JP2014092030A - Creep torque control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a creep torque control device for a vehicle capable of attaining an optimization of the creep torque for a control to increase the creep torque when "a slip-down" occurs at a vehicle.SOLUTION: In the case that a vehicle speed upon occurrence of "slip-down" of a vehicle is a prescribed value V1 or lower, an adding amount ADD is set to "A" and if the vehicle speed exceeds the prescribed value V1, the adding amount ADD is set to "B". If a previous value of the adding amount ADD is different from a present value (a result YES at a step ST11), the set adding amount ADD is added to a base value BASE to compute a desired number of rotation TGTN and then the number of rotation of an engine is controlled to the desired number of rotation TGTN. In the case that the previous value of the adding amount ADD is the same as the present value (a result NO at the step ST11), a preset limited adding value β is added to the previous desired number of rotation TGTN to compute a present desired number of rotation TGTN (at a step ST12) and the number of rotation of the engine is controlled to the desired number of rotation TGTN.

Description

  The present invention relates to a creep torque control device for a vehicle. In particular, the present invention relates to an improvement in creep torque control when a vehicle travels in a direction opposite to a travel direction corresponding to a selected travel range (hereinafter referred to as “sliding down”).

  Conventionally, when a vehicle stopped on an uphill road starts, when the braking force is released (for example, when the driver depresses the brake pedal), the forward running range (for example, D range) ) May be selected, but “sliding down (reversing the vehicle)” may occur.

  As a technique for preventing or suppressing the “sliding down”, it is known to increase the creep torque by increasing the output torque of the engine when the “sliding down” occurs (see, for example, Patent Document 1 and Patent Document 2). In the techniques disclosed in these patent documents, the creep torque is increased as the vehicle speed at the time of “sliding down” increases. By controlling the creep torque, the “sliding down” can be eliminated or suppressed, and engine stall can be prevented.

JP-A-8-145154 JP 2010-96051 A

  However, when the control is performed such that the creep torque is increased as the vehicle speed is simply increased at the time of “sliding down”, there are problems described below.

  In other words, when the vehicle speed at the time of “sliding down” is relatively high, the creep torque may be significantly higher than the appropriate value. In this case, the behavior of the vehicle becomes unstable. There is a possibility of giving the passenger a sense of incongruity.

  In order to avoid such a situation, it is conceivable that the increase amount of the creep torque when the “sliding” occurs is set to a small value regardless of the vehicle speed. There is a possibility that the function of suppressing the sliding down may not be sufficiently exhibited.

  The present invention has been made in view of such a point, and the object of the present invention is to optimize the creep torque with respect to the control for increasing the creep torque when the vehicle "slids down". An object of the present invention is to provide a creep torque control device for a vehicle.

-Solution principle of the invention-
The solution principle of the present invention taken in order to achieve the above object is that when the amount of increase in the target creep torque is updated every predetermined period in accordance with the vehicle speed at the time of occurrence of “sliding”, the amount of increase is increased. If the previous value and the current value match, the creep torque target value may be excessive, and the target creep torque is limited to an increase amount that is more limited than the increase amount. The setting is made. This prevents the creep torque from becoming excessive and the vehicle behavior from becoming unstable.

-Solution-
Specifically, according to the present invention, the target creep is increased so that the creep torque applied to the wheel is increased in the event of a “sliding down” in which the vehicle travels in the direction opposite to the traveling direction corresponding to the selected traveling range. A creep torque control device for a vehicle that performs control to correct torque is assumed. Compared to the increase correction amount of the target creep torque at the start of the control for correcting the target creep torque, the increase correction amount of the target creep torque in the predetermined period after the start of the control is made. It is configured to add restrictions.

  As used herein, “sliding down” refers to, for example, when a vehicle starts moving in a forward direction on an uphill road, when the vehicle moves backward even though the selected driving range is the forward driving range, or on a downhill road When the vehicle starts in the reverse direction, there is a case where the vehicle moves forward although the selected travel range is the reverse travel range. Further, the case where the forward travel range is selected is not limited to the case where the “drive range” in which automatic transmission of the automatic transmission is performed is selected, but “first speed (1ST)” or “first” In the automatic transmission in which “second speed (2ND)” can be selected, the case where these gears are selected is also included. Further, the automatic transmission capable of so-called sequential shift includes a case where the sequential shift mode is selected.

  When the target creep torque is corrected due to the occurrence of “slip down” due to the specific matter described above, the start of the control is compared with the increase correction amount of the target creep torque at the start of the correction control. A restriction is imposed on the amount of increase correction of the target creep torque in a predetermined period later. Specifically, during the predetermined period, when correction control similar to the increase correction amount of the target creep torque at the start of the correction control is performed (when the target creep torque is sequentially increased by this increase correction amount) ), The target creep torque becomes too large, and the behavior of the vehicle may become unstable. Considering this, the present solution means limits the increase correction amount of the target creep torque during the predetermined period to avoid the target creep torque from becoming too large. In addition, since the above-described restriction is not added to the target creep torque increase correction amount at the start of correction control, a sufficient target creep torque increase correction amount corresponding to “slipping” is secured, and “slipping” This prevents the vehicle speed from becoming too high. As described above, by changing the increase correction amount of the target creep torque, it is possible to sufficiently exhibit the slip-down suppressing function without causing instability of the behavior of the vehicle.

  Specific examples of the predetermined period for limiting the increase correction amount of the target creep torque include the following. That is, when the increase correction amount of the target creep torque is set according to the vehicle speed for each predetermined period when the “sliding” occurs, the increase correction amount of the target creep torque is limited. The predetermined period is a period in which the previous value and the current value of the increase correction amount of the target creep torque set for each predetermined period coincide with each other.

  In the case where the previous value and the current value of the increase correction amount of the target creep torque coincide with each other, if there is no restriction on the increase correction amount of the target creep torque, an increase corresponding to the vehicle speed is performed every predetermined period. The target creep torque is increased by the correction amount. In this case, there is a possibility that the target creep torque becomes excessive and the behavior of the vehicle becomes unstable. In the present solution, the target creep torque increase correction amount is limited during the period when the previous value and the current value of the target creep torque increase correction amount coincide with each other. It is possible to avoid the creep torque from becoming too large, and to stabilize the behavior of the vehicle.

  Specifically, as the value that can be taken as the increase correction amount of the target creep torque, the vehicle speed is equal to or less than a predetermined value, and the previous value and the current value of the increase correction amount of the target creep torque set for each predetermined period The first increase correction amount set when the two do not match, the vehicle speed exceeds a predetermined value, the previous value and the current value of the target creep torque increase correction amount set for each predetermined period, In a situation where the second increase correction amount set when the two do not match and the increase correction amount of the target creep torque is set to the first increase correction amount or the second increase correction amount, A third increase correction amount that is set when the previous value and the current value of the target creep torque increase correction amount match each other is defined. The first increase correction amount is set as a value smaller than the second increase correction amount, and the third increase correction amount is set as a value smaller than the first increase correction amount. .

