JP2016035214A - Engine control unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine control unit capable of more reliably holding down a shift shock while more reliably avoiding the occurrence of unexpected acceleration during shifting.SOLUTION: A gear position at a time of start of shifting is estimated, a gear position higher by one than the gear position at the time of start of the shifting is estimated as a gear position after the shifting, a rotational speed of an engine 2 synchronous with a stepped transmission 5 after the shifting is estimated on the basis of the gear position after the shifting, this estimated value is determined as a target rotational speed, the engine rotational speed is controlled to be equal to this target rotational speed during the shifting, and the engine rotational speed is controlled, during this control over the engine rotational speed, so that a change rate of the engine rotational speed with respect to a difference between the target rotational speed and an actual engine rotational speed is lower if the engine rotational speed is controlled to increase than if the engine rotational speed is controlled to decrease.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an engine control device connected to a stepped transmission via a clutch.

  2. Description of the Related Art Conventionally, it is known that so-called shift assist control is performed in a vehicle having an engine connected to a stepped transmission via a clutch in order to suppress a shock that occurs during a shift, that is, a shift shock.

  That is, in general, at the time of shifting, the gear stage is changed after the connection between the stepped transmission and the engine is interrupted by the clutch, and then the stepped transmission and the engine are connected again. At the time of connection, if the rotation speed on the stepped transmission side and the rotation speed of the engine are not synchronized, vibration (shift shock) occurs in the vehicle. In order to suppress this shift shock, for example, control as disclosed in Patent Document 1 is performed.

  Specifically, in Patent Document 1, when the transmission and the engine are shut off by the clutch, the gear stage after the shift is predicted based on the gear stage immediately before the shut-off, and the engine speed is determined after the predicted shift. A throttle valve is controlled so that the engine speed corresponds to the gear stage.

JP-A-9-68063

  In order to avoid the shift shock more reliably, it is desirable to control the engine speed to the engine speed synchronized with the transmission after the shift earlier than during the shift. However, in order to achieve this, if the amount of change in the engine speed is simply increased, the engine speed will increase excessively, and accordingly, the vehicle speed may increase and unexpected acceleration may occur, It is not preferable.

  The present invention has been made in view of the above points, and provides an engine control apparatus that can more reliably suppress a shift shock while more reliably avoiding unexpected acceleration during a shift. .

  In order to solve the above problems, the present invention is an engine control device mounted on a vehicle having a stepped transmission, an engine, and a clutch that connects and disconnects the stepped transmission and the engine. In addition to determining the connection state between the stepped transmission and the engine, it is determined that shifting has started when the stepped transmission and the engine are shifted from a state where they are connected to each other, and the state where the stepped transmission is started. A shift state determining means for determining that the shift is completed when the speed changer and the engine are connected to each other, and a shift start time which is a gear stage when the shift state determining means determines that the shift is started It is determined that the shift has been completed by the shift state determining means and the gear stage estimating means for estimating the gear stage and the gear stage on the first speed high speed side of the gear stage at the start of the shift. Based on the post-shift gear stage estimating means for estimating the post-shift gear stage, the vehicle speed when the shift state determining means determines that the shift is started, and the estimated post-shift gear stage. The engine speed synchronized with the stepped transmission after the shift is estimated, and it is determined that the shift is started by the target speed determining means for determining the estimated value as the target speed and the shift state determining means. And a rotational speed control means for controlling the rotational speed of the engine so as to achieve the target rotational speed. The rotational speed control means controls the engine rotational speed in the direction of increasing the engine rotational speed. The engine speed is controlled so that the increase / decrease ratio of the engine speed with respect to the difference between the target speed and the actual engine speed is smaller than when controlling in a direction to decrease the engine speed. To provide a control apparatus for an engine according to claim Rukoto (claim 1).

  According to the present invention, it is possible to suppress occurrence of a shift shock while more reliably avoiding unexpected acceleration after a shift.

