JP2005113830A - Power system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correctly and quickly detect disconnection between input and output of a transmission system. <P>SOLUTION: A power system can switch between a automatic cruise control for controlling a running status of a vehicle to be constant, and a normal control. When a speed of increase in engine speed detected by an engine speed sensor 43 exceeds an upper limit value during the automatic cruise control, an ECU 41 determines disconnection between the input and output of the transmission system and releases the automatic cruise control to return to the normal control. Therefore, the power system prevents excessive increase in engine speed caused by sudden increase in fuel injection amount with respect to sudden decrease in power transmitted to driving wheels 31, 32. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power system, and more particularly to control at the time of shifting.

  A power system for driving a driving wheel of an automobile includes an engine as a power source and a power transmission device that converts a rotational output of the engine into a rotational output having a different rotational speed. The power transmission device is capable of switching the gear ratio by disconnecting the input and output, so that an appropriate rotational output is transmitted to the wheel or the like according to the vehicle speed or load. The gear ratio is switched by, for example, disengaging a clutch interposed between the transmission and the engine by a driver's clutch pedal operation and performing a gear shift of the transmission.

  On the other hand, the fuel injection amount that defines the engine torque and the rotational speed is usually adjusted by the driver based on the accelerator pedal operation. However, in recent years, the fuel injection amount has been adjusted so that the vehicle is in a predetermined running state. For example, auto-cruise control for adjusting the vehicle speed to be kept constant has been put into practical use. Auto-cruise control is a control method employed in scenes where traffic flows at a substantially constant speed, such as on a motorway.

  In Patent Document 1 below, it is detected that the gear position has been changed based on the detection result of the gear position sensor in order to suppress the feeling of deceleration due to the engine brake torque when the gear position is changed in accordance with the manual shift operation. Then, there has been proposed a system in which the target engine torque is set so as to cancel the engine brake torque according to the changed gear position.

Further, in Patent Document 2 below, an upper limit is set on the rotational speed of the engine rotational output to limit the vehicle speed, while at the time of downshifting, the engine speed can be adjusted to an appropriate engine speed corresponding to the gear after downshifting. In the vehicle speed limiting device designed to cancel the vehicle speed limit, it has been proposed to detect that the shift lever is in the neutral position and to cancel the vehicle speed limit only for a certain period of time after detection. ing. In this technique, erroneous detection can be avoided even in the case of a driver who drives with the foot on the clutch pedal, as compared with the case where the operation of the clutch is detected by a switch provided on the clutch pedal.
Japanese Patent Laid-Open No. 2003-138953 JP-A-11-351000

  However, since the technique of Patent Document 1 detects the gear position after the shift, it copes with a sudden decrease in the load and an excessive increase in the engine speed from when the clutch is operated until the gear position is changed. I can't. In particular, during the auto-cruise control, the fuel injection amount is controlled in an increasing direction with respect to deceleration when the input / output of the power transmission device is disconnected due to clutch operation or the like, and the rotational speed may be further increased. There is.

  In addition, since the technique of Patent Document 2 does not detect the gear position after the shift, but detects that it is in the neutral position, the driver's intention to shift gears can be known earlier than the technique of Patent Document 1. However, in the case where the gear position is changed to the neutral position without the clutch operation or the detection of the gear operation is delayed due to the response delay of the switch for detecting the neutral position, it is the same as the technique of Patent Document 1. However, it is not always possible to avoid a situation where the rotational speed increases.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power system capable of optimizing the rotational speed of the rotational output of the engine at the time of gear ratio switching execution.

In the first aspect of the present invention, the engine and a power transmission device that converts the rotational output of the engine into a rotational output having a different rotational speed are provided, and the speed ratio is set by disconnecting the input and output of the power transmission device. In a switchable power system,
An operating state detecting means for detecting an operating state of the engine that changes in accordance with a decrease in engine load due to disconnection between the input and output of the power transmission device;
And determining means for determining that the input / output of the power transmission device is in a disconnected state when the magnitude of the change speed of the operating condition detected by the operating condition detecting means exceeds a preset upper limit value. .