  Thus, by setting the first increase correction amount as a value smaller than the second increase correction amount, the initial increase correction amount is set according to the vehicle speed at the initial stage of occurrence of “sliding down” (period in which the increase correction amount of the target creep torque is not limited). Further, an increase correction amount for the target creep torque can be appropriately obtained. Then, by setting the third increase correction amount as a value smaller than the second increase correction amount, it is possible to avoid the target creep torque from becoming too large thereafter, and to stabilize the behavior of the vehicle. be able to.

  Other values that can be taken as an increase correction amount of the target creep torque include the following. That is, the first increase correction amount that is set when the vehicle speed is equal to or less than a predetermined value and the previous value of the increase correction amount of the target creep torque that is set every predetermined period does not match the current value. And a second increase correction amount that is set when the vehicle speed exceeds a predetermined value and the previous value and the current value of the increase correction amount of the target creep torque that are set every predetermined period do not match. And when the increase correction amount of the target creep torque is set to the first increase correction amount, the previous value of the increase correction amount of the target creep torque matches the current value. In the situation where the fourth increase correction amount and the increase correction amount of the target creep torque are set to the second increase correction amount, the previous value and the current value of the increase correction amount of the target creep torque Set if matches Increase correction amount of the fifth and are defined. The first increase correction amount is set as a value smaller than the second increase correction amount, the fourth increase correction amount is set as a value smaller than the first increase correction amount, and the first The increase correction amount of 5 is set as a value larger than the fourth increase correction amount and smaller than the second increase correction amount.

  As in the case of the solution described above, the first increase correction amount is set to a value smaller than the second increase correction amount, so that the initial value of “slipping” occurs (the increase correction amount of the target creep torque is limited). The increase correction amount of the target creep torque according to the vehicle speed during the period during which the vehicle is not operated can be appropriately obtained. In this solution, the fourth increase correction amount is set as a value smaller than the first increase correction amount, and the fifth increase correction amount is set as a value smaller than the second increase correction amount. As a result, even during the predetermined period (a period in which the previous value and the current value of the increase correction amount of the target creep torque set for each predetermined period coincide with each other), the “sliding down” vehicle speed becomes too high. Is prevented.

  Specifically, as the creep torque control, when the vehicle includes an internal combustion engine as a driving force source, the creep torque to be applied to the wheels is set to the rotation speed at which the target rotation speed can be obtained with the target rotation speed of the internal combustion engine. It has been changed by setting it to a number.

  As a result, the creep torque can be optimized by relatively simple control such as control of the target rotational speed of the internal combustion engine.

  In the present invention, when the control for correcting the target creep torque is performed in order to suppress the “sliding down” of the vehicle, the amount of increase correction of the target creep torque in a predetermined period after the start of the control is limited. For this reason, it can be avoided that the target creep torque becomes too large, and the behavior of the vehicle can be stabilized.

1 is a schematic configuration diagram illustrating a power train of a vehicle according to an embodiment. It is a skeleton figure which shows an example of the transmission mechanism part in an automatic transmission. It is a figure which shows the engagement state for every gear stage of each clutch and each brake in an automatic transmission. It is a schematic block diagram which shows the control block containing an engine control apparatus and a transmission control apparatus. It is a figure which shows the shift gate of a shift apparatus. It is a figure which shows the shift map used for shift control. It is a flowchart figure which shows the first half of the procedure of creep torque control. It is a flowchart figure which shows the second half of the procedure of creep torque control. It is a timing chart figure which shows the change of the engine target rotation speed with respect to the change of the reverse vehicle speed of a vehicle. It is a timing chart figure which shows the change of engine target number of rotations with respect to the change of the reverse vehicle speed of vehicles in a modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, a case where the present invention is applied to an FR (front engine / rear drive) vehicle equipped with an automatic transmission will be described. First, the basic operation of the vehicle power train (vehicle drive device) and automatic transmission will be described.

  FIG. 1 is a schematic configuration diagram showing a power train of a vehicle according to the present embodiment, FIG. 2 is a skeleton diagram showing an example of a transmission mechanism 30 in the automatic transmission 2 of FIG. 1, and FIG. 4 is an engagement table of each clutch and each brake for each gear position in the mechanism unit 30.

  In FIG. 1, 1 is an engine (drive source: rotational power source), 2 is an automatic transmission, 3 is an engine control device (engine ECU), and 4 is a transmission control device (transmission ECU).

-Engine-
The engine 1 generates rotational power by burning an air-fuel mixture in which air sucked from the outside and fuel injected from an injector (fuel injection valve) 5 are mixed at an appropriate ratio by ignition of a spark plug 12. It is an internal combustion engine. The intake air amount is adjusted by the throttle valve 6. The throttle valve 6 is driven by an electric actuator (throttle motor or the like) 7, and the opening degree is adjusted by driving the actuator 7 based on the depression amount of the accelerator pedal 11 and control conditions. . The injector 5, the actuator 7 and the spark plug 12 are controlled by the engine control device 3.

-Automatic transmission-
The automatic transmission 2 changes the rotational power input from the engine 1 to the input shaft 9 and outputs it to the drive wheels via the output shaft 10, and is mainly a torque converter (fluid coupling: fluid torque transmission device). 20, a transmission mechanism unit 30, a hydraulic control device 40, and the like.

  As shown in FIG. 2, the torque converter 20 is rotationally connected to the engine 1 and includes a pump impeller 21, a turbine runner 22, a stator 23, a one-way clutch 24, a stator shaft 25, and a lock-up clutch 26. ing.

  The lock-up clutch 26 enables the pump impeller 21 (input side) and the turbine runner 22 (output side) of the torque converter 20 to be directly connected, and the pump impeller 21 and the turbine runner 22 are connected as necessary. The state is switched between a directly engaged state, a released state in which the pump impeller 21 and the turbine runner 22 are disconnected, and a half-engaged state (slip state) between these engaged state and released state.

  The engagement force of the lockup clutch 26 is controlled by controlling the hydraulic pressure applied to the pump impeller 21 and the turbine runner 22 by the lockup control valve 27.

  As shown in FIG. 2, the speed change mechanism 30 mainly includes a first planetary 31, a second planetary 32, a third planetary 33, clutches C1 to C4, brakes B1 to B4, one-way clutches F0 to F3, and the like. Thus, a shift of 6 forward speeds and 1 reverse speed is possible.

  The first planetary 31 is a gear type planetary mechanism called a double pinion type, and includes a sun gear S1, a ring gear R1, a plurality of inner pinion gears P1A, a plurality of outer pinion gears P1B, and a carrier CA1. It is the structure containing.

  The sun gear S1 is selectively connected to the input shaft 9 via the clutch C3. The sun gear S1 is selectively connected to the housing via the one-way clutch F2 and the brake B3, and is prevented from rotating in the reverse direction (the direction opposite to the rotation of the input shaft 9). The carrier CA1 is selectively connected to the housing via the brake B1, and is always prevented from rotating in the reverse direction by the one-way clutch F1 provided in parallel with the brake B1. The ring gear R1 is integrally connected to the ring gear R2 of the second planetary 32, and is selectively connected to the housing via the brake B2.