  Specifically, in the present invention, the gear stage after the shift is estimated to be a gear stage on the high speed side of the first gear stage at the start of the shift that is likely to cause a shift shock and is often performed. Further, the engine speed is controlled so as to be the speed corresponding to the gear stage on the one-speed side. Therefore, the occurrence of shift shock can be suppressed more reliably.

  Moreover, in the present invention, when the engine speed is controlled to the target speed that is an appropriate speed, the control is performed in the direction of decreasing the engine speed when the engine speed is controlled to increase. Control is performed so that the rate of change of the engine speed with respect to the difference between the target speed and the actual engine speed becomes smaller than the case. For this reason, the engine speed is changed at an early stage by the speed corresponding to the gear stage after the shift, that is, the gear stage on the high speed side of the gear stage at the start of the shift, so that the occurrence of a shift shock can be avoided more reliably. However, it is possible to prevent unexpected acceleration from occurring due to unexpected increases in engine speed and vehicle speed. Specifically, at the time of shifting to change the gear stage to the high speed side, the engine speed corresponding to the gear stage after shifting is smaller than the engine speed at the start of shifting, and it is necessary to reduce the engine speed. There is. Therefore, by controlling as described above, the engine speed can be reduced to the speed corresponding to the gear stage after the shift earlier, and the engine speed is reduced due to the engine speed being excessively reduced. When the number is increased, it is possible to suppress the increase amount from becoming excessively large.

  In the present invention, the engine speed control means controls the engine speed so that the rate of increase of the engine speed per unit time is less than or equal to a preset upper limit value when controlling the engine speed to increase. The number is preferably controlled (claim 2).

  In this way, increases in engine speed and vehicle speed can be more reliably suppressed, and unexpected acceleration can be avoided and safety can be improved.

  As described above, according to the present invention, it is possible to suppress occurrence of shift shock while more reliably avoiding unexpected acceleration after shifting.

1 is a diagram showing an outline of a vehicle to which an engine control device according to an embodiment of the present invention is applied. It is a figure which shows the control block which concerns on the control apparatus of the engine which concerns on embodiment of this invention. It is the graph which showed the relationship between a gear stage and synchronous rotation speed. It is the flowchart which showed the control procedure of shift assist control. It is the flowchart which showed the control procedure of rotation speed control. It is a figure for demonstrating the effect of this invention.

  Hereinafter, an engine control apparatus 1 according to an embodiment of the present invention will be described with reference to the drawings.

(1) Overall Configuration FIG. 1 is a schematic diagram showing a vehicle to which an engine control device 1 is applied.

  The engine 2 shown in FIG. 1 is an engine mounted on a vehicle as a driving source for traveling. FIG. 1 shows an in-line four-cylinder direct injection engine as the engine 2. As shown in FIG. 1, the engine 2 discharges exhaust gas generated in the engine body 20, an engine body 20 in which a plurality of cylinders are formed, an intake passage 21 for introducing air into the engine body 20. The exhaust passage 22 is provided. The engine body 20 is supplied with ignition energy by spark discharge to an injector (see FIG. 2) 23 for injecting fuel into each cylinder, and to a mixture of fuel and air injected from the injector 23. An ignition plug 29 for burning the air-fuel mixture is provided for each cylinder.

  The intake passage 21 includes four independent intake passages 21a communicating with each cylinder, a surge tank 21b commonly connected to the upstream end of each independent intake passage 21a, and one upstream extending from the surge tank 21b. And an intake pipe 21c. An openable / closable throttle valve 25 for adjusting the flow rate of intake air introduced into the engine body 20 is provided in the middle of the intake pipe 21c.

  A clutch 4, a transmission (stepped transmission) 5, and a differential 6 are interposed between the engine 2 and the wheel 3 configured as described above, and a driving force generated by the engine 2. Is transmitted to the wheel 3 via these.

