JP2682303B2 - Vehicle engine output characteristic switching control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for switching the engine output characteristic of a vehicle which can be driven by power from a variable output characteristic engine.

[0002]

2. Description of the Related Art As an output characteristic variable engine, for example, as disclosed in Japanese Patent Laid-Open No. 3-111610, the output characteristic with respect to the throttle opening is switched by not using only one type of intake and exhaust valves of the engine but by properly using a plurality of cams. There is known a so-called variable valve type engine which is adapted to obtain the above. This engine has three kinds of cams for each intake and exhaust valve, and these cams, that is, the fuel economy cams for which the engine partial load is important as shown in FIG. A low speed cam (hereinafter referred to as L cam) useful at low speed and a high speed cam (hereinafter referred to as H cam) useful at high speed from the engine drive load and the engine speed. It is used properly to match the condition. Depending on this use, the engine can be used when the P cam is used and when the L cam is used, as shown in FIG. 6, which shows the output shaft torque characteristic with respect to the engine speed Ne when the throttle opening is fully opened.
The output characteristics can be switched when the H cam is used.

[0003]

By the way, in the variable output characteristic engine represented by the engine as described above, when the output characteristic (cam) is switched at a point other than the equal torque point indicated by E in FIG. , There is a step in the torque, causing a switching shock. For example, when switching to H cam or L cam during engine operation at F point using P cam,
The engine output shaft torque sharply increases to the G point or H point, and conversely, the engine output shaft torque sharply decreases when switching to the P cam. This means that in a vehicle that is driven by power from the variable output characteristic engine as described above, the effectiveness of engine braking varies depending on the selected output characteristic (cam). Therefore, if the output characteristic is switched while the vehicle is coasting, the effect of engine braking suddenly changes, causing a problem that the occupant feels uncomfortable.

It is an object of the present invention to eliminate the above-mentioned uncomfortable feeling by prohibiting the switching of the output characteristic during coasting of the vehicle.

[0005]

To this end, according to the present invention, as shown in the concept of FIG. 1, an output capable of changing an output characteristic with respect to a throttle opening by switching and using a plurality of kinds of intake / exhaust valve opening / closing operations. In a vehicle equipped with a variable characteristic engine and capable of traveling via a creep prevention type automatic transmission by the power from this engine, the inertia traveling detection means for detecting the coasting of the vehicle and the automatic transmission are in the creep prevention state. And an output characteristic switching prohibition means for prohibiting the switching of the intake / exhaust valve opening / closing operation during coasting of the vehicle in response to signals from these means, and interrupting this prohibition during creep prevention. And is provided.

[0006]

The engine is used by switching a plurality of types of intake / exhaust valve opening / closing operations and is operated with output characteristics according to the selected intake / exhaust valve opening / closing operations. Then, the vehicle can be driven by the power from the engine via the creep prevention type automatic transmission. During this time, when the inertia traveling detection means detects the inertia traveling of the vehicle, the output characteristic switching prohibiting means prohibits the switching of the intake / exhaust valve opening / closing operation in response to the signal from this.
Therefore, the intake / exhaust valve opening / closing operation is not switched during coasting, and the engine output characteristic is not switched accordingly. For this reason, it is possible to prevent a feeling of strangeness in which the way the engine brake works suddenly changes during the inertia running. When the output characteristic prohibiting means receives the creep prevention detection signal from the creep prevention detecting means, the output characteristic prohibiting means interrupts the prohibition of switching the intake / exhaust valve opening / closing operation and executes the switching even during coasting. Therefore, during creep prevention, since the clutch is slipping, even if the output characteristic is changed by switching the opening / closing operation of the intake / exhaust valve, there is no sudden change in the engine braking force, but the switching is unnecessarily prohibited. It can eliminate inconvenience.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows an embodiment of the engine output characteristic switching control device of the present invention, in which 1 is an engine, 2 is an automatic transmission, and the device of the present example shows the engine output characteristic of the present invention in a tandem power train. Appropriate control should be made to meet the purpose.

The engine 1 burns the injected fuel with the air sucked from the air cleaner 3 through the throttle valve 4, inputs the output thus obtained into the automatic transmission 2, and outputs the combustion exhaust gas from the exhaust pipe 5 to the outside. To release. By the way, the engine 1 is assumed to be electronically controlled via the throttle actuator 7 without mechanically connecting the throttle valve 4 to the accelerator pedal 6 operated by the driver, and the intake / exhaust described above is performed in synchronization with the engine rotation. The intake / exhaust valve for opening and closing the valve is as described above with reference to FIGS.
The variable valve as described in Japanese Patent No. 610 is used, and the three kinds of cams are switched by a cam switching mechanism 9 that responds to the cam switching control valve 8.

The automatic transmission 2 changes the rotational power from the engine 2 at a gear ratio corresponding to the selected gear and transmits it to the output shaft 10 to drive the wheels of the vehicle, for example, and is issued by Nissan Motor Co., Ltd. RE4R01A type automatic transmission maintenance manual ", and the gear shift is electronically controlled via the control valve 11. However, in this example, the creep phenomenon due to the drag torque of the torque converter during the stop including immediately before the stop is prevented. In order to
Creep prevention control is also performed to put the transmission clutch in a slip state.