  The second planetary 32 is a gear-type planetary mechanism called a single pinion type, and includes a sun gear S2, a ring gear R2, a plurality of pinion gears P2, and a carrier CA2.

  The sun gear S2 is integrally connected to the sun gear S3 of the third planetary 33, and is selectively connected to the input shaft 9 via the clutch C4. The sun gear S2 is selectively connected to the input shaft 9 via the one-way clutch F0 and the clutch C1, and is prevented from rotating in the opposite direction relative to the input shaft 9. The carrier CA2 is integrally connected to the ring gear R3 of the third planetary 33, is selectively connected to the input shaft 9 via the clutch C2, and is selectively connected to the housing via the brake B4. The The carrier CA2 is always prevented from rotating in the reverse direction by a one-way clutch F3 provided in parallel with the brake B4.

  The third planetary 33 is a gear-type planetary mechanism called a single pinion type, and includes a sun gear S3, a ring gear R3, a plurality of pinion gears P3, and a carrier CA3. The carrier CA3 is integrally connected to the output shaft 10.

  The clutches C1 to C4 and the brakes B1 to B4 are configured by a wet multi-plate friction engagement device (friction engagement element) using the viscosity of oil.

  The hydraulic control device 40 establishes an appropriate shift speed (forward 1st to 6th speed, reverse speed) by individually engaging and releasing the clutches C1 to C4 and the brakes B1 to B4 in the speed change mechanism 30. is there. Since the basic configuration of the hydraulic control device 40 is known, detailed illustration and explanation are omitted here.

  Here, the conditions for establishing each gear position in the above-described transmission mechanism 30 will be described with reference to FIG.

  FIG. 3 is an engagement table showing engagement or disengagement states of the clutches C1 to C4, the brakes B1 to B4, and the one-way clutches F0 to F3 for each gear position of the transmission mechanism unit 30. In this engagement table, ◯ indicates “engaged”, x indicates “released”, ◎ indicates “engaged during engine braking”, and Δ indicates “engagement that does not transmit power”.

  Note that the clutch C1 is called a forward clutch (input clutch) and, as shown in the engagement table of FIG. 3, the vehicle other than the parking position (P), the reverse position (R), and the neutral position (N) It is used in the engaged state when establishing a shift stage for moving forward.

  The configuration of the transmission mechanism unit 30 to which the present invention is applied is not limited to that shown in FIG. 2, and the present invention can be applied to a vehicle equipped with various transmission mechanism units. Yes.

-Engine control device and transmission control device-
The engine control device 3 drives the engine 1 by controlling the air-fuel mixture supplied to the engine 1 and the combustion timing in accordance with the traveling state.

  The transmission control device 4 controls the hydraulic control device 40 to establish an appropriate shift stage, that is, a power transmission path in the transmission mechanism unit 30.

  The engine control device 3 and the transmission control device 4 are connected so as to be able to transmit and receive information necessary for engine control and transmission control.

  Although not shown, the engine control device 3 and the transmission control device 4 are both generally known ECUs (Electronic Control Units), which are respectively a CPU (Central Processing Unit), a ROM (Read Only Memory), A RAM (Random Access Memory) and a backup RAM are provided.

  The ROM stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU executes arithmetic processing based on various control programs and maps stored in the ROM. The RAM is a memory for temporarily storing calculation results in the CPU, data input from each sensor, and the like. The backup RAM is a non-volatile memory for storing data to be saved when the engine 1 is stopped. is there.

  As shown in FIG. 4, the engine control device 3 includes a crank angle sensor 101 for detecting the rotation angle (crank angle CA) of the crankshaft of the engine 1 and a throttle opening for detecting the opening of the throttle valve 6. Various sensors for detecting the operating state of the engine 1 such as the degree sensor 102 and the air flow meter 103 for detecting the intake air amount are connected, and signals of the respective sensors are inputted. The engine control device 3 also changes the phase of the fuel injection amount and fuel injection timing of the actuator (throttle motor) 7 of the throttle valve 6 and the injector 5, the ignition timing of the spark plug 12, and the intake / exhaust valve opening / closing timing. The VVT (Variable Valve Timing) mechanism 13 is controlled.

  A torque estimation map for estimating the output torque of the engine 1 is stored in the ROM of the engine control device 3. From this torque estimation map, the engine speed calculated based on the output signal from the crank angle sensor 101, the throttle opening detected by the throttle opening sensor 102, the intake air amount detected by the air flow meter 103, and Can estimate the current output torque of the engine 1 based on the fuel injection amount from the injector 5, the ignition timing of the spark plug 12, and the intake / exhaust valve opening / closing timing adjusted by the VVT mechanism 13.

  The transmission control device 4 includes an input shaft rotational speed sensor 110 that detects the rotational speed (rotational speed) of the input shaft 9, an output shaft rotational speed sensor 111 that detects the rotational speed (rotational speed) of the output shaft 10, and a driver. An accelerator opening sensor 112 for detecting the opening degree of the operated accelerator pedal 11, a shift position sensor 113 for detecting the shift lever position of the automatic transmission 2, a wheel speed sensor 114 for detecting the speed (wheel speed) of the drive wheel, A G sensor 115 that detects a change in the longitudinal G of the vehicle, a brake pedal sensor 116 that detects an operation amount of the brake pedal 14 operated by a driver, and the like are connected.

  The transmission control device 4 outputs a lockup clutch control signal to the lockup control valve 27. Based on the lock-up clutch control signal, the lock-up control valve 27 controls the engagement pressure of the lock-up clutch 26, and the lock-up clutch 26 is engaged (torque state), released (completely slipped), The semi-engaged state (slip state: also called flex lockup state) is switched.

  Further, the transmission control device 4 outputs a solenoid control signal (hydraulic command signal) to the hydraulic control device 40 of the automatic transmission 2. Based on this solenoid control signal, a linear solenoid valve, an on-off solenoid valve, and the like provided in the hydraulic control circuit of the hydraulic control device 40 are controlled, and predetermined gears (first to sixth gears, reverse gear) Etc.), the clutches C1 to C4 and the brakes B1 to B4 of the automatic transmission 2 are engaged or released in a predetermined state.

-Shift device-
Moreover, the shift apparatus 50 is arrange | positioned in the vicinity of the driver's seat of the vehicle which concerns on this embodiment (refer FIG. 1). The shift device 51 is provided with a shift lever 51 so that it can be displaced. Further, as shown in FIG. 5, the shift device 50 includes a shift having a parking (P) position, a reverse (R) position, a neutral (N) position, a drive (D) position, and a sequential (S) position. A gate is formed so that the driver can displace the shift lever 51 to a desired shift position. The shift positions of these parking (P) position, reverse (R) position, neutral (N) position, drive (D) position, and sequential (S) position (including the “+” position and “−” position described below) are , Detected by the shift position sensor 113.

  In the state where the shift lever 51 is operated to the “drive (D) position”, the automatic transmission 2 is set to the “automatic transmission mode (automatic mode)”, and the gear position is selected according to a transmission map described later to automatically change the gear. Operation is performed.