  The transmission 5 is a stepped transmission. In this embodiment, a five-speed transmission having five gears is used as the forward gear. That is, the transmission 5 includes an input shaft 5a to which the driving force of the engine 2 is input, and an output shaft 5b that outputs the driving force to the wheel 3 side, and between the input shaft 5a and the output shaft 5b. Have five gears with different gear ratios. The transmission 5 is also provided with a rear gear. The transmission 5 is a manual transmission, and the gear stage is changed by a driver operating a shift lever (not shown).

  The clutch 4 connects and disconnects the engine 2 and the transmission 5. The clutch 4 has a clutch plate 4a connected to the output shaft of the engine 2 and a clutch plate 4b connected to the input shaft 5a of the transmission 5, and the clutch plates 4a and 4b are in pressure contact with each other. And the connection state of the engine 2 and the transmission 5 is changed by switching to the separated state. The clutch 4 changes the connection state between the engine 2 and the transmission 5 according to the operation of the clutch pedal 11 by the driver. Specifically, when the clutch pedal 11 is depressed (clutch cut), the clutch plates 4a and 4b are separated to disconnect the connection state between the engine 2 and the transmission 5, and the clutch pedal 11 is depressed. When the operation is released, the clutch plates 4a and 4b are pressed to bring the engine 2 and the transmission 5 into a connected state.

  The differential 6 distributes the driving force transmitted from the transmission 5 to the left and right wheels 3 and 3. The differential 6 includes a final reduction gear 6a, and the driving force transmitted from the transmission 5 is transmitted to the wheels 3 and 3 after being decelerated by the final reduction gear 6a.

(2) Control system (2-1) Overview The control system of the engine 2 will be described. In this embodiment, each part of the engine is centrally controlled by an ECU (engine control unit) 50 shown in FIGS. 1 and 2. As is well known, the ECU 50 is a microprocessor including a CPU, a ROM, a RAM, and the like.

  The engine 2 and the vehicle are provided with a plurality of sensors for detecting the state quantities of the respective parts, and information from each sensor is input to the ECU 50.

  For example, the engine body 20 is provided with a crank angle sensor SN1 that detects the engine speed. Specifically, the crank angle sensor SN1 detects the rotation angle and rotation speed of the crankshaft, and the engine speed is specified based on the rotation speed of the crankshaft detected by the crank angle sensor SN1. Is done.

  The vehicle is provided with a vehicle speed sensor SN2 that detects the vehicle speed. Specifically, the vehicle speed sensor SN2 detects the rotation speed of the output shaft 5b of the transmission 5, and the wheel speed is determined based on the rotation speed of the output shaft 5b of the transmission 5 detected by the vehicle speed sensor SN2. 3 and the vehicle speed are specified.

  The vehicle is also provided with a clutch switch SN3 that detects depression of the clutch pedal 11 and an accelerator sensor SN4 that detects the opening (accelerator opening) of the accelerator pedal 12 operated by the driver. In the present embodiment, the clutch switch SN3 determines whether or not the depression amount of the clutch pedal 11 is greater than or equal to a predetermined amount, and outputs a predetermined signal when the depression amount exceeds a predetermined value.

  The ECU 50 is electrically connected to the sensors SN1 to SN4, and based on signals input from the sensors, the above-described various information (engine speed, vehicle speed, depression state of the clutch pedal, accelerator opening) To get.

  The ECU 50 controls each part of the vehicle while executing various determinations and calculations based on the input signals from the sensors SN1 to SN4. For example, the ECU 50 is electrically connected to the injector 23, the throttle valve 25, and the spark plug 29, and outputs a drive control signal to each of these devices based on the result of the calculation.

(2-2) Explanation of Each Part Related to Shift Assist Control The ECU 50 is a shift state determination unit (shift state determination unit) as a specific functional element related to shift assist control for suppressing a shift shock that may occur during a shift. 51, a shift start gear stage estimation unit (shift start gear stage estimation unit) 52, a post-shift gear stage estimation unit (post-shift gear stage estimation unit) 53, a target rotational speed determination unit (target rotational speed determination unit) 54, A rotation speed control unit (rotation speed control means) 55 is provided.