  When the input / output of the power transmission device is disconnected, the engine load is suddenly reduced correspondingly, and the operating state changes accordingly. Therefore, it is known that the input / output of the power transmission device is disconnected by comparing the change speed with the reference value. Since it does not depend on the sensors and is not affected by the response delay of the sensors, the responsiveness is good. Therefore, the number of revolutions of the engine output can be optimized by promptly taking measures to appropriately reduce the fuel injection amount.

  According to a second aspect of the present invention, in the configuration of the first aspect of the invention, the operating state detecting means is means for detecting the rotational speed of the rotational output of the engine, and the determining means is detected by the operating state detecting means. Means for comparing the speed of increase in the rotational speed with the upper limit value.

  When the connection between the input and output of the power transmission device is disconnected, the engine load is suddenly reduced accordingly, and the rotational speed of the rotational output of the engine in the operating state is increased accordingly. Therefore, when the speed of increase in the rotational speed of the engine rotational output exceeds the upper limit value, it can be determined that the input / output of the power transmission device is disconnected.

  In addition, the sensor for detecting the rotational speed of the rotational output of the engine is basically provided in the engine, so that it is not necessary to newly provide sensors and the configuration can be simplified.

According to a third aspect of the present invention, in the configuration of the first aspect of the invention, the operating state detecting means is means for detecting the rotational speed of the rotational output of the power transmission device, and the determining means is determined by the operating state detecting means. Means for comparing the magnitude of the detected decrease speed of the rotational speed with an upper limit value.

  When the input / output of the power transmission device is disconnected, the engine load is drastically reduced. This means a sudden decrease in power output from the power transmission device. Along with this, the rotational speed of the rotational output of the power transmission device in the operating state is rapidly reduced. Therefore, when the rate of decrease in the rotational speed of the rotational output of the power transmission device exceeds the upper limit value, it can be determined that the input / output of the power transmission device is disconnected.

  According to a fourth aspect of the present invention, in the configuration of the first aspect of the invention, the operating state detecting means is means for detecting a voltage generated by an alternator powered by engine rotation output, and the determining means is the operating state detecting means. Means for comparing the magnitude of the rising speed of the generated voltage detected by the means with an upper limit value.

  When the input / output of the power transmission device is disconnected, the engine load is drastically reduced. This provides a margin for the power of the alternator, which is one of the equipment that loads the engine. Along with this, the generated voltage of the alternator in the operating state rises rapidly. Therefore, if the rate of increase of the voltage generated by the alternator exceeds the upper limit value, it can be determined that the input / output of the power transmission device is disconnected.

  According to a fifth aspect of the present invention, in the configuration of the first to fourth aspects of the present invention, a power system is provided that can select an automatic cruise control that feedback-controls the engine fuel injection amount command value so that the vehicle is in a predetermined running state. And when it determines with the input-output between the said power transmission devices being in a disconnection state, the auto-cruise control stop part which stops the said auto-cruise control is provided.

  In auto-cruise control, the fuel injection amount command value is controlled so that the vehicle maintains a predetermined traveling state, so that if the input / output of the power transmission device is disconnected and power is not sufficiently transmitted from the power transmission device, In order to avoid a decrease in the vehicle speed, the fuel injection amount command value is increased. For this reason, the increase in the rotational speed of the engine rotational output is further spurred. Therefore, the advantage of applying the invention according to claims 1 to 4 to a power system compatible with auto cruise control is great. Further, since the vehicle maintains a predetermined running state, the engine operating state is also relatively stable, and the engine operating state according to a decrease in engine load due to disconnection between the input and output of the power transmission device Can be accurately detected. Therefore, it becomes a particularly suitable application example.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a power system of the present invention. This embodiment is applied to an automobile. A power transmission device 2 is provided for converting the rotational output taken out from the crankshaft 111 of the engine 11 into rotational outputs having different rotational speeds, and the rotational output is transmitted to the drive wheels 31 and 32 of the automobile. A part of the rotational output of the engine 11 is used as power for the alternator 13 via a belt (not shown).

  The power transmission device 2 includes a clutch 21, a transmission 22, a propeller shaft 23, a differential 24, and the like from the engine 11 side. The transmission 22 can select a plurality of gear positions including a neutral position. Normally, when the driver depresses the clutch pedal 52, the clutch 21 is disconnected and the engine 11 and the transmission 22 are disconnected, and a gear shift is performed by the driver operating the shift lever.