  On the other hand, when the shift lever 51 is operated to the “sequential (S) position”, the automatic transmission 2 is set to the “manual shift mode (sequential shift mode)”. A “+” position and a “−” position are provided before and after the S position. The “+” position is a position where the shift lever 51 is operated during a manual upshift, and the “−” position is a position where the shift lever 51 is operated during a manual downshift. When the shift lever 51 is at the S position and the shift lever 51 is operated to the “+” position or the “−” position with the S position as a neutral position, the gear position of the automatic transmission 2 is increased or decreased. Is done. Specifically, the gear position is increased by one step for each operation to the “+” position (for example, 1st → 2nd →... → 6th). On the other hand, the gear stage is lowered by one stage (for example, 6th → 5th →... → 1st) for each operation to the “−” position.

-Shift map-
The shift control of the automatic transmission 2 in the “automatic shift mode” is performed according to a shift map (shift condition) as shown in FIG. 6, for example. This shift map has a vehicle speed V and an accelerator opening θTH (or throttle opening) as parameters, and a plurality of speed maps for obtaining an appropriate shift stage according to the vehicle speed V and accelerator opening θTH (or throttle opening). A map in which an area is set, and is stored in the ROM of the transmission control device 4. Each region of the shift map is partitioned by a plurality of shift lines (shift stage switching lines). In the shift map shown in FIG. 6, the upshift line (shift line) is indicated by a solid line, and the downshift line (shift line) is indicated by a broken line. In addition, each switching direction of the upshift and the downshift is indicated using numerals and arrows in the drawing.

-Shift control operation of automatic transmission-
Next, the shift control operation of the automatic transmission 2 configured as described above will be described.

  First, the “automatic transmission mode” in which the shift lever 51 is operated to the “drive (D) position” will be described.

  The transmission control device 4 calculates the vehicle speed V based on the output signal of the output shaft rotational speed sensor 111, calculates the accelerator opening θTH from the output signal of the accelerator opening sensor 112, and determines the vehicle speed V and the accelerator opening. Based on θTH, the target shift speed is calculated with reference to the shift map of FIG. Further, the present gear stage is determined by obtaining the ratio of the number of revolutions obtained from the output signals of the input shaft revolution number sensor 110 and the output shaft revolution number sensor 111 (output revolution number / input revolution number). It is determined whether or not a shift operation is necessary by comparing with the target shift stage.

  If the result of the determination indicates that there is no need for a shift (when the current shift stage and the target shift stage are the same and the shift stage is set appropriately), a solenoid control signal (hydraulic command) is used to maintain the current shift stage. Signal) to the hydraulic control device 40 of the automatic transmission 2.

  On the other hand, when the current shift speed and the target shift speed are different, shift control is performed. For example, when the traveling state of the vehicle changes from a state where the shift stage of the automatic transmission 2 is in the “fourth speed” state, for example, the point A changes to the point B shown in FIG. Since the change occurs across the shift line [4 → 5], the target shift speed calculated from the shift map is “5-speed”, and the solenoid control signal (hydraulic command signal) for setting the 5-speed shift speed is automatically shifted. Output to the hydraulic control device 40 of the machine 2 to perform a shift (4 → 5 up shift) from the fourth gear to the fifth gear.

  In addition, for example, when the traveling state of the vehicle changes from a state where the shift stage of the automatic transmission 2 is traveling in the state of “sixth speed”, for example, from point C to point D shown in FIG. Since the shift shifts across the downshift shift line [6 → 5], the target shift speed calculated from the shift map is “5-speed”, and a solenoid control signal (hydraulic command signal) for setting the 5-speed shift speed is set. Output to the hydraulic control device 40 of the automatic transmission 2 to perform a shift from the sixth gear to the fifth gear (6 → 5 downshift).

  On the other hand, in the “manual shift mode” in which the shift lever 51 is operated to the “sequential (S) position”, the shift operation is performed by operating the shift lever 51 as described above. That is, every time the shift lever 51 is operated to the “+” position once with the S position as the neutral position, the gear position is increased by one step, and each time the shift lever 51 is operated to the “−” position, the gear position is increased. Down one step at a time.

-Creep torque control-
Next, creep torque control, which is an operation characteristic of the present embodiment, will be described.

  First, an outline of the creep torque control will be described.

  In the conventional technology, when a “sliding down”, which is a phenomenon in which the vehicle travels in a direction opposite to the traveling direction corresponding to the traveling range selected by the shift lever, occurs, In order to eliminate or suppress it, the output torque of the engine is increased to increase the creep torque. In addition, the creep torque is increased as the vehicle speed at the time of the occurrence of the “sliding down” is increased.

  For example, when a vehicle stopped on an uphill road starts, when the driver depresses the brake pedal, the vehicle moves backward despite the shift lever operating position being the “drive position”. In this case, it is determined that “sliding down” has occurred. The engine output torque is increased to increase the creep torque as the "sliding down" vehicle speed (reverse vehicle speed) increases.

  However, such control may lead to a situation in which the creep torque becomes significantly higher than the appropriate value when the vehicle speed at the time of “sliding” is relatively high. May become unstable and give the passenger a sense of incongruity. In addition, if the increase amount of the creep torque at the time of “sliding” is set small regardless of the vehicle speed, the instability of the behavior of the vehicle can be suppressed, but with this, the creep torque cannot be sufficiently obtained, There is a possibility that the original sliding suppression function is not sufficiently exhibited.

  In view of this point, in the present embodiment, compared with the target creep torque increase correction amount (change amount to the creep torque increase side) at the start of the control for increasing the creep torque, in a predetermined period after the start of the control. A limit is imposed on the increase correction amount of the target creep torque. Further, as the predetermined period, the target creep torque increase correction amount is set according to the vehicle speed for each predetermined period, and the previous value of the target creep torque increase correction amount set according to the vehicle speed, The target creep torque increase correction amount set in accordance with the vehicle speed is set in a period that coincides with the current value. That is, during the period in which the previous value and the current value of the increase correction amount of the target creep torque coincide with each other, the increase correction amount of the target creep torque is limited and set by the limited increase correction amount. Creep torque control is executed so as to obtain the target creep torque.

  Next, a specific procedure for creep torque control will be described. In the following description, the case where the target creep torque and the increase correction amount thereof are defined by the engine speed will be described. That is, a case where the creep torque is adjusted by controlling the engine speed will be described.

  7 and 8 are flowcharts showing the procedure of creep torque control. The routines shown in FIGS. 7 and 8 are executed every predetermined time or every predetermined rotation angle of the crankshaft.

  First, in step ST1, it is determined whether or not a creep torque control execution flag stored in advance in the transmission control device 4 is ON. This creep torque control execution flag is turned ON when the occurrence of “sliding” is detected, and turned OFF when this “sliding” has not occurred and when the occurrence of “sliding” has been resolved. The The detection of “sliding down” will be described later.

  If the creep torque control execution flag is OFF and NO is determined in step ST1, the process proceeds to step ST2. For example, when the driver is depressing the brake pedal 14 while the vehicle is stopped and the vehicle is in a stopped state (no “sliding down”), the creep torque The control execution flag is OFF, and NO is determined in step ST1. In addition, when the driver depresses the accelerator pedal 11 and the engine torque increases and the vehicle starts, no "slipping" occurs, so the creep torque control execution flag is OFF, A NO determination is made in step ST1.