  The shift state determination unit 51 determines whether the engine 2 and the transmission 5 are connected or disconnected, and determines whether a shift is being performed according to the connection state. To do. In the present embodiment, the shift state determination unit 51 performs the above determination based on the detection signal of the clutch switch SN3.

  Specifically, the shift state determination unit 51 outputs a predetermined signal from the clutch switch SN3, and when the clutch switch SN3 detects that the clutch pedal 11 is depressed more than a predetermined amount. It is determined that the engine 2 and the transmission 5 are in a disconnected state. On the other hand, the shift state determination unit 51 determines that the engine 2 and the transmission 5 are connected if a predetermined signal is not output from the clutch switch SN3. When the shift state determination unit 51 determines that the engine 2 and the transmission 5 are switched from the connected state to the disconnected state, the shift state determination unit 51 determines that the shift is started, and the engine 2 and the transmission 5 are disconnected. If it is determined that the state has shifted to the connected state, it is determined that the shift has been completed. Hereinafter, the time point at which the shift state determination unit 51 determines that the shift has started is simply referred to as a shift start time, and the time point at which the shift state determination unit 51 determines that the shift has ended is simply referred to as a shift end time. is there.

  The shift start gear stage estimation unit 52 estimates a gear stage at the start of a shift (hereinafter referred to as a shift start gear stage as appropriate). The shift start gear stage estimation unit 52 estimates the shift start gear stage based on the engine speed NE and the vehicle speed Vsp at the start of the shift.

  In the present embodiment, the gear position estimation unit 52 at the start of shifting is such that the vehicle speed Vsp and the engine speed NE at the start of shifting are any of the preset first region A1 to fifth region A5 shown in FIG. If it is in the first area A1, the gear position at the start of the shift is estimated as the first speed, if it is in the second area A2, the second speed, if it is in the third area A3, the third speed, If it is in the fourth area, it is estimated to be 4th speed, and if it is in the fifth area, it is estimated to be 5th speed.

  The regions A1 to A5 are regions that are set in consideration of a predetermined amount of deviation from the reference synchronous rotational speed with reference to the reference synchronous rotational speed at each gear stage. Here, the reference synchronous rotational speed is the rotational speed of the engine 2 synchronized with the transmission 5 in a reference state in which there is no tire reduction, tire slip, and resistance / mechanical loss in the clutch 4 and the transmission 5 or the like. It is. The reference synchronous rotation speed NEs_i (i: gear stage, i = 1 to 5) at each gear stage is Vsp, the gear ratio of each gear stage is KGEAR_i (i = 1 to 5), and the reduction ratio of the final reduction gear 6a. Where FGR is the reference tire diameter and TS is the reference tire diameter, NEs_i = Vsp × FGR × KGEAR_i × K (K is a constant). Lines L1 to L5 in FIG. 3 indicate reference synchronous rotation speeds in the first to fifth gears, respectively.

  Each of the areas A1 to A5 is set to an area extending from the lower side to the higher side around the lines L1 to L5 of the reference synchronous speed. In the present embodiment, the second to fourth regions A2 to A4 are boundary lines L11 to L15 passing through the center of adjacent reference synchronous rotation speed lines (median engine speed at the same vehicle speed), that is, adjacent lines. Is set in a region sandwiched between lines L11 to L15, which is derived by applying the average value of the gear ratios of adjacent gear stages to the gear ratio of the above formula A. Yes. Further, the first region A1 is set to the entire lower vehicle speed side than the center line L11 of the line L1 of the first-speed reference synchronous rotation speed and the line L2 of the second-speed reference synchronous rotation speed. Further, the fifth region A5 is set on the entire high vehicle speed side from the center line L14 of the line L4 of the fourth-speed reference synchronous rotation speed and the line L5 of the fifth-speed reference synchronous rotation speed.

