JPH05106719A - Engine brake compensator in power train - Google Patents

Abstract

PURPOSE:To remove the inconvenience of engine brake not being obtained when it is detected that an automatic transmission is within an engine brake range and the deceleration operation of an engine exists, by prohibiting the selection of an output characteristic by which engine brake is not obtained. CONSTITUTION:An engine controller 12, while receiving information that is from a transmission controller 13, carries out a control program, and checks whether an idle switch 15 is ON or not, and also checks whether an automatic transmission 2 is made to come within an engine brake range or not. A command to prohibit the use of a P cam by which engine brake is not obtained, is given to a cam command CAM during the deceleration of an engine made to come within the engine brake range, and in cases other than the above, the cam command CAM is decided by ordinary cam selection control. Thus, there is no selection of the P cam by which engine brake is not obtained, during deceleration operation under the engine brake range, and the inconvenience of engine brake becoming impossible can be avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine brake compensator for a power train in which a variable output characteristic engine and an automatic transmission are connected in tandem.

[0002]

2. Description of the Related Art As an output characteristic variable engine, for example, as described 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 (hereinafter, referred to as fuel economy cams for the partial load of the engine which shows the valve lift amount characteristic in FIG. 4). P-cam), a low-speed cam useful at low rotation (hereinafter referred to as L-cam), and a high-speed cam useful at high rotation (hereinafter referred to as H-cam) based on engine drive load and engine speed. It is used properly to match the driving conditions of. By selectively using this, the engine can switch the output characteristic between when the P cam is used, when the L cam is used, and when the H cam is used, as shown in FIG. 5, which shows the output shaft torque characteristic when the throttle opening is fully opened. .

On the other hand, the automatic transmission is selectively hydraulically actuated by various line frictional friction elements (clutch, brake) as seen in, for example, an automatic transmission RE4R01A (see the same maintenance manual) being developed and used by the applicant of the present application. Thus, the shift speed that matches the operating condition is automatically selected, and the gear shift to another shift speed is performed by changing the friction element that operates.

[0005]

By the way, in the power train in which the output characteristic variable engine and the automatic transmission are tandem-coupled as described above, the engine brake is desired and the automatic transmission is set to the engine brake range. Even when the engine is decelerated by releasing the accelerator pedal, if the engine carries out the normal output characteristic selection control, the following inconvenience will occur.

That is, as shown in FIG. 5, the engine output shaft torque is small when the P-cam is used with an emphasis on fuel consumption, which means that sufficient engine braking cannot be obtained with the engine output characteristic. If the engine performs normal cam (output characteristic) selection control even during deceleration operation in the engine brake range, some cams may not be able to obtain engine brake even when the vehicle is requesting engine braking. It may be selected, which causes the inconvenience that the engine cannot be braked.

An object of the present invention is to prevent the above-mentioned inconvenience of incapability of engine braking from occurring by prohibiting the selection of engine output characteristics in which engine braking cannot be obtained during deceleration operation in the engine braking range. And

[0008]

To this end, the present invention has a tandem coupling of an output characteristic variable engine for switching and using a plurality of output characteristics with respect to a throttle opening and an automatic transmission, as the concept is shown in FIG. In the power train, the engine brake range detecting means for detecting the selection of the engine brake range of the automatic transmission, the decelerating operation detecting means for detecting the decelerating operation of the engine, and the decelerating operation in the engine brake range by these means are performed. Is detected, output characteristic limiting means for prohibiting selection of the engine output characteristic in which engine braking is not obtained is provided.

[0009]

The engine is operated in accordance with the selected output characteristic, and the power from this point is output by the automatic transmission with a gear ratio changed in accordance with the selected gear. On this occasion,
When the engine brake range detecting means detects that the automatic transmission is in the engine brake range, and the decelerating operation detecting means detects the decelerating operation of the engine, the output characteristic limiting means responds to the signals from these means and the output characteristic limiting means Prohibits the selection of output characteristics that cannot be obtained. Therefore, during the engine deceleration operation in the engine braking range, the engine does not select the output characteristic that cannot expect engine braking, and it is possible to eliminate the inconvenience that engine braking becomes impossible.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 shows an embodiment of an engine brake compensating device of the present invention, in which 1 is an engine and 2 is an automatic transmission, and the device of the present example compensates for engine braking in a power train which is a tandem connection of these.

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.
A variable valve as described in Japanese Patent No. 610 is used, and the three types of cams are switched by a cam switching mechanism 9 that responds to the cam switching control valve 8. The automatic transmission 2 shifts the rotational power from the engine 1 at a gear ratio according to the selected shift stage and transmits it to the output shaft 10 to drive the wheels of the vehicle, for example, "RE4R01A Automatic" issued by Nissan Motor Co., Ltd. As described in "Transmission Maintenance Manual", the shift control is electronically controlled through the control valve 11.

The engine controller 12 controls opening of the throttle valve 4 via the throttle actuator 7 in the engine 1 (control command TVO), 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 line pressure control (control command L) via the control valve 11 of the automatic transmission 2, and other automatic transmission control 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 the accelerator stroke sensor 14 that detects the depression amount AST of the accelerator pedal 6 and a signal I from the idle switch 15 that is turned on when the accelerator pedal 6 is released.
Further, the automatic transmission information such as the transmission output speed (vehicle speed V) and the selection range R is input from the automatic transmission 2 to the transmission controller 13.

The engine controller 12 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. That is, first, in step 21, it is checked whether or not the idle switch 15 is ON, and in step 22, it is determined from the R information from the transmission controller 13 whether the automatic transmission is in the engine braking range such as the II range or the I range. Check if Idle switch 15 ON
Indicates that the accelerator pedal 6 is released, that is, the engine is in the decelerating operation, and the engine brake range indicates that the driver is requesting the engine brake travel. During the deceleration operation of the engine in the engine braking range, step 2
As described above in 3, the cam command CAM is instructed to prohibit the use of the P-cam that does not provide engine braking. Then, otherwise, in step 24, the cam command CAM is determined by the normal cam selection control.

Thus, it is possible to avoid the inconvenience that the engine brake cannot be disabled because the P-cam which cannot obtain the engine brake is not selected during the deceleration operation in the engine brake range where the engine brake is required. You can

[0015]

As described above, according to the first aspect of the present invention, the engine output characteristic (P in the illustrated example is such that the engine brake cannot be obtained during deceleration operation in the engine brake range).
Since the cam is not allowed to be selected, it is possible to eliminate the inconvenience that the engine arbitrarily selects the output characteristic and the engine braking does not work.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an engine brake compensating device for a power train according to 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 a control program executed by the engine controller of the same example.

FIG. 4 is an operational characteristic diagram of three types of intake / exhaust valve cams.

FIG. 5 is an output performance diagram of the engine according to 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

Claims (1)

[Claims] 1. An engine for detecting selection of an engine brake range of the automatic transmission in a power train in which a variable output characteristic engine for switching and using a plurality of output characteristics with respect to a throttle opening is used and a tandem connection with the automatic transmission. Brake range detection means, deceleration operation detection means for detecting deceleration operation of the engine, and when these means detect deceleration operation in the engine brake range, selection of engine output characteristics for which engine braking is not obtained is prohibited. An engine brake compensating device in a power train, comprising: output characteristic limiting means.