  In step ST2, it is determined whether or not “sliding” has occurred. Specifically, the G sensor 115 detects that the road surface is inclined (uphill road or downhill road) by this G sensor 115, and the current operation position (shift position) of the shift lever 51 is selected. When the actual traveling direction is opposite to the traveling direction corresponding to the selected traveling range, it is determined that “sliding down” has occurred.

  For example, when a vehicle stopped on an uphill road starts, when the driver depresses the brake pedal 14, the operation position of the shift lever 51 is the “drive (D) position”. When the vehicle moves backward, it is determined that “sliding down” has occurred. That is, the G sensor 115 detects that the road surface is an uphill road, the shift position sensor 113 detects that the operation position of the shift lever 51 is the drive (D) position, and the wheel speed sensor 114 detects the wheel. When it is determined that the rotation direction of the vehicle is the reverse direction of the vehicle, it is determined that “sliding down” has occurred. It should be noted that the presence or absence of the occurrence of “sliding down” may be determined only by the detection signal of the shift position sensor 113 (the operation position signal of the shift lever 51) and the detection signal of the wheel speed sensor 114 (the wheel rotation direction signal). Good.

  It should be noted that, when the vehicle stopped on the downhill road moves backward, when the driver depresses the brake pedal 14, the operation position of the shift lever 51 is the “reverse (R) position”. Even when the vehicle moves forward, it is determined that “sliding down” has occurred.

  If “sliding” has not occurred, a NO determination is made in step ST2, the process proceeds to step ST17, and the base value BASE stored in advance in the transmission control device 4 is set to “0”. The addition amount ADD added to the base value BASE is also set to “0”.

  The base value BASE is an engine speed that defines a torque value that serves as a reference when executing creep torque control to be described later (to obtain this reference torque). This base value BASE is set by experiments and simulations as the engine speed for obtaining the minimum creep torque necessary when the vehicle starts on a slope. The base value BASE changes according to the vehicle speed at the time of “sliding down”. For example, the base value BASE increases as the vehicle speed increases. The parameter for determining the value of the base value BASE is not limited to the vehicle speed. For example, you may make it change with front-back G etc. of a vehicle. Further, the addition amount ADD defines a torque value to be added to the base value BASE when performing creep torque control (in order to obtain the added torque) (increase in engine speed) Min). As will be described later, the addition amount ADD is set according to the vehicle speed, and is set by experiments and simulations as the engine speed for obtaining an increase in creep torque according to the vehicle speed.

  After both the base value BASE and the addition amount ADD are set to “0” in step ST17, the process proceeds to step ST18, the creep torque control execution flag is turned OFF, and the process returns. If the creep torque control execution flag has already been turned OFF (NO in step ST1), the creep torque control execution flag is kept in the OFF state.

  On the other hand, if “sliding” has occurred, YES is determined in step ST2, and the process proceeds to step ST3, where the creep torque control execution flag is turned ON.

  Thereafter, the process proceeds to step ST4, in which it is determined whether or not the current vehicle speed (vehicle speed in the downward direction) calculated based on the output signal of the wheel speed sensor 114 exceeds a predetermined value V1. An example of the predetermined value V1 is 5 km / h. This value is not limited to this and is set as appropriate.

  If the current vehicle speed is equal to or less than the predetermined value V1 and NO is determined in step ST4, the process proceeds to step ST5, and as the target addition amount calculation process, the addition amount ADD (the engine speed for increasing the creep torque is increased). The addition amount) is set to “A (first increase correction amount in the present invention; corresponding to the increase correction amount of the target creep torque)”, and this value (addition amount ADD = A) is stored in the RAM of the engine control device 3. Remember once. On the other hand, if the current vehicle speed exceeds the predetermined value V1 and YES is determined in step ST4, the process proceeds to step ST6, where the addition amount ADD is set to “B (first in the present invention) as the target addition amount calculation process. 2) (corresponding to an increase correction amount of the target creep torque) ”, and this value (addition amount ADD = B) is temporarily stored in the RAM of the engine control device 3. As the value of the addition amount ADD, “B” is set to be larger than “A”, and each value is appropriately set by experiment or simulation. As an example, “A” is 100 rpm as an increase amount of the engine speed, and “B” is 200 rpm as an increase amount of the engine speed. It is not limited to these values. As described above, when the vehicle speed of “sliding down” is relatively low (when it is equal to or less than the predetermined value V1), the addition amount ADD is also set to a low value, and the increase amount of the creep torque is suppressed to be low. This prevents the behavior of the vehicle from becoming unstable due to a sudden increase in creep torque accompanying a sudden change in the rotational speed. On the other hand, when the vehicle speed of “sliding down” is relatively high (when it exceeds the predetermined value V1), the addition amount ADD is also set to a high value to increase the increase amount of the creep torque. This prevents the “down” vehicle speed from further increasing.

  After the creep torque addition amount ADD is set according to the vehicle speed in this way, the process proceeds to step ST7 (FIG. 8), and it is determined whether or not a preset subtraction condition is satisfied. This subtraction condition is a condition for subtracting the creep torque, and is satisfied, for example, when the depression operation of the brake pedal 14 is performed or when the depression operation of the accelerator pedal 11 is performed. That is, when the depression of the brake pedal 14 is performed and the vehicle speed decreases and “sliding down” is resolved, it is not necessary to increase the creep torque, so the subtraction condition is satisfied. Further, when the accelerator pedal 11 is depressed, the torque of the engine 1 is greatly increased, and even when the vehicle is started, the “sliding down” is eliminated. Since it is not necessary to increase, the subtraction condition is satisfied.

  If the subtraction condition is not satisfied and NO is determined in step ST7, the process proceeds to step ST8, and a target rotational speed calculation process is performed. In this target rotational speed calculation processing, the target rotational speed (TGTN = BASE + ADD) is added to the base value BASE by adding the addition amount ADD (“A” or “B”) set in step ST5 or step ST6. Is to be calculated. This target rotational speed is calculated as an engine rotational speed for obtaining a creep torque suitable for the current vehicle speed. That is, when the current vehicle speed is equal to or less than V1, the addition amount ADD is set to “A”, so that a relatively low value is calculated as the engine speed for obtaining the creep torque. On the other hand, when the current vehicle speed exceeds V1, the addition amount ADD is set to “B”, so that a relatively high value is calculated as the engine speed for obtaining the creep torque.

  Thereafter, the process proceeds to step ST9, where it is determined whether or not the addition amount ADD set in the previous routine is “0”. The amount of addition ADD is “0” until “sliding” occurs, and after “sliding” occurs and creep torque control is started, a value other than “0” such as “A” or “B”. Value. That is, when the addition amount ADD set in the previous routine is “0” and the addition amount ADD set in the current routine is other than “0” (“A” or “B”), the previous routine Then, “sliding down” has not occurred, and “sliding down” has started to occur from this routine. For this reason, when “sliding down” starts to occur from the current routine, a YES determination is made in step ST9. On the other hand, if the addition amount ADD set in the previous routine is not “0”, the creep torque control has already been started. For this reason, if “sliding” has occurred since before the previous routine, a NO determination is made in step ST9.