  Thus, in this embodiment, the total engine speed and the total vehicle speed region are set to any one of the gear region, and the gear step at the start of the shift is set to 1 to 1 by the gear start estimation unit 52 at the start of the shift. It is definitely determined as one of the five stages. However, in a normal state in which the clutch 4 is not slipping and the engine 2 and the transmission 5 are firmly connected, the engine speed and the vehicle speed are substantially the values on the reference synchronous speed lines L1 to L5. .

  The post-shift gear stage estimation unit 53 estimates a gear stage at the end of the shift (hereinafter, appropriately referred to as a post-shift gear stage). The post-shift gear stage estimation unit 53 estimates the gear stage on the first speed high speed side of the estimated shift start gear stage as the post-shift gear stage. For example, if the gear stage at the start of the shift is the second speed, the third speed is estimated as the post-shift gear stage.

  The target rotational speed determination unit 54 determines the rotational speed of the engine synchronized with the transmission 5 after the shift as the target rotational speed. Here, there is almost no change in the vehicle speed during the shift in which the connection between the engine 2 and the transmission 5 is cut off, and the engine speed synchronized with the transmission 5 after the shift is equal to the vehicle speed at the start of the shift and after the shift. It is considered that the rotation speed corresponds to the gear stage. Therefore, in the present embodiment, the target rotational speed determination unit 54 determines the target rotational speed based on the vehicle speed at the start of the shift and the post-shift gear stage estimated by the post-shift gear stage estimation unit 53. The target rotational speed determination unit 54 extracts a value corresponding to the vehicle speed at the start of shifting from the reference synchronous rotational speed of the post-shift gear stage, and determines the target rotational speed. Specifically, the target rotational speed determination unit 54 determines the engine rotational speed that is derived when the gear ratio of the post-shift gear stage estimated by the above equation A and the vehicle speed are applied as the target rotational speed.

  The rotational speed control unit 55 controls the engine rotational speed to the target rotational speed set by the target rotational speed determination unit 54. Details of the engine speed control by the engine speed controller 55 will be described later.

(2-3) Shift Assist Control Flow A control flow performed by the respective parts 51 to 55 configured as described above will be described with reference to the flowchart of FIG.

  First, in step S1, it is determined whether or not shifting has been started. As described above, this determination is performed by the shift state determination unit 51, and the shift state determination unit 51 performs this determination based on a signal from the clutch switch SN3. The determination in step S1 is repeated until it is determined that the determination result is YES and the shift is started.

  If the determination in step S1 is YES and it is determined that the shift is started, the gear stage at the start of the shift is estimated in step S2. As described above, this determination is performed by the shift start gear stage estimation unit 52. The shift start gear stage estimation unit 52 estimates the shift start gear stage based on the engine speed and the vehicle speed at the start of the shift.

  Next, in step S3, the gear stage after the shift is estimated. As described above, this determination is performed by the post-shift gear stage estimation unit 53, and the post-shift gear stage estimation unit 53 sets the gear stage on the higher speed side of the shift start gear stage estimated in step S2 to the post-shift gear stage. Estimate as

  Next, in step S4, the target rotational speed is determined. As described above, this determination is performed by the target rotation speed determination unit 54. The target rotation speed determination unit 54 determines the target rotation speed based on the post-shift gear stage estimated in step S3 and the vehicle speed at the start of the shift. To do.

  Next, in step S5, the engine speed is controlled to the target speed. As described above, this control is performed by the rotation speed control unit 55.

  Next, in step S6, it is determined whether or not the shift has been completed. As described above, this determination is performed by the shift state determination unit 51, and the shift state determination unit 51 performs this determination based on a signal from the clutch switch SN3.

  If the determination in step S6 is YES and it is determined that the shift has been completed, the process proceeds to step S7, where control for setting the engine speed to the target speed, that is, shift assist control is stopped. On the other hand, if the determination in step S6 is no, the process returns to step S5. That is, step S5 is performed until the determination in step S6 is YES.

(2-4) Details of Control by the Rotational Speed Control Unit Details of engine rotational speed control by the rotational speed control unit 55 will be described. FIG. 5 is a flowchart showing the flow of this engine speed control.

