vehicle speed V3 (allowable limit speed) near the overrun reaches the running state H3 is determined by the vehicle speed or the engine speed. Next, when reaching H3, the upshift is prohibited and the engine output is reduced. The upshift is prohibited because the allowable rotational speed V3 and the upshift point are the same or close to each other. That is, even if the engine output is being reduced in the present embodiment, it is possible to accidentally cross the upshift line. Furthermore, in order to finally maintain the safety of this control, set the engine overrun rotation speed (engine guard rotation speed) that corresponds to a vehicle speed higher than V3, and set the engine rotation speed above the overrun rotation speed. When the number reaches the limit, the prohibition of upshifting is lifted and upshift is performed from the third speed to OD.

Next, the control of this embodiment will be described with reference to the flowchart of FIG. First, it is determined whether or not the accelerator depression amount is a predetermined value (85%) or more (full throttle) (step 100). In the present embodiment, step 140 described later
Except during the throttle opening control which is performed in step 1, the accelerator depression amount (%) and the throttle opening (%) are controlled to be the same. The throttle opening is controlled by driving the throttle actuator 11 based on the detection value of the accelerator depression amount sensor 17. Next, it is determined whether or not the vehicle speed has decreased and a downshift (OD → 3,3 → 2,2 → 1) has occurred (step 110). Then, it is determined whether or not the engine speed has reached the permissible limit speed in the vicinity of overrun in the downshifted state with the vehicle speed reduced at the above-mentioned full throttle (step 12).
0). When the allowable limit speed is reached, upshifting (3 → OD, 2 → 3,1 → 2) is prohibited (step 130), the throttle opening is adjusted (step 140), and the engine speed is changed. The allowable rotational speed is maintained and upshifts are prevented. The above-mentioned adjustment of the throttle opening is performed by an unillustrated engine torque characteristic diagram (a diagram in which engine torque is calculated from the engine speed and throttle opening) and an unillustrated gradient characteristic diagram (gradient and vehicle speed by throttle opening). The calculation is performed based on the vehicle speed and the detection value of a gradient sensor (not shown) according to the calculated figure).

Further, as another means for adjusting the throttle opening, the allowable limit rotational speed may be set and the vehicle speed or the engine rotational speed may be fed back to control the throttle opening.

Next, in order to improve the safety of this control, it is determined whether the engine speed is equal to or higher than the overrun speed (step 150). That is, if it is less than the overrun speed, it is determined that this control is operating normally.
On the other hand, if it is equal to or higher than the overrun speed, it is determined that an abnormality has occurred in this control, and this control is released (step
160,170). That is, in the release, the throttle opening is matched with the accelerator depression amount (step 160), and the upshift prohibition is released (step 17).
0).

On the other hand, when it is determined in step 100 that the main control is not necessary, that is, when the accelerator depression amount is less than the predetermined amount (part throttle) (step 100), the main control is released (step 100). 160,170).
That is, the throttle opening is matched with the accelerator depression amount (step 160), and the prohibition of upshift is released (step 170).

As described above, according to the present embodiment, the vehicle speed is reduced at full throttle, the vehicle speed is increased in the downshifted state, and when the allowable limit speed is reached, the engine output is reduced. The vehicle speed will not increase. Therefore, the vehicle speed does not increase above the allowable limit rotational speed, and the upshift is not performed. In other words, it is possible to prevent a busy shift in which a downshift and an upshift are repeated due to an increase / decrease in the vehicle speed depending on the shift gear position on an uphill or the like. As a result, the busy shift is prevented and the drivability of the vehicle is improved.

In this embodiment, the limit rotation speed and the overrun rotation speed are determined on the basis of the engine rotation speed, so that the busy shift can be performed in all types of shift (OD3 speed, 3 speed 2 speed, 2 speed 1 speed). Can handle.

On the other hand, instead of the allowable limit based on the engine speed and the overrun speed, the allowable limit vehicle speed and the overrun vehicle speed based on the vehicle speed for each shift type may be set. By using the vehicle speed, the control can be performed with the same data as the shift control, and the consistency with the shift control is improved.

[Brief description of drawings]

FIG. 1 is a flow chart exemplifying control contents executed by an engine control device for a vehicle equipped with an automatic transmission according to the present invention;
FIG. 3 is a configuration diagram of an embodiment of the present invention, FIG. 3 is a configuration diagram of a control circuit of the present embodiment, FIG. 4 is an explanatory diagram for explaining control of the present embodiment, and FIG. FIG. 6 is a graph showing a conventional shift line, and FIG. 7 is an explanatory diagram for explaining the problems of the present invention. 10 …… Engine 11 …… Throttle actuator 17 …… Accelerator depression sensor 20 …… Automatic transmission 30 …… Control circuit

Claims (1)

(57) [Claims] 1. A means for determining that a downshift has been performed when the engine load is above a predetermined level, and a means for determining that the engine speed has reached an allowable limit speed after the downshift has been performed. A means for prohibiting an upshift when the engine speed reaches an allowable limit speed after the downshift, and an engine for maintaining the engine speed at the allowable limit speed together with the prohibition of the upshift. An engine control device for a vehicle equipped with an automatic transmission, comprising means for reducing output.