  If the addition amount ADD set in the previous routine is “0” and YES is determined in step ST9, the process proceeds to step ST10, and the addition amount ADD set in the current routine (the addition amount stored in the RAM). It is determined whether or not (ADD) is “A”. That is, it is determined whether or not “sliding down” occurs from the current routine and the current vehicle speed is equal to or less than the predetermined value V1. That is, it is determined whether or not the addition amount ADD is “0” in the previous routine and the addition amount ADD is “A” in the current routine.

  If this determination is YES, the process proceeds to step ST14, where creep torque control is executed so that the target rotational speed TGTN (= base value BASE + A) calculated in step ST8 is obtained. That is, by increasing the opening degree of the throttle valve 6 by controlling the actuator 7 of the throttle valve 6 and increasing the fuel injection amount from the injector 5, the engine speed is reduced to the target speed TGTN (= base value BASE + A). The torque of the engine 1 is increased to increase the creep torque generated on the wheels. The opening degree of the throttle valve 6 and the fuel injection amount from the injector 5 set according to the target rotational speed TGTN are obtained in advance by experiments and simulations. For example, a map for setting the opening degree of the throttle valve 6 and the fuel injection amount from the injector 5 in accordance with the target rotational speed TGTN is stored in the ROM of the engine control device 3, and the target rotational speed TGTN calculated in step ST8 is stored. Is applied to this map, and the control amount is adjusted by reading the opening degree of the throttle valve 6 and the fuel injection amount from the injector 5.

  On the other hand, if the addition amount ADD is “B” in this routine (the addition amount ADD stored in the RAM is “B”) and the determination in step ST10 is NO, the process proceeds to step ST11, and the previous time. The addition amount ADD set in the routine is compared with the addition amount ADD set in the current routine, and it is determined whether or not they are different (previous ADD ≠ current ADD).

  As described above, the case where NO is determined in step ST10 is a case where “sliding” occurs from the current routine and the current vehicle speed exceeds the predetermined value V1. In this case, since the addition amount ADD set in the previous routine is “0” and the addition amount ADD set in the current routine is “B”, YES is determined in step ST11 and the process proceeds to step ST14. In step ST14, creep torque control is executed so that the target rotational speed TGTN (= base value BASE + B) calculated in step ST8 is obtained. At this time, the opening degree of the throttle valve 6 is increased and the fuel injection from the injector 5 is made as compared with the case where YES is determined in step ST10 (when the engine speed is increased with the target speed TGTN = base value BASE + A). The amount will be increased. That is, since the vehicle speed due to “sliding down” is high, the target engine speed TGTN of the engine speed is set high so that the creep torque generated on the wheels can be obtained even higher. In this case, the opening degree of the throttle valve 6 and the fuel injection amount from the injector 5 set in accordance with the target rotational speed TGTN are also adjusted according to a map obtained in advance through experiments and simulations.

  In this way, after the creep torque control is executed by controlling the engine 1 so that the target rotational speed TGTN set according to the vehicle speed is obtained, the creep torque control execution flag is already set to ON in the next routine. Therefore, YES is determined in step ST1, and the operations in steps ST4 to ST9 are performed again on condition that the subtraction condition is not satisfied.

  At this time, since the creep torque control has already been started, the addition amount ADD set in the previous routine is a value other than “0” (“A” or “B”). For this reason, NO determination is made in step ST9, and the process proceeds to step ST11.

  In step ST11, as described above, the addition amount ADD set in the previous routine is compared with the addition amount ADD set in the current routine, and whether or not they are different (previous ADD ≠ current ADD). Determined.

  If the previous ADD and the current ADD are different (previous ADD ≠ current ADD), a YES determination is made in step ST11 and the process proceeds to step ST14 so that the target rotational speed TGTN calculated in step ST8 is obtained. Creep torque control is executed. Specifically, if the addition amount ADD set in the previous routine is “A” and the addition amount ADD set in the current routine is “B”, YES determination is made in this step ST11. become. For example, when the vehicle speed in the previous routine is equal to or lower than V1, whereas the vehicle speed in the current routine exceeds V1, the addition amount ADD is changed from “A” to “B”, so step ST11. Is determined as YES, a target rotational speed TGTN (= base value BASE + B) with the addition amount ADD being “B” is obtained, and creep torque control (control of the engine rotational speed) is executed so as to obtain this target rotational speed TGTN. Is done. Even when the addition amount ADD set in the previous routine is “B” and the addition amount ADD set in the current routine is “A”, YES is determined in step ST11. . In this case, a target rotational speed TGTN (= base value BASE + A) with the addition amount ADD being “A” is obtained, and creep torque control (control of the engine rotational speed) is performed so as to obtain this target rotational speed TGTN. .

  On the other hand, if the previous ADD is equal to the current ADD (previous ADD = current ADD), NO is determined in step ST11, and the process proceeds to step ST12. Specifically, if the addition amount ADD set in the previous routine and the addition amount ADD set in the current routine are both “A” or both are “B”, NO determination is made in step ST11. Then, it moves to step ST12. That is, when both the vehicle speed in the previous routine and the vehicle speed in the current routine are V1 or less, the addition amount ADD is maintained at “A”, so that NO is determined in step ST11 and the process proceeds to step ST12. Become. Similarly, when both the vehicle speed in the previous routine and the vehicle speed in the current routine exceed V1, the addition amount ADD is maintained at “B”, so that a NO determination is made in step ST11 and the process proceeds to step ST12. It will be.

  In step ST12, the guard process 1 is executed. This guard process 1 is performed by adding “β (third increase correction amount in the present invention; limit) as a limit addition amount (addition amount limited to the addition amount ADD) to the target rotational speed TGTN set in the previous routine. A value obtained by adding “equivalent to the target creep torque increase correction amount”) is calculated as the target rotational speed TGTN. This limit addition amount “β” is set in advance as a smaller value than “A” and “B” which are addition amounts ADD set according to the vehicle speed. That is, in the guard process 1, the target rotational speed TGTN having a value lower than the target rotational speed TGTN obtained by determining the addition amount ADD according to the vehicle speed is calculated. The limit addition amount “β” is set to a value that is ½ of the addition amount ADD “A” (for example, 50 rpm as an increase amount of the engine speed). This limited addition amount “β” is not limited to this, and is appropriately set by experiment or simulation.

  After the target rotation speed TGTN having a low value is thus calculated by the guard process 1, the process proceeds to step ST13 and the guard process 2 is executed. In the guard process 2, the target rotational speed TGTN is limited to a preset upper limit value TNmax or less. That is, in step ST12, when the target rotational speed TGTN obtained by adding “β” as the limit addition amount to the previous target rotational speed TGTN does not exceed the upper limit value TNmax, the target rotational speed TGTN is used as it is. adopt. On the other hand, when the target rotational speed TGTN obtained by adding “β” as the limit addition amount to the previous target rotational speed TGTN exceeds the upper limit value TNmax, the target rotational speed TGTN is limited to the upper limit value TNmax. To do.