  First, in step S11, the rotational speed control unit 55 determines the target rotational speed determined by the target rotational speed determination unit 54 in step S4 and the actual engine rotational speed (hereinafter referred to as actual engine rotational speed as appropriate). , Which is a value obtained by subtracting the actual engine speed from the target speed.

  Next, in Step S12, the rotational speed control unit 55 determines whether or not the rotational speed deviation calculated in Step S11 is less than 0, that is, whether or not the target rotational speed is smaller than the actual engine rotational speed. .

  After the determination in step S12, the process proceeds to step S13 or S15 to determine the control gain. Here, in this embodiment, proportional control is performed, and the control gain determined in steps S13 and S14 is a proportional gain.

  When the determination in step S12 is YES and the target engine speed is smaller than the actual engine speed, and control is performed to decrease the engine speed accordingly, the engine speed control unit 55 proceeds to step S13. The control gain is set to a predetermined first gain. After step S13, the process proceeds to step S14, and the engine speed reduction rate that is the engine speed to be reduced per unit time is set. The rotational speed control unit 55 calculates a value obtained by multiplying the rotational speed deviation calculated in step S11 by the first gain, which is the control gain set in step S13, as the rotational speed reduction rate. After step S14, the process proceeds to step S20.

  On the other hand, if the determination in step S12 is NO and the target engine speed is greater than the actual engine speed, and control is performed to increase the engine speed accordingly, the process proceeds to step S15 and the control gain is set to a predetermined value. Set to the 2nd gain. The second gain is set to a value smaller than the first gain, and when performing control to increase the engine speed, the control gain is set to be smaller than when performing control to decrease the engine speed. The These first gain and second gain are preset values. For example, the first gain is set to 3 and the second gain is set to 1.

  After step S15, the process proceeds to step S16 to set a rotation speed increase rate that is an engine speed to be increased per unit time. The rotation speed control unit 55 calculates a value obtained by multiplying the rotation speed deviation calculated in step S11 by the second gain, which is the control gain set in step S15, as the rotation speed increase rate. As described above, the second gain is smaller than the first gain, and the rotation speed increase rate is calculated smaller than the rotation speed decrease rate. That is, the increase / decrease rate (change rate) of the rotational speed with respect to the difference between the target rotational speed and the actual engine rotational speed is made smaller when increasing the rotational speed than when decreasing it. In this embodiment, when the determination in step S12 is NO and control is performed to increase the engine speed, the engine speed controller 55 does not proceed to step S20 immediately after step S16, but proceeds to step S17. .

  In step S17, the rotation speed control unit 55 determines whether or not the rotation speed increase rate calculated in step S16 is smaller than a preset upper limit value. If this determination is YES, the process proceeds to step S20. On the other hand, if this determination is NO and the rotational speed increase rate is equal to or greater than the upper limit, the process proceeds to step S18, and the rotational speed increase rate is set to the upper limit value. That is, in the present embodiment, the engine speed that is increased per unit time is suppressed below this upper limit value. After step S18, the process proceeds to step S20.

  In step S20, the rotation speed control unit 55 calculates an increase / decrease amount of torque necessary to increase / decrease the engine rotation speed. The rotation speed control unit 55 calculates a torque increase / decrease amount based on the rotation speed increase / decrease rate set in step S14, S16 or S18. A torque increase / decrease amount required to increase the engine speed by the speed increase / decrease rate is calculated. Specifically, the rotation speed control unit 55 stores a map of the required torque increase / decrease amount with respect to a preset rotation speed increase / decrease rate, and from this map, the required torque increase / decrease amount corresponding to the rotation speed increase / decrease rate is determined. Extract. As described above, the rotational speed increase rate is smaller than the rotational speed decrease rate, and the increase / decrease amount of the required torque when the engine speed is increased, that is, the increase amount of the required torque is the required torque when the engine speed is decreased. It is calculated smaller than the increase / decrease amount, that is, the decrease amount of the required torque. Further, the rotational speed increase rate is suppressed to the upper limit value or less, and accordingly, the increase amount of the required torque per unit time is suppressed to the predetermined value or less.