The engine controller 12 controls the opening of the throttle valve 4 via the throttle actuator 7 in the engine 1 (control command TVO), the cam switching control via the control valve 8 (control command CAM), and other engine controls. The transmission controller 13 performs shift control (control command S) and creep prevention control (control command C) via the control valve 11 of the automatic transmission 2 and other automatic transmission controls by the transmission controller 13. Information shall be mutually exchanged among the thirteen. For these controls, information such as the engine speed Ne is input to the controller 12 from the engine 1, and a signal from an accelerator stroke sensor 14 for detecting the depression amount AST of the accelerator pedal 6 and the release of the accelerator pedal 6 are performed. The signal I from the idle switch 15 which is turned on, and further the signal from the longitudinal G sensor 16 which detects the longitudinal acceleration G of the vehicle are input, and the transmission controller 13
Information such as the transmission output speed (vehicle speed V) is input from the automatic transmission 2.

The engine controller 12 basically executes the control program shown in FIG. 3 while receiving the information from the transmission controller 13 to execute the engine output characteristic switching control (cam switching control) aimed at by the present invention. To do. That is, first in step 21, the vehicle longitudinal acceleration G is read, and in the next step 22, it is checked whether the vehicle is coasting or not depending on whether it is negative. During coasting, the change of the signal CAM is prohibited in step 23, that is, switching of the cam is prohibited. In other than coasting, the optimum cam is determined normally in step 24 and the signal CAM is instructed to perform the cam switching control. Run normally.

Thus, switching of the cam (engine output characteristic) is prohibited during coasting of the vehicle, and it is possible to eliminate the uncomfortable feeling that the engine brake during this traveling suddenly changes. And
The switching of the cam is executed immediately when the coasting of the vehicle ends, and the switching does not stop.

While the automatic transmission 2 is executing the above-mentioned creep prevention control, the clutch of the transmission system is in the slipping state, so that even if the cam is switched during coasting, the engine accompanying it is changed. The change in the effectiveness of the brake can be absorbed by the slip of the clutch,
The above-mentioned discomfort does not occur. Therefore, particularly in the present invention, step 25 is added as shown in FIG. 4, and when it is determined in this step that the creep prevention control is being performed (determinable from the signal C in FIG. 2), even if the vehicle is coasting, Execute cam switching control. In this case, it is possible to prevent the cam switching from being unnecessarily prohibited, and the responsiveness of the cam switching is improved, which is convenient.

In the above description, when the inertial traveling is detected, the vehicle acceleration G detected by the front-rear G sensor 16 is defined as the inertial traveling, but the vehicle acceleration G is the difference between the sampling values of the vehicle speed V in the sampling cycle. It can be indirectly obtained by a differential operation such as division, and the accelerator stroke AST detected by the sensor 14 instead of the vehicle acceleration.
It is also possible to detect inertia running by whether or not is 0 or whether or not the idle switch 15 is ON.

[0015]

As described above, according to the engine output characteristic switching control of the present invention, switching of the intake / exhaust valve opening / closing operation (engine output characteristic) is prohibited during coasting of the vehicle, and this prohibition is prevented from creeping. Since the engine is configured to be interrupted, it is possible to eliminate the discomfort that the engine braking force suddenly changes during coasting and to switch the engine output characteristics unnecessarily during creep prevention that does not cause this sudden engine braking force change. The harmful effects of being prohibited can be eliminated.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an engine output characteristic switching control device of the present invention.

FIG. 2 is a schematic diagram of a power train and its control system showing an embodiment of the present invention.

FIG. 3 is a flowchart showing the basics of a cam switching control program executed by the engine controller of the same example.

FIG. 4 is a flowchart showing the actual state of a cam switching control program according to the present invention.

FIG. 5 is an operational characteristic diagram of three types of intake / exhaust valve cams.

FIG. 6 is an output performance diagram of the engine depending on the proper use of the cam.

[Explanation of symbols]

 1 engine 2 automatic transmission 3 air cleaner 4 throttle valve 5 exhaust pipe 6 accelerator pedal 7 throttle actuator 8 cam switching control valve 9 cam switching mechanism 10 transmission output shaft 11 control valve 12 engine controller 13 transmission controller 14 accelerator stroke sensor 15 idle Switch 16 Front and rear G sensor

Claims (1)

(57) [Claims] 1. A variable output characteristic engine capable of changing an output characteristic with respect to a throttle opening by switching and using a plurality of types of intake / exhaust valve opening / closing operations, and a creep preventing automatic transmission is provided by power from this engine. In a vehicle that can travel through, a coasting detection unit that detects coasting of the vehicle, a creep prevention detection unit that detects that the automatic transmission is in creep prevention, and a vehicle that responds to signals from these units. An engine output characteristic switching control device for a vehicle, comprising: output characteristic switching inhibiting means for inhibiting switching of the intake / exhaust valve opening / closing operation during coasting of the vehicle, and interrupting the inhibition during creep prevention.