  Thereafter, the process proceeds to step ST14, where creep torque control is executed. In other words, creep torque control is executed with the target rotational speed TGTN as a target rotational speed TGTN in a range where the target rotational speed TGTN does not exceed the upper limit value TNmax and a value obtained by adding “β” as a limit addition amount to the previous target rotational speed TGTN. It will be.

  The operation of adding “β” as the limit addition amount to the target rotational speed TGTN is in a state where the previous ADD and the current ADD are different (previous ADD ≠ current ADD) until YES is determined in step ST11. (For example, until the addition amount ADD switches from “A” to “B”), until “slipping” is resolved and NO is determined in step ST2, or the subtraction condition is satisfied and YES in step ST7. It will be repeated until it is determined. That is, in the period until these conditions are satisfied, the limit addition amount “β” is added to the target rotational speed TGTN for each routine, and the target rotational speed TGTN gradually increases. The engine speed in creep torque control will also increase gradually.

  On the other hand, when the subtraction condition is satisfied and YES is determined in step ST7, the process proceeds to step ST15, and the target rotational speed subtraction process is performed. In this target rotational speed subtraction process, a value obtained by subtracting “α” as a subtraction amount from the target rotational speed TGTN set in the previous routine is calculated as the target rotational speed TGTN. This “α” is set in advance through experiments and simulations. For example, it is set according to the vehicle body weight and the like, and is set as a smaller value as the vehicle body weight increases. Note that the method of setting the subtraction amount “α” is not limited to this.

  After the target rotational speed TGTN is subtracted in this way, the process proceeds to step ST16, and the guard process 3 is executed. This guard process 3 limits the target rotational speed TGTN to a preset lower limit value TNmin or more. That is, in step ST15, when the target rotational speed TGTN obtained by subtracting “α” as the subtraction amount from the previous target rotational speed TGTN is not less than the lower limit value TNmin, this target rotational speed TGTN is adopted as it is. To do. On the other hand, when the target rotational speed TGTN obtained by subtracting “α” as the subtraction amount from the previous target rotational speed TGTN is below the lower limit value TNmin, the target rotational speed TGTN is limited to the lower limit value TNmin. . This lower limit value TNmin can be arbitrarily set. For example, the lower limit value TNmin is set to “0”.

  Thereafter, the process proceeds to step ST14, where creep torque control is executed. In other words, creep torque control is executed with the target rotational speed TGTN as a target rotational speed TGTN in a range where the target rotational speed TGTN does not fall below the lower limit value TNmin and a value obtained by subtracting “α” as a subtraction amount from the previous target rotational speed TGTN. Become.

  The above operation is repeated, and the target rotational speed TGTN set according to the change in the vehicle speed and the target rotational speed TGTN (comparison between the addition amount ADD set in the previous routine and the addition amount ADD set in the current routine) is The engine speed is controlled so as to be obtained, and the creep torque is adjusted.

  FIG. 9 is a timing chart showing changes in the engine target speed with respect to changes in the reverse vehicle speed of the vehicle when the creep torque control is performed.

  First, “sliding down” occurs at timing t1 in the figure. Since the vehicle speed at this time is equal to or less than the predetermined value V1, the addition amount ADD is set to “A”, and the addition amount “A” is added to the base value BASE to obtain the target rotational speed TGTN. Thus, the engine speed is controlled so that the target speed TGTN is obtained.

  Thereafter, “A” is maintained as the addition amount ADD until the vehicle speed exceeds the predetermined value V1, and therefore the guard process 1 is executed. That is, a value obtained by adding “β” as the limit addition amount to the target rotational speed TGTN set in the previous routine is calculated as the target rotational speed TGTN, and the engine rotational speed is controlled so that the target rotational speed TGTN is obtained. Go. That is, the engine speed gradually increases.

  Then, when the vehicle speed exceeds the predetermined value V1 at the timing t2 in the figure, the addition amount ADD becomes “B”. At this time, since the addition amount ADD set in the previous routine is different from the addition amount ADD set in the current routine, the guard process 1 is canceled and is the addition amount ADD set in the current routine. The target rotational speed TGTN is obtained by adding “B” to the base value BASE, and the engine rotational speed is controlled so that the target rotational speed TGTN is obtained.

  Thereafter, the guard process 1 is executed again. That is, a value obtained by adding “β” as the limit addition amount to the target rotational speed TGTN set in the previous routine is calculated as the target rotational speed TGTN, and the engine rotational speed is controlled so that the target rotational speed TGTN is obtained. Go.

  In FIG. 9, the subtraction condition is satisfied, for example, by depressing the brake pedal 14 at timing t3. As this subtraction condition is satisfied, a value obtained by subtracting “α” as a subtraction amount from the target rotational speed TGTN set in the previous routine is obtained as the target rotational speed TGTN, and this target rotational speed TGTN is obtained. The engine speed is controlled. As a result, the engine speed gradually decreases.

  As described above, in the present embodiment, when the target rotational speed (target creep torque) is corrected due to occurrence of “sliding down”, the target rotational speed is added at the start of the correction control. Compared to the amount, a limit is imposed on the amount of addition of the target rotational speed in a predetermined period after the start of the control. Specifically, in a period in which the previous value and the current value of the target rotational speed addition amount ADD coincide with each other, the target rotational speed addition amount ADD (“A” or “B” described above) at the start of creep torque control. When the same correction control as in () is performed (when the target rotational speed is sequentially increased by the addition amount ADD), the target rotational speed becomes too high and the behavior of the vehicle becomes unstable. there is a possibility. In consideration of this, in the present embodiment, a limit is added to the target rotational speed addition amount during the period in which the previous value of the target rotational speed addition amount ADD coincides with the current value (the limited additional amount “β”). To prevent the target rotational speed from becoming too high. Further, since the above-described restriction is not applied to the target rotational speed addition amount ADD at the start of creep torque control, a sufficient target rotational speed addition amount ADD corresponding to “sliding down” is ensured, and “sliding down” Is prevented from becoming too high. Thus, by changing the addition amount ADD of the target rotational speed, it is possible to sufficiently exhibit the slip-down suppressing function without causing instability of the behavior of the vehicle.

  Further, as the addition amount ADD, “A” set when the vehicle speed is V1 or less is set as a value smaller than “B” set when the vehicle speed exceeds V1, An increase correction amount of the target rotational speed (target creep torque) according to the vehicle speed at the initial time of occurrence of “down” can be obtained appropriately. Then, by setting the limit addition amount “β” as a value smaller than the addition amount “A”, it is possible to avoid the target rotational speed (target creep torque) from becoming too large thereafter, and the behavior of the vehicle Can be stabilized.

-Modification-
Next, a modified example will be described. In the embodiment, when the previous ADD and the current ADD are equal (previous ADD = current ADD), the limit addition amount with respect to the target rotational speed TGTN is set to “β”. In other words, the target is set when the vehicle speed is V1 or less and the addition amount ADD is set to “A”, and when the vehicle speed exceeds V1 and the addition amount ADD is set to “B”. The limit addition amount with respect to the rotational speed TGTN was set to “β”.