  Next, in step S21, the rotation speed control unit 55 calculates a rotation speed maintenance torque that is an engine torque necessary to maintain the current engine rotation speed. Specifically, the rotation speed control unit 55 stores a map of preset engine rotation speed and rotation speed maintenance torque, and extracts a value corresponding to the actual engine rotation speed from this map.

  Next, in step S22, the rotation speed control unit 55 maintains the engine rotation speed at the current value, and increases or decreases the engine torque by the torque increase / decrease amount calculated in step S20. Is calculated. Specifically, the rotation speed control unit 55 calculates a value obtained by adding the rotation speed maintenance torque calculated in step S21 and the torque increase / decrease amount calculated in step S20 as the target torque.

  Next, in step S23, the rotational speed control unit 55 calculates the target output of the engine necessary to increase or decrease the engine torque by the torque increase / decrease amount calculated in step S20 while maintaining the engine rotational speed at the current value. To do. In the present embodiment, the final required torque is calculated by adding the auxiliary torque required for operating the engine auxiliary machine such as the alternator and the mechanical resistance torque caused by the engine rotation to the target torque calculated in step S22. Then, a pumping loss amount is further added to the engine output necessary to obtain this final required torque to obtain the target engine output.

  Next, in step S24, the rotation speed control unit 55 determines a target air amount and an ignition timing for outputting the target engine output based on the target engine output calculated in step S23, and determines the determined target air. The opening degree of the throttle valve for supplying the amount to the engine 2 is determined. Further, the fuel injection amount is determined according to the target air amount.

  In step S25, the rotation speed control unit 55 controls the throttle valve 25, the spark plug 29, and the injector 23 so that the throttle valve opening, the ignition timing, and the fuel injection amount determined in step S24 are obtained.

(3) Operation FIG. 6 shows changes in the output of the clutch switch SN3, that is, the depression amount of the clutch pedal 11 and the engine speed when the shift assist control is performed. FIG. 6 shows a case where the shift up to the one-stage high speed side is performed. Further, in the engine speed of FIG. 6, the solid line indicates the result when the control according to the present embodiment is performed, and the alternate long and short dash line indicates the control gain when increasing the engine speed and the control gain when decreasing. Are the same values (first gain).

  When the output of the clutch switch SN3 reaches a predetermined value as the clutch pedal 11 is depressed at time t1, it is determined that the shift has started, and accordingly, the target rotational speed NEtrg is determined. Then, control of the engine speed is started so as to reach the target speed NEtrg. As described above, in the present embodiment, the control gain for reducing the engine speed is set to the first gain, and accordingly, the amount of decrease in the required torque is calculated to a large value, and the target torque and the target torque are calculated. The engine output, that is, the reduction amount of the engine output is increased. Therefore, at the time t2 earlier than the time t3 when the depression of the clutch pedal is released (the signal of the clutch switch SN3 returns to 0), the engine speed decreases to near the target speed NEtrg. On the other hand, since the control gain is high, the engine speed decreases to a value smaller than the target speed NEtrg at time t2. As the engine speed falls below the target speed NEtrg, control is performed to increase the engine speed after time t2.

  Here, in FIG. 6, when the control gain for increasing the engine speed is also set large as shown by the one-dot chain line, the engine speed is increased with a large control gain after time t2. As a result, the engine speed increases beyond the target speed NEtrg, and at time t3, the engine speed exceeds the target speed NEtrg, that is, the speed at which the transmission 5 and the engine 2 are synchronized after the shift. Therefore, in this case, a relatively large shift shock occurs when the engine 2 and the transmission 5 are reconnected at time t3, and the engine speed exceeds the target speed NEtrg at time t3 and thereafter. Therefore, the driver's unexpected acceleration occurs.