  Various controls such as fuel injection control are performed by the ECU 41. The ECU 41 includes, for example, a microcomputer including a CPU, a RAM, and a ROM, an input / output circuit, and the like. In order to execute the control, the ECU 41 includes sensors 42 for detecting the state (operating state) of each part of the engine. Signals from 43, 44 and 45 are input. As such sensors, an accelerator opening degree sensor 42 that detects the opening degree of the throttle valve 12 and an engine speed that is an operating state detection means that detects the rotational speed of the rotational output of the engine 11 (hereinafter referred to as engine speed as appropriate). A sensor 43, a vehicle speed sensor 44 for detecting the vehicle speed, a clutch sensor 45 for detecting the clutch connection / disconnection state, and the like are provided. In addition to these sensors, although not shown, sensors such as an A / F sensor attached to a general engine are provided.

  In the ECU 41, the fuel injection amount is basically calculated by using the depression amount of the accelerator pedal 51 that the driver steps on as a torque request of the driver. Specifically, it is set according to the map with the accelerator opening and the engine speed as inputs. The fuel injection amount command value is set by another method during auto-cruise control. Auto-cruise control is effective when the operation unit provided on the instrument panel of the vehicle is switched to the cruise mode by the driver's operation, and the detected vehicle speed becomes the requested vehicle speed set by the driver. The injection amount command value is set as follows.

  The cruise mode is canceled under a predetermined condition, and the fuel injection amount command value is switched to the normal mode based on the depression amount of the accelerator pedal. FIG. 2 shows cruise mode release control. The cruise mode release control is activated when the cruise mode is switched. Steps S101 and S102 are processing as determination means. In step S101, the previous engine speed NEi-1 is subtracted from the current engine speed NEi, and this difference (NEi-number NEi-1) is compared with the upper limit value ΔNEth. Then, it is determined whether or not the difference (NEi−number NEi−1) exceeds the upper limit value ΔNEth. The current engine speed, that is, the latest engine speed is taken in at a predetermined cycle by a timer interrupt. Since the taking-in cycle of the engine speed is constant, the difference (NEi−number NEi−1) can be regarded as the increasing speed of the engine speed. The upper limit value ΔNEth is preset and stored in the ROM together with the control program.

  If the difference (NEi−NEi−1) does not reach the upper limit value ΔNEth and the determination in step S101 is negative, step S101 is repeated with the newly taken engine speed NEi as the current engine speed NEi. After the execution of step S101, the previous engine speed NEi-1 is updated with the current engine speed NEi. Since the engine speed is stable during the cruise mode with a constant vehicle speed, a negative determination is usually made in step S101.

  If a positive determination is made in step S101, the neutral position is determined in step S102, and the cruise mode is canceled in the subsequent step S103.

  The cancellation of the cruise mode is also executed when the driver steps on the brake pedal, as in a power system that can execute conventional auto-cruise control.

  FIG. 3 shows the operating state during gear shifting in the power system (hereinafter referred to as the present invention as appropriate), and FIG. 3 shows the operation of an example of a conventional engine system (hereinafter referred to as a comparative example as appropriate) compared with the power system. Indicates the state. In the comparative example, the gear position sensor detects that the shift position is in the neutral position, the engine speed has reached the allowable upper limit speed, or the neutral position is detected, or the brake pedal is depressed to It is of the type that cancels the mode. In the example shown in the drawing, the gear shift is performed without disconnecting the clutch.

  In the comparative example, when the previous gear is released and shifted to the neutral position, the input / output of the power transmission device is disconnected, so that the engine load is suddenly reduced and the engine speed is increased. This increase in engine speed is due to a sudden decrease in engine load and an increase in fuel injection amount by auto-cruise control. The latter is because the fuel injection command value is corrected in the increasing direction in order to maintain the decrease in the vehicle speed due to the disconnection between the input and output of the power transmission device. If the detection of the neutral position is delayed due to a response delay of the gear position sensor or the like, the neutral position is determined for the first time when the engine speed exceeds the allowable upper limit speed during auto-cruise control. . As a result, the driver's intention to shift gears is confirmed, and the auto-cruise control is released. Then, the rapid increase in the fuel injection amount and the engine speed stops.

  On the other hand, in this power system, when the gear is disengaged, the difference (NEi−NEi−1), which is the increasing speed of the engine speed, exceeds the upper limit value ΔNEth, and is immediately determined as the neutral position. Since the cruise control is released, the fuel injection amount converges before it increases too much, and an excessive increase in engine speed can be prevented.