  In this modification, when the vehicle speed is V1 or less and the addition amount ADD is set to “A”, the limit addition amount for the target rotational speed TGTN and the vehicle speed exceeds V1 and the addition amount ADD is “B”. In this case, the limit addition amount with respect to the target rotational speed TGTN is set as a value different from each other.

  Specifically, when the vehicle speed is V1 or less and the addition amount ADD is set to “A”, the limit addition amount with respect to the target rotational speed TGTN is set to “γ (fourth increase correction amount in the present invention)”. The limit addition amount with respect to the target rotational speed TGTN when the vehicle speed exceeds V1 and the addition amount ADD is set to “B” is “δ (the fifth increase correction amount in the present invention)”. The limit addition amount “γ” is a value smaller than the addition amount “A” (for example, 50 rpm as an increase amount of the engine speed), and the limit addition amount “δ” is the addition amount. A value larger than “γ” and smaller than the addition amount “B” is set (for example, 80 rpm as an increase amount of the engine speed).

  In this way, by making the limit addition amount different when the previous ADD and the current ADD are equal to each other according to the vehicle speed, the vehicle speed of “sliding down” can be obtained even in a period in which the previous ADD and the current ADD are equal. It can be prevented from becoming too high.

  FIG. 10 is a timing chart showing a change in the target engine speed with respect to a change in the reverse vehicle speed of the vehicle when the creep torque control is performed in this modification.

  Here, only differences from the timing chart shown in FIG. 9 in the embodiment will be described.

  In this modification, as described above, when the vehicle speed is V1 or less and the addition amount ADD is set to “A”, the limit addition amount with respect to the target rotational speed TGTN is set to “γ”, and the vehicle speed exceeds V1. The limit addition amount for the target rotational speed TGTN when the cage addition amount ADD is set to “B” is “δ”. The limit addition amount “γ” is smaller than the addition amount “A”, and the limit addition amount “δ” is larger than the limit addition amount “γ” and the addition amount “B”. Is set to a value smaller than "."

  For this reason, the engine speed during the period when the addition amount ADD is set to “B” is compared with the increase amount per unit time of the engine speed during the period when the addition amount ADD is set to “A”. The increase per unit time is large. That is, the increase amount of the creep torque is set large in the latter period. Therefore, the reverse vehicle speed after the timing when the addition amount ADD becomes “B” (timing t2 in the figure) is rapidly decreasing, and after the reverse vehicle speed is increased (after exceeding the predetermined vehicle speed V1). The “sliding down” has been resolved rapidly.

-Other embodiments-
In the embodiment and the modification described above, the case where the present invention is applied to the FR vehicle equipped with the automatic transmission 2 capable of shifting at six forward speeds has been described. The present invention is not limited to this, and may be applied to a vehicle equipped with an automatic transmission capable of shifting forward 5 speed, 8 forward speed, etc., an FF (front engine / front drive) type vehicle, and a four-wheel drive vehicle. Is possible. Moreover, as a structure of a transmission, CVT (Continuously Variable Transmission) may be sufficient.

  In the above-described embodiments and modifications, the case where the present invention is applied to a vehicle equipped with a gasoline engine has been described. However, the present invention can also be applied to a vehicle equipped with another engine such as a diesel engine. is there.

  In the embodiment and the modification described above, the present invention is applied to a conventional vehicle (a vehicle in which only an engine is mounted as a driving force source), and the creep torque is increased by increasing the torque of the engine 1. It was like that. The present invention is not limited to this. For example, the present invention may be applied to a hybrid vehicle (a vehicle equipped with an engine and an electric motor as a driving force source), and the creep torque may be increased by torque control of a motor generator.

  The present invention is applicable to creep torque control when a vehicle starts from a stop state on a slope.

1 engine (internal combustion engine)
2 Automatic transmission 3 Engine control device 4 Transmission control device 5 Injector 6 Throttle valve 50 Shift device 51 Shift lever 101 Crank angle sensor 113 Shift position sensor 114 Wheel speed sensor 115 G sensor TGTN Target rotational speed BASE Base value ADD Addition amount

Claims (5)

Vehicle that performs control to correct the target creep torque so that the creep torque to be applied to the wheels is increased in the event of a “sliding down” in which the vehicle travels in the opposite direction to the traveling direction corresponding to the selected traveling range. In the creep torque control device of
Compared to the increase correction amount of the target creep torque at the start of the control for correcting the target creep torque, the increase correction amount of the target creep torque in a predetermined period after the start of the control is limited. A creep torque control device for a vehicle. The creep torque control device for a vehicle according to claim 1,
The increase correction amount of the target creep torque is set according to the vehicle speed every predetermined period at the time of occurrence of the “sliding down”,
The predetermined period of limiting the increase correction amount of the target creep torque is a period in which the previous value and the current value of the increase correction amount of the target creep torque set for each predetermined period coincide with each other. A creep torque control device for a vehicle. The creep torque control device according to claim 2,
As an increase correction amount of the target creep torque,
A first increase correction amount that is set when the vehicle speed is equal to or lower than a predetermined value, and the previous value and the current value of the increase correction amount of the target creep torque set for each predetermined period do not match;
A second increase correction amount that is set when the vehicle speed exceeds a predetermined value, and the previous value and the current value of the increase correction amount of the target creep torque set for each predetermined period do not match;
In a situation where the increase correction amount of the target creep torque is set to the first increase correction amount or the second increase correction amount, the previous value and the current value of the increase correction amount of the target creep torque coincide with each other. And a third increase correction amount that is set when the
The first increase correction amount is set as a value smaller than the second increase correction amount, and the third increase correction amount is set as a value smaller than the first increase correction amount. A creep torque control device for a vehicle. The creep torque control device according to claim 2,
As an increase correction amount of the target creep torque,
A first increase correction amount that is set when the vehicle speed is equal to or lower than a predetermined value, and the previous value and the current value of the increase correction amount of the target creep torque set for each predetermined period do not match;
A second increase correction amount that is set when the vehicle speed exceeds a predetermined value, and the previous value and the current value of the increase correction amount of the target creep torque set for each predetermined period do not match;
Set when the target creep torque increase correction amount is set to the first increase correction amount and the previous value of the target creep torque increase correction amount matches the current value. A fourth increase correction amount;
Set when the previous value and the current value of the increase correction amount of the target creep torque match in the situation where the increase correction amount of the target creep torque is set to the second increase correction amount. A fifth increase correction amount is defined,
The first increase correction amount is set as a value smaller than the second increase correction amount, the fourth increase correction amount is set as a value smaller than the first increase correction amount, and the fifth increase correction amount is set as the fifth increase correction amount. An increase correction amount is set as a value larger than the fourth increase correction amount and smaller than the second increase correction amount. In the creep torque control device according to any one of claims 1 to 4,
The vehicle includes an internal combustion engine as a driving force source,
The creep torque control device for a vehicle, wherein the creep torque applied to the wheel is changed by setting a target rotational speed of the internal combustion engine to a rotational speed at which the target creep torque is obtained.

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