  On the other hand, in this embodiment, the control gain when increasing the engine speed is set small. Therefore, as indicated by the solid line, after time t2, the engine speed gradually approaches the target speed NEtrg, converges to the target speed NEtrg near time t3 without substantially exceeding the target speed NEtrg, and shifts. The shift is completed without causing shock and unexpected acceleration.

  As described above, in this embodiment, the control gain, that is, the increase rate of the engine speed with respect to the deviation between the target engine speed and the actual engine speed is set to be larger when the engine speed is decreased than when the engine speed is decreased. As a result, the engine speed is reduced to the target speed at an early stage, and the engine speed is prevented from increasing beyond the target speed, resulting in unexpected acceleration after a shift shock and a shift. Can be avoided.

  Further, in the present embodiment, the gear stage after the shift is estimated to be a gear stage on the high speed side of the first gear stage at the start of the shift that is likely to cause a shift shock and is often performed. The engine speed is controlled so that the speed corresponds to the gear speed on the high speed side. Therefore, the occurrence of shift shock can be suppressed more reliably.

  Furthermore, in this embodiment, when the engine speed is controlled to increase, the engine speed is controlled so that the rate of increase of the engine speed per unit time is equal to or less than a preset upper limit value. . Therefore, the increase in the engine speed and the vehicle speed can be more reliably suppressed, and unexpected acceleration can be avoided to improve safety.

  Further, in this embodiment, since the control gain when the engine speed is decreased is set to be large, as shown in FIG. 6, the engine speed falls below the target speed until the end of the shift. There is a high possibility that the time during which the engine speed is equal to or lower than the target speed is secured for a relatively long time. Therefore, for example, the gear stage after the shift is not the first high speed side at the start of the shift but the higher gear stage such as the second stage, and the speed of the engine 2 synchronized with the transmission 5 after the shift is the target speed. Even if the rotation speed is lower than the number, the difference from the synchronous rotation speed can be kept small, and the shift shock can be kept small.

(4) Modification The specific value of the control gain is not limited to the above, and can be set as appropriate.

  Further, the number of transmission stages is not limited to five.

2 Engine 4 Clutch 5 Transmission (Stepped transmission)
51 Shift state determination unit (shift state determination means)
52 Shift start gear stage estimation unit (shift start gear stage estimation means)
53 Post-shift gear stage estimation section (post-shift gear stage estimation means)
54 Target rotational speed determination unit (target rotational speed determination means)
55 Rotational speed control unit (Rotational speed control means)

Claims (2)

A control device for an engine mounted on a vehicle having a stepped transmission, an engine, and a clutch for connecting and disconnecting the stepped transmission and the engine,
In addition to determining the connection state between the stepped transmission and the engine, it is determined that shifting has started when the stepped transmission and the engine are shifted from a state where they are connected to each other, and the state where the stepped transmission is started. Shift state determining means for determining that the shift has been completed when the stage transmission and the engine are connected to each other;
A shift start gear stage estimating means for estimating a shift start gear stage which is a gear stage when it is determined by the shift state determining means that a shift is started;
A post-shift gear stage estimation means for estimating a gear stage on the first speed high speed side of the shift start gear stage as a post-shift gear stage which is a gear stage when the shift state determination means determines that the shift has been completed; ,
Based on the vehicle speed when it is determined that the shift is started by the shift state determining means and the estimated gear after the shift, the engine speed synchronized with the stepped transmission after the shift is estimated, and this Target rotational speed determining means for determining the estimated value as the target rotational speed;
A rotational speed control means for controlling the rotational speed of the engine so as to achieve the target rotational speed when the shift state determination means determines that a shift has been started;
When the engine speed is controlled in the direction in which the engine speed is increased, the engine speed control means is more sensitive to the difference between the target engine speed and the actual engine speed than in the direction in which the engine speed is decreased. An engine control device that controls an engine speed so that an increase / decrease rate of the engine speed becomes small. The engine control device according to claim 1,
When the engine speed is controlled in the direction of increasing the engine speed, the engine speed control unit controls the engine speed so that the rate of increase of the engine speed per unit time is equal to or less than a preset upper limit value. An engine control device.

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