  In addition, the engine speed sensor is a sensor necessary for setting the fuel injection amount as described above, and is basically provided in the engine. Therefore, it is not necessary to newly provide sensors, and the configuration can be simplified.

  In order to detect that the power transmission device is disconnected between the input and output, the rotational speed of the rotational output of the power transmission device is detected, and the magnitude of the reduction speed of the rotational speed is compared with the upper limit value. Good. When the input / output of the power transmission device is disconnected, the engine load is drastically reduced. This means a sudden decrease in power output from the power transmission device. Along with this, the rotational speed of the rotational output of the power transmission device in the operating state is rapidly reduced. Therefore, when the rate of decrease in the rotational speed of the rotational output of the power transmission device exceeds the upper limit value, it can be determined that the input / output of the power transmission device is disconnected. Here, the rotational speed of the power transmission device may be replaced with a vehicle speed having a size substantially proportional to this. This is because a sensor that detects the rotation of a drive wheel that rotates substantially always in conjunction with a propeller shaft connected to the transmission and its output side is usually used as the vehicle speed sensor.

  Further, in order to detect that the power transmission device is disconnected between the input and the output, the generated voltage of the alternator may be detected and the magnitude of the rising speed of the generated voltage may be compared with an upper limit value. When the input / output of the power transmission device is disconnected, the engine load is drastically reduced. This provides a margin for the power of the alternator, which is one of the equipment that loads the engine. Along with this, the generated voltage of the alternator in the operating state rises rapidly. Therefore, if the rate of increase of the voltage generated by the alternator exceeds the upper limit value, it can be determined that the input / output of the power transmission device is disconnected.

  In addition, the engine state that is detected in order to determine whether or not to cancel the cruise mode changes in response to a decrease in engine load due to disconnection between the input and output of the power transmission device in addition to the engine speed and the like. It can be used in any driving state.

It is a figure which shows the structure of the power system of this invention. It is a flowchart which shows the control performed by ECU which comprises the said motive power system. It is a timing chart which shows the operating state of the power system. It is a timing chart which shows the operating state of the conventional power system for comparing with the power system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Engine 111 Crankshaft 12 Throttle valve 2 Power transmission device 21 Clutch 22 Transmission 23 Propeller shaft 24 Differential gear 31, 32 Drive wheel 41 ECU (determination means, auto-cruise control stop means)
42 Accelerator opening sensor 43 Rotational speed sensor (Operating state detection means)
44 Vehicle speed sensor 45 Clutch sensor

Claims (5)

In a power system having an engine and a power transmission device that converts the rotational output of the engine into a rotational output having a different rotational speed, and capable of switching a gear ratio by disconnecting between input and output of the power transmission device,
An operating state detecting means for detecting an operating state of the engine that changes in accordance with a decrease in engine load due to disconnection between the input and output of the power transmission device;
And determining means for determining that the input / output of the power transmission device is in a disconnected state when the magnitude of the change speed of the operating condition detected by the operating condition detecting means exceeds a preset upper limit value. A power system characterized by that.   2. The power system according to claim 1, wherein the operating state detecting means is means for detecting the rotational speed of the rotational output of the engine, and the determining means is the magnitude of the increasing speed of the rotational speed detected by the operating state detecting means. A power system that is a means to compare the value with the upper limit.   2. The power system according to claim 1, wherein the operating state detecting means is means for detecting the rotational speed of the rotational output of the transmission, and the determining means is a speed reduction rate detected by the operating state detecting means. A power system that is a means of comparing the size with an upper limit.   2. The power system according to claim 1, wherein the operating state detecting means is a means for detecting a generated voltage of an alternator that uses engine rotation output as power, and the determining means is a means for detecting the generated voltage detected by the operating state detecting means. A power system that is a means of comparing the magnitude of the ascent rate with an upper limit value.   5. The power system according to claim 1, wherein the power system is capable of selecting an auto-cruise control that feedback-controls the fuel injection amount command value of the engine so that the vehicle is in a predetermined traveling state, and the power transmission. A power system provided with an auto-cruise control stop means for stopping the auto-cruise control when it is determined that the input / output between the devices is in a disconnected state.

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